sábado, 23 de fevereiro de 2008

Supernovas - Boletim Brasileiro de Astronomia - Ed. 449


 

http://www.boletimsupernovas.com.br/

Quinta-feira, 21 de fevereiro de 2008 - Edicao No. 449

Indice:

_ BRASIL E ARGENTINA ANALISAM CONSTRUCAO DE SATELITE
_ FOGUETE BRASILEIRO LEVA 72 TILAPIAS AO ESPACO
_ A DESTRUICAO DE UM SATELITE POR MISSIL 'A LUZ DO DIREITO ESPACIAL
_ CARLOS GANEM E' INDICADO PARA ASSUMIR A AGENCIA ESPACIAL BRASILEIRA
(AEB)
_ ASTRONOMIA E ASTRONAUTICA TEM DESTAQUE DURANTE CAMPUS PARTY BRASIL 2008
_ ASTRONOMOS CALIBRAM A ESCALA DE DISTANCIAS DO UNIVERSO
_ ESTRELA JOVEM NO SEU COBERTOR DE PO
_ GALAXIA ULTRA-JOVEM E' ENCONTRADA NO UNIVERSO DISTANTE
_ AS RESERVAS DE HIDROCARBONETOS DE TITA' SUPERAM AMPLAMENTE AS DA TERRA
_ DESCOBERTO POSSIVEL PROGENITOR DE UM TIPO PARTICULAR DE SUPERNOVA
_ DESCOBERTO O PRIMEIRO ASTEROIDE TRIPLO PROXIMO DA TERRA
_ DESCOBERTO SISTEMA PLANETARIO DISTANTE PARECIDO COM O NOSSO
_ ROBOS MARCIANOS QUESTIONAM AS CONDICOES DE MARTE PARA HOSPEDAR VIDA
_ TALVEZ A MAIOR PARTE DAS ESTRELAS DO TIPO SOLAR PROXIMAS POSSAM
FORMAR PLANETAS
_ EFEMERIDES PARA A SEMANA

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ASTRONOMIA NO BRASIL
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BRASIL E ARGENTINA ANALISAM CONSTRUCAO DE SATELITE
14/02/208. O presidente da Agencia Espacial Brasileira (AEB/MCT),
Miguel Henze, participou na terca-feira (12/2) da reuniao do Grupo de
Trabalho Brasil-Argentina sobre Cooperacao nos Usos Pacificos do
Espaco Exterior, em Buenos Aires. Representantes dos dois paises
avaliarao o projeto de construcao de um satelite conjunto, batizado de
Sabia, e elaborar uma declaracao conjunta de cooperacao na area
espacial que deve ser assinada pelo presidente dos dois paises. No
ultimo encontro, realizado em novembro de 2007, brasileiros e
argentinos concordaram em propor uma missao espacial conjunta, que
inclui projetar, produzir e lancar um satelite de observacao da Terra
com tecnologias avancadas. Os principais objetivos da missao serao
fornecer informacoes globais das propriedades opticas dos oceanos, com
aplicacoes nas areas de oceanografia e climatologia, e monitorar
recursos naturais, com enfase em prospeccao mineral e protecao ao
meio-ambiente. O satelite deve ser baseado numa plataforma de alto
desempenho, estabilizada em tres eixos, com capacidade de carga util
de ate' 800 kg com 700 W de potencia media. O sensor optico tera'
caracteristicas tecnologicas inovadoras, cuja especificacao preliminar
preve' entre 15 e 25 bandas selecionaveis dentro do espectro visivel e
infravermelho. O projeto contribuira' para a independencia tecnologica
da Argentina e do Brasil na area de sensores de qualidade espacial,
cuja obtencao no mercado internacional esta' sujeita a restricoes. O
novo satelite sera' o primeiro desenvolvido em conjunto. ( Fonte:
Coordenacao de Comunicacao Social da AEB )
Ed: CE

FOGUETE BRASILEIRO LEVA 72 TILAPIAS AO ESPACO
12/02/2008. Animais ficarao em ambiente sem gravidade em experiencia
sobre a doenca do movimento. Por incrivel que pareca, os peixes tambem
ficam mareados. Como os seres humanos, algumas especies sofrem a
chamada doenca do movimento ou cinetose, marcada por sintomas como
tontura, enjoo e nausea. Para entender mais sobre a doenca, que faz
com que algumas pessoas sintam se mal em carros, barcos e outros meios
de transporte, um foguete brasileiro sera' lancado ao espaco, hoje, na
Suecia, levando 72 tilapias para um experimento que busca esclarecer
as causas da cinetose. O foguete VSB-30 sera' lancado no Centro
Espacial de Esrange, no norte do pais, em uma missao que e' parte do
Projeto Texus, conduzido por cientistas alemaes com financiamento da
Agencia Espacial Europeia (ESA). As tilapias (Oreochr omis mo ss am
bic us ) vao ser elevadas a uma altura de 260 km a 270 km. Durante
aproximadamente seis minutos, o foguete ficara em ambiente de
microgravidade (valores de gravidade proximos de zero), a fim de
possibilitar o experimento. Resultados poderao ser uteis em estudos
com humanos Segundo o cientista alemao Ralf Anken, as tilapias foram
escolhidas por serem peixes extremamente resistentes. A escolha dos
peixes como cobaias se deve ao fato de que eles tambem podem ficar
enjoados, embora nem todas as especies sofram do problema. Peixes com
cinetose nadam em circulos continuos. Como sao animais vertebrados,
com estruturas de ouvido interno semelhantes `as dos mamiferos, o
experimento permitira' aplicar as suas conclusoes aos estudos
realizados com humanos. A causa da cinetose ainda nao e' conhecida.
Acredita-se que o enjoo seja resultado de informacoes desencontradas,
que confundem o cerebro quando se anda de barco, por exemplo. ( Fonte:
O Globo )
Ed: CE

