J/AJ/162/294 HIRES radial velocity follow up of K2-182 & K2-199 (Murphy+, 2021)
Another superdense sub-Neptune in K2-182b and refined mass measurements for
K2-199b and c.
Murphy J.M.A., Kosiarek M.R., Batalha N.M., Gonzales E.J., Isaacson H.,
Petigura E.A., Weiss L.M., Grunblatt S.K., Ciardi D.R., Fulton B.,
Hirsch L.A., Behmard A., Rosenthal L.J.
<Astron. J., 162, 294-294 (2021)>
=2021AJ....162..294M 2021AJ....162..294M (SIMBAD/NED BibCode)
ADC_Keywords: Exoplanets; Spectra, optical; Radial velocities
Keywords: RV; Exoplanets
Abstract:
We combine multiple campaigns of K2 photometry with precision radial
velocity measurements from Keck-HIRES to measure the masses of three
sub-Neptune-sized planets. We confirm the planetary nature of the
massive sub-Neptune K2-182b (Pb=4.7days, Rb=2.69R⊕) and
derive refined parameters for K2-199b and c (Pb=3.2days,
Rb=1.73R⊕ and Pc= 7.4days, Rc=2.85R⊕). These planets
provide valuable data points in the mass-radius plane, especially as
TESS continues to reveal an increasingly diverse sample of
sub-Neptunes. The moderately bright (V=12.0mag) early K dwarf K2-182
(EPIC 211359660) was observed during K2 campaigns 5 and 18. We find
that K2-182b is potentially one of the densest sub-Neptunes known to
date (20±5M⊕ and 5.6±1.4g/cm3). The K5V dwarf K2-199
(EPIC212779596; V=12.3mag), observed in K2 campaigns 6 and 17, hosts
two recently confirmed planets. We refine the orbital and planetary
parameters for K2-199b and c by modeling both campaigns of K2
photometry and adding 12 Keck-HIRES measurements to the existing
radial velocity data set (N=33). We find that K2-199b is likely rocky,
at 6.9±1.8M⊕ and 7.2-2.0+2.1g/cm3, and that K2-199c
has an intermediate density at 12.4±2.3M⊕ and
2.9-0.6+0.7g/cm3. We contextualize these planets on the
mass-radius plane, discuss a small but intriguing population of
"superdense" sub-Neptunes (Rp<3R⊕, Mp>20M⊕), and
consider our prospects for the planets' atmospheric characterization.
Description:
We obtained high-resolution spectra of both K2-182 and K2-199 with
Keck-HIRES to measure precise RVel. The observations of K2-182 were
taken between UTC 2019 March 27 and May 29 with a median exposure time
of 1208s and a median S/N of 100/pixel. The observations of K2-199
were taken between UTC 2019 February 18 and May 30 with a median
exposure time of 1402s and a median S/N of 100/pixel. All spectra were
collected with the C2 decker (14"x0.86", R=60000) to allow for sky
subtraction.
Objects:
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RA (2000) DE Designation(s) (Periodb) (Periodc)
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08 40 43.28 +10 58 58.6 K2-182 = K2-182 (P=4.7369683)
13 55 36.41 -06 08 10.1 K2-199 = K2-199 (P=3.2253993) (P=7.3744897)
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table6.dat 31 12 K2-182 radial velocities
table7.dat 31 45 K2-199 radial velocities
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
VI/120 : High-resolution synthetic stellar library (Coelho+, 2005)
J/A+A/541/A9 : M dwarfs activity and radial velocity (Gomes da Silva+, 2012)
J/PASP/124/1279 : Q3 Kepler's combined photometry (Christiansen+, 2012)
J/ApJS/224/2 : K2 EPIC stellar properties for 138600 targets (Huber+, 2016)
J/AJ/153/71 : Kepler follow-up observation program I. Imaging (Furlan+, 2017)
J/AJ/154/109 : California-Kepler Survey. III. Planet radii (Fulton+, 2017)
J/AJ/154/5 : Transit timing variations of 145 Kepler planets (Hadden+, 2017)
J/ApJ/836/167 : K2 planetary syst. around low-mass stars. I. (Dressing+, 2017)
J/ApJ/866/99 : Revised radii KIC stars & planets using GaiaDR2 (Berger+, 2018)
J/ApJS/239/5 : Variable stars and cand. planets from K2 (Crossfield+, 2018)
J/MNRAS/474/2094 : Inferring proba. stellar rotation periods (Angus+, 2018)
J/AJ/161/36 : 117 exoplanets habitable zone with Kepler DR25 (Bryson+, 2021)
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d BJD [2458568/2458633] Barycentric Julian Date
15- 20 F6.2 m/s RVel [-14.9/8.79] Radial velocity
22- 25 F4.2 m/s e_RVel [1.4/1.7] Uncertainty in RVel (1)
27- 31 A5 --- Inst Instrument
--------------------------------------------------------------------------------
Note (1): Uncertainties reported here are added in quadrature with an
instrumental parameter for RVel jitter, σj=4.3m/s,
that was fit to the data.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d BJD [2457562/2458634] Barycentric Julian Date
15- 20 F6.2 m/s RVel [-19.2/13.7] Radial velocity
22- 25 F4.2 m/s e_RVel [1.3/2.3] Uncertainty in RVel (1)
27- 31 A5 --- Inst Instrument
--------------------------------------------------------------------------------
Note (1): Uncertainties reported here are added in quadrature with an
instrumental parameter for RVel jitter, σj=4.14m/s,
that was fit to the data.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 11-Mar-2022