| Planet around WD+dM binary NN Serpentis? | |
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+3Sirius_Alpha Lazarus Edasich 7 posters |
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Edasich dK star
Number of posts : 2289 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Planet around WD+dM binary NN Serpentis? 3rd November 2009, 5:00 am | |
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: Planet around WD+dM binary NN Serpentis? 3rd November 2009, 4:03 pm | |
| Another pre-cataclysmic binary eh? If confirmed this could be another case where the planet may have accreted substantial amounts of mass from the matter lost from the red giant star. Wonder what impact that would have on any moon system. | |
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Sirius_Alpha Admin
Number of posts : 4320 Location : Earth Registration date : 2008-04-06
| Subject: Re: Planet around WD+dM binary NN Serpentis? 3rd November 2009, 4:35 pm | |
| I would imagine the increased mass of the planet, plus drag from the moon orbiting within the expelled RGB envelope would lower the moon's orbit quite a bit. _________________ Caps Lock: Cruise control for 'Cool'!
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Edasich dK star
Number of posts : 2289 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: Planet around WD+dM binary NN Serpentis? 3rd November 2009, 4:37 pm | |
| - Lazarus wrote:
- Another pre-cataclysmic binary eh? If confirmed this could be another case where the planet may have accreted substantial amounts of mass from the matter lost from the red giant star. Wonder what impact that would have on any moon system.
It seems there is another one hiding. OV Carinae seems likely to host a 16 Mj object at 17 AUs and it's quite a CV | |
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Sirius_Alpha Admin
Number of posts : 4320 Location : Earth Registration date : 2008-04-06
| Subject: Re: Planet around WD+dM binary NN Serpentis? 3rd November 2009, 4:43 pm | |
| So, since SWIFT J1756.9-2508 (planetary-mass white dwarf + accreting pulsar) is considered a WD + pulsar, would a planet that has accreted enough mass to raise it into the brown dwarf regime still count as a planet? _________________ Caps Lock: Cruise control for 'Cool'!
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: Planet around WD+dM binary NN Serpentis? 3rd November 2009, 5:15 pm | |
| - Sirius_Alpha wrote:
- So, since SWIFT J1756.9-2508 (planetary-mass white dwarf + accreting pulsar) is considered a WD + pulsar, would a planet that has accreted enough mass to raise it into the brown dwarf regime still count as a planet?
What do you mean by the "brown dwarf regime" - fusion of deuterium (which I'd argue does not make a useful boundary between planets and BDs anyway, despite what the IAU WGESP says) or the far side of the brown dwarf desert? | |
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Sirius_Alpha Admin
Number of posts : 4320 Location : Earth Registration date : 2008-04-06
| Subject: Re: Planet around WD+dM binary NN Serpentis? 3rd November 2009, 5:27 pm | |
| Yeah I was thinking the 13 M_j + range. But... yeah.... _________________ Caps Lock: Cruise control for 'Cool'!
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Edasich dK star
Number of posts : 2289 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: Planet around WD+dM binary NN Serpentis? 6th November 2009, 3:28 pm | |
| http://en.wikipedia.org/wiki/NN_Serpentis Been edited by me. There is a correction: I get a luminosity of 4.2 Solar for the white dwarf. Thus water zone would be located at 2 AUs. So the planet would be fairly habitable? At the moment... | |
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Sirius_Alpha Admin
Number of posts : 4320 Location : Earth Registration date : 2008-04-06
| Subject: Re: Planet around WD+dM binary NN Serpentis? 6th November 2009, 10:04 pm | |
| That's odd, I always assumed white dwarfs had sub-solar luminosities. _________________ Caps Lock: Cruise control for 'Cool'!
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Edasich dK star
Number of posts : 2289 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: Planet around WD+dM binary NN Serpentis? 7th November 2009, 5:11 am | |
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: Planet around WD+dM binary NN Serpentis? 7th November 2009, 6:11 am | |
| ...or it is a very young white dwarf.
Note the quoted radius of the white dwarf is roughly 10 times smaller than V391 Peg and the sdB star in HW Virginis. | |
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Edasich dK star
Number of posts : 2289 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: Planet around WD+dM binary NN Serpentis? 7th November 2009, 6:49 am | |
| - Lazarus wrote:
- ...or it is a very young white dwarf.
