Planets at ο UMa, ο CrB, HD 5608, 75 Cet

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Planets at ο UMa, ο CrB, HD 5608, 75 Cet

Post by Sirius_Alpha on 15th July 2012, 8:13 pm

Substellar Companions to Seven Evolved Intermediate-Mass Stars
http://arxiv.org/abs/1207.3141

We report the detections of substellar companions orbiting around seven evolved intermediate-mass stars from precise Doppler measurements at Okayama Astrophysical Observatory. o UMa (G4 II-III) is a giant with a mass of 3.1 M_sun and hosts a planet with minimum mass of m_2sini=4.1 M_J in an orbit with a period P=1630 d and an eccentricity e=0.13. This is the first planet candidate (< 13 M_J) ever discovered around stars more massive than 3 M_sun. o CrB (K0 III) is a 2.1 M_sun giant and has a planet of m_2sini=1.5 M_J in a 187.8 d orbit with e=0.19. This is one of the least massive planets ever discovered around ~2 M_sun stars. HD 5608 (K0 IV) is an 1.6 M_sun subgiant hosting a planet of m_2sini=1.4 M_J in a 793 d orbit with e=0.19. The star also exhibits a linear velocity trend suggesting the existence of an outer, more massive companion. 75 Cet (G3 III:) is a 2.5 M_sun giant hosting a planet of m_2sini=3.0 M_J in a 692 d orbit with e=0.12. The star also shows possible additional periodicity of about 200 d and 1880 d with velocity amplitude of ~7--10 m/s, although these are not significant at this stage. nu Oph (K0 III) is a 3.0 M_sun giant and has two brown-dwarf companions of m_2sini= 24 M_J and 27 M_J, in orbits with P=530.3 d and 3190 d, and e=0.126 and 0.17, respectively, which were independently announced by Quirrenbach et al. (2011). The ratio of the periods is close to 1:6, suggesting that the companions are in mean motion resonance. We also independently confirmed planets around k CrB (K0 III-IV) and HD 210702 (K1 IV), which had been announced by Johnson et al. (2008) and Johnson et al. (2007a), respectively. All of the orbital parameters we obtained are consistent with the previous results.

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Re: Planets at ο UMa, ο CrB, HD 5608, 75 Cet

Post by Edasich on 16th July 2012, 8:50 am

Omicron Ursae Majoris is a notable star. Proper name is Muscida, the "bear's muzzle". Smile

I see confirmed Kappa Coronae Borealis b, but I wonder if astrometric determination of true mass really assess it at 17-23 Jupiter masses (sensu Reffert & Quirrenbach 2011).
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Re: Planets at ο UMa, ο CrB, HD 5608, 75 Cet

Post by Lazarus on 16th July 2012, 12:25 pm

The Nu Ophiuchi system is a nice one, given the time limit from the star's evolution in assembling the two companions.
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Re: Planets at ο UMa, ο CrB, HD 5608, 75 Cet

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