Kuiper belts at 82 Eri and HD 38858

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Kuiper belts at 82 Eri and HD 38858

Post by Lazarus on 10th March 2015, 2:25 pm

Kennedy et al. "Kuiper belt structure around nearby super-Earth host stars"
http://arxiv.org/abs/1503.02073

Not yet clear whether the inner cleared region is due to planets or not. There may be a link between planet mass and disc radial width.

Also the planet candidate HD 38858 b turns out to be an alias of the stellar activity cycle:
HD 38858b was announced by Mayor et al. (2011), as a planet with a minimum mass of 30.55 M orbiting at 1 au, using 52 RV measurements taken over eight years. With additional data it has become clear that this signal was spurious and arises due to an alias of the magnetic cycle of the star, which has a period of 2930 days. The additional data (now 96 measurements with several years more coverage) have however revealed a planetary signal with a period of 198 ± 1 days (0.64 au) and minimum mass of 12 ± 2M
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Re: Kuiper belts at 82 Eri and HD 38858

Post by Sunchaser on 12th March 2015, 8:21 am

Based on HD 38858's mass and the newer planet's distance, could it be habitable?

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Re: Kuiper belts at 82 Eri and HD 38858

Post by Shellface on 4th April 2015, 1:12 pm

Based on HD 38858's mass and the newer planet's distance, could it be habitable?
It lies slightly interior to the "optimistic" inner HZ boundary for the star (0.69 AU), and given that it has a minimum mass approximately equal to Uranus, it seems unlikely to be terrestrial. So, unfortunately, most probably not.

Good to see some further study from the same authors of the previous paper. HD 38858's disk seems to be fairly normal for a disked solar-type star. In contrast, HD 20794's is exceptionally faint and fairly close-in, and its detection probably owes somewhat to how close the star is (6 parsecs). Given that the star is something like 12 Gyr old, HD 20794's disk may be valuable in future as an exceptionally long-lived, small disk.

…Interesting to note that the authors revise HD 38858 b's parameters, but say nothing of the sort for HD 20794's system.

…not like I've studied it or anything.

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Re: Kuiper belts at 82 Eri and HD 38858

Post by Stalker on 29th April 2015, 9:29 am

Should the new planet be considered as "confirmed"?

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Re: Kuiper belts at 82 Eri and HD 38858

Post by Shellface on 29th April 2015, 5:06 pm

It's not new; it's a revision of the parameters of the previously published planet. So yes, it is confirmed, but as a replacement to the previous parameters.

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Re: Kuiper belts at 82 Eri and HD 38858

Post by Stalker on 29th April 2015, 5:21 pm

Ok tx.

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