J/A+A/688/A116 ESO SupJup Survey I. DENIS J0255-4700 (de Regt+, 2024)
The ESO SupJup Survey. I: Chemical and isotopic characterisation of the late
L-dwarf DENIS J0255-4700 with CRIRES+.
de Regt S., Gandhi S., Snellen I.A.G., Zhang Y., Ginski C.,
Gonzalez Picos D., Kesseli A.Y., Landman R., Molliere P., Nasedkin E.,
Sanchez-Lopez A., Stolker T.
<Astron. Astrophys. 688, A116 (2024)>
=2024A&A...688A.116D 2024A&A...688A.116D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, brown dwarf ; Spectra, infrared
Keywords: techniques: spectroscopic - planets and satellites: atmospheres -
brown dwarfs
Abstract:
It has been proposed that the distinct formation and evolutionary
pathways of exoplanets and brown dwarfs may affect the chemical and
isotopic content of their atmospheres. Recent work has indeed shown
differences in the 12C/13C isotope ratio, which have provisionally
been attributed to the top-down formation of brown dwarfs and the core
accretion pathway of super-Jupiters.
The ESO SupJup Survey is aimed at disentangling the formation pathways
of isolated brown dwarfs and planetary-mass companions using chemical
and isotopic tracers. The survey utilises high-resolution spectroscopy
with the recently upgraded CRyogenic high-resolution InfraRed Echelle
Spectrograph (CRIRES+) at the Very Large Telescope, covering a total
of 49 targets. Here, we present the first results of this survey: an
atmospheric characterisation of DENIS J0255-4700, an isolated brown
dwarf near the L-T transition.
We analysed its observed CRIRES+ K-band spectrum using an
atmospheric retrieval framework in which the radiative transfer code
petitRADTRANS was coupled with the PyMultiNest sampling algorithm.
Gaussian processes were employed to model inter-pixel correlations. In
addition, we adopted an updated parameterisation of the
pressure-temperature profile.
Abundances of CO, H2O, CH4, and NH3 were retrieved for this
fast-rotating L-dwarf. The ExoMol H2O line list provides a
significantly better fit than that of HITEMP. A free-chemistry
retrieval is strongly favoured over equilibrium chemistry, caused by
an under-abundance of CH4. The free-chemistry retrieval constrains
a super-solar C/O-ratio of ∼0.68 and a solar metallicity. We find
tentative evidence (∼3σ) for the presence of 13CO, with a
constraint on the isotopologue ratio of 12CO/13CO=184+61-40
and a lower limit of ≳97, which suggests a depletion of 13C
compared to the local interstellar medium (12C/13C∼68).
High-resolution, high signal-to-noise K-band spectra provide an
excellent means of constraining the chemistry and isotopic content of
sub-stellar objects, which is the main objective of the ESO SupJup
Survey.
Description:
Reduced VLT/CRIRES+ spectra of DENIS J0255-4700. The reduced data of
DENIS J0255 are flux-calibrated using the 2MASS Ks-band magnitude and
the tellurics are corrected for using a standard
Objects:
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RA (2000) DE Designation(s)
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02 55 03.69 -47 00 51.36 J0255 = DENIS J025503.3-470049
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
j0255.dat 74 43008 Flux-calibrated and telluric-corrected CRIRES+
spectrum of DENIS J0255-4700
transm.dat 50 43008 Telluric transmissivity
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Byte-by-byte Description of file: j0255.dat
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Bytes Format Units Label Explanations
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1- 24 E24.18 nm lambda Wavelength
26- 49 E24.18 10mW/m2/nm Flux ?=- Flux density (in erg/s/cm2/nm)
51- 74 E24.18 10mW/m2/nm e_Flux ?=- Uncertainty in flux density
(in erg/s/cm2/nm)
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Byte-by-byte Description of file: transm.dat
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Bytes Format Units Label Explanations
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1- 24 E24.18 nm lambda Wavelength
26- 50 E25.18 --- transm ?=- Telluric transmissivity
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Acknowledgements:
Sam de Regt, regt(at)strw.leidenuniv.nl
(End) Sam de Regt [Leiden Observatory], Patricia Vannier [CDS] 10-Jun-2024