J/MNRAS/443/L89 Kapteyn's star spectroscopic measurements (Anglada-Escude+ 2014)
Two planets around Kapteyn's star : a cold and a temperate super-Earth orbiting
the nearest halo red-dwarf.
Anglada-Escude G., Arriagada P., Tuomi M., Zechmeister M., Jenkins J.S.,
Ofir A., Dreizler S., Gerlach E., Marvin C.J., Reiners A., Jeffers S.V.,
Butler R.P., Vogt S.S., Amado P.J., Rodriguez-Lopez C., Berdinas Z.M.,
Morin J., Crane J.D., Shectman S.A., Thompson I.B., Diaz M., Rivera E.,
Sarmiento L.F., Jones H.R.A.
<Mon. Not. R. Astron. Soc. 443, L89 (2014)>
=2014MNRAS.443L..89A 2014MNRAS.443L..89A
ADC_Keywords: Stars, variable ; Radial velocities ; Line Profiles
Keywords: techniques: radial velocities - stars: individual: Kapteyn's star -
planetary systems
Abstract:
Exoplanets of a few Earth masses can be now detected around nearby
low-mass stars using Doppler spectroscopy. In this paper, we
investigate the radial velocity variations of Kapteyn's star, which is
both a sub-dwarf M-star and the nearest halo object to the Sun. The
observations comprise archival and new HARPS, HIRES and PFS Doppler
measurements. Two Doppler signals are detected at periods of 48 and
120 days using likelihood periodograms and a Bayesian analysis of the
data. Using the same techniques, the activity indices and archival
ASAS-3 photometry show evidence for low-level activity periodicities
of the order of several hundred days. However, there are no
significant correlations with the radial velocity variations on the
same time-scales. The inclusion of planetary Keplerian signals in the
model results in levels of correlated and excess white noise that are
remarkably low compared to younger G, K and M dwarfs. We conclude that
Kapteyn's star is most probably orbited by two super-Earth mass
planets, one of which is orbiting in its circumstellar habitable zone,
becoming the oldest potentially habitable planet known to date. The
presence and long-term survival of a planetary system seems a
remarkable feat given the peculiar origin and kinematic history of
Kapteyn's star. The detection of super-Earth mass planets around halo
stars provides important insights into planet-formation processes in
the early days of the Milky Way.
Description:
Time-series of spectroscopic measurements used in the paper. Median
value and a perspective acceleration were subtracted to each RVs set
(Ins. 1 is HARPS, 2 is HIRES, 3 is PFS). Measurements of the FWHM, BIS
of the cross-correlation profiles and measurements of the S-index are
provided for HARPS data only. Uncertainty in the FWHM is 2.5 times the
uncertainty in BIS. Check (2012ApJS..200...15A 2012ApJS..200...15A), for more detailed
definitions of the measurements and their uses.
Objects:
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RA (2000) DE Designation(s)
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05 11 40.58 -45 01 06.3 Kapteyn's star = GJ 191
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 60 135 Spectroscopic observables
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See also:
J/ApJS/200/15 : HARPS-TERRA project. I. (Anglada-Escude+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d JD Barycentric Julian date
15- 19 F5.2 m/s RV Radial velocity
21- 24 F4.2 m/s e_RV Uncertainy in RV
26 I1 --- Inst [1/3] Instrument used: 1=HARPS, 2=HIRES; 3=PFS
28- 33 F6.2 m/s BIS ?=0 Bisector span of the CCF
35- 38 F4.2 m/s e_BIS ?=0 Uncertainty in BIS
40- 46 F7.5 km/s FWHM ?=0 FWHM of the CCF (uncertainty=2.5*e_BIS)
48- 53 F6.4 --- Sidx ?=0 CaII H+K S-index in the Mount Wilson system
55- 60 F6.4 --- e_Sidx ?=0 Uncertainty in S-index
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Acknowledgements:
Guillem Anglada-Escude, g.anglada(at)qmul.ac.uk
References:
Mayor et al., 2003Msngr.114...20M 2003Msngr.114...20M Setting New Standards with HARPS
Anglada-Escude & Butler, 2012ApJS..200...15A 2012ApJS..200...15A, Cat. J/ApJS/200/15
The HARPS-TERRA Project. I. Description of the Algorithms.
Vogt et al., 1994SPIE.2198..362V 1994SPIE.2198..362V
HIRES: the high-resolution echelle spectrometer on the Keck 10-m Telescope
Crane et al., 2010SPIE.7735E.170C 2010SPIE.7735E.170C
The Carnegie Planet Finder Spectrograph: integration and commissioning
(End) Patricia Vannier [CDS] 28-May-2014