uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
MOST discovers a multimode delta Scuti star in a triple system: HD 61199
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
Show others and affiliations
2008 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, Vol. 492, no 1, 185-195 p.Article in journal (Refereed) Published
Abstract [en]

Context. A field star, HD61199 (V approximate to 8), simultaneously observed with Procyon by the MOST (Microvariability & Oscillations of STars) satellite in continuous runs of 34, 17, and 34 days in 2004, 2005, and 2007, was found to pulsate in 11 frequencies in the delta Scuti range with amplitudes from 1.7 down to 0.09 mmag. The photometry also showed variations with a period of about four days. To investigate the nature of the longer period, 45 days of time-resolved spectroscopy was obtained at the Thuringer Landessternwarte Tautenburg in 2004. The radial velocity measurements indicate that HD61199 is a triple system. Aims. A delta Scuti pulsator with a rich eigenspectrum in a multiple system is promising for asteroseismology. Our objectives were to identify which of the stars in the system is the delta Scuti variable and to obtain the orbital elements of the system and the fundamental parameters of the individual components, which are constrained by the pulsation frequencies of the delta Scuti star.Methods. Classical Fourier techniques and least-squares multi-sinusoidal fits were applied to the MOST photometry to identify the pulsation frequencies. The groundbased spectroscopy was analysed with least-squares-deconvolution (LSD) techniques, and the orbital elements derived with the KOREL and ORBITX routines. Asteroseismic models were also generated. Results. The photometric and spectroscopic data are compatible with a triple system consisting of a close binary with an orbital period of 3.57 days and a d Scuti companion (HD61199 A) as the most luminous component. The d Scuti star is a rapid rotator with about v sin i = 130 km s(-1) and an upper mass limit of about 2.1 M-circle dot. For the close binary components, we find they are of nearly equal mass, with lower mass limits of about 0.7 M-circle dot. Comparisons to synthetic spectra indicate these stars have a late-F spectral type. The observed oscillation frequencies are compared to pulsation models to further constrain the evolutionary state and mass of HD61199 A. The orbit frequency of the close binary corresponds to the difference of the two d Scuti frequencies with the highest amplitudes a coincidence that is remarkable, but not explained.

Place, publisher, year, edition, pages
2008. Vol. 492, no 1, 185-195 p.
Keyword [en]
binaries: close, stars: variables: delta Scuti, techniques: photometric, techniques: spectroscopic, techniques: radial velocities
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-107040DOI: 10.1051/0004-6361:200809996ISI: 000261253100025OAI: oai:DiVA.org:uu-107040DiVA: diva2:227593
Available from: 2009-07-15 Created: 2009-07-15 Last updated: 2009-07-16Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text
By organisation
Department of Physics and Astronomy
In the same journal
Astronomy and Astrophysics
Physical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 201 hits
ReferencesLink to record
Permanent link

Direct link