A DESTRUICAO DE UM SATELITE POR MISSIL 'A LUZ DO DIREITO ESPACIAL
"Como conciliar o uso militar do espaco, suas ameacas e efeitos
incontrolaveis, seus danos e perdas imprevisiveis, com o dever de
atender ao bem e aos interesses da totalidade dos paises numa
atividade vista como atributo de toda a especie humana?" A destruicao
do satelite espiao norte-americano NROL-21 por um missil
anti-balistico, decretada pelo governo dos EUA, levanta questoes
juridicas internacionais sobre o uso militar do espaco cosmico que
merecem ser conhecidas e estudadas com muita atencao. Ainda que o
missil anti-balistico nao esteja sendo usado em missao de guerra, e'
obvio que o fato, se efetivado, podera' ser visto como preparacao para
uma guerra no espaco. Certo, o lancamento de misseis balisticos nao
esta' proibido pelo Tratado do Espaco, de 1967, a lei maior das
atividades espaciais, ratificado por cerca de 100 paises e de
aceitacao universal. O Artigo 4º deste tratado proibe a colocacao em
orbita da Terra de artefatos de destruicao em massa (nucleares,
quimicos e biologicos). Mas os voos sub-orbitais (que nao entram em
orbita) de misseis, inclusive com armas de destruicao em massa a
bordo, nao estao proibidos. Um missil anti-balistico, quando acionado,
nao precisa entrar em orbita para cumprir sua missao. Um voo
sub-orbital basta. Ocorre que o Tratado do Espaco, embora nao vete o
voo sub-orbital dos misseis anti-balisticos, consagra acima de tudo,
em seu espirito e logica interna, o uso do espaco para fins pacificos.
Ja' no preambulo, ele reconhece "o interesse que representa para toda
a humanidade o programa de exploracao e uso do espaco cosmico para
fins pacificos" e expressa o desejo de "contribuir para o
desenvolvimento de ampla cooperacao internacional no que concerne aos
aspectos cientificos e juridicos da exploracao e uso do espaco cosmico
para fins pacifico". O Artigo 9º, por sua vez, determina que se um
pais "tem razoes para crer que uma atividade ou experiencia realizada
por ele mesmo ou seus nacionais no espaco cosmico (...) criaria um
obstaculo capaz de prejudicar as atividades dos demais Estados (...)
em materia de exploracao e utilizacao pacifica do espaco cosmico
(...), devera' fazer as consultas internacionais adequadas antes de
empreender a referida atividade ou experiencia". Isso implica que os
EUA, que ratificaram o Tratado do Espaco, deveriam consultar os demais
paises antes de destruir o seu satelite inoperante, pois isso podera'
produzir efeitos potencialmente perigosos aos outros paises. Nao
parece que esta regra tenha sido respeitada. O compromisso do Tratado
do Espaco com a paz e a cooperacao fica ainda mais evidente no Artigo
1º, chamado "clausula do bem comum". Segundo ele, as atividades
espaciais "deverao ter em mira o bem e o interesse de todos os paises,
qualquer que seja o estagio de seu desenvolvimento economico e
cientifico, e sao incumbencia de toda a humanidade". Dai' a pergunta:
como conciliar o uso militar do espaco, suas ameacas e efeitos
incontrolaveis, seus danos e perdas imprevisiveis, com o dever de
atender ao bem e aos interesses da totalidade dos paises numa
atividade vista como atributo de toda a especie humana? Numa epoca de
terrorismo desenfreado, promovido com e sem o apoio de governos, este
desafio se torna especialmente complicado. O mais coerente, natural e
necessario, neste momento, e' seguir o caminho do bem comum. Ele nos
conduz a um grande tratado internacional, como o proposto pela Russia
e China na Conferencia de Desarmamento, em Genebra, na terca-feira
passada, dia 12, proibindo o uso de armas no espaco. Tanto a China
quanto os EUA ja' estao na corrida pela criacao de armas
anti-satelites, que vao desde misseis ate' canhoes de laser. A China
testou um missil ao abater um velho satelite meteorologico, em 11 de
janeiro de 2007. Os EUA estao empenhados ha' anos em instalar um
sistema global anti-missil, capaz de se converter em um sistema de
eliminacao de satelites que eles proprios considerem, de forma
unilateral, como "inimigos". Essa tendencia, claro, poe em risco a
seguranca de um sem-numero de paises. E so' podera' ser revertida por
amplo acordo, que nao so' interrompa o processo armamentista atual mas
tambem garanta a seguranca permanente de seus signatarios e de toda a
comunidade de paises. Hoje tal acordo esta' longe de ser alcancado.
Mas um novo governo norte-americano podera' repensar positivamente a
questao. O jornal "The New York Times", em editorial publicado sabado
ultimo, dia 16, afirma que "os EUA, como a nacao mais dependente de
satelites, deveria trabalhar para banir todas as armas
anti-satelites", porque "esta e' a melhor forma de proteger a
seguranca dos EUA e sua credibilidade". Seria talvez bem-vindo, em um
eventual novo clima norte-americano, um posicionamento mais vigoroso
sobre o assunto por parte das chamadas potencias medias. A Europa, com
certeza, nao negaria seu apoio a tao sensata mudanca de rumo. Afinal,
nao se trata, ainda, de fechar o espaco cosmico a todo e qualquer uso
militar – inexistem condicoes politicas para tanto no mundo atual. Por
ora, trata-se apenas de impedir a instalacao e o uso de qualquer tipo
de arma no espaco. A medida, obviamente, convem `a esmagadora maioria
dos paises, que nao tem motivos para ver o espaco cosmico a nao ser
como um santuario de paz e uma fonte inesgotavel de beneficios para
seus programas nacionais de desenvolvimento sustentado aqui na Terra.
Alguma duvida? Jose' Monserrat Filho e' professor de Direito Espacial
e chefe da Assessoria de Assuntos Internacionais do Ministerio da
Ciencia e Tecnologia. ( Fonte: Jose' Monserrat Filho, JC )
Ed: CE

CARLOS GANEM E' INDICADO PARA ASSUMIR A AGENCIA ESPACIAL BRASILEIRA (AEB)
20/02/2008. Ganem foi indicado pelo ministro da C&T, Sergio Rezende, e
sua designacao deve ser assinada pelo presidente Luiz Inacio Lula da
Silva. Apos a saida de Sergio Gaudenzi, em agosto do ano passado, para
a Infraero, o engenheiro Miguel Henze assumiu interinamente a
presidencia da AEB. Ganem diz que recebeu o convite como uma
convocacao e que seu trabalho sera' "estruturar uma agenda numa
agencia que e' fundamental pro pais." Para ele, a hora e' de decisao
para o pais. "Ou Brasil entra definitivamente ou fica fora de um
espaco que e' absolutamente visivel aos olhos das grandes potencias e
dos paises que querem participar da corrida do espaco. Devemos
enxergar o espaco como um novo nicho, uma nova oportunidade de
negocios, alem de novas fontes de pesquisa para os jovens e de acoes
que podem desenvolver outras atividades industriais brasileiras". Ele
cita como um caso de sucesso a distribuicao de imagens feita pelo
Inpe, a partir do projeto Cbers. "Hoje, o Brasil cede imagens a um
conjunto de paises, que nao tem a nossa capacidade, justamente pela
falta de investimentos. Esse programa do Inpe representa hoje um
mercado potencial para o pais na area de alta tecnologia. Se
conseguirmos juntar a isso o lancamento de satelites, aproveitando a
nossa posicao geografica estrategica, ai entao e' que nos seremos
felizes sem fazer forca, mas esse e' um esforco muito grande que
depende de uma atitude focada do governo para que o Brasil possa se
apresentar como `player' desse negocio de bilhoes de dolares". Para
Ganem, o Brasil tem uma forte vocacao para a area espacial. "Temos um
forte contingente de natureza cientifica, de natureza tecnica e
vocacional, ai' estou fazendo uma simplificacao do que significa a
nossa comunidade academica, tecnologica e da comunidade
estrategico-militar. Essa associacao faz com que possamos ser
protagonista em relacao aos negocios no espaco". Falta, a seu ver, uma
decisao dos governos e da sociedade em geral. "Com a mesma enfase que
se fala nisso hoje, se falava em inovacao ha' 20 anos. Hoje a inovacao
existe, mas e' preciso um esforco para que as coisas acontecam", diz.
"Se o Brasil quer lancar foguete, o Centro de Lancamento de Alcantara
deve ser tratado como estrategico. Se o Brasil pretende ter um papel
de protagonista, Alcantara tem que ser entendida e respeitada como
tal", defende o indicado para a Agencia. Ele, porem, na ignora a
questao social envolvida na implantacao do Centro, no Maranhao. "Tenho
a capacidade de entende as distancias, os reclames locais, e saber
construir entre os interessados a melhor agenda, que concilie
interesses de uma comunidade que ali esta' ha' anos com aquilo que o
progresso e o desenvolvimento local e do pais exigem". Mas, para ele,
o CLA e' um imperativo. "Eu diria que sem pensar numa base lancadora o
Brasil nao esta' de fato conjugando o verbo `espaciar'. Isso tem que
ser entendido no ambito do governo federal e tambem no ambito dos
estados e municipios e, sobretudo, pelo conjunto representado pela
sociedade civil, no ambito das parcerias publico-privadas. Acho que a
engenharia brasileira vai ser capaz de prover solucoes, de construir
parcerias e de estabelecer um modelo no qual a comunidade academica
junto com a comunidade empresarial saibam fazer parcerias proveitosas
que resultem num negocio novo, em Alcantara, no Maranhao, e na
Barreira do Inferno, no Rio Grande do Norte. Carlos Ganem e'
economista, ex-advogado e administrador de empresa, e ja' exerceu
muitas funcoes tanto no setor publico, quanto no privado. Trabalhou na
Embratel, no BNDES, na Interbras, no Sebrae, entre outras entidades.
Foi consultor de agencias internacionais como o BID, FAO, Unido e
PNUD. ( Fonte: Luis Amorim, JC )
Ed: CE

