Matching Stellar Models to Oscillation Data

Guenther, D. B.; Brown, Kevin I. T.

doi:10.1086/379644

Cited by 59 publications

(92 citation statements)

References 40 publications

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“…We used the usual χ 2 fitting procedure, first described in Guenther and Brown (2004). The match between the observed and model spectra is quantified by the following χ 2 equation:…”

Section: Asteroseismic Modelingmentioning

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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“…We used the usual χ 2 fitting procedure, first described in Guenther and Brown (2004). The match between the observed and model spectra is quantified by the following χ 2 equation:…”

Section: Asteroseismic Modelingmentioning

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

Self Cite

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“…In the past, χ 2 -minimization techniques [13] (i.e., minimizing the difference between observed and model frequencies) have been used to search for a best fit. This approach, however, assumes that the theoretical frequencies are free of systematic uncertainties but it is know that stellar surface layers, rotation, and magnetic fields imprint erratic frequency shits, trends, and other non-random behaviour in the frequency spectra.…”

Section: Grid Modellingmentioning

confidence: 99%

Bayesian Magic in Asteroseismology

Kallinger

2015

EPJ Web of Conferences

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Abstract. Only a few years ago asteroseismic observations were so rare that scientists had plenty of time to work on individual data sets. They could tune their algorithms in any possible way to squeeze out the last bit of information. Nowadays this is impossible. With missions like MOST, CoRoT, and Kepler we basically drown in new data every day. To handle this in a sufficient way statistical methods become more and more important. This is why Bayesian techniques started their triumph march across asteroseismology. I will go with you on a journey through Bayesian Magic Land, that brings us to the sea of granulation background, the forest of peakbagging, and the stony alley of model comparison.

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“…where, ν 0 and A are related to the sound speed (see Guenther & Brown 2004), and and B are constants that are functions of the equilibrium model. Combining the definition given by Eq.…”

Section: The Ratio R 01mentioning

confidence: 99%

A new asteroseismic diagram of solar-like stars

Tang¹,

Gai

2008

A&A

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Aims. We attempt to develop a new asteroseismic diagram and investigate its characteristics, based on the ratio "r 01 " of adjacent, average, small separations. Methods. The ratio r 01 is defined following the asymptotic formula of stellar p-modes. Using the low-degree, theoretical, numerical value of adiabatic frequencies of stellar model, we compute the ratio r 01 and construct an additional asteroseismic diagram. Results. The additional asteroseismic diagram, which is similar to the C-D diagram (i.e. the famous asteroseismic HR diagram, socalled Christensen-Dalsgaard diagram), represents a composite of the average, large separations Δν and the ratio r 01 of the adjacent, small separations. A distinct separation is identified between the effects of varying both mass and age. The diagram can therefore provide information that is complementary to that provided by a C-D diagram, which can be used to estimate directly both the stellar mass and evolutionary state. Interestingly, the age of star can be derived from the new asteroseismic diagram. Furthermore, we investigate the parameter r 01 , which can be a useful direct indicator of stellar age.

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Matching Stellar Models to Oscillation Data

Cited by 59 publications

References 40 publications

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

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

Bayesian Magic in Asteroseismology

A new asteroseismic diagram of solar-like stars

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