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Rolf-Peter Kudritzki

Publications and source records attributed to Rolf-Peter Kudritzki.

112 records · Page 7Linked to original sources
arXiv2002

STIS UV spectroscopy of early B supergiants in M31

We analyze STIS spectra in the 1150-1700 Angstrom 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 half of the sample we find evidence for an enhanced maximum turbulent velocity when compared to Galactic counterparts.

astro-ph↗
arXiv2001

Spectroscopy of blue supergiants in NGC 300

We have obtained VLT low-resolution (~5 A) multi-object spectroscopy in the 4,000-5,000 A spectral range of about 70 blue supergiant candidates in the Sculptor Group spiral galaxy NGC 300. We present a detailed spectral catalog containing identification, magnitudes, colors and spectral types. We employ synthetic spectra to determine metal abundances for two A0 supergiants of the sample. In agreement with the expectations, the star closer to the galactic center is found to be more metal rich than the object at a larger galactocentric distance. Using the Balmer Hbeta line profile we have estimated the mass-loss rate for one of the brightest A2 supergiants in the sample. We determined the wind momentum of the star and compared it to the value expected from the empirical wind momentum-luminosity relationship (WLR) for A-type supergiants of Kudritzki et al. (1999). Good agreement is obtained.

astro-ph↗
arXiv2000

Stellar spectroscopy far beyond the Local Group

Multi-object spectroscopic observations of blue supergiants in NGC 3621, a spiral galaxy at a distance of 6.7 Mpc, carried out with the ESO VLT and FORS are presented. We demonstrate the feasibility of quantitative stellar spectroscopy at distances approaching a ten-fold increase over previous investigations by determining chemical composition, stellar parameters, reddening, extinction and wind properties of one of our targets, a supergiant of spectral type A1 Ia located in the outskirts of NGC 3621. The metallicity (determined from iron group elements) is reduced by a factor of two relative to the sun in qualitative agreement with results from previous abundance studies based on H II region oxygen emission lines. Reddening and extinction are E(B-V) = 0.12 and Av = 0.37, respectively, mostly caused by the galactic foreground. Comparing stellar wind momentum and absolute V magnitude with galactic and M31 counterparts we confirm the potential of the wind momentum-luminosity relationship as an alternative tool to estimate extragalactic distances.

astro-ph↗