Photoelectric magnitudes and polarization data for possible BL Lacertae objects

Journal Article · Thu Apr 01 04:00:00 EST 1976 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/154244· OSTI ID:7270188

Kinman, T D

Photoelectric UBV magnitudes and polarization data are given for a sample of radio sources with continuous or weak-lined optical spectra which are possible BL Lacertae objects. The majority show optical variability and significant variable polarization. If no extended optical component is visible, the mean colors are consistent with these objects having power-law spectra F (..nu..) proportional..nu../sup -//sup alpha/, where +0.7<..cap alpha..<+2.4; the most negative indices are likely to be spurious because of the effect of an unseen extended component. Objects with and without visible extended components are separated on a plot of spectral index against apparent magnitude. It is shown to be difficult to adopt a useful sharp definition of a BL Lacertae object, and the similarity of this general class to the variable emission-line quasars is stressed. The separation of BL Lacertae objects from field stars on the (U: V)/(B: R) two-color diagram is suggested as a means of identification. (AIP)

• Research Organization: Kitt Peak National Observatory
• OSTI ID: 7270188
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 205:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640103* -- Astrophysics &amp; Cosmology-- Quasi-Stellar
Radio
&amp; X-Ray Sources-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COLOR
COSMIC RADIO SOURCES
EMISSION SPECTRA
OPTICAL PROPERTIES
ORGANOLEPTIC PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
POLARIZATION
QUASARS
SPECTRA
VARIATIONS