A companion close to the planet/brown-dwarf transition around HD16760

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A companion close to the planet/brown-dwarf transition around HD16760

Post by Edasich on 22nd July 2009, 3:44 am

The SOPHIE northern extrasolar planets. I. A companion close to the planet/brown-dwarf transition around HD16760

We report on the discovery of a substellar companion or a massive Jupiter orbiting the G5V star HD16760 with the spectrograph SOPHIE installed on the OHP 1.93-m telescope. Characteristics and performances of the spectrograph are presented, as well as the SOPHIE exoplanet consortium program. With a minimum mass of 14.3 Mjup, an orbital period of 465 days and an eccentricity of 0.067, HD16760b seems to be located just at the end of the mass distribution of giant planets, close to planet/brown-dwarf transition. Its quite circular orbit supports a formation in a gaseous protoplanetary disk.

The planet/brown dwarf limit discussion is still open cyclops

Plus, I've found hints of an exoplanet around the bright F star Theta Cygni (paper likely upcoming)

As part of the SOPHIE consortium programs, the detectionof four exoplanets have been published up to now: HD43691band HD132406b (Da Silva et al. 2008), HD45652b (Santos etal. 2008), and θ Cygni b (Desort et al. 2009). These planets haverespectively minimum masses of 2.5, 5.6, 0.5 and 2.3 MJup witha 37, 975, 44 and 154 day periods.
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Re: A companion close to the planet/brown-dwarf transition around HD16760

Post by Lazarus on 29th July 2009, 2:55 pm

Definitely seems that using deuterium fusion as the discriminator is not reflecting very well how nature puts solar systems together, even if it is significant in determining the object's evolution. In any case, "planet" is a category that comprises objects as different from each other as Mercury and Jupiter. (Likewise the term "star" embraces objects that evolve in very different ways too)

HD 16760 is a member of the binary system ADS 2056, separation >700 AU. No mention made of radial velocity observations of the companion star (HIP 12635) though.
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Re: A companion close to the planet/brown-dwarf transition around HD16760

Post by Lazarus on 30th July 2009, 2:27 am

Independent discovery by N2K

They adopt a lower stellar mass thus obtain a lower m sin i for the companion of 13.13 Jupiter masses
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Re: A companion close to the planet/brown-dwarf transition around HD16760

Post by AVBursch on 30th July 2009, 5:37 am

Fortuitously, this system would be a lot like HD 28185. The companion (likely a brown dwarf) is in the right spot, within the HZ of the yellow dwarf primary, to possibly have Earth-like worlds orbiting it. Even if the companion formed in the same way that planets do, the companion could still have one or more moons of sufficient mass to have Earth-like characteristics.

The HD 16760 system is worth further scritinization, especially when astronomers are able to searh for exo-moons.

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Re: A companion close to the planet/brown-dwarf transition around HD16760

Post by Lazarus on 30th July 2009, 4:12 pm

The second paper gives a luminosity for the star of 0.72 times solar, so the object would receive about 60% Earth insolation, rather more than Mars does but still beyond some more conservative estimates of the outer HZ boundary. HD 28185b on the other hand receives more Earthlike insolation and is located close to the inner edge.
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Re: A companion close to the planet/brown-dwarf transition around HD16760

Post by Edasich on 31st July 2009, 6:03 am

However the massive planet could emit heat and make putative moons less frosty. Smile
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Re: A companion close to the planet/brown-dwarf transition around HD16760

Post by Sirius_Alpha on 31st July 2009, 6:19 am

Indeed. Would calculating the temperature of an orbiting body around HD 16760 b be as simple as adding up the fluxes from both the central star and HD 16760 b? (assuming of course we know b's brightness).

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