Query : 2012A&A...542L..32K

2012A&A...542L..32K - Astronomy and Astrophysics, volume 542, L32-32 (2012/6-1)

Detection of a 1.59 h period in the B supergiant star HD 202850.


Abstract (from CDS):

Photospheric lines of B-type supergiants show variability in their profile shapes. In addition, their widths are much wider than can be accounted for purely by stellar rotation. This excess broadening is often referred to as macroturbulence. Both effects have been linked to stellar oscillations, but B supergiants have not been systematically searched yet for the presence of especially short-term variability caused by stellar pulsations. We have started an observational campaign to investigate the line profile variability of photospheric lines in a sample of Galactic B supergiants. These observations aim to improve our understanding of the physical effects acting in the atmospheres of evolved massive stars. We obtained four time-series of high-quality optical spectra for the Galactic B supergiant HD202850. The spectral coverage of about 500Å around Hα encompasses the SiIIλλ6347, 6371, and the HeIλ6678 photospheric lines. The line profiles were analysed by means of the moment method. The time-series of the photospheric SiII and HeI lines display a simultaneous, periodic variability in their profile shapes. Proper analysis revealed a period of 1.59h in all three lines. This period is found to be stable with time over the observed span of 19 months. This period is much shorter than the rotation period of the star and might be ascribed to stellar oscillations. Since the star seems to fall outside the currently known pulsational instability domains, the nature of the discovered oscillation remains unclear.

Abstract Copyright:

Journal keyword(s): stars: early-type - supergiants - stars: atmospheres - stars: oscillations - stars: individual: HD 202850

VizieR on-line data: <Available at CDS (J/A+A/542/L32): list.dat spectra/*>

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 HD 46769 * 06 35 15.8285310432 +00 53 24.785166300 5.43 5.84 5.86 5.78 5.81 B7Ib-II 87 0
2 * alf Leo PM* 10 08 22.31099 +11 58 01.9516 0.88 1.24 1.40 1.37 1.47 B8IVn 847 1
3 * 27 Vul * 20 37 04.6724184888 +26 27 43.006388904   5.528 5.583     B8V 68 0
4 NAME IV CYG ASSOC. As* 21 15 +37.9           ~ 48 0
5 * sig Cyg sg* 21 17 24.9524404 +39 23 40.852798 3.98 4.37 4.24 4.06 3.92 A0Ia 264 0

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