ASTRONOMIA E ASTRONAUTICA TEM DESTAQUE DURANTE CAMPUS PARTY BRASIL 2008
20/02/2008. Foram seis dias incansaveis de tecnologia e claro, muita
astronomia. Esse foi o clima da semana que foi realizada a primeira
Campus Party no Brasil, no complexo da Bienal na capital paulista. O
grande evento tecnologico que ocorre habitualmente na Espanha,
conquistou sua versao brasileira com o verdadeiro tempero tropical. O
Boletim Supernovas (BSN) acompanhou de perto todo evento realizado do
dia 11 a 17 de fevereiro. Aproximadamente de cinco mil participantes e
visitantes tornaram a CP 2008 Brasil um grande sucesso. Na area de
astronomia a programacao foi completa e despertou interesse tanto em
amantes de ciencia, como apenas em curiosos. Diversas sessoes de
planetarios, inflavel e o Planetario do Ibirapuera, emocionaram o
publico que pode presenciar uma bela simulacao dos dos astros no ceu.
A programacao comecou com uma verdadeira aula de historia da
astronomia. O professor Walmir Cardoso relatou sua experiencia com os
indios brasileiros, onde na oportunidade trabalhou com a comunidade
dos Tukanos no Amazonas, em oficinas para construcao de cartas
celestes e calendarios a partir da observacao a olho nu. Roberto de
Andrade Martins apresentou um belo conteudo na mesma linha, trazendo
as visoes antigas dos ceus e a integracao do processo do historiador
com a tecnologia da Internet. Alias, tecnologia na astronomia nao
faltou! Tivemos palestras sobre softwares que simulam fielmente o ceu,
e aplicacoes astronomicas que enriquecem os recursos do conhecido
software Google Earth. Cristovao Jaques promoveu um verdadeiro curso
sobre automacao de telescopios, desde a estrutura do observatorio, a
controles do telescopio e cameras. Em condicoes meteorologicas
favoraveis, foi possivel controlar e ate' obter imagens remotamente, a
partir do telescopio situado dentro da cidade de Belo Horizonte, em
Minas Gerais. Dentro do tema, Jose' C. Diniz e Fabio "Plocos"
enriqueceram brilhantemente o conteudo, trazendo e explorando todos os
recursos da astrofotografia moderna. Diversas palestras e oficinas
exploraram as varias maneiras de capturar as imagens dos astros usando
desde telescopios avancados a uma simples webcam. Os participantes
aprenderam muito com a larga experiencia do Diniz, e muitos puderam
utilizar as tecnicas ensinadas durante a semana para capturar imagens
para o concurso de astrofotografia. "A intencao e' mostrar que hoje e'
possivel fotografar os astros sem muita complicacao, utilizando
cameras digitais das mais simples", disse Diniz. Outras atracoes na
area de Astronautica tambem enriqueceram as atividades. Uma exposicao
de foguetes experimentais chamou a atencao que quem passava proximo ao
estande. Os foguetes foram construidos pelo grupo Avangers, de
Piracicaba (SP). Os participantes tambem puderam construir seu proprio
foguete durante uma oficina ministrada por Joao Paulo Delicato. Cada
um aprendeu os principios do funcionamento do foguete e confeccionou o
proprio kit para levar e lancer em casa com seguranca. No fim da
oficina, alguns foguetes foram demonstrados e lancados proximo ao lago
do Ibirapuera. Joao Paulo tambem trouxe muita emocao humana ao
apresentar o paralelo entre sonhar e ousar, com a palestra "Voar e'
para humanos". Em seguida toda a Campus Party pode acompanhar a
palestra especial e especial do astronauta brasileiro, Marcos Pontes.
Com 20 anos de idade, Jerusa Luciana Bezerra saiu sozinha de Foz do
Iguacu direto para a Campus Party em Sao Paulo, exclusivamente para
acompanhar as atividades de astronomia. A jovem, que sonha em ser
fisica, tambem e' apaixonada por astronautica. "A ousadia sempre fez
parte da vida dos grandes herois. Foi com ousadia e persistencia que
uma dia o ser humano realizou um sonho e foi ao espaco", comentou
Jerusa. Alem de acompanhar todo o evento, o Boletim Supernovas
apresentou um forum onde foi contada a historia de nove anos de
boletim, trazendo toda a experiencia do corpo editorial ao longo
desses anos. O novo site de noticias foi explorado em seus detalhes,
assim como uma oficina mostrando como as noticias sao selecionadas,
editadas e postadas no sistema do boletim, exibindo todos os detalhes
do processo de publicacao. Os rumos futuros do BSN tambem foram
discutidos, com sugestoes e aperfeicoamentos. Naelton Araujo e Paulo
pedrosa tracaram uma panorama das listas de discussao de astronomia na
Internet, alem de trazer uma oficina de como criar e divulgar sua
propria lista. Temas como poluicao luminosa, planetarismo, clubes,
muito bate-papo e troca de experiencias complementaram a semana. Um
concurso de astrofotografia que foi executado durante todo o evento,
fechou com chave de ouro a participacao da astronomia como um todo. Um
vencedor e uma vencedora, que fizeram suas fotos do ceu durante a
semana, ganharam dois telescopios Celestron com premio. "Estamos com a
sensacao de dever cumprido. Espero que todos que estiveram conosco
tenham gostado de tudo que foi preparado e apresentado. Foi uma grande
festa de conhecimento", disse Walmir Cardoso, coordenador de
Astronomia da Campus Party 2008.
Ed: CE

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ASTRONOMIA NO MUNDO
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ASTRONOMOS CALIBRAM A ESCALA DE DISTANCIAS DO UNIVERSO
11/02/2008. Aproveitando a presenca do `eco de luz', uma equipe de
astronomos utilizou o Telescopio de Nova Tecnologia, NTT, da
Organizacao Observatorio Europeu Austral (ESO), em La Silla, no Chile,
para medir com 1% de nivel de precisao, a distancia da estrela RS Pup,
que e' uma estrela variavel cefeida, classe que constitui um dos
primeiros passos na escala cosmica de distancias. ( Fonte:
http://www.eso.org/public/outreach/press-rel/pr-2008/pr-05-08.html )
Ed: JG

ESTRELA JOVEM NO SEU COBERTOR DE PO
11/02/2008. Estrelas recem nascidas, sao vistas furtivamente sob seu
cobertor de berco de po' na imagem dinamica da nuvem escura de Rho
Ophiuchi, obtida pelo Telescopio Espacial Spitzer, da NASA. Chamada de
Rho Oph pelos astronomos, e' uma das regioes de formacao de estrelas
mais proxima do Sistema Solar. Localizada entre as constelacoes de
Ophiuchus e Scorpius, a nebulosa esta' a apenas 407 anos luz de
distancia da Terra. ( Fonte:
http://www.jpl.nasa.gov/news/news.cfm?release=2008-023 )
Ed: JG

GALAXIA ULTRA-JOVEM E' ENCONTRADA NO UNIVERSO DISTANTE
12/02/2008. As imagens realizadas pelos telescopios espaciais Hubble e
Spitzer, auxiliados por um zoom natural provocado pela lente
gravitacional gerada por um massivo aglomerado de galaxias, revelaram
uma galaxia que talvez seja uma das mais jovens e brilhantes vistas no
meio da epoca chamada de `idade escura', a cerca de 700 milhoes de
anos apos o Big Bang. ( Fonte:
http://hubblesite.org/newscenter/archive/releases/2008/2008/08/full/ )
Ed: JG

AS RESERVAS DE HIDROCARBONETOS DE TITA' SUPERAM AMPLAMENTE AS DA TERRA
13/02/2008. O satelite natural alaranjado de Saturno, Tita', tem
centenas de vezes mais hidrocarbonetos liquidos que todas as reservas
conhecidas de petroleo e gas natural que existem na Terra, segundo
novos dados da missao Cassini. Os hidrocarbonetos chovem do ceu se
acumulando em vastos depositos que formam lagoas e dunas. As novas
descobertas desse estudo liderado por Ralph Lorenz, membro da equipe
do radar de Cassini, pertencente ao Laboratorio de Fisica Aplicada da
Universidade Johns Hopkins, estao publicadas na Geophysical Research
Letters de 29 de janeiro de 2008. ( Fonte:
http://www.esa.int/esaCP/SEMCSUUHJCF_index_0.html )
Ed: JG

DESCOBERTO POSSIVEL PROGENITOR DE UM TIPO PARTICULAR DE SUPERNOVA
13/02/2008. Imagem publicada pelo telescopio espacial Chandra, da
NASA, mostra evidencias da possivel deteccao de um sistema binario de
estrelas que foi posteriormente destruido na explosao da Supernova
2007on, na galaxia eliptica NGC 1404. Descoberta pelo telescopio
robotico de 25 cm chamado de TAROT, em La Silla, no Chile, em novembro
de 2007. A imagem do Chandra foi obtida 4 anos antes da deteccao da
Supernova, conhecida como de tipo Ia. ( Fonte:
http://chandra.harvard.edu/photo/2008/ngc1404/ )
Ed: JG

DESCOBERTO O PRIMEIRO ASTEROIDE TRIPLO PROXIMO DA TERRA
13/02/2008. Considerado um asteroide medio simples, 2001 SN263, agora
esta' se revelando o primeiro asteroide triplo proximo da Terra. O
asteroide, com tres corpos em orbita uns dos outros, foi descoberto na
semana passada por astronomos que usam o telescopio radar da Fundacao
Nacional das Ciencias (NSF) no Observatorio de Arecibo, em Porto Rico.
( Fonte:
http://www.news.cornell.edu/stories/Feb08/AreciboAsteroid.html )
Ed: JG

