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ToSeek
2004-May-11, 04:05 PM
Two Extremely Hot Exoplanets Caught in Transit - VLT Measures Properties of New Jupiter-Size Objects in Very Close Orbits (http://www.spaceref.com/news/viewpr.html?pid=14191)


This result confirms the existence of a new class of giant planets, designated "very hot Jupiters" because of their size and very high surface temperature. They are extremely close to their host stars, orbiting them in less than 2 (Earth) days.

Kullat Nunu
2004-May-11, 07:22 PM
Indeed they are fascinating worlds.

By the way, The Extrasolar Planets Encyclopaedia (http://www.obspm.fr/encycl/encycl.html) reported the findings almost a month ago.

Definitely a site to visit regularly if you are an extrasolar planet enthusiast.

PS. Original press release (http://www.eso.org/outreach/press-rel/pr-2004/pr-11-04.html) from the European Southern Observatory.

Russ
2004-May-11, 08:43 PM
This is a very interesting article. The one thing that set off my ** detector is the assumption that these are "Hot Jupiters". At the stated distances from their respective stars, could they not be hot super earths? (Big rocks) I mean, one is 6 stellar radii from the star, the stellar wind at that distance would fantastic. I would think it would boil and blow away any atmosphere. Wouldn't you? Plus, at those distances, you'b be getting pretty close the roche lobes.

Any thoughts?

harlequin
2004-May-12, 01:31 AM
This is a very interesting article. The one thing that set off my ** detector is the assumption that these are "Hot Jupiters". At the stated distances from their respective stars, could they not be hot super earths? (Big rocks) I mean, one is 6 stellar radii from the star, the stellar wind at that distance would fantastic. I would think it would boil and blow away any atmosphere. Wouldn't you? Plus, at those distances, you'b be getting pretty close the roche lobes.

Any thoughts?

Well since many "Hot Jupiters" (though not as extreme as these) have been discovered via their gravity it would seem to be moot issue. And the shadow of a "Hot Earth" would be much smaller than a "Hot Jupiter." I doubt that current instruments would find a "Hot Earth" at that distance. One could estimate the size from the extent that the transit dimishes the light we receive. We know that mass of the star and we also can see how long the transit lasts. So a crude estimate of the physical size of the planet is clearly possible. If one also observes how the planet deflects the star via its gravity (which the article says has been done) then this can be combined with the transit data to give the mass of the planet.

Also consider that the planet does not have to last forever, it only has to exist where it is now. The planet might not originated at its current location. Consider creationist arguments that Saturn's rings could only last x years therefore Saturn can only be x years old at the most. The logical fallacy here is that Saturn's rings might not be as old as Saturn. (There are other problems with that argument but they are irrelevent for our purposes here.) The same thing applies to this "Hot Jupiter." If it could only exist for a "short" time where it is not absurd. It only means that it probably has not spent its entire existence at its present location.

Jpax2003
2004-May-12, 05:59 AM
This got me thinking... Could hot jupiters be the building blocks of multi body solar systems? Perhaps a hot jupiter is torn apart into smaller planets by tidal forces or by a solar explosion. What would happen if a planet that big crashed into the sun? What would happen such a planet were in the vicinity of a supernova. Would a supernova ignite fusion in the gas giant creating more heavy elements than a supernova alone would make? Would the difference be appreciable? Would it help explain dark matter and such?

Just wondering.

eburacum45
2004-May-12, 07:52 AM
I've made a fictional solid planet-hot jupiter based on current understanding of the formation of these bodies;

it is posted here
http://www.orionsarm.com/worlds/Sisyphos.html

You will see that the diameter is only 25,000km, the mass is only 10 xEarth, the gravity is 2.5 gee; if you suppose a planet with more stony crust and less iron core the density and the gravity goes down, but the diameter only increases to 27000 km.

There can't be rocky planets much bigger than this or they start to retain thick atmospheres, and would have to be unfeasibly close to the star to make the atmosphere evaporate.