相关论文: UV Spectral Synthesis of Vega
UV, optical, and near-IR spectra of Vega have been combined to test our understanding of stellar atmospheric opacities, and to examine the possibility of constraining chemical abundances from low-resolution UV fluxes. We have carried out a…
Vega, the second brightest star in the northern hemisphere, serves as a primary spectral type standard. While its spectrum is dominated by broad hydrogen lines, the narrower lines of the heavy elements suggested slow to moderate rotation,…
We have obtained high-precision interferometric measurements of Vega with the CHARA Array and FLUOR beam combiner in the K' band at projected baselines between 103m and 273m. The measured visibility amplitudes beyond the first lobe are…
Spectral synthesis is a powerful tool with which to find the fundamental parameters of stars. Models are usually restricted to single values of temperature and gravity, and assume spherical symmetry. This approximation breaks down for…
The theoretically studied impact of rapid rotation on stellar evolution needs to be confronted with the results of high resolution spectroscopy-velocimetry observations. A weak surface magnetic field had recently been detected in the A0…
Ultraviolet (UV; rest-frame $\sim1200-2000$ A) spectra provide a wealth of diagnostics to characterize fundamental galaxy properties, such as their chemical enrichment, the nature of their stellar populations, and their amount of…
Near-infrared (2.2 um) long baseline interferometric observations of Vega are presented. The stellar disk of the star has been resolved, and the data have been fitted with a limb darkened stellar disk of diameter Theta_{LD} = 3.28 +/- 0.01…
The atmospheric abundances of elements provide essential insights into the formation and evolution history of stars. The visible wavelength window has been used almost exclusively in the past to determine the abundances of chemical elements…
In early type stars the ultraviolet spectral region is important for several reasons. Firstly, since the majority of the total flux is emitted here, it provides a rather sensitive indicator of a photospheric temperature and luminosity.…
We present an analysis of high resolution spectra in the far-UV -- UV range (~905-2000\AA) with non-LTE, spherical, hydrodynamical, line-blanketed models, of three O-type Galactic stars, and derive their photospheric and wind parameters.…
We present preliminary results of a large project aimed at creating an extended theoretical and observational database of stellar spectra in the ultraviolet wavelength range. This library will consist of IUE spectra at low and high…
We present an analysis of 1524 spectra of Vega spanning 10 years, in which we search for periodic radial velocity variations. A signal with a periodicity of 0.676 days and a semi-amplitude of ~10 m/s is consistent with the rotation period…
We present a comprehensive analysis of high-resolution, far-UV HST/STIS, FUSE, and optical spectra of 17 O stars in the SMC. Our analysis is based on NLTE metal line-blanketed model atmospheres calculated with our NLTE code TLUSTY. We…
We present chemical composition and fundamental parameters (the effective temperature, surface gravity and radius) for four sharp-lined A-type stars ${\gamma}$ Gem (HD 41705), o Peg (HD 214994), ${\theta}$ Vir (HD 114330) and ${\nu}$ Cap…
This paper presents an analysis of the UV spectrum of some nebulae with clearly identified illuminating stars, all observed by the IUE satellite. The data show remarkable properties of the UV spectrum of the nebulae. Each spectrum is the…
Optical and infrared interferometers definitively established that the photometric standard Vega (alpha Lyrae) is a rapidly rotating star viewed nearly pole-on. Recent independent spectroscopic analyses could not reconcile the inferred…
We present long-slit NIR spectra, obtained using the ISAAC instrument at the Very Large Telescope, for nine radio galaxies at z~2.5. One-dimensional spectra have been extracted and cross calibrated with optical spectra from the literature…
The discovery that Vega is a rapidly rotating pole-on star has raised a number of questions about this fundamental standard, including such issues as its composition, and in turn its mass and age. We report here a reanalysis of Vega's…
We present a detailed analysis of the UV spectrum of the calibration star Bd+28 4211 using high-quality spectra obtained with the HST and FUSE satellites. To this aim, we compare quantitatively the observed data with model spectra obtained…
To fully understand the Be star phenomenon, one must have a reasonable degree of knowledge about the star beneath the disk, which is often found to be rapidly rotating. Rapid rotation complicates modelling because fundamental properties…