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¿MALAS? NOTICIAS DESDE TAU CETI:

 
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MensajePublicado: Jue 30 Sep 2004 16:47:32    Asunto: ¿MALAS? NOTICIAS DESDE TAU CETI: Responder citando

http://www.solstation.com/stars/tau-ceti.htm
http://www.newscientist.com/news/news.jsp?id=ns99996123
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MensajePublicado: Vie 1 Oct 2004 16:45:51    Asunto: Responder citando

Aquí está el artículo.No lo traduzco,porque nunca me han gustado los traductores de Internet Razz

Life unlikely in asteroid-ridden star system


15:21 07 July 04

NewScientist.com news service

A nearby star system thought of as a candidate for harbouring life has 10 times the number of asteroids and comets as found in our Solar System. The sheer number of bodies raging around the Sun-like star may mean that any potential life is choked off, say UK researchers.

The star, Tau Ceti, lies just 12 light-years away and has been eyed as a possible oasis for life because of its similarity to the Sun and the inference of a surrounding debris disk that may harbour planets.

Imaging the disk has now identified the 10-billion-year-old Tau Ceti as the oldest of about a dozen stars with confirmed disks. Its span is similar to our Solar System's Kuiper Belt.

This shadowy belt consists of a ring of comets and asteroids reaching just past Pluto's orbit. But the amount of dust around Tau Ceti suggests it is circled by more than 10 times as many of the objects.

If there are planets around the star, says lead researcher Jane Greaves, an astronomer at the University of St Andrews, UK, this means "it is likely that they will experience constant bombardment from asteroids of the kind believed to have wiped out the dinosaurs".

"It is likely that with so many large impacts life would not have the opportunity to evolve," says Greaves, whose team imaged Tau Ceti for the first time.


Giant planet


But other astronomers say the implications for life are not so clear. "You could argue the other way as well," says Glenn Schneider of the University of Arizona in Tucson, US. He says the key factor is whether the impacts would occur in the habitable zone - the region around the star where liquid water can exist.

Scott Kenyon, an astronomer at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, US, agrees. He says a giant planet could orbit the star, gravitationally deflecting comets and asteroids away from planets that may support life in the same way that Jupiter protects Earth.

But, says Kenyon, "it's a really exciting observation to see the dust around that old a star". Stars are born in a swirl of gas and dust, which in less than a million years is thought to coalesce into larger objects such as comets. These collide over time, producing more dust, but the star's radiation blows it away, eroding the disk.

For a star like Tau Ceti to have a dust disk at its advanced age, "you need to have something that keeps making and stirring the dust", Kenyon told New Scientist.

That something is the collision of comets and asteroids, according to Greaves and her team. They imaged Tau Ceti's disk at submillimetre wavelengths with the SCUBA camera on the James Clerk Maxwell Telescope in Hawaii.

But why the disks differ so much between such similar stars remains a mystery. "It could be that the Sun passed relatively close to another star at some point in its history and that the close encounter stripped most of the comets and asteroids from around the Sun," says team member Mark Wyatt of the UK Astronomy Technology Centre in Edinburgh.

"It may be that Tau Ceti just didn't have a flyby at the right time," agrees Kenyon. "I think it's too early to say which [situation] is more common, but I think it's exciting you can see the difference."


No creo que haya un gigante de gas en órbita de Tau Ceti que haga de "escudo gravitatorio" y protega los posibles planetas internos de impactos asteroides y cometas.Si lo hubiera,tal planeta no cabe duda habría sido detectado (supongo que los apenas 12 años luz a ésa estrella lo haría relativamente fácil)...a menos que orbitara a una buena distancia de la estrella,no sé hasta que distancia se podría detectar un planeta de tipo Júpiter a la distancia de Tau Ceti...
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MensajePublicado: Sab 2 Oct 2004 18:16:40    Asunto: Responder citando

No es el mismo artículo, pero sí uno que trata el mismo tema. Aquí está la traducción de un colega de Astroseti:
http://www.astroseti.org/vernew.php?codigo=403
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