The spectrum of the central star in the reflection nebula NGC 7023.

Abstract

view Abstract Citations (6) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The spectrum of the central star in the reflection nebula NGC 7023. Weston, Edwin B. Abstract The spectrum of this star, BD $6701283, HD 200775, MWC 361, has been described in a recent note submitted to Publications of the Astronomical Society of the Pacific. The results of measurement of additional plates of this star show that the central hydrogen absorption cores probably have a variable radial velocity. Very weak lines of Na I were also found on a more recent panchromatic plate of moderate dispersion. The radial velocities determined from the EFe iij lines agreed well with those determined for the star from the C ii and Mg ii absorption lines. The central absorption cores of the hydrogen lines gave highly accordant radial velocities that differed appreciably from those of the star. Hence, it is probable that the EFe II lines, which presumably are produced by collisional excitation, originate in a cloud of low density gas at rest relative to the star, whereas the hydrogen lines are produced in a shell of higher density rotating about the star. This phenomenon is perhaps not too dissimilar to that found for the much cooler and less luminous T Tauri type stars located in nebulosity. Observatory, University of Michigan, Ann Arbor, Mich. Publication: The Astronomical Journal Pub Date: October 1950 DOI: 10.1086/106443 Bibcode: 1950AJ.....55R..82W full text sources ADS | data products SIMBAD (2)