The evolutionary status of the semiregular variable QY Sge
| العنوان: | The evolutionary status of the semiregular variable QY Sge |
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| المؤلفون: | M. V. Yushkin, Valentina G. Klochkova, V. E. Panchuk, E. L. Chentsov |
| المصدر: | Astrophysical Bulletin. 62:217-234 |
| بيانات النشر: | Pleiades Publishing Ltd, 2007. |
| سنة النشر: | 2007 |
| مصطلحات موضوعية: | Physics, Photosphere, Absorption spectroscopy, Metallicity, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Star (graph theory), law.invention, Telescope, law, Microturbulence, Supergiant, Absorption (electromagnetic radiation), Instrumentation |
| الوصف: | Repeated spectroscopic observations made with the 6m telescope of yielded new data on the radial-velocity variability of the anomalous yellow supergiant QYSge. The strongest and most peculiar feature in its spectrum is the complex profile of NaI D lines, which contains a narrow and a very wide emission components. The wide emission component can be seen to extend from -170 to +120 km/s, and at its central part it is cut by an absorption feature, which, in turn, is split into two subcomponents by a narrow (16km/s at r=2.5) emission peak. An analysis of all the Vr values leads us to adopt for the star a systemic velocity of Vr=-21.1 km/s, which corresponds to the position of the narrow emission component of NaI. The locations of emission-line features of NaI D lines are invariable, which point to their formation in regions that are external to the supergiant's photosphere. Differential line shifts of about 10km/s are revealed. The absorption lines in the spectrum of QYSge have a substantial width of FWHM~45 km/s. The method of model atmospheres is used to determine the following parameters: Teff=6250K, lg g=2.0, and microturbulence Vt=4.5km/s. The metallicity of the star is found to be somewhat higher than the solar one with an average overabundance of iron-peak elements of [Met/H]=+0.20. The star is found to be slightly overabundant in carbon and nitrogen, [C/Fe]=+0.25, [N/Fe]=+0.27. The alpha-process elements Mg, Si, and Ca are slightly overabundant [alpha/H]=+0.12. The strong sodium excess, [Na/Fe]=+0.75, is likely to be due to the dredge-up of the matter processed in the NeNa cycle. Heavy elements of the s-process are underabundant relative to the Sun. On the whole, the observed properties of QYSge do not give grounds for including this star into the group of RCrB or RVTau-type type objects. 29 pages, 8 figures, 4 tables; accepted by Astrophys. Bulletin |
| تدمد: | 1990-3421 1990-3413 |
| DOI: | 10.1134/s1990341307030030 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2b3f42dbfade672745737222fc9997e2 https://doi.org/10.1134/s1990341307030030 |
| Rights: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....2b3f42dbfade672745737222fc9997e2 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 19903421 19903413 |
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| DOI: | 10.1134/s1990341307030030 |