J/AJ/157/97 Radial velocity measurements of K2-3 & GJ3470 (Kosiarek+, 2019)
Bright opportunities for atmospheric characterization of small planets: masses
and radii of K2-3 b, c, and d and GJ3470 b from radial velocity measurements and
Spitzer transits.
Kosiarek M.R., Crossfield I.J.M., Hardegree-Ullman K.K., Livingston J.H.,
Benneke B., Henry G.W., Howard W.S., Berardo D., Blunt S., Fulton B.J.,
Hirsch L.A., Howard A.W., Isaacson H., Petigura E.A., Sinukoff E., Weiss L.,
Bonfils X., Dressing C.D., Knutson H.A., Schlieder J.E., Werner M.,
Gorjian V., Krick J., Morales F.Y., Astudillo-Defru N., Almenara J.-M.,
Delfosse X., Forveille T., Lovis C., Mayor M., Murgas F., Pepe F.,
Santos N.C., Udry S., Corbett H.T., Fors O., Law N.M., Ratzloff J.K.,
del Ser D.
<Astron. J., 157, 97 (2019)>
=2019AJ....157...97K 2019AJ....157...97K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, bright ; Stars, M-type ; Stars, dwarfs ;
Radial velocities ; Exoplanets
Keywords: planets and satellites: composition - techniques: photometric -
techniques: radial velocities
Abstract:
We report improved masses, radii, and densities for four planets in two
bright M-dwarf systems, K2-3 and GJ3470, derived from a combination of
new radial velocity and transit observations. Supplementing K2 photometry
with follow-up Spitzer transit observations refined the transit ephemerides
of K2-3 b, c, and d by over a factor of 10. We analyze ground-based
photometry from the Evryscope and Fairborn Observatory to determine
the characteristic stellar activity timescales for our Gaussian Process
fit, including the stellar rotation period and activity region decay
timescale. The stellar rotation signals for both stars are evident in
the radial velocity data and is included in our fit using a Gaussian
process trained on the photometry. We find the masses of K2-3 b, K2-3 c,
and GJ3470 b to be 6.48-0.93+0.99, 2.14-1.04+1.08, and
12.58-1.28+1.31 M⊕, respectively. K2-3 d was not significantly
detected and has a 3σ upper limit of 2.80 M⊕. These two
systems are training cases for future TESS systems; due to the low planet
densities (ρ<3.7 g/cm-3) and bright host stars (K<9 mag), they
are among the best candidates for transmission spectroscopy in order
to characterize the atmospheric compositions of small planets.
Description:
We obtained RV measurements of K2-3 and GJ3470 using the High Resolution
Echelle Spectrometer (HIRES; Vogt et al. 1994SPIE.2198..362V 1994SPIE.2198..362V) on the Keck I
Telescope. We collected 74 measurements of K2-3 from 2015 February 4
to 2017 April 11 and 56 measurements of GJ3470 from 2012 September 25
to 2017 March 15. These spectra were taken with an iodine cell and the
C2 decker; a template spectrum was also taken in order to calibrate
the wavelength and estimate the RV uncertainty. On average, measurements
of K2-3 were collected with an exposure time of 1600 s in order to reach
a signal-to-noise (S/N) ratio of 87/pixel (80k counts on the HIRES exposure
meter). Measurements of GJ3470 were collected with an exposure time of
1200 s in order to reach an S/N of 60/pixel (40k counts). The observations
and data reduction followed the California Planet Search method described
in Howard et al. (2010ApJ...721.1467H 2010ApJ...721.1467H). RV data for K2-3 and GJ3470 are
shown in Tables 4 and 5.
Objects:
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RA (ICRS) DE Designation(s)
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11 29 20.39 -01 27 17.3 K2-3 = 2MASS J11292037-0127173
07 59 05.84 +15 23 29.2 GJ3470 = LP 424-4
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 49 74 K2-3 HIRES relative RV measurements
table5.dat 49 108 GJ3470 relative RV measurements
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See also:
J/A+A/546/A27 : Radial velocity and photometry for GJ3470 (Bonfils+, 2012)
J/A+A/559/A32 : Light curves of GJ3470b (Nascimbeni+, 2013)
J/A+A/559/A33 : Near-IR Spectrophotometry of GJ 3470b (Crossfield+, 2013)
J/ApJ/770/95 : g'RcIcJ photometry of the hot Uranus GJ3470b (Fukui+, 2013)
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (TESS) (Sullivan+, 2015)
J/A+A/615/A69 : K2-3 system characterized with HARPS-N & HARPS (Damasso+, 2018)
Byte-by-byte Description of file: table4.dat table5.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD Barycentric Julian Date; TDB
16- 27 F12.6 m/s RV [-15.693013/26520.36] Radial velocity
29- 36 F8.6 m/s e_RV [1.315844/7.07] Uncertainty in RV
38- 43 F6.4 --- SHK [0.2492/2.341]? SHK index
45- 49 A5 --- Inst Instrument used (HIRES or HARPS) (only in Table 5)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 03-Jun-2019