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FUSE Atlases of OB Stars

Galactic OB Stars

The first of the two FUSE data catalogs below contains an atlas of far-ultraviolet spectra of 45 OB (O2-B3) stars in the Galaxy (see Pellerin, Fullerton, Robert et al. 2002; ) for the spectral region 920-1180  Å. If you are interested in line identifications, this is probably the site for you because of the expanded wavelength scale. On the other hand, the site contains objects that tend to be heavily extincted by the ISM below 1000 Å.

The full range of spectral type/luminosity classes is represented in this sample. The atlas plots map the locations of principal features of ions of He, C, N, O, P, and S. The dagger and Earth symbols indicate the wavelengths of stellar Lyman lines and telluric lines, respectively. The last section, of great value to proposers of ISM-extincted objects, gives plots of the predicted line profiles of molecular hydrogen at various interstellar column densities.

All data were obtained through the 30×30 arcsec (large) science aperture. The original data resolution and reciprocal spectral dispersion were 15-20 km/s and 0.062-0.067 Å/pixel, respectively. The data were further resampled to 0.12Å/pixel for this atlas. Date of observation and integration time (typically 5 ks) are given in the FITS headers. Most spectra were obtained in a series of back-to-back exposures. Tests indicated that apparent wavelength shifts among them are less than ½ a resolution element. The final spectra were constructed with simple coadditions.

Clicking on "Available Data" below brings one to a table organized as in the publication, according to spectral type/class (rows) and detector wavelength region (columns). The "view montage" links will bring up one of several panels of spectra organized by wavelength region for each of several spectral type intervals. Clicking on individual table entries (with left and right mouse button!) permits the downloading of FITS files on which these spectra are based. These data files contain three columns: wavelengths, fluxes, and smoothed fluxes. Smoothed fluxes are given in the plots and were generated with a 20-"pixel" boxcar function.

Note finally that a link on the star name brings the reader to the SIMBAD query result page for that star.

Magellanic OB Stars

The second catalog, placed directly below the Galactic OB star catalog, is a table that serves data for 47 OB stars in the Large and Small Magellanic Clouds (see Walborn et al. 2002, ApJS, 141, 443). This spectral atlas covers essentially the same spectral type and luminosity ranges of the Pellerin et al. atlas. The same observing configuration was used as for the other atlas. However, for this atlas the data have been rebinned to steps of 0.25 Å. The primary difference is that the spectra are less attenuated below 1000Å by Galactic ISM and H2 extinction. This atlas is particularly valuable because of its annotation of metallic ISM features. The atlas is also useful because the spectra have been carefully coadded among the FUSE detectors, merged, and rectified. In fact the continuum is fully rectified (flat) and normalized to unity, bringing the conditioning of FUSE data to its fullest potential for immediate analysis purposes. Finally, metallicity differences between the two Magellanic Cloud galaxies can be noticed among many (generally unsaturated) lines.

The "Available Data" link brings the reader to a table for each of the two spectral atlases. The Magellanic Cloud data list (second) table is organized differently from the Galactic table. As in the first table, the first column gives the star name, and clicking on its link takes you to the SIMBAD query result page for this star. Each group of stars is highlighted by a dark blue bar with a link "view montage" on the right. Clicking on this link takes one to the panel array of all spectra in the category denoted and over the full FUSE spectral range. Clicking on the links on the right hand columns opposite the star name brings the reader to the gzipped fits file of the data (be sure to click on the mouse button combination that allows you to "save link as"). These datafiles give the wavelength, normalized (and rectified) flux, and unnormalized flux vectors. Note again that the data comprise the full FUSE wavelength coverage.

Available Data

Copyright Statement: The data presented here will be published in the Astrophysical Journal Supplements. and appears with the permission of the American Astronomical Society and the author cited above. Reuse or redistribution of these data is subject to the copyright policies of the American Astronomical Society.