He i lines in the spectra of QSOs and Seyfert galaxies

Journal Article · Wed Feb 01 04:00:00 EST 1978 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/155843· OSTI ID:5040986

Netzer, H

Detailed calculations of He i line strengths for several models of QSOs and Seyfert galaxy nuclei are given. It is shown that an enhancement of the He i lambda5876 and He i lambda7065 lines by a factor of approx.2-10, is caused near quasars in emission regions 1-3 pc in diameter (0.1-0.3 pc for Seyfert galaxies). Line enhancement is practically independent of the gas density as long as N/sub H/> or approx. =2 x 10/sup 9/ cm/sup -3/, and is a function of distance from the ionizing continuum source. The broad and strong He i lines observed in the spectrum of some active objects are discussed. It is argued that in the cases where the He i lambda5876 line shows a broader profile than H..beta.., and possibly in other cases, the lines are formed in a gravitationally bound system, rather than in an atmosphere expanding under radiation pressure forces.

• Research Organization: Department of Physics and Astronomy, Tel-Aviv University
• OSTI ID: 5040986
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 219:3; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMICAL COMPOSITION
COSMIC RADIO SOURCES
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
ENERGY SPECTRA
ENERGY-LEVEL TRANSITIONS
FLUIDS
FUNCTIONS
GALAXIES
HELIUM
MECHANICS
NONMETALS
NUCLEAR REACTIONS
QUANTUM MECHANICS
QUASARS
RARE GASES
SEYFERT GALAXIES
SPECTRA
SPECTRAL FUNCTIONS