Planets around stellar remnants

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Planets around stellar remnants

Post by Lazarus on 16th January 2012, 7:14 pm

Conference webpage

Some interesting bits and pieces in the abstract book... I'd heard about the potential candidate pulsar planet system in NGC 6440 a while back (it isn't NGC 6440 X2), was wondering where that one had got to.
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Re: Planets around stellar remnants

Post by Lazarus on 17th January 2012, 6:50 pm

Being less cryptic about the potential NGC 6440 system...

Steve Bégin: "A search for fast pulsars in globular clusters"
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Re: Planets around stellar remnants

Post by Sirius_Alpha on 17th January 2012, 7:12 pm

A Mars-mass planet, nice.
What's the theoretical lower limit to the mass of a companion star after mass transfer to the pulsar?

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Re: Planets around stellar remnants

Post by Lazarus on 18th January 2012, 3:31 am

Good question... potentially zero I guess...

On the other hand this one does not look like this kind of remnant, the orbital period is too long. If it exists it may be more of an analogue to the PSR B1257+12 planets.
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Re: Planets around stellar remnants

Post by Edasich on 18th January 2012, 8:42 am

Download the abstract books. Very very interesting discoveries

http://www.mpia-hd.mpg.de/PLANETS2012/abstracts/Abstract_book.pdf

A taste?



Evidence for a low-mass companion around the extremely hot pre-white dwarf central star WD 0044-121 of the planetary nebula NGC 246 Wei Wang (National Astronomical Observatories of China)


The numerous exoplanet detections during the last two decades have opened the possibility to study the evolution of planetary systems. There remains the challenging question if planets survive the final phase of stellar evolution. To answer this question, we initiated a pilot survey to search for substellar companions around nearby bright white dwarfs with the radial-velocity (RV) technique, using the FEROS instrument at the 2.2m MPG/ESO telescope. We detected a RV variation with a period of ~4 days and a semi-amplitude of 1.85 km/s in the hot white dwarf WD 0044-121. After investigating stellar pulsations and activity, such as a stellar wind, modulated by stellar rotation as the source of the RV variation, we concluded that the RV variation is probably caused by an orbiting low-mass companion. We derived the companion minimum mass to be 10.48(2.06) M_Jup and an orbital semi-major axis of 0.046 AU. This finding suggests that giant planets or brown dwarfs can either survive the violent evolution stages or have the chance to be 'born-again' in the dusty disk of an evolved system.
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Re: Planets around stellar remnants

Post by Lazarus on 23rd February 2012, 4:26 pm

Some of the presentation slides and posters are now up.

E.g. Ronny Lutz "Substellar companion candidates around two pulsating sdB stars" (pdf):

HS 0444+0458b
m sin i = (31.41±7.25) MJ
a = (0.269±0.001) AU

HS 0702+6043b
m sin i = (5.58±1.44) MJ
a = (1.148±0.050) AU

Also potentially something interesting going on with PSR B1620-26...
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Re: Planets around stellar remnants

Post by Sirius_Alpha on 24th February 2012, 8:28 am

The latter is now in the EPE under the unconfirmed planets list.
http://exoplanet.eu/planet.php?p1=HS+0702&p2=b

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Re: Planets around stellar remnants

Post by Lazarus on 25th February 2012, 6:05 am

Also not looking good for GD 66 b:

JJ Hermes "8 Years On: A Search for Planets Around Isolated White Dwarfs"

The O-C diagrams for different modes are out-of-phase with each other, which would not be the case if the reason for the variations was an orbiting planet. Need to confirm a planet using multiple modes before claiming discovery.

Perhaps a planet at WD 1354+0108 which has 4 modes in relative lockstep but clearly have to be careful about this interpretation.
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Re: Planets around stellar remnants

Post by tommi59 on 25th February 2012, 1:46 pm

Looking for planets around white dwarfs is not really interesting as all life on planets are destroyed during red giaht phase
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Re: Planets around stellar remnants

Post by jyril on 25th February 2012, 4:36 pm

Why planets without potential life would be uninteresting? Following that logic there would be only one interesting world in the Solar System...

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