J/MNRAS/502/6117 A faint companion around CrA-9 (Christiaens+, 2021)
A faint companion around CrA-9: protoplanet or obscured binary?
Christiaens V., Ubeira-Gabellini M.-G., Canovas H., Delorme P., Pairet B.,
Absil O., Casassus S., Girard J.H., Zurlo A., Aoyama Y., Marleau G.-D.,
Spina L., Van Der Marel N., Cieza L., Lodato G., Perez S., Pinte C.,
Price D.J., Reggiani M.
<Mon. Not. R. Astron. Soc., 502, 6117-6139 (2021)>
=2021MNRAS.502.6117C 2021MNRAS.502.6117C (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Exoplanets ; Protostars ; Spectra, infrared
Keywords: techniques: image processing - planets and satellites: formation -
planet-disc interactions - protoplanetary discs
Abstract:
Understanding how giant planets form requires observational input from
directly imaged protoplanets. We used VLT/NACO and VLT/SPHERE to
search for companions in the transition disc of 2MASS
J19005804-3645048 (hereafter CrA-9), an accreting M0.75 dwarf with an
estimated age of 1-2Myr. We found a faint point source at
∼0.7-arcsec separation from CrA-9 (∼108au projected separation). Our
3-epoch astrometry rejects a fixed background star with a 5σ
significance. The near-IR absolute magnitudes of the object point
towards a planetary-mass companion. However, our analysis of the
1.0-3.8um spectrum extracted for the companion suggests it is a
young M5.5 dwarf, based on both the 1.13um Na index and comparison
with templates of the Montreal Spectral Library. The observed spectrum
is best reproduced with high effective temperature (3057+119-36K)
BT-DUSTY and BT-SETTL models, but the corresponding photometric radius
required to match the measured flux is only 0.60+0.01-0.04 Jovian
radius. We discuss possible explanations to reconcile our
measurements, including an M-dwarf companion obscured by an edge-on
circum-secondary disc or the shock-heated part of the photosphere of
an accreting protoplanet. Follow-up observations covering a larger
wavelength range and/or at finer spectral resolution are required to
discriminate these two scenarios.
Description:
This catalog contains:
(1) the processed images obtained by NACO and SPHERE (after modelling
and subtraction of the stellar signal)
(2) the SED of CrA-9 and the best-fit BT-SETTL model, incl.
uncertainties
(3) the contrast spectrum of the companion with respect to the star
(i.e. how much fainter it is compared to the star at each wavelength)
(4) the SED of the companion, including uncertainties and spectral
correlation matrix
(5) the best-fit BT-SETTL, BT-DUSTY and DRIFT-PHOENIX models to the
SED of the companion
(6) the best-fit template spectra from the Montreal Spectral Library
to the SED of the companion
Objects:
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RA (2000) DE Designation(s)
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19 00 58.04 -36 45 04.9 2MASS J19005804-364504 = TIC 254051150
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
spectra.dat 224 13 List of fits spectra
sp/* . 13 Individial fits spectra
images.dat 115 4 List of post-processed fits images
fits/* . 4 Individial fits images
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Byte-by-byte Description of file: spectra.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Row1 Quantity in the first row of the fits array
12- 13 A2 --- Units1 Units of the first row of the fits array
15- 37 A23 --- Row2 Quantity in the second row
39- 50 A12 --- Units2 Units of the second row
52- 59 A8 --- Row3 Quantity in the third row
61- 72 A12 --- Units3 Units of the third row
74- 84 A11 --- Row4 Quantity in the fourth row
86- 97 A12 --- Units4 Units of the fourth row
99-107 A9 --- GOFlabel Goodness of fit indicator
109-113 F5.1 --- GOFvalue Value of the goodness of fit indicator
115-118 I4 Kibyte size Size of the fits file
120-154 A35 --- FileName FITS filename in subdirectory sp
156-224 A69 --- Title Title of the file
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Byte-by-byte Description of file: images.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 35 F8.6 arcsec/pix scale Plate scale
37- 39 I3 Kibyte size Size of the fits file
41- 68 A28 --- FileName FITS filename in subdirectory fits
70-115 A46 --- Title Title of the file
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Acknowledgements:
Valentin Christiaens, valentin.christiaens(at)monash.edu
(End) Valentin Christiaens [Monash Univ.], Patricia Vannier [CDS] 29-Apr-2021