Detailed Far-UV Spectral Atlas of B Main Sequence Stars
Myron A. Smith
The far-UV spectral atlas of B stars
contains high resolution data in the far-UV wavelength region (defined here
as the range 949-1225 Ångstroms) for 10 B stars near the main sequence.
The spectrum for type B0 is taken, with permission from the
author, from the still classic Copernicus satellite atlas of τ
Scorpii (Rogerson and Upson 1977).
For all other types the spectra
were obtained from the MAST/FUSE data archives (Far Ultraviolet Spectroscopic
Explorer) in the range 949-1188Å, and from the archives of either the
HST/STIS or IUE archives for wavelengths above 1188Å;
whenever both data sources
were available the STIS spectrum was selected. This atlas has been published
by the IOP (Institute of Physics) Press as an Astrophysical Journal Supplement
both in paper and on-line formats.
The FITS-formatted data on which the atlas is based are available only
through this website.
With respect to the data in the MAST archives, the altas spectra are enhanced, first, in that wavelength irregularities for the FUSE Side 1 and Side 2 spectra have been removed to the extent possible and corrections made for the stars' radial velocities. The spectra were then resampled to restore the wavelength zeropoints and increments of the original spectra. Second, the depressed fluxes in the FUSE 1B LiF detector segment due to the primary "worm" have been corrected by means of the quasi-continuum fluxes in the 2A LiF segment. Third, a "star/ISM flag" vector was added to the FITS files to designate those wavelengths for which the fluxes are dominated by local molecular hydrogen lines.
This work is practically unique among stellar spectral atlases in its attempt to identify all visible photospheric and interstellar lines in this wavelength region by means of existing atomic and molecular line sources. For this reason it is called a "detailed" spectral atlas. These identifications are shown in a long table containing three subtables. These are referred to as Tables 3a-c in the Journal paper, and each includes about two thousand line identifications. The lines are designated as either "primary" or "secondary" for each of three spectral types, B0, B2, and B8, where the attached secondary lines have smaller equivalent widths than the primary lines within a common wavelength instrumental resolution of 0.05Å and 0.075Å for Copernicus and FUSE, respectively.
This atlas also presents expanded plots and line identification tables of the entire wavelength range for spectra at types B0, B2, and B8 approximately representing the extremes and middle of the ionizations of iron in the B range. When secondary lines contribute to line blends, the total number of features in a wavelength bin is given following the wavelength/ion identification string. Molecular hydrogen lines and spectral regions are shown by vertical red tick marks. The FUSE Side 1 and 2 spectra are shown as large dots and green lines, respectively. (The Copernicus spectrum for type B0 is a single spectrum.)
Spectral Types of Far-UV Atlas Stars