Real planets dimension?

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Real planets dimension?

Post by Daniele_bianchino on 2nd November 2012, 11:24 am

Good Morning,
I write from Italy - Rome, congratulations for your site, I follow a long.
My Avatar is my Gliese 581d reimagined;
I would like to ask a question ..
The planets in this site are really so 'great compared to Jupiter? or maybe too big?
for example:

11 Com:
http://exoplanet.hanno-rein.de/system.php?id=11+Com+b

ups Andromedae:
http://exoplanet.hanno-rein.de/system.php?id=ups+And+c

HD 202206:
http://exoplanet.hanno-rein.de/system.php?id=HD+202206+b


..and I believe that this site fits the habitable zone, only according to that of our solar system;
in the Gliese 581 system the habitable zone not shows:
http://exoplanet.hanno-rein.de/system.php?id=Gliese+581+b

and in hd85512:
http://exoplanet.hanno-rein.de/system.php?id=HD+85512+b

ups and d is taken out of the habitable zone (little out Mars orbit), but is within the habitable zone, they do not consider that the ups and star is more warm than our sun?
Many Thanks, Daniele

?

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Re: Real planets dimension?

Post by Sirius_Alpha on 16th November 2012, 4:54 pm

It does seem to me like that website is not accurately drawing the habitable zones.

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Re: Real planets dimension?

Post by Lazarus on 17th November 2012, 5:23 am

In the following graph, the planets are scaled according to their mass, assuming a simple model with constant density. The planets in our own solar system are plotted as a comparison.
(emphasis added)

Such a model is not going to reproduce the radii of the planets accurately: more massive planets undergo more compression for the same composition. E.g. radii of "cold" (i.e. insignificant effect of internal heat on the planet's radius) Jupiters should peak at a few times Jupiter's mass, then gradually decrease again as the increase in compression outweighs the extra volume of the added material.

As for Gliese 581, the HZ is plotted outside the orbit of "f": http://exoplanet.hanno-rein.de/system.php?id=Gliese+581+f

It is stated they are using mass and spectral type of the star to estimate the HZ but not the actual details of the calculation. I'd guess their mass-luminosity relationship is somewhat off!

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