J/A+A/628/A64 EPIC 212036875b griz light curves (Persson+, 2019)
Greening of the brown-dwarf desert.
EPIC 212036875b: a 51 MJ object in a 5-day orbit around an F7V star.
Persson C.M., Csizmadia S., Mustill A.J., Fridlund M., Hatzes A.P.,
Nowak G., Georgieva I., Gandolfi D., Davies M.B., Livingston J.H., Palle E.,
Montanes Rodriguez P., Endl M., Hirano T., Prieto-Arranz J., Korth J.,
Grziwa S., Esposito M., Albrecht S., Johnson M.C., Barragan O.,
Parviainen H., Van Eylen V., Alonso Sobrino R., Beck P.G., Cabrera J.,
Carleo I., Cochran W.D., Dai F., Deeg H.J., de Leon J.P., Eigmueller P.,
Erikson A., Fukui A., Gonzalez-Cuesta L., Guenther E.W., Hidalgo D.,
Hjorth M., Kabath P., Knudstrup E., Kusakabe N., Lam K.W.F., Lund M.N.,
Luque R., Mathur S., Murgas F., Narita N., Nespral D., Niraula P.,
Olofsson A.O.H., Paetzold M., Rauer H., Redfield S., Ribas I., Skarka M.,
Smith A.M.S., Subjak J., Tamura M.
<Astron. Astrophys. 628, A64 (2019)>
=2019A&A...628A..64P 2019A&A...628A..64P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry, SDSS
Keywords: planetary systems - stars: fundamental parameters -
stars: individual: EPIC 212036875 - techniques: photometric -
techniques: radial velocities
Abstract:
Although more than 2000 brown dwarfs have been detected to date,
mainly from direct imaging, their characterisation is difficult due to
their faintness and model dependent results. In the case of transiting
brown dwarfs it is, however, possible to make direct high precision
observations.
Our aim is to investigate the nature and formation of brown dwarfs by
adding a new well-characterised object, in term of its mass, radius
and bulk density, to the currently small sample of less than 20
transiting brown dwarfs.
One brown dwarf candidate was found by the KESPRINT consortium when
searching for exoplanets in the K2 space mission Campaign 16 field. We
combined the K2 photometric data with a series of multi-colour
photometric observations, imaging and radial velocity measurements to
rule out false positive scenarios and to determine the fundamental
properties of the system.
We report the discovery and characterisation of a transiting brown
dwarf in a 5.17 day eccentric orbit around the slightly evolved F7V
star EPIC 212036875.
EPIC 212036875b is a rare object that resides in the brown dwarf
desert. In the mass-density diagram for planets, brown dwarfs and
stars, we find that all giant planets and brown dwarfs follow the same
trend from 0.3MJ to the turn-over to hydrogen burning stars at
73MJ. EPIC 212036875b falls on the theoretical line for H/He
dominated planets in this diagram as determined by interior structure
models, as well as on the empirical fit. We argue that EPIC 212036875b
formed via gravitational disc instabilities in the outer part of the
disc, followed by a quick migration. Orbital tidal circularisation may
have started early in its history for a brief period when the brown
dwarf's radius was larger. The lack of spin-orbit synchronisation
points to a weak stellar dissipation parameter which implies a
circularisation timescale of 23Gyr, or suggests an interaction
between the magnetic and tidal forces of the star and the brown dwarf.
Description:
The data consists of a multicolour transit light curve observed with
the MuSCAT2 imager installed in the Carlos Sanchez Telescope in the
Teide Observatory on the night of 3.4.2018. The data is stored as a
fits file with the light curves for g', r', i', and z' filters stored
as separate binary table extensions. The time column contains the
mid-exposure times as BJD_TDB, the flux column contains the detrended
flux, the trend column the removed trends, and the model column the
fitted transit model.
Objects:
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RA (2000) DE Designation(s)
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08 58 45.67 +20 52 08.7 EPIC 212036875b = 2MASS J08584567+2052088
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gband.dat 99 821 EPIC 212036875b MuSCAT2 g' light curve
iband.dat 99 827 EPIC 212036875b MuSCAT2 i' light curve
rband.dat 99 805 EPIC 212036875b MuSCAT2 r' light curve
zband.dat 99 826 EPIC 212036875b MuSCAT2 z' light curve
m2180403.fits 2880 114 Fits file of the light curves
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Byte-by-byte Description of file: gband.dat iband.dat rband.dat zband.dat
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Bytes Format Units Label Explanations
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3- 24 E22.17 d Time Mid-exposure time as BJD, TDB
28- 49 E22.17 --- Flux Detrended flux
52- 74 E23.17 --- Trend Removed trends
78- 99 E22.17 --- Model Fitted transit model
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Acknowledgements:
Carina M. Persson, hpparvi(at)gmail.com
(End) Patricia Vannier [CDS] 21-Jul-2019