J/A+A/618/A142 Radial velocity for GJ 1132 (Bonfils+, 2018)
Radial velocity follow-up of GJ1132 with HARPS.
A precise mass for planet b and the discovery of a second planet.
Bonfils X., Almenara J.-M., Cloutier R., Wunsche A., Astudillo-Defru N.,
Berta-Thompson Z., Bouchy F., Charbonneau D., Delfosse X., Diaz R.,
Dittmann J., Doyon R., Forveille T., Irwin J., Lovis C., Mayor M., Menou K.,
Murgas F., Newton E., Pepe F., Santos N. C., Udry S.
<Astron. Astrophys. 618, A142 (2018)>
=2018A&A...618A.142B 2018A&A...618A.142B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Radial velocities
Keywords: techniques: radial velocities - stars: late-type - planerary systems
Abstract:
The source GJ1132 is a nearby red dwarf known to host a transiting
Earth-size planet. After its initial detection, we pursued an intense
follow-up with the HARPS velocimeter. We now confirm the detection of
GJ1132b with radial velocities alone. We refined its orbital
parameters, and in particular, its mass (mb= 1.66±0.23M☉),
density (ρb=6.3±1.3g/cm3), and eccentricity (eb<0.22;
95%). We also detected at least one more planet in the system. GJ1132c
is a super-Earth with period Pc=8.93±0.01-days and minimum mass
mcsinic=2.64±0.44M☉. Receiving about 1.9 times more flux
than Earth in our solar system, its equilibrium temperature is that of
a temperate planet (Teq=230-300K for albedos A=0.75-0.00), which
places GJ1132c near the inner edge of the so-called habitable zone.
Despite an a priori favorable orientation for the system, Spitzer
observations reject most transit configurations, leaving a posterior
probability <1% that GJ11 32c transits. GJ1132(d) is a third signal
with period Pd=177±5-days attributed to either a planet candidate
with minimum mass mdsinid=8.4+1.7-2.5M☉ or stellar
activity. Its Doppler signal is the most powerful in our HARPS time
series but appears on a timescale where either the stellar rotation or
a magnetic cycle are viable alternatives to the planet hypothesis. On
the one hand, the period is different than that measured for the
stellar rotation (∼125-days), and a Bayesian statistical analysis we
performed with a Markov chain Monte Carlo and Gaussian processes
demonstrates that the signal is better described by a Keplerian
function than by correlated noise. On the other hand, periodograms of
spectral indices sensitive to stellar activity show power excess at
similar periods to that of this third signal, and radial velocity
shifts induced by stellar activity can also match a Keplerian
function. We therefore prefer to leave the status of GJ1132(d)
undecided.
Description:
The tables contain radial-velocity and spectroscopic indices time
series of GJ1132. They were obtained with he HARPS spectrograph on the
3.6m telescope at La Silla, Chile.
Objects:
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RA (2000) DE Designation(s)
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10 14 51.89 -47 09 24.6 GJ1132 = LHS 281
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 84 128 HARPS measurements for GJ 1132
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See also:
J/AJ/153/191 : Transiting planet GJ 1132 (Southworth+, 2017)
J/AJ/154/142 : GJ 1132 corrected photometry for all eclipses (Dittmann+, 2017)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 12 F12.4 d BJD Barycentric Julian date
14- 20 F7.4 km/s RV Barycentric radial velocity
22- 27 F6.4 km/s e_RV Radial-velocity uncertainty
29- 34 F6.4 --- Halpha Halpha spectral index
36- 41 F6.4 --- e_Halpha Halpha spectral index uncertainty
43- 48 F6.4 --- Hbeta Hbeta spectral index
50- 55 F6.4 --- e_Hbeta Hbeta spectral index uncertainty
57- 62 F6.4 --- NaD Sodium doublet spectral index
64- 69 F6.4 --- e_NaD Sodium doublet spectral index uncertainty
71- 77 F7.4 --- S S calcium index
79- 84 F6.4 --- e_S S calcium index uncertainty
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Acknowledgements:
Xavier Bonfils, xavier.bonfils(at)univ-grenoble-alpes.fr
(End) Xavier Bonfils [IPAG], Patricia Vannier [CDS] 04-Jul-2018