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Jackdaw
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Something must be wrong with this exoplanet...

19 Jul 2017 03:05

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 1.898×10[sup]27[/sup] kg, and it's radius is 71492 km, so we could get the mean density of this exoplanet -- it's about 1.76×10[sup]6[/sup] kg/m[sup]3[/sup] ! We all know that Earth's mean density is about 5.514×10[sup]3[/sup] kg/m[sup]3[/sup], while a typical white dwarf has a density of between 10[sup]7[/sup] and 10[sup]10[/sup] kg/m[sup]3[/sup]. 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 04:10

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 0.7M[sub]J[/sub] 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 04:38

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 0.7M[sub]J[/sub] 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."

CPU: AMD Ryzen 5 2600X GPU: AMD Radeon RX 580 8G RAM: 32 GBs Storage (of SE): WD SN750 250G
 
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problemecium
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Something must be wrong with this exoplanet...

19 Jul 2017 13:06

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