DESCOBERTO SISTEMA PLANETARIO DISTANTE PARECIDO COM O NOSSO
14/02/2008. Uma equipe internacional de astronomos descobriram dois
planetas num sistema planetario distante – a cerca de 5.000 anos-luz –
que lembram versoes menores de Jupiter e Saturno . A descoberta sugere
que a nossa galaxia alberga muitos sistemas parecidos com o nosso, diz
Scott Gaudi, professor assistente de Astronomia na Universidade do
Estado de Ohio. Gaudi e os seus colegas apresentaram seus resultados
no numero de 15 de fevereiro de 2008, da Science. ( Fonte:
http://researchnews.osu.edu/archive/analog.htm )
Ed: JG

ROBOS MARCIANOS QUESTIONAM AS CONDICOES DE MARTE PARA HOSPEDAR VIDA
15/02/2008. Como o sal que se utiliza como conservante, as altas
concentracoes de minerais dissolvidos no ambiente umido primordial de
Marte –conhecido pelas descobertas do robo' Opportunity da NASA – pode
ter frustrado qualquer desenvolvimento ou sobrevivencia de microbios.
( Fonte:
http://www.nasa.gov/mission_pages/mer/news/mer-20080215.html )
Ed: JG

TALVEZ A MAIOR PARTE DAS ESTRELAS DO TIPO SOLAR PROXIMAS POSSAM FORMAR
PLANETAS
17/02/2008. Astronomos descobriram que os planetas terrestres podem
ter se formado ao redor de muitas, senao da maioria, das estrelas
proximas similares ao Sol, da nossa galaxia. Esses novos resultados
sugerem que os mundos com possibilidades de vida poderiam ser mais
comuns do que se pensava. O astronomo Michael Meyer, da Universidade
do Arizona, em Tucson, e seus colegas utilizaram o telescopio espacial
Spitzer, da NASA, para determinar se os sistemas planetarios como o
nosso sao comuns ou raros na nossa galaxia, a Via Lactea. Eles
descobriram que pelo menos 20 por cento, e possivelmente ate' 60 por
cento, das estrelas similares ao Sol sao candidatas `a formacao de
planetas rochosos. ( Fonte:
http://www.jpl.nasa.gov/news/news.cfm?release=2008-027 )
Ed: JG

----------------------------------------------------------
EFEMERIDES PARA A SEMANA
----------------------------------------------------------
21/02/2008 a 01/03/2008
Efemerides dia-a-dia
Ed: RG

21 Fevereiro
Eclipse Total da Lua, Inicio da Totalidade 01:00
Maximo Eclipse Lunar total, mag 1.111, Duracao da fase de totalidade
51.0 min. Duracao da fase parcial 206.1 min. Duracao
da fase Penumbral 342.3 min. 01:26
Lua Cheia 01:30
Lua em Libracao Este 01:38
Eclipse Lunar, Final da Totalidade 01:51
Eclipse Lunar, Final do Eclipse 03:09
Sol inicia rotacao de numero 2067 15?46

22 Fevereiro
Sonda Cassini sobrevoa a lua Titan
Ganymed, 5.4mag, Inicio de sombra 05:07

23 Fevereiro
Europa, 6.4mag, Inicio de Transito 05:22
Europa, Final da Sombra 06:05

24 Fevereiro
Saturno proximo da Terra a 8.291 UA 04:00
Saturno em Oposicao , 0.2mag 07:00

25 Fevereiro
Cometa P/2000 B3 LINEAR em Perielio a 1.709UA do Sol 21:08
Mercurio e Venus em conjuncao separados a 1.3 graus 23:35

26 Fevereiro
Cometa P/200 B3 LINEAR em Perielio a 1.709 UA do sol
Asteroide 2002 TD66 passa a 0.043 UA da Terra
Io, 5.8mag, Inicio de Sombra 04:49
Mercurio e Venus em Conjuncao separacao de 1.2 graus 14:52

27 Fevereiro
Mercurio e Venus separados a 1.1 grau 05:47
Lua em Apogeu a 40.4403.4 km da Terra 22:25
Lua em Libracao Noprte 22:29

28 Fevereiro
Io, 5.8mag, Final de Transito 02:34
Mercurio em meia fase 04:09

29 Fevereiro
Lua em Libracao Maxima 18:48

1 de Marco
Chuveiro Rho Leonids, maximo de 1 a 4 de marco
Europa(6.4 mag), inicio de sombra 04:59
Luz cinerea 05:02

----------------------------------------------------------
GLOSSARIO
----------------------------------------------------------

Os verbetes deste Glossario foram extraidos do Astro.dic -
Dicionario de Astronomia e Areas Afins, que disponibiliza todo seu
conteudo no Site:
http://www.ceaal.al.org.br/astrodic/
Ed: LL

----------------------------------------------------------
Supernovas - Boletim Brasileiro de Astronomia, e' uma publicacao
semanal em forma de boletim eletronico, via e-mail, estruturado em
diferentes Editorias e elaborado pela comunidade astronomica
profissional e amadora brasileira com o objetivo de ampliar a
divulgacao de informacoes sobre a Astronomia no Brasil e no mundo.
Semanalmente, ele e' enviado a aproximadamente 10000 interessados.
Informacoes gerais sobre Astronomia e Ciencias afins podem ser
encontradas no site do Boletim na Internet, no endereco:
http://www.boletimsupernovas.com.br/
Para receber semanalmente o Boletim, envie um e-mail para
<
boletimsupernovas-subscribe@yahoogroups.com> e para deixar de
assina-lo envie um e-mail para
<
boletimsupernovas-unsubscribe@yahoogroups.com>. Nao e' necessaria
nenhuma informacao no corpo desses e-mails.
Devido a limitacoes de diversos provedores de e-mails, a acentuacao
grafica das edicoes sao omitidas.
Informacoes, sugestoes e criticas podem ser encaminhadas aos
editores, abaixo relacionados:

Site:
http://www.boletimsupernovas.com.br
E-mail: boletim@boletimsupernovas.com.br

Editores Chefes:
Angela Minatel (AM): <
angela@boletimsupernovas.com.br>
Beatriz Ansani (BVA): <
beatriz@boletimsupernovas.com.br>
Carlos Eduardo Contato (CE): <
cadu@boletimsupernovas.com.br>
Jorge Honel (JH): <
honel@boletimsupernovas.com.br>
Marcelo Breganhola (MB): <
breganhola@boletimsupernovas.com.br>

Editores de Astronomia no Brasil:
Alexandre Amorim (AA): <
amorim@boletimsupernovas.com.br>
Carlos Eduardo Contato (CE): <
cadu@boletimsupernovas.com.br>
Ednilson Oliveira (EO): <
ednilson@boletimsupernovas.com.br>
Edvaldo Trevisan (EJT): <
edvaldo@boletimsupernovas.com.br>
Kepler Oliveira (KO): <
kepler@boletimsupernovas.com.br>
Marcelo Breganhola (MB): <
breganhola@boletimsupernovas.com.br>

Editores de Astronomia no Mundo:
Jaime Garcia (JG): <
jaime@boletimsupernovas.com.br>

Editor de Efemerides:
Rosely Gregio (RG): <
rosely@boletimsupernovas.com.br>

Editor do Glossario:
Luiz Lima (LL): <
lima@boletimsupernovas.com.br>

.
 
