First spectroscopic observations of the substellar companion of the young debris disk star PZ Telescopii
MetadataShow full item record
Context. In 2010 a substellar companion to the solar analog pre-main sequence star PZ Tel and member of the approximately 12 Myr old beta Pic moving group was found by high-contrast direct imaging independently by two teams. Aims. In order to determine the basic parameters of this companion more precisely and independent of evolutionary models, hence age-independent, we obtained follow-up spectroscopic observations of the primary and companion. Methods. We used the Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) at the Very Large Telescope Unit 4/Yepun of ESO's Paranal Observatory in the H + K band and processed the data using the spectral deconvolution technique. The resulting spectrum of the companion was then compared to a grid of DRIFT-PHOENIX synthetic model spectra, a combination of a general-purpose model atmosphere code with a non-equilibrium, stationary cloud and dust model, using a chi(2) minimization analysis. Results. We find a best fitting spectral type of G6.5 for PZ Tel A. The extracted spectrum of the substellar companion, at a spatial position compatible with earlier orbit estimates, yields a temperature T-eff = 2500(-115)(+138) K, a visual extinction A(V) = 0.53(-0.53)(+0.84) mag, a surface gravity of log g = 3.50(-0.30)(+0.51) dex, and a metallicity at the edge of the grid of [M/H] = 0.30(-0.30) dex. Conclusions. We derive a luminosity of log(L-bol/L-circle dot) = -2.66(-0.08)(+0.06), a radius of R = 2.42(-0.34)(+0.28) R-Jup, and a mass of M = 7.5(-4.3)(+16.9) M-Jup for the PZ Tel companion, which is consistent with most earlier estimates using photometry alone. Combining our results with evolutionary models, we find a best-fitting mass of about 21 Jupiter masses at an age corresponding to the recently determined lithium depletion age of 7(-2)(+4) Myr. Hence, the PZ Tel companion is most likely a wide brown dwarf companion in the 12(-4)(+8) Myr old beta Pic moving group.
Schmidt , T O B , Mugrauer , M , Neuhäuser , R , Vogt , N , Witte , S , Hauschildt , P H , Helling , C & Seifahrt , A 2014 , ' First spectroscopic observations of the substellar companion of the young debris disk star PZ Telescopii ' , Astronomy & Astrophysics , vol. 566 , A85 . https://doi.org/10.1051/0004-6361/201321625
Astronomy & Astrophysics
© ESO, 2014
DescriptionT.O.B.S. and R.N. acknowledge support from the German National Science Foundation (Deutsche Forschungsgemeinschaft, DFG) in grant NE 515/30-1. N.V. acknowledges support by Comité Mixto ESO-Gobierno de Chile, as well as by the Gemini-CONICYT fund 32090027. Ch.H. highlights financial support of the European Community under the FP7 by an ERC starting grant.
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.