Preliminary scientific results from UVSTAR: The FUV spectra of BD+28° 4211 and NGC 246

Year: 1998

Authors: Stalio R., Bratina V., Holberg J.

Autors Affiliation: Dipartimento di Astronomia, Università di Trieste, Italy; Ctr. for Adv. Res. in Space Optics, Area Science Park, Trieste, Italy; Lunar and Planetary Laboratory, University of Arizona, United States

Abstract: UVSTAR, Ultraviolet Spectrograph Telescope for Astronomical Research operates in the 500 – 1200 Å waveband; it has capability for long slit spectral imaging of extended cosmic sources. UVSTAR has recently flown as a Hitchhiker-M payload on the STS 85 mission (August 7-18, 1997) of the Shuttle Discovery. UVSTAR is a joint collaboration between the University of Arizona (Tucson) and the University of Trieste. The instrument consists of a movable platform and an optical system. The platform provides fine pointing (±5 arcsec) within ±3 degrees from the nominal view direction, which is near the Shuttle +Y axis, i.e. perpendicular to the long axis of the Shuttle and in the plane of the wings. The optical system has two channels, each formed of a telescope and Rowland concave-grating spectrograph with intensified CCD detector. The first channel, FUV, operates in the 850 – 1250 Å spectral range, the second, EUV, has covered the 500 – 900 Å region. UVSTAR includes capabilities for independent target acquisition and tracking. Here we report FUV observations, obtained in August 1997, of the sdO star BD +28°4211 which is a secondary flux standard and of the central star of the planetary nebula NGC 246, a hot degenerate star which shows strong OV1 lines in the optical region. The UVSTAR spectrum of NGC 246 displays remarkable P Cygni profiles indicating a very fast stellar wind.

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KeyWords: FUV spectroscopy; Planetary nebula; Stellar wind; UVSTAR