J/A+A/676/A123 GQ Lup b and GSC 06214-00210 b spectra (Demars+, 2023)
Emission line variability of young 10-30 Mjup companions.
I. The case of GQ Lup b and GSC 06214-00210 b.
Demars D., Bonnefoy M., Dougados C., Aoyama Y., Thanathibodee T.,
Marleau G.-D., Tremblin P., Delorme P., Palma-Bifani P., Petrus S.,
Bowler B.P., Chauvin G., Lagrange A.-M.
<Astron. Astrophys. 676, A123 (2023)>
=2023A&A...676A.123D 2023A&A...676A.123D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Spectra, infrared
Keywords: planets and satellites: formation -
planets and satellites: individual: GQ Lup b -
planets and satellites: individual: GSC 06214-00210 b -
accretion, accretion disks
Abstract:
Emission lines indicative of active accretion have been seen on a
handful of low-mass companions (M<30MJup) to stars. Line variability
is ubiquitous on stellar accretors but has never been characterized in
detail on low-mass companions and can give insights on the accretion
mechanism at play
We aim to characterize the short- to long-term HI Paschen β
emission line variability of two 10 to 30MJup companions on wide
orbits - GQ Lup b and GSC 06214-00210 b - to clarify the accretion
mechanisms at play.
We used J-band observations at R=1800-2360, obtained with VLT/SINFONI
in 2017, to record time series investigating hours-to-week variability
of the HI Paschen β emission line (1.282um). Contrary to Hα
it should be less affected by chromospheric activity contamination. The
photospheric emission is analyzed at each epoch and removed with the
FORMOSA forward modeling tool, using new grids of ATMO models
exploring different C/O and [M/H] values. The time series of line
profiles and intensities are compared to those of more massive
accretors and to predictions from the latest magnetospheric accretion
and shock models. To complement, we also re-investigate archival
spectroscopic observations at near-infrared wavelengths of each target
to increase the time span up to a decade and build a more
comprehensive understanding of the variability processes at play.
For GQ Lup b, we find line variability on months and decade
timescales, while it is within noise level at shorter timescales. For
GSC 06214-00210 b, we find line variability on timescales of tens of
minutes up to a decade. The line profiles of GSC 06214-00210 b are
partly resolved in at least one epoch. Both objects show HI Paschen
β flux variability that is moderate (<50%) at timescales below
their rotation period, and more important at longer timescales (up to
1000% on decade timescales), a behavior similar to that of classical T
Tauri stars. The line profiles of GQ Lup b are blue-shifted and can
only be reproduced by magnetospheric accretion models, while GSC
06214-00210 b's are fairly well reproduced by both magnetospheric
accretion and shock models, except for one epoch for which the shock
model is highly favored. The companions have C/O values broadly
consistent with solar values.
While magnetospheric accretion is favored for GQ Lup b, higher
resolution (R>10000) observations are required to disentangle the two
(non-exclusive) emitting mechanisms. The similar variability behavior
observed in these low mass companions and in classical T Tauri stars
may support similar accretion mechanisms. The high amplitude of
variability at months and longer timescales found in both objects
could be key to explain the low yield of Hα imaging campaigns.
Description:
SINFONI and OSIRIS spectra of both GQ Lup b and GSC06214-00210b.
SINFONI spectra have a spectral resolution of 2360 for GQ Lup b and
1800 for GSC06214-00210b. OSIRIS spectra have a spectral resolution of
3800. They are corrected from BERV and systemic radial velocity
shifts. GQ Lup b spectra are normalized to J2MASS=14.38.
GSC06214-00210b spectra are normalized to J2MASS=16.25. Spectra are
given as (wavelength, flux, error), with units (um, W/m2/um, W/m2/um)
Objects:
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RA (2000) DE Designation(s)
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15 49 12.05 -35 39 05.1 GQ Lup b = WDS J15492-3539Ab
16 21 54.67 -20 43 11.3 GSC 06214-00210 b = WDS J16219-2043B
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 130 45 List of fits spectra
fits/* . 45 Individual fits spectra
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See also:
J/AJ/157/71 : Keck/NIRC2 astrometry for GSC 6214-210 b (Pearce+, 2019)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Name Star name
18- 19 I2 h RAh Right ascension (J2000)
21- 22 I2 min RAm Right ascension (J2000)
24- 28 F5.2 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 39 F4.1 arcsec DEs Declination (J2000)
41- 44 I4 --- Nx Number of pixels along X-axis
46- 68 A23 "datime" Obs.date Observation date
70- 73 I4 --- Res [1800/3800] Spectral resolution of the spectrum
75- 81 A7 --- Inst Insturment name
83- 84 I2 Kibyte size Size of FITS file
86- 97 A12 --- FileName Name of FITS file, in subdirectory fits
99-130 A32 --- Title Title of the FITS file
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Acknowledgements:
Dorian Demars, dorian.demars(at)univ-grenoble-alpes.fr
(End) Patricia Vannier [CDS] 22-May-2023