The effective temperatures of hot stars

Crowther, P. A.

doi:10.1017/s0074180900116614

Cited by 5 publications

(4 citation statements)

References 47 publications

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“…Crowther (1998). Note, however, that the data used here do not give any evidence of significant deviations from a linear approximation, at least not in the covered range of spectral subclasses.…”

Section: Input Parametersmentioning

confidence: 57%

Bright OB stars in the Galaxy

Маркова

Puls

Repolust

et al. 2003

A&A

118

201

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Abstract. We study mass-loss and wind momentum rates of 29 Galactic O-type stars with luminosity classes I, III and V by means of a pure Hα profile analysis and investigate to what extent the results compare to those originating from a state-ofthe-art, complete spectral analysis. Our investigation relies on the approximate method developed by Puls et al. (1996) which we have modified to account for the effects of line-blanketing. Effective temperatures and gravities needed to obtain quantitative results from such a simplified approach have been derived by means of calibrations based on most recent spectroscopic NLTE analyses and models of Galactic stars by Repolust et al. (2003) and Martins et al. (2002). Comparing (i) the derived winddensities to those determined by Repolust et al. (2003) for eleven stars in common and (ii) the Wind-momentum Luminosity Relationship (WLR) for our sample stars to those derived by other investigations, we conclude that our approximate approach is actually able to provide consistent results. Additionally, we studied the consequences of "fine tuning" some of the direct and indirect parameters entering the WLR, especially by accounting for different possible values of stellar reddening and distances. Combining our data set with the corresponding data provided by Herrero et al. (2002) and Repolust et al. (2003) we finally study the WLR for the largest sample of Galactic O-type stars gathered so far, including an elaborate error treatment. The established disagreement between the theoretical predictions and the "observed" WLRs being a function of luminosity class is suggested to be a result of wind clumping. Different strategies to check this hypothesis are discussed, particularly by comparing the Hα mass-loss rates with the ones derived from radio observations.

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Section: Input Parametersmentioning

confidence: 57%

Bright OB stars in the Galaxy

Маркова

Puls

Repolust

et al. 2003

A&A

118

201

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“…Regarding the effective temperature (T eff ), its determination in OB stars is a complex task (e.g. Böhm-Vitense 1981, Crowther 1998. Given the need for a detailed treatment of non-LTE effects and the presence of stellar winds (Kudritzki & Hummer 1990), satisfactory modeling of such atmospheres that includes the effects of numerous metal-lines remains difficult to achieve (cf.…”

Section: Figmentioning

confidence: 99%

Asiago eclipsing binaries program IV. SZ Camelopardalis, aβ Cephei pulsator in a quadruple, eclipsing system

Tamajo

Munari

Siviero

et al. 2012

A&A

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We present a spectroscopic and photometric analysis of the multiple system and early-type eclipsing binary SZ Cam (O9 IV + B0.5 V), which consists of an eclipsing SB2 pair of orbital period P = 2.7 days in a long orbit (∼55 yrs) around a non-eclipsing SB1 pair of orbital period P = 2.8 days. We have reconstructed the spectra of the individual components of SZ Cam from the observed composite spectra using the technique of spectral disentangling. We used them together with extensive and accurate BV I C CCD photometry to obtain an orbital solution. Our photometry revealed the presence of a β Cep variable in the SZ Cam hierarchical system, probably located within the non-eclipsing SB1 pair. The pulsation period is (0.33265 ± 0.00005) days and the observed total amplitude in the B band is (0.0105 ± 0.0005) mag. NLTE analysis of the disentangled spectra provided atmospheric parameters for all three components, consistent with those derived from orbital solution.

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“…For a more quantitative estimate of the photospheric contribution to the Hα wind profile, we computed synthetic Balmer line profiles for Hα to Hγ using Atlas 9 LTE model atmospheres and the Balmer 9 LTE line formation code (Kurucz 1993). We adopted an effective temperature of T eff = 25 000 K according to a spectral type of B0.5 Ib using the temperature scale by Crowther (1999). For solar abundances and a microturbulence of ξ micro = 2 km s −1 we obtained a good fit for the mostly unblended Hβ line for a gravity of log g(cgs) = 3.3.…”

Section: The Projected Equatorial Rotation Velocitymentioning

confidence: 99%

Evidence for a connection between photospheric and wind structure in HD 64760

Kaufer

Prinja

Stahl³

2002

A&A

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Abstract. We report on the results of an extended optical spectroscopic monitoring campaign on the earlytype B supergiant HD 64760 (B0.5 Ib). The study is based on high-resolution echelle spectra obtained with the Landessternwarte Heidelberg's Heros instrument at ESO La Silla. Ninety-nine spectra were collected over 103 nights between January 19 and May 1, 1996. The Hα line shows a characteristic profile with a central photospheric absorption superimposed by symmetrically blue-and red-shifted wind-emission humps. The time-averaged line profile is well described by a differentially rotating and expanding radiation-driven wind: the redistribution of the wind emission flux into a double peak profile is interpreted in terms of the resonance zone effect in rotating winds as first described by Petrenz & Puls (1996). Detailed time-series analyses of the line profile variations across the Hα profile reveal for the first time in an optical data set of HD 64760 a periodic 2.4-day modulation of the inner and outer flanks of the Hα emission humps. The stronger modulations of the inner flanks of the emission humps at photospheric velocities are due to complex width variations of the underlying photospheric Hα profile. The weaker variations of the outer flanks are in phase and reflect variations at the base of the stellar wind. The detected 2.4-day modulation period together with a second period of 1.2 days (in the red emission hump only) is in excellent agreement with the outer-wind modulation periods as reported by Fullerton et al. (1997) from intensive IUE UV time-series observations in 1993 and 1995. The 2.4-day period is further detected in the photospheric He i λ4026 line as prograde traveling (pseudo-)absorption and emission features. The observed variability pattern is indicative for low-order non-radial pulsations in the photosphere of HD 64760. The non-radial pulsations are identified as the source of persistent, regularly spaced stellar surface structure which is maintained throughout the photosphere -wind transition zone (this work) out into the UV regime of the terminal velocity outflow.

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The effective temperatures of hot stars

Cited by 5 publications

References 47 publications

Bright OB stars in the Galaxy

Bright OB stars in the Galaxy

Asiago eclipsing binaries program IV. SZ Camelopardalis, aβ Cephei pulsator in a quadruple, eclipsing system

Evidence for a connection between photospheric and wind structure in HD 64760

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