Posted by:
Lucimary Vargas
Presidente
Observatório Monoceros
Além Paraíba-MG-Brasil
http://www.monoceros.xpg.com.br
http://astronomicando.blogspot.com
http://arqueoastronomy.blogspot.com
http://www.arquivohistorico-mg.com.br

sexta-feira, 22 de fevereiro de 2008

Astronomia.com - Newsletter 22 febbraio 2008


Caro appassionato/a,
come ogni settimana Astronomia.com Ti invia le utlime pubblicazioni:

Una galassia appena nata (21 febbraio) - di Claudio Elidoro
Scoperta quella che probabilmente è la più giovane e brillante galassia mai osservata finora nell'infanzia dell'universo.
News completa: http://www.astronomia.com/2008/02/21/una-galassia-appena-nata/

Il primo NEO triplo (20 febbraio) - di Claudio Elidoro
Le osservazioni radar compiute dagli astronomi di Arecibo indicano che intorno al NEO 2001 SN263 orbitano due satelliti.
News completa: http://www.astronomia.com/2008/02/20/il-primo-neo-triplo/

Eclisse Totale di Luna (19 febbraio) - di Francesca Diodati
La sera di mercoledì 20, in America la luna piena si vestirà di rosso, forse anche di turchese. Avremo un'eclissi totale di luna, per la prossima dovremo attendere fino a dicembre 2010.
Articolo completo: http://www.astronomia.com/2008/02/19/eclisse-totale-di-luna/

Un nome per il Telescopio Spaziale! (18 febbraio) - di Stefano Simoni
La NASA chiede aiuto al pubblico appassionato per il nome definitivo da assegnare al Gamma-Ray Large Area Space Telescope, attualmente battezzato GLAST, prima del suo lancio in orbita a metà 2008.
Articolo completo: http://www.astronomia.com/2008/02/18/un-nome-per-il-telescopio-spaziale/

Un ponte di gas (16 febbraio) - di Claudio Elidoro
Scoperto grazie a osservazioni radio il punto di contatto con la Via Lattea del gigantesco ponte di idrogeno che la unisce alle Nubi di Magellano.
News completa: http://www.astronomia.com/2008/02/16/un-ponte-di-gas/

Asteroidi e Comete (15 febbraio) - di Pierluigi Panunzi
Negli ultimi anni, grazie alle immagini che alcune sonde spaziali ci hanno inviato nel corso delle loro missioni, abbiamo studiato nel dettaglio molti oggetti appartenti al nostro Sistema Solare: gli asteroidi e le comete.
Articolo completo: http://www.astronomia.com/2008/02/15/asteroidi-e-comete/

Un grande pianeta al di là di Nettuno? (11 febbraio) - di Claudio Elidoro
Accettato per la pubblicazione su Astronomical Journal un complesso studio che spiega la struttura della Fascia di Edgeworth-Kuiper invocando la presenza di un massiccio pianeta transnettuniano.
News completa: http://www.astronomia.com/2008/02/11/un-grande-pianeta-al-di-la-di-nettuno/

Appuntamento alla prossima settimana!
Lo staff di Astronomia.com

quarta-feira, 20 de fevereiro de 2008

Total Lunar Eclipse--Full Coverage


Space Weather News for Feb. 19, 2008
http://spaceweather.com/

LUNAR ECLIPSE: On Wednesday night, February 20th, the full Moon will turn a
delightful shade of red and possibly turquoise, too. It's a total lunar
eclipse-the last one until Dec. 2010. Sky watchers in Europe, the Americas,
parts of the Middle East and Africa are favored for good views of the
two-hour event. Visit http://spaceweather.com/ for full coverage including
maps and timetables, live webcasts and discussion.

SPY SATELLITE UPDATE: The US Navy's first attempt to hit malfunctioning spy
satellite USA 193 with a missile could come on Wednesday night during the
lunar eclipse. This is based on an air traffic advisory warning pilots to
steer clear of a patch of Pacific Ocean near Hawaii just when USA 193 is due
to pass overhead. Until the satellite is shot down, it remains visible to
casual sky watchers during evening passes over US and Canadian towns and
cities; experienced observers say the decaying satellite is sometimes as
bright as the stars of Orion, making it an easy target for unaided eyes and
off-the-shelf digital cameras. Details, photos and more information are
available at http://spaceweather.com/. Subscribers to Spaceweather PHONE
(http://spaceweatherphone.com/) will receive email and telephone alerts when
the spy-sat is about to appear over their backyards.


Posted by:
Lucimary Vargas
Além Paraíba-MG-Brasil
observatorio.monoceros@gmail.com

domingo, 17 de fevereiro de 2008

Lunar eclipse visible for North America

Don't miss this total lunar eclipse, the last one for nearly 3 years.
Lunar eclipse chart
The Moon glows red among the background stars of Leo the Lion during the February 20/21 total lunar eclipse. The bright planet Saturn also lies nearby. Astronomy: Roen Kelly [View Larger Image]
February 11, 2008
The last total lunar eclipse until December 20, 2010, will thrill observers throughout North America February 20.

"This eclipse is perfect for getting the family together," Astronomy Senior Editor Michael Bakich says, "because it begins early in the evening."

On February 20, eclipse observers should plan to get out lawn chairs, binoculars, and low-power eyepieces. And, this year, better add a blanket.

A lunar eclipse occurs when the Moon, in orbit around Earth, passes into Earth's shadow. Because the Sun isn't a point of light, the shadow has two parts — the inner, darker umbra and the outer, lighter penumbra. If the whole Moon enters the umbra, the eclipse is total. If the umbra hides only part of the Moon, the eclipse is partial.

The eclipse's umbral phase begins at 8:43 P.M. EST. On the East Coast, the Moon already stands one-third of the way up in the eastern sky. For West Coast observers, the Moon rises minutes after the umbra touches its surface.

Earth's shadow takes 78 minutes to envelop the Moon. Totality (when the Moon lies completely within Earth's umbra) begins at 10:01 P.M. EST. The Moon won't disappear, however. Some sunlight passing through Earth's atmosphere falls on the lunar surface. The cleaner our atmosphere is, the lighter the eclipse will be. Dark eclipses generally occur after large volcanic eruptions.
Lunar eclipse
August's lunar eclipse, seen here, put on a nice show from western North America. This month's total eclipse, in contrast, favors the whole continent. Stephen James O'Meara [View Larger Image]
What color will the Moon turn at mideclipse? During past total eclipses, the Moon has appeared brown, orange, crimson, and brick red. Lunar eclipses exhibit a range of shades because sunlight passing through Earth's atmosphere becomes scattered and reddened. It's this dim glow that fills Earth's shadow and lights the eclipsed Moon.

During totality, the Moon's northern edge will appear darker than its southern side. This disparity occurs because the Moon's northern limb will lie closer to the center of Earth's shadow.

Totality lasts 51 minutes. During the first half, as the sky becomes progressively darker, the background stars of Leo the Lion will appear. The constellation's brightest star, Regulus, appears 3° (6 Moon-widths) above the Moon.

You also will spot Saturn easily 4° (8 Moon-widths) to the Moon's lower left. The eclipse is a great time to notice how the Moon moves through the sky. As the eclipse begins, the Moon lies 4.4° from Saturn. When the event ends, the gap measures only 3.5°.

After totality, it takes the Moon another 78 minutes to leave Earth's umbra.

Real-time space radiation forecasting in place

This advancement in predicting space weather is important to human space exploration.
Provided by the SwRI
This sketch images the inner solar system at the time the light and electrons from solar activity reach the Earth. Fast electrons and the slower ions follow magnetic lines of force. SwRI [View Larger Image]
February 15, 2008
A new method for predicting the approach and intensity of hazardous particles from extreme solar events that would threaten astronauts and technology in space is now in place. Researchers are using this initial forecasting phase to qualify the method for operational use in space exploration activities.

The forecasting development team met its early-February deadline to coincide with NASA's launch of shuttle Atlantis to transport a European laboratory to the International Space Station. Useful but not critical for shuttle operations in low-Earth orbit, testing the method in real time during realistic flight scenarios will help improve the safety of future missions to the moon and Mars.

Developed eight months ago by Dr. Arik Posner, a research scientist at Southwest Research Institute (SwRI), the methodology and hands-on approach are examples of how the latest results generated from basic heliophysics research can be transformed rapidly into operational applications.

"This system provides advance warning up to about one hour," says Posner. "Although it seems relatively short notice, the warning can be mission critical during extravehicular activities, such as on the lunar surface, but in most cases it will simply reduce astronauts' total exposure to radiation."
The one-million-degree solar corona in extreme ultraviolet light taken by the Solar and Heliospheric Observatory's Extreme ultraviolet Imaging Telescope in November 2003. Hazardous solar activity is only minutes away. Another SOHO instrument, the COSTEP, monitors space for electrons from the Sun. SwRI [View Larger Image]
"Expanding our capabilities for monitoring radiation outbursts from the Sun is one of the critical issues that we must continue to address for human space exploration. This becomes even more crucial for Exploration class missions. The transition of scientific data into an operationally useful tool is an important and invaluable approach," says Stephen Guetersloh, member of the Space Radiation Analysis Group of NASA's Johnson Space Center in Houston.

The method was developed based on observations by the Comprehensive Suprathermal and Energetic Particle Analyzer (COSTEP) instrument, funded by the German Space agency DLR, on the Solar and Heliospheric Observatory. "The instrument was developed and built at the University of Kiel (Germany) in collaboration with the Alcala University (Spain). It is currently the only instrument in space which can provide the input for Posner's forecasting method," says Professor Bernd Heber from the University of Kiel.

