Line-by-line opacity stellar model atmospheres

Shulyak, D.; Tsymbal, V.; Ryabchikova, T. A.; Stütz, Ch.; Weiß, W. W.

doi:10.1051/0004-6361:20034169

Cited by 339 publications

(321 citation statements)

References 32 publications

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“…We computed model atmospheres of KIC 7661054 using the LLmodels stellar model atmosphere code (Shulyak et al 2004). Local Thermodynamical Equilibrium (LTE) and plane-parallel geometry were assumed for all the calculations.…”

Section: Line Broadening -V Sin I and Vmacromentioning

confidence: 99%

Near-uniform internal rotation of the main-sequence γ Doradus pulsator KIC 7661054

Murphy

Fossati

Bedding

et al. 2016

Mon. Not. R. Astron. Soc.

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We used Kepler photometry to determine the internal rotation rate of KIC 7661054, a chemically normal γ Dor star on the main sequence at spectral type F2.5 V. The core rotation period of 27.25 ± 0.06 d is obtained from the rotational splittings of a series of dipole g modes. The surface rotation period is calculated from a spectroscopic projected rotation velocity and a stellar radius computed from models. Literature data, obtained without inclusion of macroturbulence as a line-broadening mechanism, imply that the surface rotates much more quickly than the core, while our detailed analysis suggests that the surface may rotate slightly more quickly than the core and that the rotation profile is uniform within the 1-σ uncertainties. We discuss the pitfalls associated with the determination of surface rotation rates of slow rotators from spectroscopy in the absence of asteroseismic constraints. A broad signal is observed at low frequency, which we show cannot be attributed to rotation, contrary to previous suggestions concerning the origin of such signals.

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Section: Line Broadening -V Sin I and Vmacromentioning

confidence: 99%

Near-uniform internal rotation of the main-sequence γ Doradus pulsator KIC 7661054

Murphy

Fossati

Bedding

et al. 2016

Mon. Not. R. Astron. Soc.

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“…4 stev.oapd.inaf.it/YZVAR/cgi-bin/form (Bertelli et al 2008). 5 www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/en/cfht 6 www.ast.obs-mip.fr/projets/espadons/espadons.html archive (Piskunov et al 1995;Ryabchikova et al 1999;Kupka et al 1999) and of the model atmospheres calculated with the LLmodels stellar model atmosphere code (Shulyak et al 2004). For all calculations we assumed a microturbulence velocity of 0.85 km s −1 (Valenti & Fischer 2005).…”

Section: From Observationsmentioning

confidence: 99%

A seismic and gravitationally bound double star observed byKepler

Appourchaux

Antia

Ball

et al. 2015

A&A

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Context. Solar-like oscillations have been observed by Kepler and CoRoT in many solar-type stars, thereby providing a way to probe stars using asteroseismology. Aims. The derivation of stellar parameters has usually been done with single stars. The aim of the paper is to derive the stellar parameters of a double-star system (HIP 93511), for which an interferometric orbit has been observed along with asteroseismic measurements. Methods. We used a time series of nearly two years of data for the double star to detect the two oscillation-mode envelopes that appear in the power spectrum. Using a new scaling relation based on luminosity, we derived the radius and mass of each star. We derived the age of each star using two proxies: one based upon the large frequency separation and a new one based upon the small frequency separation. Using stellar modelling, the mode frequencies allowed us to derive the radius, the mass, and the age of each component. In addition, speckle interferometry performed since 2006 has enabled us to recover the orbit of the system and the total mass of the system. Results. From the determination of the orbit, the total mass of the system is 2.34 +0.45 −0.33 M . The total seismic mass using scaling relations is 2.47 ± 0.07 M . The seismic age derived using the new proxy based upon the small frequency separation is 3.5 ± 0.3 Gyr. Based on stellar modelling, the mean common age of the system is 2.7-3.9 Gyr. The mean total seismic mass of the system is 2.34-2.53 M consistent with what we determined independently with the orbit. The stellar models provide the mean radius, mass, and age of the stars as R A = 1.82−1.87 R , M A = 1.25−1.39 M , Age A = 2.6-3.5 Gyr; R B = 1.22−1.25 R , M B = 1.08−1.14 M , Age B = 3.35-4.21 Gyr. The models provide two sets of values for Star A: [1.25-1.27] M and [1.34-1.39] M . We detect a convective core in Star A, while Star B does not have any. For the metallicity of the binary system of Z ≈ 0.02, we set the limit between stars having a convective core in the range [1.14-1.25] M .

