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Fraser
2004-Oct-06, 05:21 PM
SUMMARY: Astronomers using the Gemini observatories have got themselves a bit of a mystery. They've found a binary system at EF Eridanus, located 300 light-years away from Earth, where one of the objects defies classification. It's about the size of Jupiter but it's way too massive to be a planet. It's the temperature of a brown dwarf, but its light doesn't match a brown dwarf's characteristics. The researchers believe that the object was once a regular star, but then it had most of its material stripped away by the gravity of the larger star over the course of 5 billions years. Eventually it just couldn't give any more.

What do you think about this story? Post your comments below.

StarLab
2004-Oct-06, 07:12 PM
Maybe it's just a normal main sequence star that's been exposed to space?:shrug:

antoniseb
2004-Oct-06, 07:19 PM
Originally posted by StarLab@Oct 6 2004, 07:12 PM
Maybe it's just a normal main sequence star that's been exposed to space?
Right. That should be a rare event. Not many main sequence stars get exposed to 'space'. Mostly they're kept indoors where they'll be safe. ;)

StarLab
2004-Oct-07, 02:48 AM
Well, maybe I screwed up because I typed "star" instead of "core." So, where's you indoors now? ;) :lol: :P

bunny
2004-Oct-07, 09:12 AM
Just because this stars doesn't have the same spectra as a brown dwarf, shouldn't mean that it isn't one. Spectra give an idea of the composition, each element contributing lines to the spectra. Surely we could not expect every brown dwarf to form exactly the same way with the same composition? I thought the clasification relied on size/mass and brightness.

antoniseb
2004-Oct-07, 11:56 AM
Originally posted by StarLab@Oct 7 2004, 02:48 AM
I typed "star" instead of "core."
That's a relief. Everything I've seen you write so far indicated that you knew a lot better than to think the star had been kept indoors. My mistake here was not putting enough smiley-faces after the message for you to realize I wasn't making a serious criticism.

Yes, the object's composition will most likely be that of a main sequence core, and inner envelopes interrupted at some unknown phase of life along its path on the HR diagram.

dave_f
2004-Oct-09, 01:34 PM
Originally posted by antoniseb@Oct 7 2004, 11:56 AM
Yes, the object's composition will most likely be that of a main sequence core, and inner envelopes interrupted at some unknown phase of life along its path on the HR diagram.
This would be an instructional object to study. It probably resembles a gas giant somewhat (stellar cores are made up of mostly hydrogen/helium). The small size is probably what would happen to our Sun if all that thermal energy output just stopped and gravity were allowed to take over.

I wonder what will happen if/when those two objects collide... I imagine a Type I supernova maybe? (one of them is a white dwarf... no mention of how massive it is though).

antoniseb
2004-Oct-09, 02:23 PM
Originally posted by dave_f@Oct 9 2004, 01:34 PM
I wonder what will happen if/when those two objects collide
The white dwarf has a mass of about 0.6 solar masses. The dead core has a mass of about 0.1 solar masses. It could never become a supernova. It is also probably the case that if, hundreds of billions of years from now, the two objects do manage to spiral in together, the dead core will slowly dump more Helium and Hydrogen onto the white dwarf, and it will give off x-ray flares for a while. It seems doubtful that there will ever be a big splat as a large body hits another large body in this system.