Rotational Velocities of the Components of 23 Binaries

Glazunova, L. V.; Yushchenko, A. V.; Tsymbal, V.; Mkrtichian, D. E.; Lee, J. J.; Kang, Yun Hee; Valyavin, G. G.; Lee, B.-C.

doi:10.1088/0004-6256/136/4/1736

Cited by 38 publications

(44 citation statements)

References 44 publications

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“…For v sin i values larger than about 10 km s −1 , the SPC values tend to be systematically larger than those from SME. Part of this may be related to differences in the continuum-fitting algorithms used in the two techniques (see, e.g., Behr 2003;Royer et al 2002aRoyer et al , 2002bGlazunova et al 2008;Hensberge et al 2000).…”

Section: Unconstrained Determinationsmentioning

confidence: 99%

Improved Spectroscopic Parameters for Transiting Planet Hosts

Torres

Fischer

Sozzetti

et al. 2012

ApJ

331

361

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We report homogeneous spectroscopic determinations of the effective temperature, metallicity, and projected rotational velocity for the host stars of 56 transiting planets. Our analysis is based primarily on the stellar parameter classification (SPC) technique. We investigate systematic errors by examining subsets of the data with two other methods that have often been used in previous studies (Spectroscopy Made Easy (SME) and MOOG). The SPC and SME results, both based on comparisons between synthetic spectra and actual spectra, show strong correlations between T eff , [Fe/H], and log g when solving for all three quantities simultaneously. In contrast the MOOG results, based on a more traditional curve-of-growth approach, show no such correlations. To combat the correlations and improve the accuracy of the temperatures and metallicities, we repeat the SPC analysis with a constraint on log g based on the mean stellar density that can be derived from the analysis of the transit light curves. Previous studies that have not taken advantage of this constraint have been subject to systematic errors in the stellar masses and radii of up to 20% and 10%, respectively, which can be larger than other observational uncertainties, and which also cause systematic errors in the planetary mass and radius.

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Section: Unconstrained Determinationsmentioning

confidence: 99%

Improved Spectroscopic Parameters for Transiting Planet Hosts

Torres

Fischer

Sozzetti

et al. 2012

ApJ

331

361

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“…To search for variations in the spectral line shapes, we measured the BVS using the mean profile of the spectral lines. We calculated the mean profile of spectral lines using the least squares deconvolution (LSD) technique (Glazunova et al 2008). We used the Vienna Atomic Line Database (VALD; Piskunov et al 1995) to prepare the list of spectral lines.…”

Section: Line Bisector Variationsmentioning

confidence: 99%

A likely exoplanet orbiting the oscillating K-giantαArietis

Lee

Mkrtichian

Han

et al. 2011

A&A

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Aims. To search for extrasolar planets around intermediate-mass stars, we are conducting a precise RV survey around K-giants. Methods. We present high-accuracy RV measurements of α Ari made from November 2003 to February 2010. This star belongs to our sample of 55 K-giants studied for extrasolar planet and pulsation searches using the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) attached to the 1.8-m telescope at Bohyunsan Optical Astronomy Observatory (BOAO) in Korea.Results. We find a planetary companion with long-period and low-amplitude radial velocity (RV) variations in oscillating K2 III star α Ari (HD 12929). We do not find the correlation between RV variations and chromospheric activity indicators (Ca II H & K region, Hα line). The bisector analysis also shows that the bisector velocity span (BVS) does not show any obvious correlation with RV variation but has periodic component that may be attributed to the rotation of the star. If the RV variation is indeed caused by a planetary companion, an orbital solution with a period of P = 381 days, a semi-amplitude of K = 41 m s −1 , and an eccentricity of e = 0.25 fits the data best. Assuming a possible stellar mass of M = 1.5 M , we estimate the minimum mass for the planetary companion of m 2 sin i = 1.8 M Jup with an orbital semi-major axis of 1.2 AU. Conclusions. Our finding of a likely exoplanet in α Ari supports searching for extrasolar planets around giant stars with multiperiodic oscillations.

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“… References: 1 –van Hamme & Wilson (1990); 2 –Etzel & Olson (1993); 3 –Mukherjee, Peters & Wilson (1996); 4 –Soydugan et al (2007); 5 –Glazunova et al (2008). …”

Section: Observations and Motivationmentioning

confidence: 99%

Spin angular momentum evolution of the long-period Algols

Dervişoğlu¹,

Tout²,

İbanoǧlu³

2010

Monthly Notices of the Royal Astronomical Society

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We consider the spin angular momentum evolution of the accreting components of Algol‐type binary stars. In wider Algols the accretion is through a disc so that the accreted material can transfer enough angular momentum to the gainer that material at its equator should be spinning at breakup. We demonstrate that even a small amount of mass transfer, much less than required to produce today's mass ratios, transfers enough angular momentum to spin the gainer up to this critical rotation velocity. However the accretors in these systems have spins typically between 10 and 40 per cent of the critical rate. So some mechanism for angular momentum loss from the gainers is required. Unlike solar‐type chromospherically active stars, with enhanced magnetic activity which leads to angular momentum and mass loss, the gainers in classical Algols have radiative envelopes. We further find that normal radiative tides are far too weak to account for the necessary angular momentum loss. Thus enhanced mass loss in a stellar wind seems to be required to spin‐down the gainers in classical Algol systems. We consider generation of magnetic fields in the radiative atmospheres in a differentially rotating star and the possibility of angular momentum loss driven by strong stellar winds in the intermediate‐mass stars, such as the primaries of the Algols. Differential rotation, induced by the accretion itself, may produce such winds which carry away enough angular momentum to reduce their rotational velocities to the today's observed values. We apply this model to two systems with initial periods of 5 d, one with initial masses 5 and and the other with 3.2 and . Our calculations show that, if the mass outflow rate in the stellar wind is about 10 per cent of the accretion rate and the dipole magnetic field is stronger than about 1 kG, the spin rate of the gainer is reduced to below breakup velocity even in the fast phase of mass transfer. Larger mass loss is needed for smaller magnetic fields. The slow rotation of the gainers in the classical Algol systems is explained by a balance between the spin‐up by mass accretion and spin‐down by a stellar wind linked to a magnetic field.

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Rotational Velocities of the Components of 23 Binaries

Cited by 38 publications

References 44 publications

Improved Spectroscopic Parameters for Transiting Planet Hosts

Improved Spectroscopic Parameters for Transiting Planet Hosts

A likely exoplanet orbiting the oscillating K-giantαArietis

Spin angular momentum evolution of the long-period Algols

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