Exoplanet circles 'normal star'

[Notebook]

http://news.bbc.co.uk/1/hi/sci/tech/7617031.stm

N.

 

[SiberianTiger]

Can't wait for the pics to be obtained by JWST...

 

[Belisarius]

Typical BBC confusion when it comes to tricky stuff like numbers:

"The new planet is huge, with a mass about eight times that of Jupiter."

"The object is about 1,500C (1,800 Kelvin) - much hotter than Jupiter, which it resembles in terms of size."

OK, where are we? Is it 8 times bigger than Jupiter or does it resemble Jupiter in terms of size? Do they even read the stuff they write?

 

[SiberianTiger]

"The new planet is huge, with a mass about eight times that of Jupiter."

"The object is about 1,500C (1,800 Kelvin) - much hotter than Jupiter, which it resembles in terms of size."

One thing does not rule out the other. There is a top value for an exoplanet's radius, I believe, about 2 times bigger than Jupiter. At the same time, mass of such a planet can exceed Jupiter's by much. It's all defined by a gas pressure / gravitational equilibrium function, that makes the size flatten out in the area of high masses (until transition to the "brown dwarf" area).

 

[Belisarius]

Now I'm completely confused... If there's a top value for exoplanet status 2 times bigger than Jupiter and this one is 8 times bigger, then what is it?

 

[SiberianTiger]

Now I'm completely confused... If there's a top value for exoplanet status 2 times bigger than Jupiter and this one is 8 times bigger, then what is it?

The key word is "heavier", not "bigger". Something 2 times as heavy as Jupiter would be only a little bit "bigger" (not sure how much). A planet 8 times as heavy would be 2 times as big (and much hotter due to extra gravity-enforced pressure in the core).

 

[Thunder Chicken]

Here's another link, same story:

http://www.sciencenews.org/view/gen..._snapshot_of_a_planet_beyond_the_solar_system

 

[Linguofreak]

that makes the size flatten out in the area of high masses (until transition to the "brown dwarf" area).

Well, actually the peak in size (2 Jupiter Radii sounds right) happens in the middle of the brown dwarf region, and past a certain mass adding mass actually decreases the radius, until the central temperatures neccesary for hydrogen fusion are reached and the object becomes a star. In fact, the largest brown dwarfs and smallest stars are pretty close to Jupiter's radius, and nearly 80 times as massive