Two jovian planets at HD 60532 from HARPS

Extrasolar planets and brown dwarfs around A-F type stars V. A planetary system found with HARPS around the F6IV-V star HD 60532
http://arxiv.org/abs/0809.3862

Abstract wrote:

Aims: In the frame of the search for extrasolar planets and brown dwarfs around early-type stars, we present the results obtained for the F-type main-sequence star HD 60532 (F6V) with HARPS.
Methods: Using 147 spectra obtained with HARPS at La Silla on a time baseline of two years, we study the radial velocities of this star.
Results: HD 60532 radial velocities are periodically variable, and the variations have a Keplerian origin. This star is surrounded by a planetary system of two planets with minimum masses of 1 and 2.5 Mjup and orbital separations of 0.76 and 1.58 AU respectively. We also detect high-frequency, low-amplitude (10 m/s peak-to-peak) pulsations. Dynamical studies of the system point toward a possible 3:1 mean-motion resonance which should be confirmed within the next decade.

Looks like the system may be a bit chaotic, with eccentricities being exchanged back and forth.

Oddly EPE lists 313 exoplanets, while previous number was 310. A typo or another exoplanet upcoming?

Moreover HD 60532 c seems laying in the system habitable zone assuming host star's water zone within 1.6 AUs and stellar radius similar to mass.

EDIT = CT Chamaeleontis' companion is included amongst "Candidated detected by imaging". So here is the 313rd (alike Donald Duck's car LOL)

Michael Johne wrote:

Hi!

Edasich wrote:

Oddly EPE lists 313 exoplanets, while previous number was 310. A typo or another exoplanet upcoming?

--> CT Cha b

Bye!

You've missed my edit....

A low metallicity star this one, [Fe/H] = -0.42 (i.e. 38% of the solar iron-to-hydrogen ratio), but also a relatively massive star - as the paper points out, it is one of only two known main-sequence extrasolar planet host stars with a mass above 1.3 solar masses. Also quite luminous, the HZ is at roughly 3 AU.

tesh90 wrote:

Why is the title "extrasolaplanets and brown drawfs..." - they don't really present any data on brown drawfs?

That's the title of the series of papers: this is the fifth in the series. So while this particular paper doesn't discuss brown dwarfs, some of the other papers do (e.g. Extrasolar planets and brown dwarfs around A-F type stars. IV. A candidate brown dwarf around the A9V pulsating star HD180777)

How did you find the luminosity?

Either use absolute magnitude (this gives visual luminosity, but this probably isn't too bad an estimate in spectral types G and F), or work from mass, gravity and temperature. (Note that the log g value in the paper appears to have picked up a spurious minus sign).

Furthermore, the NASA/IPAC/NExSci Star and Exoplanet Database at http://nsted.ipac.caltech.edu/ has HD 60532's luminosity.

Nearly 9 times more luminous than Sun (L_{HD 60532}=8.6 L_Sol).

If I understood the abstract right, here's confirmation of 3:1 resonance, and a determination of inclination?

HD60532, a planetary system in a 3:1 mean motion resonance
http://arxiv.org/abs/0902.0667

Abstract wrote:

In a recent paper it was reported a planetary system around the star HD60532, composed by two giant planets in a possible 3:1 mean motion resonance, that should be confirmed within the next decade. Here we show that the analysis of the global dynamics of the system allows to confirm this resonance. The present best fit to data already corresponds to this resonant configuration and the system is stable for at least 5Gry. The 3:1 resonance is so robust that stability is still possible for a wide variety of orbital parameters around the best fit solution and also if the inclination of the system orbital plane with respect to the plane of the sky is as small as 15 deg. Moreover, if the inclination is taken as a free parameter in the adjustment to the observations, we find an inclination ~ 20 deg, which corresponds to M_b =3.1 M_Jup and M_c = 7.4 M_Jup for the planetary companions.

Nice to see a proper 3:1 resonant system now that 55 Cancri b+c are no longer thought to be in that configuration. Interesting that the best-fit inclination is so close to the limit of the stable region. More evidence for packed planetary systems?

Formation of the resonant system HD 60532
http://arxiv.org/abs/1004.5488

Abstract wrote:

Among multi-planet planetary systems there are a large fraction of resonant systems. Studying the dynamics and formation of these systems can provide valuable informations on processes taking place in protoplanetary disks where the planets are thought have been formed. The recently discovered resonant system HD 60532 is the only confirmed case, in which the central star hosts a pair of giant planets in 3:1 mean motion resonance. We intend to provide a physical scenario for the formation of HD 60532, which is consistent with the orbital solutions derived from the radial velocity measurements. Observations indicate that the system is in an antisymmetric configuration, while previous theoretical investigations indicate an asymmetric equilibrium state. The paper aims at answering this discrepancy as well. We performed two-dimensional hydrodynamical simulations of thin disks with an embedded pair of massive planets. Additionally, migration and resonant capture are studied by gravitational N-body simulations that apply properly parametrized non-conservative forces. Our simulations suggest that the capture into the 3:1 mean motion resonance takes place only for higher planetary masses, thus favouring orbital solutions having relatively smaller inclination i=20 degrees. The system formed by numerical simulations qualitatively show the same behaviour as HD 60532. We also find that the presence of an inner disk (between the inner planet and the star) plays a very important role in determining the final configurations of resonant planetary systems. Its damping effect on the inner planet's eccentricity is responsible for the observed antisymmetric state of HD 60532.

Stability Analysis of Possible Terrestrial Planets in the HD 60532 System
http://arxiv.org/abs/1304.1563

Quote :

Investigations were carried out on the stability of the two gas giant system HD 60532 itself including additional, smaller bodies. The methods used were numerical simulations with the Lie Series integration method, and secular perturbation theory. The aims were to find stable regions for potential Earth-like planets within the system, and confirming the stability of the detected planets. As results, the given configuration can be considered stable for a period of at least 65 million years. The two planets create a large unstable section between 0.25 and 3.6 AU, where no additional body is able to remain stable. Variations in the mutual inclination between test bodies and the rest of the system of up to 20{\deg} have little effects on the size of the zone of instability.