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J/A+A/510/A99       Epsilon Indi Ba and Bb IR spectra        (King+, 2010)

Epsilon Indi Ba, Bb: a detailed study of the nearest known brown dwarfs. King R.R., McCaughrean M.J., Homeier D., Allard F., Scholz R.-D., Lodieu N. <Astron. Astrophys. 510, A99 (2010)> =2010A&A...510A..99K
ADC_Keywords: Stars, nearby ; Spectra, infrared ; Spectra, red Keywords: stars: atmospheres - stars: fundamental parameters - stars: brown dwarfs - stars: individual: epsilon Indi B - binaries: general - stars: late-type Abstract: The discovery of epsilon Indi Ba, Bb, a binary brown dwarf system very close to the Sun, makes possible a concerted campaign to characterise the physical parameters of two T dwarfs. Recent observations suggest substellar atmospheric and evolutionary models may be inconsistent with observations, but there have been few conclusive tests to date. We therefore aim to characterise these benchmark brown dwarfs to place constraints on such models. We have obtained high angular resolution optical, near-infrared, and thermal-infrared imaging and medium-resolution (up to R∼5000) spectroscopy of epsilon Indi Ba, Bb with the ESO VLT and present VRIzJHKL'M' broad-band photometry and 0.63-5.1 micron spectroscopy of the individual components. The photometry and spectroscopy of the two partially blended sources were extracted with a custom algorithm. Furthermore, we use deep AO-imaging to place upper limits on the (model-dependent) mass of any further system members. We derive luminosities of log L/L_☉=-4.699±0.017 and -5.232±0.020 for epsilon Indi Ba, Bb, respectively, and using the dynamical system mass and COND03 evolutionary models predict a system age of 3.7-4.3Gyr, in excess of previous estimates and recent predictions from observations of these brown dwarfs. Moreover, the effective temperatures of 1352-1385K and 976-1011K predicted from the COND03 evolutionary models, for epsilon Indi Ba and Bb respectively, are in disagreement with those derived from the comparison of our data with the BT-Settl atmospheric models where we find effective temperatures of 1300-1340K and 880-940K, for epsilon Indi Ba and Bb respectively, with surface gravities of logg=5.25 and 5.50. Finally, we show that spectroscopically determined effective temperatures and surface gravities for ultra-cool dwarfs can lead to underestimated masses even where precise luminosity constraints are available. Description: 0.63-5.1 micron spectroscopy of the T dwarfs epsilon Indi Ba and Bb. These observations were made with the ESO VLT ISAAC and FORS2 instruments. For each spectrum, the wavelength, flux, relative uncertainty on the flux, and the uncertainty on the absolute flux scale (from the photometric calibration) is given. Objects: ------------------------------------------------------------------ RA (2000) DE Designation(s) (SpType) ------------------------------------------------------------------ 22 04 10.6 -56 46 58 epsilon Indi Ba = * eps Ind Ba (T1) 22 04 10.6 -56 46 58 epsilon Indi Bb = * eps Ind Bb (T6) ------------------------------------------------------------------ File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table.dat 53 11 Flux ratio (Ba/Bb) of eps Indi Ba, Bb in the observed FORS2 and ISAAC filters and derived apparent magnitudes sp/* 55 2 Spectra of epsilon Indi Ba and epsilon Indi Bb
See also: J/other/ARA+A/43.195 : L and T dwarf stars (Kirkpatrick, 2005) J/ApJ/648/629 : Radio observations of late M, L, and T dwarfs (Berger+, 2006) J/ApJ/637/1067 : T dwarfs near-IR spectral classification (Burgasser+, 2006) J/ApJ/651/502 : Spitzer IRAC photometry of M, L, and T dwarfs (Patten+, 2006) J/AJ/133/971 : Low-mass stars & brown dwarfs wide companions (Allen+ 2007) J/MNRAS/383/831 : New DENIS nearby L and late-M dwarfs (Phan-Bao+, 2008) Byte-by-byte Description of file: table.dat
Bytes Format Units Label Explanations
1- 5 A5 --- Filt Filter name 9- 12 F4.2 --- FRatio ? Flux ratio (Ba/Bb) in band "Filt" 14- 17 F4.2 --- e_FRatio ? rms uncertainty on FRatio 19- 23 F5.3 um lam.eff ? Effective wavelength of filter "Filt" 25- 29 F5.3 um Dlam ? Half-power width of filter "Filt" 31- 35 F5.2 mag Bamag ? {elsilon} Indi Ba magnitude in filter "Filt" 37- 40 F4.2 mag e_Bamag ? rms uncertainty on Bamag 42- 43 A2 --- l_Bbmag [≥] Limit flag on Bbmag 44- 48 F5.2 mag Bbmag ? {elsilon} Indi Bb magnitude in filter "Filt" 50- 53 F4.2 mag e_Bbmag ? rms uncertainty on Bamag
Byte-by-byte Description of file: sp/*
Bytes Format Units Label Explanations
1- 10 F10.4 0.1nm lambda Wavelength 11- 25 E15.4 W/m2/um Flux Flux (Flambda) 26- 40 E15.4 W/m2/um e_Flux Relative uncertainty on flux 41- 55 E15.4 W/m2/um eFlux Absolute uncertainty on flux
Acknowledgements: Robert King,
(End) Patricia Vannier [CDS] 20-Oct-2009
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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