A Caltech Library Service

Direct detection of exoplanet host star companion γ Cep B and revised masses for both stars and the sub-stellar object

Neuhäuser, R. and Mugrauer, M. and Fukagawa, M. and Torres, G. and Schmidt, T. (2007) Direct detection of exoplanet host star companion γ Cep B and revised masses for both stars and the sub-stellar object. Astronomy and Astrophysics, 462 (2). pp. 777-780. ISSN 0004-6361. doi:10.1051/0004-6361:20066581.

PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


Context. The star γ Cep is known as a single-lined spectroscopic triple system at a distance of 13.8 pc, composed of a K1 III-IV primary star with V = 3.2 mag, a stellar-mass companion in a 66-67 year orbit (Torres 2007, ApJ, 654, 1095), and a substellar companion with M_p sin i = 1.7 M_(Jup) that is most likely a planet (Hatzes et al. 2003, ApJ, 599, 1383). Aims. We aim to obtain a first direct detection of the stellar companion, to determine its current orbital position (for comparison with the spectroscopic and astrometric data), its infrared magnitude and, hence, mass. Methods. We use the Adaptive Optics camera CIAO at the Japanese 8 m telescope Subaru on Mauna Kea, Hawaii, with the semi-transparent coronograph to block most of the light from the bright primary γ Cep A, and to detect at the same time the faint companion B. In addition, we also used the IR camera Ω Cass at the Calar Alto 3.5 m telescope, Spain, to image γ Cep A and B by adding up many very short integrations (without AO). Results. γ Cep B is clearly detected on our CIAO and Ω Cass images. We use a photometric standard star to determine the magnitude of B after PSF subtraction in the Subaru image, and the magnitude difference between A and B in the Calar Alto images, and find an average value of K = 7.3 ± 0.2 mag. The separations and position angles between A and B are measured on 15 July 2006 and 11 and 12 Sept. 2006, B is slightly south of west of A. Conclusions. By combining the radial velocity, astrometric, and imaging data, we have refined the binary orbit and determined the dynamical masses of the two stars in the γ Cep system, namely 1.40 ± 0.12 M_☉ for the primary and 0.409 ± 0.018 M_☉ for the secondary (consistent with being a M4 dwarf). We also determine the minimum mass of the sub-stellar companion to be M_p sin i = 1.60 ± 0.13 M_(Jup).

Item Type:Article
Related URLs:
URLURL TypeDescription
Torres, G.0000-0002-5286-0251
Additional Information:© 2007 ESO. Received 17 October 2006; accepted 24 October 2006. We would like to thank the staff at the Subaru and Calar Alto telescopes for their help during our observations as well as Kengo Tachihara for his support. G.T. acknowledges partial support for this work from NSF grant AST-0406183 and NASA Origins grant NNG04LG89G. T.S. acknowledges support from a Thuringian State Scholarship (until July 2006) and from a Scholarship of the Evangelisches Studienwerk e.V. Villigst (since August 2006).
Funding AgencyGrant Number
Thuringian State ScholarshipUNSPECIFIED
Evangelisches Studienwerk e.V. VilligstUNSPECIFIED
Subject Keywords:instrumentation: adapive optics; binaries: spectroscopic; binaries: visual; planetary systems; star: individual: γ Cep
Issue or Number:2
Record Number:CaltechAUTHORS:20100419-103619243
Persistent URL:
Official Citation:Direct detection of exoplanet host star companion γ Cep B and revised masses for both stars and the sub-stellar object R. Neuhäuser, M. Mugrauer, M. Fukagawa, G. Torres and T. Schmidt A&A 462 (2) 777-780 (2007) DOI: 10.1051/0004-6361:20066581
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18016
Deposited By: Jason Perez
Deposited On:19 Apr 2010 20:40
Last Modified:08 Nov 2021 23:40

Repository Staff Only: item control page