2006A&A...457..987P


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.07CET04:10:21

2006A&A...457..987P - Astronomy and Astrophysics, volume 457, 987-994 (2006/10-3)

The superimposed photospheric and stellar wind variability of the O-type supergiant α Camelopardalis.

PRINJA R.K., MARKOVA N., SCUDERI S. and MARKOV H.

Abstract (from CDS):

This study seeks to provide empirical constraints on the different physical components that can yield temporal variability in predominantly or partially wind-formed optical lines of luminous OB stars, and thus potentially affect the reliable determination of fundamental parameters, including mass-loss rates via clumped winds. Using time-series spectroscopy from epochs spread over ∼4-years, we present a case study of the O9.5 supergiant α Cam. We demonstrate that the HeI λ5876 (23P0-33D) line is an important diagnostic for photospheric and wind variability in this star. The actions of large radial velocity shifts (up to ∼30km/s) in the photospheric absorption lines can also affect the morphology of the Hα line profile, which is commonly used for measuring mass-loss rates in massive stars. We identify a 0.36-day period in subtle absorption profile changes in HeI λ5876, which likely reveals the photospheric structure, perhaps due to low-order non-radial pulsations. This signal persists over ∼2 months, but it is not present 2 years later (November 2004); it is also not seen in the stellar wind components of the line profiles. Using a pure Hα line-synthesis code we interpret maximum changes in the redward and peak emission of α Cam in terms of mass-loss rate differences in the range ∼5.1x10–6 to 6.5x10–6M/yr. However, the models generally fail to reproduce the morphology of blueward (possibly absorptive) regions of the profiles. The optical line profiles of α Cam are affected by (i) deep-seated fluctuations close to, or at, the photosphere, (ii) atmospheric velocity gradients, and (iii) large-scale stellar wind structure. This study provides new empirical perspectives on accurate line-synthesis modelling of stellar wind signatures in massive luminous stars.

Abstract Copyright:

Journal keyword(s): stars: early-type - stars: mass-loss - stars: individual: α Camelopardalis

Simbad objects: 2

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Number of rows : 2

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 * alf Cam s*b 04 54 03.0103983 +66 20 33.636467 3.47 4.34 4.29 4.18 4.18 O9Ia 641 1
2 * eps Ori s*b 05 36 12.81335 -01 12 06.9089 0.48 1.51 1.69 1.76 1.93 B0Ia 867 0

    Equat.    Gal    SGal    Ecl

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2021.03.07-04:10:21

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