ATLAS vs. NextGen model atmospheres: a combined analysis of synthetic spectral energy distributions

Дата и время публикации : 2004-06-08T20:56:10Z

Авторы публикации и институты :
E. Bertone (INAOE, Mexico)
A. Buzzoni (INAF-Oss. Astron. Bologna, Italy)
M. Chavez (INAOE, Mexico)
L. H. Rodriguez-Merino (INAOE, Mexico)

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Коментарии к статье: 18 pages, 14 figures; accepted for publication in the Astronomical Journal (scheduled for the August issue); see also and
Первичная категория: astro-ph

Все категории : astro-ph

Краткий обзор статьи: 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 SEDs for a sample of 334 target stars along the whole spectral-type sequence. The best-fitting physical parameters of stars allowed a calibration of the temperature and bolometric scale. The main conclusions of our analysis are: i) the fitting accuracy of both theoretical libraries drastically degrades at low Teff; ii) comparing with empirical calibrations, both ATLAS and NextGen fits tend to predict slightly warmer Teff, but ATLAS provides in general a sensibly better fit; 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. This is a consequence of some “degeneracy” in the solution space, partly induced by the different input physics and geometry constraints. A different T(tau) vertical structure of stellar atmosphere seems also required for NextGen synthetic SEDs in order to better account for limb-darkening effects in cool stars, as supported by the recent observations of the EROS BLG2000-5 microlensing event.

Category: Physics