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“…We reduced the DAO spectrum with IRAF in a similar way as the TS spectrum. To compute model atmospheres of HD 261711 we employed the LLmodels stellar model atmosphere code (Shulyak et al 2004). We analysed the hydrogen lines fitting synthetic spectra, calculated with synth3 (Kochukhov 2007), to the observed line profiles.…”

Section: Spectroscopic Analysismentioning

confidence: 99%

Regular frequency patterns in the youngδScuti star HD 261711 observed by the CoRoT and MOST satellites

Zwintz¹,

Fossati²,

Guenther³

et al. 2013

A&A

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Context. The internal structure of pre-main-sequence (PMS) stars is poorly constrained at present. This could change significantly through high-quality asteroseismological observations of a sample of such stars. Aims. We concentrate on an asteroseismological study of HD 261711, a rather hot δ Scuti-type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD 261711 was discovered to be a PMS δ Scuti star using the time series photometry obtained by the MOST satellite in 2006. Methods. High-precision, time-series photometry of HD 261711 was obtained by the MOST and CoRoT satellites in four separate new observing runs that are put into context with the star's fundamental atmospheric parameters obtained from spectroscopy. Frequency Analysis was performed using Period04. The spectral analysis was performed using equivalent widths and spectral synthesis. Results. With the new MOST data set from 2011/12 and the two CoRoT light curves from 2008 and 2011/12, the δ Scuti variability was confirmed and regular groups of frequencies were discovered. The two pulsation frequencies identified in the data from the first MOST observing run in 2006 are confirmed and 23 new δ Scuti-type frequencies were discovered using the CoRoT data. Weighted average frequencies for each group were determined and are related to l = 0 and l = 1 p-modes. Evidence for amplitude modulation of the frequencies in two groups is seen. The effective temperature (T eff ) was derived to be 8600 ± 200 K, log g is 4.1 ± 0.2, and the projected rotational velocity (υ sin i) is 53 ± 1 km s −1 . Using our T eff value and the radius of 1.8 ± 0.5 R derived from spectral energy distribution (SED) fitting, we get a luminosity log L/L of 1.20 ± 0.14 which agrees well to the seismologically determined values of 1.65 R and, hence, a log L/L of 1.13. The radial velocity of 14 ± 2 km s −1 we derived for HD 261711, confirms the star's membership to NGC 2264. Conclusions. Our asteroseismic models suggest that HD 261711 is a δ Scuti-type star close to the zero-age main sequence (ZAMS) with a mass of 1.8 to 1.9 M . With an age of about 10 million years derived from asteroseismology, the star is either a young ZAMS star or a late PMS star just before the onset of hydrogen-core burning. The observed splittings about the l = 0 and 1 parent modes may be an artifact of the Fourier derived spectrum of frequencies with varying amplitudes. Reduced spectra are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via

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Line-by-line opacity stellar model atmospheres

Cited by 339 publications

References 32 publications

Near-uniform internal rotation of the main-sequence γ Doradus pulsator KIC 7661054

Near-uniform internal rotation of the main-sequence γ Doradus pulsator KIC 7661054

A seismic and gravitationally bound double star observed byKepler

Regular frequency patterns in the youngδScuti star HD 261711 observed by the CoRoT and MOST satellites

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