Photoelectric Vilnius photometry of Hipparcos turn-off region stars

Bartasiute, S.; Ezhkova, O. V.; Lazauskaite, R.

doi:10.1515/astro-1999-0403

Cited by 3 publications

(3 citation statements)

References 11 publications

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“…4 and 5. 4 The bulk of metallicity estimates for our star sample comes from the catalogs of Cayrel de Strobel et al (1997Strobel et al ( , 2001; other references are Hartkopf & Yoss (1982); Luck (1982); Kjaergaard (1984); Faber et al (1985); Lambert et al (1986); Norris (1986); Burkhart & Coupry (1988); Laird,Carney,& Latham (1988); Knude (1989); Luck & Bond (1989); Eggen (1991Eggen ( , 1998; Geisler, Claria, & Minniti (1991); Taylor (1991Taylor ( , 1999; Xu (1991); Friel & Janes (1993); Thogersen, Friel, & Fallon (1993); Worthey et al (1994); Bartkevicius & Lazauskaite (1996; Claria, Piatti, & Osborn (1996); Zakhozhaj & Shaparenko (1996); Fry & Carney (1997);Flynn & Morell (1997); Schiavon, Barbuy, & Singh (1997); Takeda & Takada-Hidai (1998); Adelman (1999); Bartasiute, Ezhkova, & Lazauskaite (1999); Cenarro et al (2001); Gray, Graham, & Hoyt (2001); Haywood (2001); Andrievsky et al (2002); Venn et al (2002), based on different spectroscopic or photometric methods. Note that the only two metal-poor stars (HD 94028 and SAO 102986) in the JHC84 catalog have been excluded in our analysis so that we are eventually left with 334 objects in the GS83 plus JHC84 ...…”

Section: The Theoretical Spectral Librariesmentioning

confidence: 99%

ATLAS Versus NextGen Model Atmospheres: A Combined Analysis of Synthetic Spectral Energy Distributions

et al. 2004

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We carried out a critical appraisal of the two theoretical models, Kurucz' ATLAS9 and PHOENIX/NextGen, for stellar atmosphere synthesis. Our tests relied on the theoretical fit of spectral energy distributions (SED) for a sample of 334 target stars along the whole spectraltype sequence, from the classical optical catalogs of Gunn & Stryker (1983) and Jacoby et al. (1984). The best-fitting physical parameters (T eff , log g) of stars allowed an independent calibration of the temperature and bolometric scale vs. empirical classification parameters (i.e. spectral type and MK luminosity class); in addition, the comparison of the synthetic templates from the ATLAS and NextGen grids allowed us to probe the capability of the models to match spectrophotometric properties of real stars and assess the impact of the different input physics. We can sketch the following main conclusions of our analysis:i) fitting accuracy of both theoretical libraries drastically degrades at low T eff , where both ATLAS and NextGen models still fail to properly account for the contribution of molecular features in the observed SED of K-M stars.ii) Comparing with empirical calibrations, both ATLAS and NextGen fits tend, in average, to predict slightly warmer (by 4-8%) T eff for both giant and dwarf stars of fixed spectral type, but ATLAS provides in general a sensibly better fit (a factor of two lower σ of flux residuals) than NextGen.iii) There is a striking tendency of NextGen to label target stars with an effective temperature and surface gravity in excess with respect to ATLAS. The effect is especially evident for MK I-III objects, where a fraction of stars of about one in four is clearly misclassified by NextGen in log g. This is a consequence of some "degeneracy" in the solution space, partly induced by the different input physics and geometry constraints in the computation of the integrated emerging flux (ATLAS model atmospheres assume standard plane-parallel layers, while NextGen adopts, for low-gravity stars, a spherical-shell geometry). A different T (τ ) vertical structure of stellar atmosphere seems also required for NextGen synthetic SEDs in order to better account for limbdarkening effects in cool stars, as supported by the recent observations of the EROS BLG2000-5 microlensing event.

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Section: The Theoretical Spectral Librariesmentioning

confidence: 99%

ATLAS Versus NextGen Model Atmospheres: A Combined Analysis of Synthetic Spectral Energy Distributions

et al. 2004

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“…Measurements were made by S. Bartašiūtė with the 1 m Ritchey-Chretien telescope at Maidanak Observatory (Uzbekistan) during the course of the photometric program devoted to the study of the halo and thick disk stars (Bartkevičius, Lazauskaitė & Bartašiūtė 2002). The procedures of observations and data reductions are described by and Bartašiūtė, Ezhkova & Lazauskaitė (1999). The color -indices of the Vilnius system are presented in Bartkevičius, Lazauskaitė & Bartašiūtė (2002).…”

Section: Vilnius System Photometrymentioning

confidence: 99%

Kinematics of 11 Bidelman's weak‐lined stars

Bartkevicius¹,

Sperauskas

2003

Astron Nachr

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Abstract. Radial velocities obtained with the CORAVEL-type spectrometer are presented for 11 Bidelman's weak-lined stars, classified from moderate dispersion objective prism spectra. Standard errors of the measurements are smaller than 1 km/s. For five of these stars, measured in the Vilnius photometric system, only small metal deficiency is established. Kinematically, most of the stars belong to the thin disk and only two stars, HD 71185 and BD +75 AE 641, are consistent with membership of the thick disk population.

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“…Bartasiute (1999) has obtained photoelectric seven-color photometry in the Vilnius medium-band system for 374 stars in four MEGA proper-motion fields near the North Galactic Pole. Bartasiute, Ezhkova & Lazauskaite (1999) present seven-color photometry in the Vilnius system and hence derive spectral type, absolute magnitude and metallicity for 145 Hipparcos stars with accurate parallaxes. Progress on a new calibration of the Vilnius photometric system in terms of temperature and absolute magnitudes (based on temperatures of 450 stars determined by the infrared flux method or from angular stellar diameters and absolute magnitudes) of 2100 stars with Hipparcos parallaxes is given by Straizys, Kaslauskas & Bartasiute (1999).…”

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confidence: 99%

Commission 45: Stellar Classification: (Classification Stellaire)

Evans¹,

Corbally²,

Drilling³

et al. 2002

Trans. Int. Astron. Union

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This report, like its predecessor, focuses on areas which have been especially active since the last General Assembly. A major development has been the appearance of the first data and results from such large-scale surveys as 2MASS and the Sloan Digital Spectroscopic Survey, as well as major projects conducted from the ground. We give, for the first time, electronic addresses for selected catalogues and atlases. 2. Working Groups The following working groups all publish a newsletter, which may be accessed along with information on their activities from the Web page of Commission 45:

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Photoelectric Vilnius photometry of Hipparcos turn-off region stars

Cited by 3 publications

References 11 publications

ATLAS Versus NextGen Model Atmospheres: A Combined Analysis of Synthetic Spectral Energy Distributions

ATLAS Versus NextGen Model Atmospheres: A Combined Analysis of Synthetic Spectral Energy Distributions

Kinematics of 11 Bidelman's weak‐lined stars

Commission 45: Stellar Classification: (Classification Stellaire)

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