Since SOHO launched in 1995, COSTEP has provided a wealth of data but not in real time. "We were so excited by Posner's project that we immediately teamed up and developed new software that displays the data and can give a warning 3 minutes after taking the measurements 1.5 million kilometers away," explains Oliver Rother from the University of Kiel.

The forecasting method calculates the appearance and intensity of solar ion events by measuring relativistic, near light-speed electrons. Relativistic electrons are highly abundant, easy to detect outside of the magnetosphere and detectable ahead of the more dangerous ions that follow. Extreme solar events create the relativistic electrons, which have characteristics that can be exploited to predict the time and intensity of later arriving ions, predominantly protons with energies more harmful to humans.

Energetic protons and heavier ions are among the main constituents of solar particle events, and exposure of the human body to such ionizing radiation elevates cancer risk. Heavy exposure to these particles can also result in acute radiation syndrome, with symptoms that include nausea, skin burns or disruption of central nervous system function.

"Earth's magnetic field helps prevent exposure to solar particle events," says Posner, "but as space exploration leads humans out of this protective magnetic cocoon toward the Moon and into the unprotected seas of outer space, this and other methods of space weather forecasting will become increasingly important."
 

Lua de Saturno tem fonte de hidrocarbonetos superior a todas as reservas de petróleo e gás da Terra

Publicada em 14/02/2008 às 11h08m
EFE ''Piscina'' deTitã, lua de Saturno - JPL/Nasa
RIO - A lua Titã, de Saturno, possui reservas de hidrocarbonetos superiores a todas as de petróleo e gás natural conhecidas na Terra, segundo observações realizadas pela sonda Cassini, revelaram o Laboratório de Propulsão a Jato (JPL) da Nasa e a Agência Espacial Européia (ESA).
Segundo cientistas do Laboratório de Física Aplicada da Universidade Johns Hopkins, esses hidrocarbonetos literalmente chovem naquele mundo e formam grandes depósitos em forma de lagos e dunas.
- Titã esta coberta por material que contém carbono. É uma gigantesca fábrica de materiais orgânicos - afirmou Ralph Lorenz, membro da equipe de cientistas que controla as operações do radar da Cassini no laboratório. - Essas enormes jazidas de carbono são uma importante janela para a geologia e a história meteorológica da lua Titã - acrescentou.
A temperatura média em Titã é de 179 graus Celsius abaixo de zero e em vez de água, sua superfície está coberta por hidrocarbonetos na forma de metano e etano.
Superfície de Titã, lua de Saturno - JPL/NasaAté agora, a Cassini realizou uma prospecção de 20% da superfície da lua Titã, e foram observados centenas de lagos e mares. Segundo a Nasa, cada uma das várias dúzias desses corpos "líquidos" contém mais hidrocarbonetos que todas as reservas de gás e petróleo conhecidas na Terra.
Além disso, suas dunas contêm um volume de materiais orgânicos centenas de vezes maior que as reservas de carvão da Terra.
- Esses cálculos se baseiam nas observações dos lagos das regiões polares setentrionais. Acreditamos que no sul podem ser similares - assinalou Lorenz.
A missão da Cassini é um projeto conjunto da Nasa, da Agência Espacial Européia e da Agência Espacial Italiana.

Sun-like star flips its magnetic field

This is the first time astronomers have observed this in a star other than our Sun.
Provided by the University of Hawaii
The magnetic field of the Sun-like star tau Bootis has flipped its north and south poles. The shortened cycle of this event may be due to interactions with its nearby massive planet. Karen Teramura/UH IfA [View Larger Image]
February 13, 2008
An international group of astronomers that includes the University of Hawaii's Evgenya Shkolnik reported today that they have discovered that the Sun-like star tau Bootis flipped its magnetic field from north to south sometime during the last year.

It has been known for many years that the Sun's magnetic field changes its direction every 11 years, but this is this is the first time that such a change has been observed in another star. The team of astronomers, who made use of Canada-France-Hawaii Telescope atop Mauna Kea, are now closely monitoring tau Bootis to see how long it will be before the magnetic field reverses again.

Magnetic field reversals on the Sun are closely linked to the varying number of sunspots seen on the Sun's surface. The last "solar minimum," the time when number of sunspots was the lowest and the magnetic flip occurred, was in 2007. The first sunspot of the new cycle appeared just last month.

The magnetic cycle of the Sun impacts the Earth's climate and is believed to have caused the little ice age in the seventeen century. The Earth's magnetic field also flips, although much less frequently and more erratically.

The international team led by Jean-Francois Donati and Claire Moutou of France caught tau Bootis in the process of flipping its magnetic field while they were mapping the magnetic fields of stars.

What makes tau Bootis even more interesting is that it harbors a giant planet orbiting very close to the surface of the star. The planet is actually so close (only one twentieth the distance between the Sun and Earth) and so massive (about 6.5 times the size of Jupiter) that it succeeded in forcing the surface of the star to co-rotate with the planet's orbital motion through tidal torques. This is the same effect that causes the moon to co-rotate around Earth so that we see only one side of the moon.

Since the astronomers managed to catch tau Bootis in this state of magnetic flipping during just 2 years of observations, it is likely that this event is much more frequent on tau Bootis than it is on the Sun. It is possible that the giant planet that has already managed to speed up the surface of tau Bootis is also spinning up the magnetic engine of its host star. The astronomers will keep their telescopes focused on tau Bootis in coming years to make sure they catch the star's next magnetic turnover. Their goal is a better understanding of how magnetic engines work in stars, including our Sun.

Slightly hotter and 20 percent more massive than the Sun, tau Bootis is fairly bright and visible with the naked eye and located only 51 light-years away from us. It is currently rises about midnight and is visible for most of the night near the bright star Arcturus in the constellation Bootis in the northeast part of the sky.

Telescopes Spot One of Earliest Galaxies

February 12, 2008
Associated Press/AP Online

By SETH BORENSTEIN WASHINGTON - Astronomers took pictures of a far-off lumpy galaxy just forming 13 billion years ago, putting it among the earliest and most distant cosmic objects ever photographed.

Though the black-and-white images are fuzzy, they are the most detailed and best confirmed look back in both time and distance that humans have seen, said Johns Hopkins University astronomy professor Holland Ford. He was part of a team of scientists taking the pictures with NASA's space telescopes, Hubble and Spitzer.

The galaxy, called A1689-zD1, is from when the universe was about 700 million years old, not long after the formation of the first galaxies.

And it's different from galaxies like our Milky Way, Ford said.

"It is much smaller. It is lumpy. It has two centers instead of one and it is undergoing extreme star formation," he said. "It is basically the building blocks for what will be a galaxy like our own in the future."

To see that far away, astronomers needed a little luck and help from the cosmos. A cluster of much closer galaxies act as a natural zoom lens for Earth's telescopes. Strong gravitational forces bend light around that cluster of galaxies, magnifying the light from directly behind it.

In this case, the infant galaxy appeared at least 10 times brighter than it would have without the natural help, Ford said. Other places behind the cluster appear hundreds of times sharper. This natural lens has to be lined up perfectly in order to see what's behind it, he said.

When Earth gets stronger telescopes in the future, including a new space telescope to be launched in 2013, this young galaxy would be a good place to look, astronomers said.

---

 

 

On the Net:

http://hubblesite.org/newscenter/archive/releases/2008/08/   

A service of YellowBrix, Inc.

 

Light Echoes Refine Cepheid Distance

RS Puppis and surrounding nebula
The bright Cepheid variable star RS Puppis (hidden behind a black occulting bar to block its glare) illuminates a dim reflection nebula around it. By seeing how long each brightness pulse from the star took to reach various blobs in the nebula, astronomers could find the true distances from the star to the blobs. That, combined with the angular star-to-blob separations on the sky, tells the distance from Earth — without relying on any other data or assumptions about the star itself.
P. Kervella and others
For nearly a century now, astronomers have used Cepheid variable stars as "standard candles" whose apparent brightnesses tell how far away they are. Starting in 1912 Cepheids provided the first good distances to nearby galaxies. One of the reasons for building the Hubble Space Telescope was to measure Cepheids in galaxies farther out than could be done through Earth's fuzzy atmosphere.

Indeed, "Hubble" was something of a double-entendre. The name honored the late Edwin Hubble, but the telescope was also intended to pin down the Hubble constant — the expansion rate of the universe — by comparing the redshifts of key galaxies to their distances found using Cepheid variables.