Note the quoted radius of the white dwarf is roughly 10 times smaller than V391 Peg and the sdB star in HW Virginis. True, but Teff is much higher (57,000 K) | |
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Sirius_Alpha Admin
Number of posts : 4320 Location : Earth Registration date : 2008-04-06
| Subject: Re: Planet around WD+dM binary NN Serpentis? 7th November 2009, 10:05 am | |
| Yeah now I'm a bit confused. With the lower radius of a white dwarf, would this mean there is less surface area from which to emit radiation, translating to less irradiation of planets despite the Teff?
Or does the white dwarf's epic gravity relativistically play with the light to cause it to lose energy before reaching a planet? _________________ Caps Lock: Cruise control for 'Cool'!
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Sedna Planetary Embryo
Number of posts : 87 Registration date : 2008-08-21
| Subject: Re: Planet around WD+dM binary NN Serpentis? 7th November 2009, 10:21 am | |
| - Sirius_Alpha wrote:
- Yeah now I'm a bit confused. With the lower radius of a white dwarf, would this mean there is less surface area from which to emit radiation, translating to less irradiation of planets despite the Teff?
Or does the white dwarf's epic gravity relativistically play with the light to cause it to lose energy before reaching a planet? At first sight, everybody could think like you. But, looking at the formula, the luminosity strongly depends on the temperature (which is raised at the 4th power, while the radius is raised at the 2nd power). So, despite the radius of the WD is 47-48 times smaller than the Sun's and the temperature is only 10 times greater, the temp is "heavier" than the radius.
Last edited by Sedna on 7th November 2009, 2:52 pm; edited 1 time in total | |
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Edasich dK star
Number of posts : 2289 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: Planet around WD+dM binary NN Serpentis? 7th November 2009, 10:49 am | |
| Moreover, as author states, it is a pre-cataclysmic variable, so it's likely the WD is young and thus hotter. | |
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Sirius_Alpha Admin
Number of posts : 4320 Location : Earth Registration date : 2008-04-06
| Subject: Re: Planet around WD+dM binary NN Serpentis? 7th November 2009, 3:25 pm | |
| - Sedna wrote:
- But, looking at the formula, the luminosity strongly depends on the temperature (which is raised at the 4th power, while the radius is raised at the 2nd power).
This applies even for degenerate stars? _________________ Caps Lock: Cruise control for 'Cool'!
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: Planet around WD+dM binary NN Serpentis? 7th November 2009, 3:48 pm | |
| It's a result that applies to blackbody radiation (the Stefan-Boltzmann law). | |
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Sedna Planetary Embryo
Number of posts : 87 Registration date : 2008-08-21
| Subject: Re: Planet around WD+dM binary NN Serpentis? 7th November 2009, 5:41 pm | |
| I have no proof that it cannot be applied for such stars, so... | |
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Edasich dK star
Number of posts : 2289 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: Planet around WD+dM binary NN Serpentis? 7th November 2009, 5:45 pm | |
| However with a luminosity of 4.2 LSolar the planet "temporarily" lies in a comfortable zone for liquid water. | |
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Borislav Jovian
Number of posts : 564 Registration date : 2008-11-12
| Subject: Two planets orbiting NN Serpentis? 1st September 2010, 10:38 am | |
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Borislav Jovian
Number of posts : 564 Registration date : 2008-11-12
| Subject: Re: Planet around WD+dM binary NN Serpentis? 1st September 2010, 11:01 am | |
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Edasich dK star
Number of posts : 2289 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: Planet around WD+dM binary NN Serpentis? 1st September 2010, 11:24 am | |
| Yeah, noticed that one. Cool find. There is even something about a white dwarf EC... something. I prefer call it QU Telescopii | |
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Sirius_Alpha Admin
Number of posts : 4320 Location : Earth Registration date : 2008-04-06
| Subject: Re: Planet around WD+dM binary NN Serpentis? 1st September 2010, 12:09 pm | |
| - Borislav wrote:
- It is possible to merge with earlier themes?
Merged the two threads that are mainly about NN Ser, left the QS Vir one alone. _________________ Caps Lock: Cruise control for 'Cool'!
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: Planet around WD+dM binary NN Serpentis? 1st September 2010, 12:58 pm | |
| Take a look at the picture on the penultimate slide... looks familiar to anyone? | |
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Borislav Jovian
Number of posts : 564 Registration date : 2008-11-12
| Subject: Re: Planet around WD+dM binary NN Serpentis? 1st September 2010, 1:26 pm | |
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| Subject: Re: Planet around WD+dM binary NN Serpentis? | |
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| Planet around WD+dM binary NN Serpentis? | |
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