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Ground-based Exo-planet discoveries
ngunn
post Dec 6 2009, 04:57 PM
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Yes I noticed the range of hypotheses offered, but they seem to focus on how A might cause B and sound a bit convoluted. I just think Hoyle's blast-your-neighbour-and-scram idea is more exciting, and it could neatly provide a single cause for both A and B.

QUOTE (Hungry4info @ Dec 6 2009, 02:26 PM) *
Interestingly, sun-like stars with close stellar companions do not seem to have this anti-correlation.


Well they wouldn't, would they? Their companions haven't exploded. smile.gif
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Hungry4info
post Dec 6 2009, 05:07 PM
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Of course it's more exciting, but only in the "All stars are actually anti-matter/matter reaction driven" sort of sense. There's no reason to support it, and there's already other ideas that better explain what is observed.

Planet hosts are lithium poor. Planets not known to have stars are lithium rich.
(anti)correlation has something to do with planets (or planet formation).

This trend only shows up for stars within +/- 100 K of Sol's effective temperature.
(anti)correlation has something to do with the structures of stars +/- 100 K of Sol's effective temperature.

Even in our solar system, the planets (or the process of their formation) were able to cause Sol to become lithium poor. There is no evidence for any of our planets having exploded in the past.

Does the idea of a exploding companions explain why only near-stellar Teff stars display this correlation?
Does it explain why binary stars in the same temperature range do not?
Is there any evidence for planetary companions blasting their neighbors and screaming?

Consider the 16 Cygni system. Two sun-like stars: the lithium-poor star hosts a planet. The lithium-rich star hosts an M-dwarf.


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ngunn
post Dec 6 2009, 09:28 PM
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QUOTE (Hungry4info @ Dec 6 2009, 05:07 PM) *
1 (anti)correlation has something to do with planets (or planet formation).

2 (anti)correlation has something to do with the structures of stars +/- 100 K of Sol's effective temperature.

3 There is no evidence for any of our planets having exploded in the past.

4 Is there any evidence for planetary companions blasting their neighbors and screaming?


1 - Agreed.
2 - Agreed.
3 - I didn't say that, and neither did Fred Hoyle. The explosion would have predated (and lead to) planet formation.
4 - I didn't say 'scream' either(!) I said scram, as in 'rapidly leave the area'.

There has also been quite a lot written over the years about the trauma to a close companion star when a supernova occurs, and about binaries becoming unbound following stellar explosions. I don't think it's far fetched to imagine that the trauma might involve lithium destruction for certain classes of star but not others.

16 Cygni B is around 1000AU from the AC pair, maybe far enough for a supernova to destroy the lithium in one but not the other.

There may be better theories as you say, but as you also say they are not complete and there is no clear winner yet so I don't think broader speculation is out of order at this stage.
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scalbers
post Jan 1 2010, 06:06 PM
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I guess we can mention GJ1214b and the MEarth project in this thread...

http://arxiv1.library.cornell.edu/abs/0912.3229

http://en.wikipedia.org/wiki/GJ_1214_b


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Guest_PhilCo126_*
post Jan 9 2010, 09:59 AM
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Guests






Keck telescopes on Mauna Kea - Hawaii discovered 2nd smallest exo-planet HD156668b at 80 light years in the constellation Hercules
http://spacefellowship.com/news/art17807/s...anet-found.html
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Mongo
post Jan 9 2010, 02:57 PM
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I will charitably assume that the reporters left out the bolded part: 2nd smallest exoplanet discovered by radial velocity variations.

I count at least 5 smaller exoplanets, one of which was discovered by radial velocity variations.
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belleraphon1
post Jan 9 2010, 08:06 PM
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Agreed Mongo...

Go to Extrsolar Planets Encyclopedia catalog http://exoplanet.eu/catalog-all.php and sort by Mass you will find the three pulsar planets, MOA-2007-BLG-192-L-b (microlensing find) and GJ581e (the smaller of the RV finds).

Actually I think the discovery of GJ1214b is far more exciting. Close enough we can learn things about it's atmosphere from current space telescopes. GO MEarth team!!!

Craig
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ngunn
post Apr 14 2010, 10:59 AM
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There is nothing like new data for shaking things up. smile.gif

http://www.sciencedaily.com/releases/2010/...00413071749.htm
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Ron Hobbs
post Jun 11 2010, 06:40 PM
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The VLT has taken pictures of a planet orbiting beta Pic.

"For the first time, astronomers have been able to directly follow the motion of an exoplanet as it moves from one side of its host star to the other. The planet has the smallest orbit so far of all directly imaged exoplanets, lying almost as close to its parent star as Saturn is to the Sun. Scientists believe that it may have formed in a similar way to the giant planets in the Solar System. Because the star is so young, this discovery proves that gas giant planets can form within discs in only a few million years, a short time in cosmic terms."

Exoplanet Caught on the Move

I want to give a shout out to the folks at ESO; they provide some really cool graphics of their discoveries.
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remcook
post Jun 24 2010, 08:06 AM
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Doing observations from the ground can have its advantages... smile.gif

http://news.bbc.co.uk/2/hi/science_and_env...nt/10393633.stm
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Drkskywxlt
post Jun 30 2010, 05:42 PM
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Confirmation of the first directly imaged planet around a sun-like star thanks to Gemini. An 8Jup-mass planet at over 300AU!
http://www.space.com/scienceastronomy/firs...med-100629.html
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ustrax
post Nov 18 2010, 07:55 PM
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It's extragalactastic! biggrin.gif
http://www.eso.org/public/news/eso1045/


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ustrax
post Nov 19 2010, 11:09 PM
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500! and 2... biggrin.gif
Wow! And to think that we just opened our eyes in 1988...what's ahead? smile.gif


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remcook
post Dec 2 2010, 09:14 AM
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Well, finally that mysterious DPS presentation got cleared up
http://www.jpl.nasa.gov/news/news.cfm?rele...mp;auid=7439932
High density atmosphere or clouds on super-Earth GJ1214b
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ngunn
post May 19 2011, 04:14 PM
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Free floating planets found by microlensing: http://science.nasa.gov/science-news/scien..._orphanplanets/

Food for WISE is probably out there. Go get 'em WISE!
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