Bazı süperdev yıldızların tayfsal analizi
Spectral analysis of some supergiant stars
- Tez No: 213844
- Danışmanlar: PROF.DR. İBRAHİM ETHEM DERMAN
- Tez Türü: Doktora
- Konular: Astronomi ve Uzay Bilimleri, Astronomy and Space Sciences
- Anahtar Kelimeler: supergiant stars, atmospheric parameters, chemical abundance, evolution
- Yıl: 2007
- Dil: Türkçe
- Üniversite: Ankara Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Astronomi ve Uzay Bilimleri Ana Bilim Dalı
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 198
Özet
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Özet (Çeviri)
In this study, line identification of Orionis, which is B0 Iae blue supergiant, is presented by using high resolution spectra together with the detail computation of the chemical abundance in both ultraviolet and visual regions, individually. The lines of the following atomic species were found to be definitely present in the atmosphere of Orionis: Al II, Al III, C II, C III, C IV, Ca II, Cr II, Cr III, Cr IV, Fe II, Fe III, Fe IV, Fe V, Ga II, H I, He I, He II, Mg II, Mn II, Mn III, N II, N III, Ne II, Ni III, Ni IV, O II, O III, O IV, P III, S III, S IV, Si II, Si III, Si IV and Ti III. The model atmosphere calculations and abundance analysis were performed using Kurucz (1995)?s LTE ATLAS9, ATLAS12 and WIDTH9 softwares. The atmospheric parameters (Tef, logg) were determined by three ways. These are; comparing observed continuum with calculated continua of model atmospheres, fitting H profile with calculated one, C II/III, N II/III, O II/III, Si II/III, Si III/IV and Ni III/IV equilibrium. Depending on these three methods, effective temperature and logarithm of gravity of Orionis is determined as Tet=26000±1000 K and logg=3.00±0.1. Microturbulence in the atmosphere of Orionis was found to be, in average, of ~ 10 km/s by using the UV lines namely Si III, Cr III and Fe III and found to be, in average, of ~ 12 km/s by using the lines N II, N III, O II and Ne II appeared in the visual region. Rotational velocity of 82±3 km/s; radial velocity of 26.34±4.5 km/s; terminal velocity of the wind of 1504 km/s and mass loss rate of 1.3 10-6 M/y were determined. Mass of 37.1 M, radius of 31.9 R and logarithm of luminosity of log (L/L) = 5.62 were calculated for Orionis. In the atmosphere of Orionis, helium appears to be overabundant by 0.39 dex with respect to solar value. The CNO values with of C being slightly deficient (0.26 dex), N being mildly excessive (0.48 dex) and O being in slight excess (0.23 dex) relative to the Sun. Depending on [N/C] ratio that Orionis has not undergone the first dredge-up phase. However, the nonzero [N/C] ratio suggests that Orionis has undergone some partial mixing by CN-cycled gas. Rotationally induced turbulent diffusive mixing may explain the abnormal abundances of Orionis. 2007, 189 pages
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