Space Telescope Imaging Spectrograph Ultraviolet Spectroscopy of Early B Supergiants in M31

Bresolin, Fabio; Kudritzki, Rolf-Peter; Lennon, Daniel J.; Smartt, Stephen J.; Herrero, Artemio; Urbaneja, Miguel A.; Puls, Joachim
Referencia bibliográfica

The Astrophysical Journal, Volume 580, Issue 1, pp. 213-224.

Fecha de publicación:
11
2002
Número de autores
7
Número de autores del IAC
2
Número de citas
17
Número de citas referidas
17
Descripción
We analyze Space Telescope Imaging Spectrograph (STIS) spectra in the 1150-1700 Å wavelength range obtained for six early B supergiants in the neighboring galaxy M31. Because of their likely high (nearly solar) abundance, these stars were originally chosen to be directly comparable to their Galactic counterparts and represent a much needed addition to our current sample of B-type supergiants, in our efforts to study the dependence of the wind momentum-luminosity relationship on spectral type and metallicity. As a first step to determine wind momenta we fit the P Cygni profiles of the resonance lines of N V, Si IV, and C IV with standard methods and derive terminal velocities for all of the STIS targets. From these lines we also derive ionic stellar wind column densities. Our results are compared with those obtained previously in Galactic supergiants and confirm earlier claims of ``normal'' wind line intensities and terminal velocities in M31. For one-half of the sample we find evidence for an enhanced maximum turbulent velocity when compared to Galactic counterparts. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.