However, this only works if you know the distances to local Cepheids in our own galaxy well enough to calibrate the Cepheid distance scale as a whole. They're rather unusual super giant stars, so none of them lie close enough to the solar system for really accurate parallax measurements of their distances. Accordingly, astronomers have been expending great efforts to deduce local Cepheids' distances accurately in any way they can.


The best such measurements recently attained an accuracy of just a few percent. Now a group of astronomers has broken that record — by using a unique method to get a range on the bright Cepheid RS Puppis good to about 1.4 percent.


They did it by measuring "light echoes" of the star's pulsations on a surrounding reflection nebula, combined with the star's accurately known pulsation period, the speed of light, and some simple geometry.


RS Puppis varies in brightness (from magnitude 6.5 to 7.6) every 41.4 days. It is 10 times more massive than the Sun, 200 times larger, and on average 15,000 times more luminous. Pierre Kervella and his colleagues used the European Southern Observatory's New Technology Telescope at La Silla, Chile, to record the faint reflections of these light pulses moving across the nebula. The speed at which they appeared to move, combined with the known speed of light, gave the distance to the nebula and star: 6,500 light years plus or minus 90.


RS Pup is the only Cepheid embedded in a large nebula. "Light that travels from the star to a dust grain to the telescope arrives a bit later than light that comes directly from the star to the telescope," explains Kervella. "As a consequence, if we measure the brightness of a particular, isolated dust blob in the nebula, we obtain a brightness curve that has the same shape as the variation of the Cepheid, but shifted in time." The delay is called a "light echo," by analogy with a sound echo off, say, a canyon wall.


"Knowing the distance to a Cepheid star with such an accuracy proves crucial to the calibration of the period-luminosity relation of this class of stars," says Kervella.


RS Pup is especially important because it's one of the longest-period nearby Cepheids, and few of these have been well measured. The new result should help firm up the entire cosmic distance scale.

Gas from Saturn's largest moon

 
Titan's surface organics surpass oil reserves on Earth.
Provided by the Jet Propulsion Laboratory
An artist's imagination of hydrocarbon pools, icy and rocky terrain on the surface of Saturn's largest moon. Steven Hobbs (Brisbane, Queensland, Australia) [View Larger Image]
February 14, 2008
Saturn's orange moon Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth, according to new data from NASA's Cassini spacecraft. The hydrocarbons rain from the sky, collecting in vast deposits that form lakes and dunes.

"Titan is just covered in carbon-bearing material, it's a giant factory of organic chemicals," says Ralph Lorenz, Cassini radar team member from the Johns Hopkins University Applied Physics Laboratory. "This vast carbon inventory is an important window into the geology and climate history of Titan."

At a balmy -290° F (-179° C), Titan is a far cry from Earth. Instead of water, liquid hydrocarbons in the form of methane and ethane are present on the moon's surface, and tholins probably make up its dunes. The term "tholins"was coined by Carl Sagan in 1979 to describe the complex organic molecules at the heart of prebiotic chemistry.

Cassini has mapped about 20 percent of Titan's surface with radar. Several hundred lakes and seas have been observed, with each of several dozen estimated to contain more hydrocarbon liquid than Earth's oil and gas reserves. The dark dunes that run along the equator contain a volume of organics several hundred times larger than Earth's coal reserves.

Proven reserves of natural gas on Earth total 130 billion tons, enough to provide 300 times the amount of energy the entire United States uses annually for residential heating, cooling and lighting. Dozens of Titan's lakes individually have the equivalent of at least this much energy in the form of methane and ethane.

"This global estimate is based mostly on views of the lakes in the northern polar regions. We have assumed the south might be similar, but we really don't yet know how much liquid is there," says Lorenz. Cassini's radar has observed the south polar region only once, and only two small lakes were visible. Future observations of that area are planned during Cassini's proposed extended mission.

Scientists estimated Titan's lake depth by making some general assumptions based on lakes on Earth. They took the average area and depth of lakes on Earth, taking into account the nearby surroundings, like mountains. On Earth, the lake depth is often 10 times less than the height of nearby terrain.

"We also know that some lakes are more than 10 meters or so deep because they appear literally pitch-black to the radar. If they were shallow we'd see the bottom, and we don't," says Lorenz.

The question of how much liquid is on the surface is an important one because methane is a strong greenhouse gas on Titan as well as on Earth, but there is much more of it on Titan. If all the observed liquid on Titan is methane, it would only last a few million years, because as methane escapes into Titan's atmosphere, it breaks down and escapes into space. If the methane were to run out, Titan could become much colder. Scientists believe that methane might be supplied to the atmosphere by venting from the interior in cryovolcanic eruptions. If so, the amount of methane, and the temperature on Titan, may have fluctuated dramatically in Titan's past.

"We are carbon-based life, and understanding how far along the chain of complexity towards life that chemistry can go in an environment like Titan will be important in understanding the origins of life throughout the universe," adds Lorenz.

Cassini's next radar flyby of Titan is on February 22, when the radar instrument will observe the Huygens probe landing site.

Isolated galaxy or corporate merger?

Hubble spies NGC 1132.
Provided by the Space Telescope Science Institute
This Hubble image shows elliptical galaxy NGC 1132. NASA/ESA/Hubble Heritage (STScI/AURA) [View Larger Image]
February 7, 2008
The elliptical galaxy NGC 1132 reveals the final result of what may have been a group of galaxies that merged together in the recent past. Another possibility is that the galaxy formed in isolation as a lone wolf in a universe ablaze with galaxy groups and clusters.

NGC 1132 is dubbed a "fossil group" because it contains enormous concentrations of dark matter, comparable to the dark matter found in an entire group of galaxies. NGC 1132 also has a strong X-ray glow from an abundant amount of hot gas that is normally only found in galaxy groups.

In visible light, however, it appears as a single, isolated, large elliptical galaxy. The origin of fossil-group systems remains a puzzle. They may be the end-products of complete merging of galaxies within once-normal groups. Or, they may be very rare objects that formed in a region or period of time where the growth of moderate-sized galaxies was somehow suppressed, and only one large galaxy formed.

Elliptical galaxies are smooth and featureless. Containing hundreds of millions to trillions of stars, they range from nearly spherical to very elongated shapes. Their overall yellowish color comes from the aging stars. Because ellipticals do not contain much cool gas, they no longer can make new stars.

This image of NGC 1132 was taken with Hubble's Advanced Camera for Surveys. Data obtained in 2005 and 2006 through green and near-infrared filters were used in the composite. In this Hubble image, NGC 1132 is seen among a number of smaller dwarf galaxies of similar color. In the background, there is a stunning tapestry of numerous galaxies that are much larger but much farther away.

NGC 1132 is located approximately 318 million light-years away in the constellation Eridanus, the River.

A Triple Threat

 
Two days ago the IAU's quaintly named Central Bureau for Astronomical Telegrams announced that astronomers have discovered a triple asteroid passing in Earth's vicinity.

This isn't the first rock trio — out in the main asteroid belt, 87 Sylvia has two small moons (Romulus and Remus) and so does 45 Eugenia (Petit-Prince and another designated S/2004 (45) 1). Multiple asteroids are no longer big news. Based on the terrestrial cratering record, about one in six impacts with Earth involves a double object.

Triple asteroid
A visualization of the radar echoes acquired February 13, 2008, from asteroid 2001 SN263. Radar illumination is from the top. Echoes from the two satellites appear thinner because they are rotating slowly and therefore don't produce as much Doppler shifting (horizontal axis) as the main mass.
National Astronomy and Ionosphere Center
But this one is a rather different animal. First, it's in an Amor-type orbit, meaning that it comes to within 96.4 million miles of the Sun but doesn't quite cross the orbit of Earth. Second, its three components are rather similar in size. The main body is roughly 1½ miles (2 km) across, whereas the other two are closer to 1,000 feet (300 meters).

The threesome came to light because a team headed by Cornell astronomer Mike Nolan used the Arecibo radio telescope in Puerto Rico to bounce radar pulses off a small asteroid passing within about 7 million miles of Earth. When three echoes came back on Tuesday, Nolan knew they'd found something special.

First seen in September 2001, this object has two official designations: 2001 SN263 (its ID when discovered) and 153591 (assigned once its orbit was known well). But this alphanumeric jumble gets worse: according to IAU convention, for now the two little satellites will be known as S/2008 (153591) 1 and S/2008 (153591) 2. Can't we just call them Moe, Larry, and Curly and be done with it?

