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http://hdl.handle.net/20.500.12386/34645
Titolo: | Probing Atlas model atmospheres at high spectral resolution. Stellar synthesis and reference template validation | Autori: | Bertone, E. BUZZONI, Alberto Chávez, M. Rodríguez-Merino, L. H. |
Data pubblicazione: | 2008 | Rivista: | ASTRONOMY & ASTROPHYSICS | Numero: | 485 | Fascicolo: | 3 | Da pagina:: | 823 | Abstract: | Aims: The fast improvement of spectroscopic observations makes mandatory a strong effort on the theoretical side to better reproduce the spectral energy distribution (SED) of stars at high spectral resolution. In this regard, relying on the Kurucz Atlas/Synthe original codes we computed the Bluered library, consisting of 832 synthetic SED of stars, that cover a large parameter space at very high spectral resolution (R = 500 000) along the 3500-7000 Å wavelength range. <BR />Methods: Bluered synthetic spectra have been used to assess in finer detail the intrinsic reliability and the performance limits of the Atlas theoretical framework. The continuum-normalized spectra of the <ASTROBJ>Sun</ASTROBJ>, <ASTROBJ>Arcturus</ASTROBJ>, and <ASTROBJ>Vega</ASTROBJ>, plus a selected list of 45 bright stars with high-quality SEDs from the Prugniel & Soubiran Elodie catalog, form our sample designed to probe the global properties of synthetic spectra across the entire range of H-R parameters. <BR />Results: Atlas models display a better fitting performance with increasing stellar temperature. High-resolution spectra of Vega, the Sun, and Arcturus have been reproduced at R=100 000, respectively, within a 0.7%, 4.5%, and 8.8% relative scatter in residual flux. In all the three cases, the residual flux distribution shows a significant asymmetry (skewness parameter γ = -2.21, -0.98, -0.67, respectively), which neatly confirms an overall “excess” of theoretical line blanketing. For the Sun, this apparent discrepancy is alleviated, but not recovered, by a systematic decrease (-40%) of the line oscillator strengths, log (gf), especially referring to iron transitions. Definitely, a straight “astrophysical” determination of log (gf) for each individual atomic transition has to be devised to overcome the problem. By neglecting overblanketing effects in theoretical models when fitting high-resolution continuum-normalized spectra of real stars, we lead to a systematically warmer effective temperature (between +80 and +300 K for the solar fit) and a slightly poorer metal content. | URI: | http://hdl.handle.net/20.500.12386/34645 | URL: | https://api.elsevier.com/content/abstract/scopus_id/53449085730 https://www.aanda.org/articles/aa/abs/2008/27/aa8923-07/aa8923-07.html |
ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361:20078923 | Bibcode ADS: | 2008A&A...485..823B | Fulltext: | open |
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