J/AJ/161/47 Radial velocity & photometry of HD106315 & GJ9827 (Kosiarek+, 2021)
Physical parameters of the multiplanet systems HD 106315 and GJ 9827.
Kosiarek M.R., Berardo D.A., Crossfield I.J.M., Laguna C., Piaulet C.,
Akana Murphy J.M., Howell S.B., Henry G.W., Isaacson H., Fulton B.,
Weiss L.M., Petigura E.A., Behmard A., Hirsch L.A., Teske J., Burt J.A.,
Mills S.M., Chontos A., Mocnik T., Howard A.W., Werner M., Livingston J.H.,
Krick J., Beichman C., Gorjian V., Kreidberg L., Morley C.,
Christiansen J.L., Morales F.Y., Scott N.J., Crane J.D., Wang S.X.,
Shectman S.A., Rosenthal L.J., Grunblatt S.K., Rubenzahl R.A., Dalba P.A.,
Giacalone S., Villanueva C.D., Liu Q., Dai F., Hill M.L., Rice M.,
Kane S.R., Mayo A.W.
<Astron. J., 161, 47 (2021)>
=2021AJ....161...47K 2021AJ....161...47K
ADC_Keywords: Exoplanets; Stars, nearby; Radial velocities; Photometry, RI
Keywords: Radial velocity ; Exoplanets ; Mini Neptunes ; Transit photometry ;
Gaussian Processes regression ; Super Earths
Abstract:
HD106315 and GJ9827 are two bright, nearby stars that host multiple
super-Earths and sub-Neptunes discovered by K2 that are well suited
for atmospheric characterization. We refined the planets ephemerides
through Spitzer transits, enabling accurate transit prediction
required for future atmospheric characterization through transmission
spectroscopy. Through a multiyear high-cadence observing campaign with
Keck/High Resolution Echelle Spectrometer and Magellan/Planet Finder
Spectrograph, we improved the planets mass measurements in
anticipation of Hubble Space Telescope transmission spectroscopy. For
GJ9827, we modeled activity-induced radial velocity signals with a
Gaussian process informed by the CalciumII H&K lines in order to more
accurately model the effect of stellar noise on our data. We measured
planet masses of Mb=4.87±0.37M⊕, Mc=1.92±0.49M⊕,
and Md=3.42±0.62M⊕. For HD 06315, we found that such
activity radial velocity decorrelation was not effective due to the
reduced presence of spots and speculate that this may extend to other
hot stars as well (Teff>6200K). We measured planet masses of
Mb=10.5±3.1M⊕ and Mc=12.0±3.8M⊕. We investigated
all of the planets compositions through comparison of their masses and
radii to a range of interior models. GJ9827b and GJ9827c are both
consistent with a 50/50 rock-iron composition, GJ9827d and HD106315b
both require additional volatiles and are consistent with moderate
amounts of water or hydrogen/helium, and HD106315c is consistent with
a ∼10% hydrogen/helium envelope surrounding an Earth-like rock and
iron core.
Description:
We collected radial velocity measurements of GJ9827 and HD106315 with
the High Resolution Echelle Spectrometer (HIRES) on the Keck I
Telescope on Maunakea. We obtained 92 measurements of GJ9827 with
HIRES between 2017 September 22 and 2020 January 8. These data were
collected with the C2 decker (R=50k) with a typical signal-to-noise
ratio (S/N) of 200/pixel.
We obtained 352 measurements of HD106315 with HIRES between 2016
December 23 and 2020 February 1 (R=50k). We obtained 25 measurements
of HD106315 with Planet Finder Spectroscope (PFS) between 2017 January
6 and 2018 June 30 (R∼80k).A single observation with an exposure time
of 10 to 25 minutes was taken per night. After a PFS upgrade in 2018
February, multiple exposures were taken with R∼130k. We collected 125
measurements on the Automated Planet Finder (APF).
Objects:
------------------------------------------------
RA (2000) DE Designation(s)
------------------------------------------------
12 13 53.40 -00 23 36.6 HD 106315 = HD 106315
23 27 04.84 -01 17 10.6 GJ 9827 = BD-02 5958
------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 50 92 GJ 9827 Radial Velocities
table4.dat 50 501 HD 106315 Radial Velocities
table6.dat 21 74 GJ 9827 Photometry
table7.dat 21 43 HD 106315 Photometry
--------------------------------------------------------------------------------
See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)
J/A+A/529/A75 : Limb-darkening coefficients (Claret+, 2011)
J/AJ/142/19 : Speckle observations of KOI (Howell+, 2011)
J/ApJ/764/3 : Hα indices in M low-mass stars (Robertson+, 2013)
J/ApJ/805/175 : Keck and APF radial velocities of HD7924 (Fulton+, 2015)
J/AJ/154/109 : California-Kepler Survey. III. Planet radii (Fulton+, 2017)
J/ApJ/844/102 : KIC star plxs from asteroseismology vs Gaia (Huber+, 2017)
J/A+A/603/L5 : HD106315c I light curve (Lendl+, 2017)
J/AJ/154/107 : California-Kepler Survey. I. 1305 stars (Petigura+, 2017)
J/ApJ/836/77 : Library of high-S/N optical spectra FGKM stars (Yee+, 2017)
J/MNRAS/484/3731 : GJ 9827 HARPS-N RV data (Rice+, 2019)
Byte-by-byte Description of file: table[34].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d BJD Barycentric Julian Date; TDB
15- 21 F7.2 m/s RVel Radial velocity
23- 27 F5.2 m/s e_RVel Uncertainty in RVel
29- 35 F7.4 --- SHK ? Calcium II H&K lines index (1)
37- 44 F8.5 --- Ha ? Hα index
46- 50 A5 --- Inst Instrument used; HIRES, APF or PFS
--------------------------------------------------------------------------------
Note (1): SHK values have an uncertainty of 0.001 for HIRES data,
0.002 for APF data, and no calculated uncertainties
for PFS data.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table[67].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.4 d HJD Heliocentric Julian Date
14- 21 F8.5 mag Rmag Differential Cousins R band magnitude
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 09-Mar-2021