Nolan notes in a press release that not much is known about the trio. But more observations in the coming days might determine whether the moonlets are orbiting in the same plane, the masses of all three objects, and whether the trio formed in the asteroid belt or due to a close brush with Earth.

Arecibo radio telescope
The 305-meter (1,000-foot) radio telescope near Arecibo, Puerto Rico, has been used for radar probing of solar-system objects since the early 1960s. The facility underwent a $27 million upgrade in the mid-1990s.
David Parker (Science Photo Library); courtesy NAIC/Arecibo Observatory
Because it's in a near-Earth orbit, breakup specialist Derek Richardson (University of Maryland) thinks 2001 SN263 could have been ripped apart by Earth's gravity in the not-too-distant past. "You need to get within 4 Earth radii or so [about 15,000 miles or 25,000 km] for anything interesting to happen."

He doesn't think the breakup occurred in the asteroid belt, citing the unlikelihood of the threesome staying intact for the millions of years it would have taken to migrate inward. Nor does he think subtle solar forces caused it to spin so rapidly that it flew apart.

Incidentally, Arecibo's unique radar observations may come to an abrupt end in 2011 (along with its other valuable contributions). That's because a 2005 review by the National Science Foundation decided that funds for the facility could be better spent elsewhere. But the facitity's astronomers aren't going down without a fight.
 

Researchers Find a Supernova, Before it Exploded

Written by Fraser Cain
SN 2007on. Image credit: Chandra
The problem with supernovae is that you never know where they're going to happen. Your only clue is the bright flash in the sky, and then it's too late. But a team of European researchers think they were lucky enough to have spotted the precursor to supernova.

In an article in the February 14th issue of the journal Nature, a team of European researchers describe how they were trying to find evidence of a binary system after one of the objects detonated as a supernova. In looking back through archived images captured by NASA's Chandra X-Ray Observatory, they were lucky enough to find one image that actually contained the system.
The supernova, known as SN 2007on exploded as a Type Ia. This is the situation where a white dwarf is in orbit around another star. It's possible that the white dwarf feeds off material ejected from the other star until it hits a critical amount of mass - approximately 1.4 times the mass of our Sun. Or maybe it's actually a collision between a white dwarf and another star, or between two white dwarfs.
Whatever the condition, the result is always the same. The white dwarf detonates suddenly with a very specific amount of energy and characteristic light curve. Astronomers use these explosions to measure distance in the Universe, since they're always exploding with the same amount of energy.
To really figure out what's going on, astronomers need more examples of these precursors. They need to be able to study a potential Type Ia supernova before it actually explodes.
So, the researchers finally have a target they can study. In the case of SN 2007on, the data gathered by the Chandra X-Ray Telescope strengthens the "mass stealing" theory. X-rays streaming from the system show the kind of fusion you would expect from a white dwarf consuming material from a neighbour.
This isn't a slam dunk, though. A higher-quality optical image shows the binary system to be in a slightly different position from where the supernova detonated. So maybe this system isn't the precursor after all.
But followup observations from Chandra show that the X-ray source is gone. Whatever was at that location isn't there any more. Perhaps it did indeed vaporize in a supernova explosion.

Bookmark in Connotea UK space strategy draws fire - February 14, 2008

The UK today launched its new space strategy (press release). Already it's being criticised by people who want more commitment to manned exploration and others who want less. The latter want space exploration money spent on propping up the UK's threatened physics and astronomy research communities instead.
Instead of going to the Moon, the strategy outlines plans to set up an international facility focusing on satellites for monitoring climate change and commercial applications as well as working on robotic space exploration. Not that the government has ruled out putting humans into space. Instead they have produced a report on their strategy which announces a review of human spaceflight.
You can listen to science minister Ian Pearson discuss manned spaceflight on Radio 4's Today Programme. "What we've said is we will have a review that will look at all the options," he says.
You might think that you'd want to review the possibility of getting involved in human spaceflight before you produce a space strategy, but nevermind.


In an opinion piece in the Times Martin Rees, the UK's Astronomer Royal and president of the Royal Society, knows what he thinks of manned missions:
The burgeoning scientific, environmental, commercial and military applications of space have not needed manned spaceflight, but have benefited from the technical advances - unimagined in the 1970s - that have given us mobile phones and the internet.


He also thinks that getting involved in NASA and the International Space Station was a bit of a mistake:

It is claimed by Nasa that tens of billions more dollars must be spent to finish the space station, in order to keep faith with the foreign partners who have built parts of it. However, whatever their public rhetoric, most European scientists regret having got involved; they could all have been contentedly paid off far more cheaply than it will cost the Americans to finish the space station.


It seems you really can't please people when it comes to space. The Guardian's coverage of the new strategy is headlined "UK carves out its place in space, but hopes for Britons on moon dashed". Its coverage continues by quoting people who want Britons in space.
Some are linking this story to the recent cutbacks in UK physics and astronomy research (see Nature here and here; subscription required). They have got something of a point: having well funded space exploration and no astronomers seems rather like buying a very expensive car and being too cheap to buy a map so you can drive it somewhere interesting.
Ever-flippant news source The Register notes:

Blighty's physics and astronomy boffins are facing severe job losses as a result, and are already up in arms. If even more of them were sacrificed to pay for a small number of space aces - some of whom at least would presumably not be scientists at all - there would be even more trouble.


Over in the comments section of the BBC's coverage one reader takes raises the fact that the UK recently slashed the amount of research it will fund in physics. "I note that this is about investing in sending up celebrities in rockets, it explains why Science and Physics research has been cut - in order to fund some more Nu labour spin. Pathetic," says Jeremy Slawson.
In the comments of the Time's coverage 'caffeineman' opines:

What will happen, indeed is already happening, is that other areas of research will be cut to bolster the funding of the manned space program. Areas of particle physics in which UK leads the world are being cut at the time of writing, by the Science and Technology Facilities Council. Money from exceptionally good science programmes will be diverted into an incredibly expensive and scientifically pointless white elephant. What a waste of the taxpayers' money !



Image color image of the sun, Earth and Venus was taken by the Voyager






Titan has "Hundreds of Times More" Liquid Hydrocarbons Than Earth

Written by Ian O'Neill
Titans landscape as seen by the Huygens probe decent through Saturns largest moons atmosphere (credit: ESA, NASA, JPL, UA, Rene Pascal)
According to new Cassini data, Saturns largest moon, Titan, has "hundreds" times more liquid hydrocarbons than all the liquid fossil fuel deposits on Earth. This is impressive as Titan's 5150 km diameter is only about 50% larger than Earth's Moon and only a little larger than the planet Mercury. Titan's hydrocarbons cycle into the atmosphere, fall as rain and collect in lakes creating massive lakes and dunes.

Titan is a planet-sized hydrocarbon factory. Instead of water, vast quantities of organic chemicals rain down on the moon's surface, pooling in huge reservoirs of liquid methane and ethane. Solid carbon-based molecules are also present in the dune region around the equator, dwarfing Earth's total coal supplies. Carl Sagan coined the term "tholins" to describe prebiotic chemicals, and the dunes of Titan are expected to be teeming with them. Tholins are essential for the beginning of carbon-based organisms, so these new observations by Cassini will stir massive amounts of excitement for planetary physicists and biologists alike.
The cold -179°C (-290°F) landscape of Titan is currently being mapped by the Cassini probe as it orbits the ringed gas giant, Saturn. Some 20% of the moons surface has been catalogued and so far several hundred hydrocarbon seas and lakes have been discovered. These lakes, individually, have enough methane/ethane energy to fuel the whole of the US for 300 years.
These new findings have been published in the January 29th issue of the Geophysical Research Letters by Ralph Lorenz from the Cassini radar team (Johns Hopkins University Applied Physics Laboratory, USA). Lorenz said on reviewing the Cassini data that, "we know that some lakes are more than 10 m or so deep because they appear literally pitch-black to the radar. If they were shallow we'd see the bottom, and we don't." He also steps into the life-beyond-Earth debate by pointing out: "We are carbon-based life, and understanding how far along the chain of complexity towards life that chemistry can go in an environment like Titan will be important in understanding the origins of life throughout the universe."
The ESA Huygens probe separated from Cassini and dropped slowly through the Titan atmosphere in January 2005 analyzing the atmospheric composition and taking some breathtaking images of the surrounding landscape. To complement the huge amount of data assembled from Huygens decent, Cassini will flyby the moon again on February 22nd to take radar data of the Huygens landing site.
Source: Physorg.com

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