The Vienna Atomic Line Data Base ? a Status Report

Ryabchikova, T. A.; Piskunov, Nikolai; Stempels, H. C.; Kupka, F.; Weiss, W. W.

doi:10.1238/physica.topical.083a00162

Cited by 145 publications

(131 citation statements)

References 14 publications

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“…In brief, our spectral modeling program, SME (VF05; Valenti & Piskunov 1996), assumes local thermodynamic equilibrium and drives a radiative transfer code using Kurucz stellar atmosphere models ( Kurucz 1993) and atomic line data ( Vienna Atomic Line Database [VALD]; Kupka et al 1999;Ryabchikova et al 1999) to create a synthetic spectrum. The code employs a nonlinear leastsquares Marquardt fitting algorithm to vary free parameters (T eA , log g, v sin i, and abundances) in order to best match continuum and spectral line profiles in selected wavelength regions of an observed spectrum.…”

Section: The Spectral Analysis Techniquementioning

confidence: 99%

The Planet‐Metallicity Correlation

Fischer

Valenti

2005

ApJ

1,433

154

1,423

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We have recently carried out spectral synthesis modeling to determine T eA , log g, v sin i, and [Fe/ H ] for 1040 FGK-type stars on the Keck, Lick, and Anglo-Australian Telescope planet search programs. This is the first time that a single, uniform spectroscopic analysis has been made for every star on a large Doppler planet search survey. We identify a subset of 850 stars that have Doppler observations sufficient to detect uniformly all planets with radial velocity semiamplitudes K > 30 m s À1 and orbital periods shorter than 4 yr. From this subset of stars, we determine that fewer than 3% of stars with À0:5 < ½Fe/H < 0:0 have Doppler-detected planets. Above solar metallicity, there is a smooth and rapid rise in the fraction of stars with planets. At ½Fe/H > þ0:3 dex, 25% of observed stars have detected gas giant planets. A power-law fit to these data relates the formation probability for gas giant planets to the square of the number of metal atoms. High stellar metallicity also appears to be correlated with the presence of multiple-planet systems and with the total detected planet mass. This data set was examined to better understand the origin of high metallicity in stars with planets. None of the expected fossil signatures of accretion are observed in stars with planets relative to the general sample: (1) metallicity does not appear to increase as the mass of the convective envelopes decreases, (2) subgiants with planets do not show dilution of metallicity, (3) no abundance variations for Na, Si, Ti, or Ni are found as a function of condensation temperature, and (4) no correlations between metallicity and orbital period or eccentricity could be identified. We conclude that stars with extrasolar planets do not have an accretion signature that distinguishes them from other stars; more likely, they are simply born in higher metallicity molecular clouds.

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Section: The Spectral Analysis Techniquementioning

confidence: 99%

The Planet‐Metallicity Correlation

Fischer

Valenti

2005

ApJ

1,433

154

1,423

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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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“…For the line opacity calculation we have created the Vienna Atomic Line Data Base Ryabchikova et al 1999 ;Kupka et al 1999), which for the moment includes 108 lists from di †erent sources with over 42 million lines. This includes all the line data from Kurucz (1992b) (published as CD-ROMs 20È22) for Ca to Ni for transitions between observed and also between predicted energy levels.…”

Section: Ine Selectionmentioning

confidence: 99%

Model Atmospheres with Individualized Abundances

Piskunov

Kupka

2001

ApJ

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We describe a new method for computing opacity distribution functions (ODFs) for model atmosphere calculations. The method is tailored to model the atmospheres of individual stars on a modern workstation. Our goal is the computation of model atmospheres for stars with abundances signiÐcantly di †er-ent from the solar or scaled solar composition typically used for grid calculations. As a consistency test, we show that the new procedure is able to reproduce the ODFs and existing model atmospheres for solar abundances, and we describe models for stars with peculiar abundances. We demonstrate that while mild chemical peculiarities can be well represented by scaled solar models, the extreme cases result in a very di †erent atmospheric structure with no analogs in scaled solar grids. Such a structure inÑu-ences the emerging spectrum as is clearly seen both in the observed Ñux distribution and in the line ratios that are much better represented by the new models.

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The Vienna Atomic Line Data Base ? a Status Report

Cited by 145 publications

References 14 publications

The Planet‐Metallicity Correlation

The Planet‐Metallicity Correlation

A seismic and gravitationally bound double star observed byKepler

Model Atmospheres with Individualized Abundances

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