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HD 77407 and GJ 577: Two new young stellar binaries Detected with the Calar Alto Adaptive Optics system ALFA

Mugrauer, M. and Neuhäuser, R. and Guenther, E. W. and Hatzes, A. P. and Huélamo, N. and Fernández, M. and Ammler, M. and Retzlaff, J. and König, B. and Charbonneau, D. and Jayawardhana, R. and Brandner, W. (2004) HD 77407 and GJ 577: Two new young stellar binaries Detected with the Calar Alto Adaptive Optics system ALFA. Astronomy & Astrophysics, 417 (3). pp. 1031-1038. ISSN 0004-6361. doi:10.1051/0004-6361:20040008.

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We present the first results from our search for close stellar and sub-stellar companions to young nearby stars on the northern sky. Our infrared imaging observations are obtained with the 3.5 m Calar Alto telescope and the AO system ALFA. With two epoch observations which were separated by about one year, we found two co-moving companion candidates, one close to HD 77407 and one close to GJ 577. For the companion candidate near GJ 577, we obtained an optical spectrum showing spectral type M 4.5; this candidate is a bound low-mass stellar companion confirmed by both proper motion and spectroscopy. We estimate the masses for HD 77407 B and GJ 577 B to be ~0.3 to 0.5 M_☉ and ~0.16 to 0.2 M_☉, respectively. Compared to Siess et al. (2000) models, each of the two pairs appears co-eval with HD 77407 A, B being 10 to 40 Myrs and GJ 577 A, B being ≥100 Myrs old. We also took multi-epoch high-resolution spectra of HD 77407 to search for sub-stellar companions, but did not find any with 3M_(Jup) as upper mass (m sin i) limit (for up to 4 year orbits); however, we detected a long-term radial velocity trend in HD 77407 A, consistent with a ~0.3 M_☉ companion at ~50 AU separation, i.e. the one detected by the imaging. Hence, HD 77407 B is confirmed to be a bound companion to HD 77407 A. We also present limits for undetected, but detectable companions using a deep image of HD 77407 A and B, also observed with the Keck NIRC2 AO system; any brown dwarfs were detectable outside of 0.5 arcsec (17 AU at HD 77407), giant planets with masses from ~6.5 to 12 M_(Jup) were detectable at ≥1.5 arcsec.

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Huélamo, N.0000-0002-2711-8143
Charbonneau, D.0000-0002-9003-484X
Additional Information:© 2004 ESO. Received: 16 May 2003. Accepted: 8 December 2003. We are grateful to our referee, Eduardo Martín, for several useful comments and the Calar Alto Time Allocation committee for continuous support. R.J. acknowledges support from NASA Origins grant NAG5-11905. The German-Spanish Astronomical Centre Calar Alto is operated by the Max-Planck-Institute for Astronomy, Heidelberg, jointly with the Spanish National Commission for Astronomy. We thank the technical staff of the TLS in Tautenburg for all their help and assistance in carrying out the observations. We thank Jens Woitas, Sebastian Els, and Martin Kürster for taking some of the spectra of HD 77407. We made use of the 2MASS public data releases and of the Simbad database operated at the Observatoire Strassburg. Some of the data presented herein were obtained at the W. M. Keck Observatory, operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautic and Space Administration. We thank Randy Campbell and David LeMignant for help during the observing run.
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Subject Keywords:stars: low mass, brown dwarfs - stars: binaries: general
Issue or Number:3
Record Number:CaltechAUTHORS:20180306-133803596
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Official Citation:HD 77407 and GJ 577: Two new young stellar binaries - Detected with the Calar Alto Adaptive Optics system ALFA M. Mugrauer, R. Neuhäuser, E. W. Guenther, A. P. Hatzes, N. Huélamo, M. Fernández, M. Ammler, J. Retzlaff, B. König, D. Charbonneau, R. Jayawardhana and W. Brandner A&A, 417 3 (2004) 1031-1038 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85140
Deposited By: Ruth Sustaita
Deposited On:06 Mar 2018 22:43
Last Modified:15 Nov 2021 20:26

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