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New high-precision orbital and physical parameters of the double-lined low-mass spectroscopic binary BY Draconis

Hełminiak, K. G. and Konacki, M. and Muterspaugh, M. W. and Browne, S. E. and Howard, A. W. and Kulkarni, S. R. (2012) New high-precision orbital and physical parameters of the double-lined low-mass spectroscopic binary BY Draconis. Monthly Notices of the Royal Astronomical Society, 419 (2). pp. 1285-1293. ISSN 0035-8711.

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We present the most precise to date orbital and physical parameters of the well-known short period (P= 5.975 d), eccentric (e= 0.3) double-lined spectroscopic binary BY Draconis (BY Dra), a prototype of a class of late-type, active, spotted flare stars. We calculate the full spectroscopic/astrometric orbital solution by combining our precise radial velocities (RVs) and the archival astrometric measurements from the Palomar Testbed Interferometer (PTI). The RVs were derived based on the high-resolution echelle spectra taken between 2004 and 2008 with the Keck I/high-resolution echelle spectrograph, Shane/CAT/HamSpec and TNG/SARG telescopes/spectrographs using our novel iodine-cell technique for double-lined binary stars. The RVs and available PTI astrometric data spanning over eight years allow us to reach 0.2–0.5 per cent level of precision in Msin ^3i and the parallax but the geometry of the orbit (i≃ 154°) hampers the absolute mass precision to 3.3 per cent, which is still an order of magnitude better than for previous studies. We compare our results with a set of Yonsei–Yale theoretical stellar isochrones and conclude that BY Dra is probably a main-sequence system more metal rich than the Sun. Using the orbital inclination and the available rotational velocities of the components, we also conclude that the rotational axes of the components are likely misaligned with the orbital angular momentum. Given BY Dra’s main-sequence status, late spectral type and the relatively short orbital period, its high orbital eccentricity and probable spin–orbit misalignment are not in agreement with the tidal theory. This disagreement may possibly be explained by smaller rotational velocities of the components and the presence of a substellar mass companion to BY Dra AB.

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Howard, A. W.0000-0001-8638-0320
Kulkarni, S. R.0000-0001-5390-8563
Additional Information:© 2011 The Authors. Monthly Notices of the Royal Astronomical Society © 2011 RAS. Accepted 2011 September 8. Received 2011 September 7; in original form 2010 June 28. Article first published online: 13 Oct. 2011. We would like to thank Professor Tsevi Mazeh for his invaluable comments and suggestions, and Arne Rau for carrying out the Keck I/HIRES observations in the years 2006–2007. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. This work benefits from the efforts of the PTI collaboration members who have each contributed to the development of an extremely reliable observational instrument. We thank PTI’s night assistant Kevin Rykoski for his efforts to maintain PTI in excellent condition and operating PTI. This research was cofinanced by the European Social Fund and the national budget of the Republic of Poland within the framework of the Integrated Regional Operational Programme, Measure 2.6. Regional innovation strategies and transfer of knowledge – an individual project of the Kuyavian–Pomeranian Voivodship ‘Scholarships for PhD students 2008/2009 – IROP’, and by the grant N N203 379936 from the Ministry of Science and Higher Education. Support for KGH is provided by Centro de Astrofísica FONDAP Proyecto 15010003, MK is supported by the Foundation for Polish Science through a FOCUS grant and fellowship and by the Polish Ministry of Science and Higher Education through grants N N203 005 32/0449 and N N203302035. MWM acknowledges support from the Townes Fellowship Programme, an internal UC Berkeley SSL grant, and the State of Tennessee Center of Excellence programme. This research was supported in part by the National Science Foundation under Grant No PHY05-51164. The observations on the TNG/SARG have been funded by the Optical Infrared Coordination network (OPTICON), a major international collaboration supported by the Research Infrastructures Programme of the European Commissions Sixth Framework Programme. This research has made use of the Simbad database, operated at CDS, Strasbourg, France, and of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.
Funding AgencyGrant Number
European Social FundUNSPECIFIED
National Budget of the Republic of PolandUNSPECIFIED
Ministry of Science and Higher Education (Poland)N N203 379936
Fondo de Financiamiento de Centros de Investigación en Áreas Prioritarias (FONDAP)15010003
Foundation for Polish ScienceUNSPECIFIED
Ministry of Science and Higher Education (Poland)N N203 005 32/0449
Ministry of Science and Higher Education (Poland)N N203302035
Townes Fellowship ProgrammeUNSPECIFIED
UC Berkeley Space Sciences Laboratory Townes Postdoctoral FellowshipUNSPECIFIED
State of Tennessee Centers of Excellence programUNSPECIFIED
Optical Infrared Coordination network (OPTICON)UNSPECIFIED
European Commissions Sixth Framework Programme Research Infrastructures ProgrammeUNSPECIFIED
Subject Keywords: techniques: interferometric; techniques: radial velocities; binaries: spectroscopic; binaries: visual; stars: fundamental parameters; stars: individual: (BY Dra)
Issue or Number:2
Record Number:CaltechAUTHORS:20120224-101408516
Persistent URL:
Official Citation:Hełminiak, K. G., Konacki, M., Muterspaugh, M. W., Browne, S. E., Howard, A. W. and Kulkarni, S. R. (2012), New high-precision orbital and physical parameters of the double-lined low-mass spectroscopic binary BY Draconis. Monthly Notices of the Royal Astronomical Society, 419: 1285–1293. doi: 10.1111/j.1365-2966.2011.19785.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29454
Deposited By: Ruth Sustaita
Deposited On:24 Feb 2012 19:36
Last Modified:03 Oct 2019 03:41

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