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Jackdaw
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Something must be wrong with this exoplanet...

19 Jul 2017 01:05

Planet EPIC 22881391 b
According to the link above, this planet's mass is 0.7 times Jupiter mass, and it's radius is, however, only 0.079 Jupiter radius. 
What does this mean? Jupiter's mass is 1.898×1027 kg, and it's radius is 71492 km, so we could get the mean density of this exoplanet -- it's about 1.76×106 kg/m3 ! We all know that Earth's mean density is about 5.514×103 kg/m3, while a typical white dwarf has a density of between 107 and 1010 kg/m3. So EPIC 22881391 b is more likely a white dwarf, but not a planet, huh? 
Or is it just a typo?
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Watsisname
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Something must be wrong with this exoplanet...

19 Jul 2017 02:10

It's not a typo.  The reported mass of 0.7 Jupiter masses is the upper limit based on constraints from radial velocity data.  (This is why exoplanet.eu says 0.7MJ with errors of +0.0 and -nan).  

A more probable mass would be found by the mass-radius relation for planets, but it depends on the composition.  The discovery paper suggests a more realistic upper limit is 3 Earth masses.
 
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Jackdaw
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Something must be wrong with this exoplanet...

19 Jul 2017 02:38

Watsisname wrote:
It's not a typo.  The reported mass of 0.7 Jupiter masses is the upper limit based on constraints from radial velocity data.  (This is why exoplanet.eu says 0.7MJ with errors of +0.0 and -nan).  

A more probable mass would be found by the mass-radius relation for planets, but it depends on the composition.  The discovery paper suggests a more realistic upper limit is 3 Earth masses.

Oh, I can see your point. It makes perfect sense. Thank you for answering my question :P
"...perch`e i nostri discorsi hanno a essere sopra un mondo sensibile, e non sopra un mondo di carta."

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problemecium
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Something must be wrong with this exoplanet...

19 Jul 2017 11:06

That, or we found something made of the same substance that makes up the Kerbal planets xD
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