J/AJ/160/207 OSIRIS K-band spectroscopy of κ Andromedae b (Wilcomb+, 2020)
Moderate-resolution K-band spectroscopy of substellar companion
κ Andromedae b.
Wilcomb+, Wilcomb K.K., Konopacky Q.M., Barman T.S., Theissen C.A.,
Ruffio J.-B., Brock L., Macintosh B., Marois C.
<Astron. J., 160, 207 (2020)>
=2020AJ....160..207W 2020AJ....160..207W
ADC_Keywords: Stars, brown dwarf; Exoplanets; Spectra, infrared
Keywords: Direct imaging ; Exoplanet atmospheres ;
High resolution spectroscopy ; Exoplanet formation ; Radial velocity
Abstract:
We present moderate-resolution (R∼4000) K-band spectra of the "super-
Jupiter," κ-Andromedae-b. The data were taken with the OSIRIS
integral field spectrograph at Keck Observatory. The spectra reveal
resolved molecular lines from H2O and CO, and are compared to a custom
PHOENIX atmosphere model grid appropriate for young planetary-mass
objects. We fit the data using a Markov chain Monte Carlo
forward-modeling method. Using a combination of our
moderate-resolution spectrum and low-resolution, broadband data from
the literature, we derive an effective temperature of Teff=1950-2150K,
a surface gravity of logg=3.5--4.5, and a metallicity of
[M/H]=-0.2--0.0. These values are consistent with previous estimates
from atmospheric modeling and the currently favored young age of the
system (<50Myr). We derive a C/O ratio of 0.70-0.24+0.09 for the
source, broadly consistent with the solar C/O ratio. This, coupled
with the slightly subsolar metallicity, implies a composition
consistent with that of the host star, and is suggestive of formation
by a rapid process. The subsolar metallicity of κ-Andromedae-b
is also consistent with predictions of formation via gravitational
instability. Further constraints on formation of the companion will
require measurement of the C/O ratio of κ-Andromedae-A. We also
measure the radial velocity of κ-Andromedae-b for the first
time, with a value of -1.4±0.9km/s relative to the host star. We
find that the derived radial velocity is consistent with the estimated
high eccentricity of κ-Andromedae-b.
Description:
κ-And-b was observed in 2016 and 2017 with the Optical System
for Imaging and low-Intermediate-Resolution Integrated Spectroscopy
(OSIRIS) integral field spectrograph at Keck Observatory in the K
broadband mode (1.965-2.381µm) with a spatial sampling of 20mas per
lenslet. R∼4000.
Objects:
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RA (2000) DE Designation(s)
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23 40 24.58 +44 20 02.8 * kap And B = * kap And B
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig2.dat 31 1665 Fully reduced, combined, and flux calibrated
moderate-resolution OSIRIS K-band spectra of
κ And b
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/463/671 : Rotational velocities of A-type stars. III. (Royer+, 2007)
J/ApJ/723/684 : NIRSPEC ultracool dwarf radial velocity survey (Blake+,2010)
J/A+A/525/A71 : Atmospheric parameters for 1273 stars (Wu+, 2011)
J/ApJ/794/146 : M dwarfs with IR excess (Theissen+, 2014)
J/MNRAS/440/1649 : ExoMol line lists for CH4 (Yurchenko+, 2014)
J/MNRAS/454/593 : Young moving groups in solar neighbourhood (Bell+, 2015)
J/ApJ/804/146 : Atmospheric parameters for nearby B-F stars (David+, 2015)
J/A+A/603/A30 : Evidence for 2 distinct giant planet pop. (Santos+, 2017)
J/AJ/157/63 : Rad. relations for low-metallicity M-dwarf (Kesseli+, 2019)
J/AJ/158/13 : The first 300 stars observed by the GPIES (Nielsen+, 2019)
J/AJ/159/63 : New AO obs. of exoplanets & brown dwarf comp. (Bowler+,2020)
Byte-by-byte Description of file: fig2.dat
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Bytes Format Units Label Explanations
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1- 11 E11.5 um Wave [1.9/2.4] Wavelength
13- 21 E9.3 W/m2/um Flux [1e-14/2.5e-14] Flux density
23- 31 E9.3 W/m2/um e_Flux [6.6e-16/6e-15] Uncertainty in Flux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 14-Jan-2021