Variability of the broad absorption lines in the QSO UM 232

• Published in: The Astrophysical journal Vol. 347; no. 2; pp. 674 - 678
• Main Authors: Barlow, Thomas A., Junkkarinen, Vesa T., Burbidge, E. Margaret
• Format: Journal Article
• Language: English
• Published: Legacy CDMS University of Chicago Press 15.12.1989
• Subjects: 640102 - Astrophysics & Cosmology- Stars & Quasi-Stellar, Radio & X-Ray Sources; ABSORPTION SPECTRA; Astronomy; Astrophysics; CHARGED PARTICLES; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COSMIC RADIO SOURCES; DENSITY; Earth, ocean, space; Exact sciences and technology; IONIZATION; IONS; LINE WIDTHS; OPACITY; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; QUASARS; Quasars. Active or peculiar galaxies, objects, and systems; SPECTRA; Stellar systems. Galactic and extragalactic objects and systems. The universe; VARIATIONS; VELOCITY; Aluminium «III; Quasar; Absorption line; Silicon IV; Stellar spectrum; Calcium Positive ion; Equivalent width; Optical thickness; Emission line; Column density; Spectroscopical observation
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/168157

Low-resolution spectra of UM 232 taken in 1978, 1979, and 1988 at Lick Observatory are presented. Large changes in the Si IV lambda 1397, CIV lambda 1549, and Al III lambda 1857 broad absorption lines are apparent. The decrease in column density in all three ions and an observed brightening of the QSO suggests that these changes are due to an increase in the ionization level driven by an increase in the central source luminosity. This mechanism has been proposed by Smith and Penston to explain small changes in the absorption spectrum of the QSO 1246-057. The spectra of UM 232 show that the fractional decrease in optical depth is smaller at higher outflow velocies. The structure of the broad absorption-line region (BALR) is investigted by estimating an ionization parameter for each ion species as a function of velocity.