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Radiation-driven winds of hot luminous stars. XIII. A description of NLTE line blocking and blanketing towards realistic models for expanding atmospheres
Pauldrach, A. W. A.; Hoffmann, T. L.; Lennon, M.
Spectral analysis of hot luminous stars requires adequate model atmospheres which take into account the effects of NLTE and radiation driven winds properly. Here we present significant improvements of our approach in constructing detailed atmospheric models and synthetic spectra for hot luminous stars. Moreover, as we regard our solution method in…
EXPORT: Spectral classification and projected rotational velocities of Vega-type and pre-main sequence stars
Rauer, H.; Schneider, J.; Eiroa, C. +19 more
In this paper we present the first comprehensive results extracted from the spectroscopic campaigns carried out by the EXPORT (EXoPlanetary Observational Research Team) consortium. During 1998-1999, EXPORT carried out an intensive observational effort in the framework of the origin and evolution of protoplanetary systems in order to obtain clues o…
The Distribution of Thermal Pressures in the Interstellar Medium from a Survey of C I Fine-Structure Excitation
Tripp, Todd M.; Jenkins, Edward B.
We used the Space Telescope Imaging Spectrograph (STIS) with its smallest entrance aperture (0.03" wide slit) and highest resolution echelle gratings (E140H and E230H) to record the interstellar absorption features for 10 different multiplets of neutral carbon at a resolving power of λ/Δλ=200,000 in the UV spectra of 21 early-type stars. Our objec…
High resolution X-ray spectroscopy of zeta Puppis with the XMM-Newton reflection grating spectrometer
Mewe, R.; Güdel, M.; Leutenegger, M. A. +5 more
We present the first high resolution X-ray spectrum of the bright O4Ief supergiant star zeta Puppis, obtained with the Reflection Grating Spectrometer on-board XMM-Newton. The spectrum exhibits bright emission lines of hydrogen-like and helium-like ions of nitrogen, oxygen, neon, magnesium, and silicon, as well as neon-like ions of iron. The lines…
Searching for the Physical Drivers of the Eigenvector 1 Correlation Space
Marziani, P.; Zwitter, T.; Sulentic, J. W. +2 more
We recently discussed an Eigenvector 1 (E1) parameter space that provides optimal discrimination between the principal classes of broad-line active galactic nuclei (AGNs). In this paper we begin a search for the most important physical parameters that are likely to govern correlations and data point distribution in E1 space. We focus on the princi…
The mass of the neutron star in Vela X-1
Kaper, L.; Telting, J. H.; Barziv, O. +2 more
We measured the radial-velocity curve of HD 77581, the B-supergiant companion of the X-ray pulsar Vela X-1, using 183 high-resolution optical spectra obtained in a nine-month campaign. We derive radial-velocity amplitudes for different lines and wavelength regions, and find all are consistent with each other, as well as with values found in previo…
Chemical abundances of planetary nebulae from optical recombination lines - III. The Galactic bulge PN M 1-42 and M 2-36
Barlow, M. J.; Liu, X. -W.; Storey, P. J. +2 more
We present deep, high-resolution optical spectra of two Galactic bulge planetary nebulae (PN), M 1-42 and M 2-36. The spectra show very prominent and rich optical recombination lines (ORLs) from C, N, O and Ne ions. Infrared spectra from [formmu10]2.4-197µm were also obtained using the Short and Long Wavelength Spectrometer (SWS and LWS) on …
Spectrophotometric Standards from the Far-Ultraviolet to the Near-Infrared: STIS and NICMOS Fluxes
Calzetti, D.; Dickinson, M. E.; Bohlin, R. C.
With photometric repeatability in the 0.2%-0.4% range and wavelength coverage from 1150 to 10,200 Å, the Space Telescope Imaging Spectrograph (STIS) low-dispersion spectrophotometry provides excellent absolute flux standards. STIS observations of 19 stars are used to update the database of Hubble Space Telescope standard stars with absolute fluxes…
High-Resolution X-Ray and Ultraviolet Spectroscopy of the Complex Intrinsic Absorption in NGC 4051 with Chandra and the Hubble Space Telescope
Brandt, W. N.; Kaspi, Shai; Elvis, Martin +6 more
We present the results from simultaneous observations of the narrow-line Seyfert 1 galaxy NGC 4051 with the Chandra High Energy Transmission Grating Spectrometer and the Hubble Space Telescope Space Telescope Imaging Spectrograph. The X-ray grating spectrum reveals absorption and emission lines from hydrogen-like and helium-like ions of O, Ne, Mg,…
The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. II. Basic Parameters of Program Stars and the Role of Microturbulence
Gray, R. O.; Graham, P. W.; Hoyt, S. R.
Paper I of this series presented precise MK spectral types for 372 late A-, F-, and early G-type stars with the aim of understanding the nature of luminosity classification on the MK spectral classification system for this range of spectral types. In this paper, a multidimensional downhill simplex technique is introduced to determine the basic par…