A giant planet in the tripple system HD 132563

A giant planet in the triple system HD132563
http://arxiv.org/abs/1107.0918

Quote :

As part of our radial velocity planet-search survey performed with SARG at TNG, we monitored the components of HD 132563 for ten years. It is a binary system formed by two rather similar solar type stars with a projected separation of 4.1 arcsec, which corresponds to 400 AU at the distance of 96 pc. The two components are moderately metal-poor and the age of the system is about 5 Gyr. We detected RV variations of HD 132563B with period of 1544 days and semi-amplitude of 26 m/s. From the star characteristics and line profile measurements, we infer their Keplerian origin. Therefore HD 132563B turns out to host a planet with a projected mass msini=1.49 MJup at 2.6 AU with a moderately eccentric orbit (e=0.22). The planet around HD 132563B is one of the few that are known in triple stellar systems, as we found that the primary HD 132563A is itself a spectroscopic binary with a period longer than 15 years and an eccentricity higher than 0.65. The spectroscopic component was not detected in adaptive-optics images taken with AdOpt@TNG, since it expected at a projected separation that was smaller than 0.2 arcsec at the time of our observations. A small excess in K band difference between the components with respect to the difference in V band is compatible with a companion of about 0.55 Msun. A preliminary statistical analysis of the occurrence of planets in triple systems indicate a similar frequency of planets around the isolated component in a triple system, components of wide binaries and single stars. There is no significant iron abundance difference between the components. The lack of stars in binary systems and open clusters showing strong enhancements of iron abundance, comparable to the typical metallicity difference between stars with and without giant planets, agrees with the idea that accretion of planetary material producing iron abundance anomalies larger than 0.1 dex is rare.

The first planet detected by Italian astonomers. Nice!

As the paper points out, all known planets in triple systems are orbiting the isolated component, this one being no exception. Would be nice to find an example of other planetary configurations in these type of system...

Wonder what the planet situation is like in higher-order stellar systems, I guess the challenges of trying to detect circumbinary planets makes this a tricky observational challenge.

[quote="Lazarus"]As the paper points out, all known planets in triple systems are orbiting the isolated component, this one being no exception. Would be nice to find an example of other planetary configurations in these type of system...

Wonder what the planet situation is like in higher-order stellar systems, I guess the challenges of trying to detect circumbinary planets makes this a tricky observational challenge.[/quote

So far circumbinary planets are found orbiting dwarf novae or CVs (HW Vir, HU Aqr, NN Ser) or imaged very far away from young binaries (Ross 458 AB, SR 12 AB). The challenge is finding circumbinary via RV or astrometry around a binary of MS stars.

Edasich wrote:

So far circumbinary planets are found orbiting dwarf novae or CVs (HW Vir, HU Aqr, NN Ser) or imaged very far away from young binaries (Ross 458 AB, SR 12 AB). The challenge is finding circumbinary via RV or astrometry around a binary of MS stars.

Well technically, the planetary systems you cite (HW Vir, HU Aqr, ...) were found through what amounts to a radial velocity method (and indeed suffers the same inclination degeneracies). The only difference is eclipse timing instead of doppler spectroscopy.

Actually the biases in eclipse timing are rather different to those of radial velocity. RV amplitude depends on orbital velocity, short period planets cause the star to move faster. Eclipse timing depends on the size of the orbit (which leads to light travel time delay), thus long-period planets are favoured.