Line variability and the broad emission line region of quasi-stellar objects. II. Changes in Balmer decrements

Journal Article · Fri Jan 01 04:00:00 EST 1988 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/165939· OSTI ID:5333491

Zheng, W

Evidence is presented for significant variations of broad emission lines in five QSOs supporting an earlier report by Zheng et al. (1987). The Balmer decrements before and after variations are compared in an effort to extract information on the broad-line regions. The broad hydrogen lines are found to vary in step with the underlying continuum, indicating that the continuum is the probable energy source for emission lines. The ratios of H-beta/H-alpha for both the varying and steady parts of the the broad lines are about 0.2, suggesting that the regions in which these line fluxes originate are exposed to similar ionizing flux and are therefore at about the same distance to the central source. The average ratio of H-gamma/H-beta is 0.8 for the variable components, considerably higher than that of the constant components. Thus, the region producing the varying line fluxes may have higher density and lower optical depth. 16 references.

• Research Organization: California Univ., La Jolla (USA); Beijing Observatory (People's Republic of China)
• OSTI ID: 5333491
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 324; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BALMER LINES
COSMIC RADIO SOURCES
ELEMENTS
EMISSION SPECTRA
ENERGY-LEVEL TRANSITIONS
FORBIDDEN TRANSITIONS
NONMETALS
OXYGEN
QUASARS
RADIATION TRANSPORT
SPECTRA
VARIATIONS