First light of the VLT planet finder SPHERE. I. Detection and characterization of the sub-stellar companion GJ 758 B
First light of the VLT planet finder SPHERE. I. Detection and characterization of the sub-stellar companion GJ 758 B
GJ758 B is a brown dwarf companion to a nearby (15.76 pc) solar-type, metal-rich (M/H = +0.2 dex) main-sequence star (G9V) that was discovered with Subaru/HiCIAO in 2009. From previous studies, it has drawn attention as being the coldest (~600K) companion ever directly imaged around a neighboring star. We present new high-contrast data obtained during the commissioning of the SPHERE instrument at the VLT. The data was obtained in Y-, J-, H-, and Ks-bands with the dual-band imaging (DBI) mode of IRDIS, providing a broad coverage of the full near-infrared (near-IR) range at higher contrast and better spectral sampling than previously reported. In this new set of high-quality data, we report the re-detection of the companion, as well as the first detection of a new candidate closer-in to the star. We use the new 8 photometric points for an extended comparison of GJ758 B with empirical objects and 4 families of atmospheric models. From comparison to empirical object, we estimate a T8 spectral type, but none of the comparison object can accurately represent the observed near-IR fluxes of GJ758 B. From comparison to atmospheric models, we attribute a Teff = 600K $\pm$ 100K, but we find that no atmospheric model can adequately fit all the fluxes of GJ758 B. The photometry of the new candidate companion is broadly consistent with L-type objects, but a second epoch with improved photometry is necessary to clarify its status. The new astrometry of GJ758 B shows a significant proper motion since the last epoch. We use this result to improve the determination of the orbital characteristics using two fitting approaches, Least-Square Monte Carlo and Markov Chain Monte Carlo. Finally, we analyze the sensitivity of our data to additional closer-in companions and reject the possibility of other massive brown dwarf companions down to 4-5 AU. [abridged]
E. Giro、E. Hugot、A. Orign¨|、R. Galicher、R. Claudi、E. Buenzli、J. Antichi、Z. Wahhaj、E. Stadler、A. Baruffolo、J. Milli、M. Kasper、D. Le Mignant、A. -L. Maire、A. Zurlo、M. Suarez、J. Hagelberg、D. Mouillet、M. Bonnefoy、D. Perret、G. Chauvin、J. -L. Baudino、J. Pragt、R. Roelfsema、D. Mesa、C. Petit、C. Thalmann、N. Hubin、A. Delboulb¨|、S. Rochat、M. Llored、D. Mawet、R. Gratton、T. Moulin、A. Boccaletti、P. Puget、F. Wildi、P. Baudoz、A. Smette、C. Moutou、P. Martinez、C. Ginski、J. Girard、H. -M. Schmid、A. Sevin、A. Costille、M. Jacquet、P. Rabou、A. Vigan、M. Janson、S. Desidera、C. Dominik、M. Turatto、F. Madec、F. Vakili、A. Pavlov、A. -M. Lagrange、M. Feldt、P. Blanchard、H. Beust、C. Gry、M. Langlois、T. Henning、L. Gluck、T. Fusco、B. Salasnich、L. Weber、V. D'Orazi、S. Udry、G. Salter、J. -F. Sauvage、J. -L. Beuzit、M. Carle、L. Malo、K. Dohlen
天文学
E. Giro,E. Hugot,A. Orign¨|,R. Galicher,R. Claudi,E. Buenzli,J. Antichi,Z. Wahhaj,E. Stadler,A. Baruffolo,J. Milli,M. Kasper,D. Le Mignant,A. -L. Maire,A. Zurlo,M. Suarez,J. Hagelberg,D. Mouillet,M. Bonnefoy,D. Perret,G. Chauvin,J. -L. Baudino,J. Pragt,R. Roelfsema,D. Mesa,C. Petit,C. Thalmann,N. Hubin,A. Delboulb¨|,S. Rochat,M. Llored,D. Mawet,R. Gratton,T. Moulin,A. Boccaletti,P. Puget,F. Wildi,P. Baudoz,A. Smette,C. Moutou,P. Martinez,C. Ginski,J. Girard,H. -M. Schmid,A. Sevin,A. Costille,M. Jacquet,P. Rabou,A. Vigan,M. Janson,S. Desidera,C. Dominik,M. Turatto,F. Madec,F. Vakili,A. Pavlov,A. -M. Lagrange,M. Feldt,P. Blanchard,H. Beust,C. Gry,M. Langlois,T. Henning,L. Gluck,T. Fusco,B. Salasnich,L. Weber,V. D'Orazi,S. Udry,G. Salter,J. -F. Sauvage,J. -L. Beuzit,M. Carle,L. Malo,K. Dohlen.First light of the VLT planet finder SPHERE. I. Detection and characterization of the sub-stellar companion GJ 758 B[EB/OL].(2015-11-12)[2025-06-21].https://arxiv.org/abs/1511.04076.点此复制
评论