The degree of optical variability of quasi-stellar objects.

1974 ◽  
Vol 86 ◽  
pp. 873 ◽  
Author(s):  
S. A. Grandi ◽  
W. G. Tifft
Keyword(s):  
Optical Variability ◽  
Stellar Objects ◽  
Quasi Stellar Objects

scholarly journals Optical Variability of Twenty-Two Quasi-Stellar Objects

1972 ◽  
Vol 44 ◽  
pp. 171-178 ◽  
Author(s):  
R. J. Angione ◽  
H. J. Smith
Keyword(s):  
Large Amplitude ◽  
Small Amplitude ◽  
Secular Trends ◽  
Apparent Magnitude ◽  
Optical Variability ◽  
Stellar Objects ◽  
Light Fluctuations ◽  
Quasi Stellar Objects ◽  
One Year

Light fluctuations have been found in all 22 QSOs studied by measurement of plates from the Harvard collection, which cover the last eighty years. The conclusions of this study are: (i) There appear to be at least three general classes of variation: (a) erratic, small-amplitude variations, (b) erratic, large-amplitude variations, and (c) slow quasi-periodic variations, e.g. as in 3C 273; (ii) No significant differences were detected between the rates of rise and decline of luminosity; (iii) Definite secular trends over at least 50 years were found in 5 QSOs; (iv) No simple clearcut periods greater than one year have been found; (v) There may be a trend of decreasing amplitude of fluctuations in apparent magnitude with increasing luminosity.

scholarly journals Statistical Properties of QSOs

1972 ◽  
Vol 44 ◽  
pp. 453-457
Author(s):  
A. Braccesi
Keyword(s):  
Optical Properties ◽  
Radio Emission ◽  
Statistical Properties ◽  
Optical Variability ◽  
Stellar Objects ◽  
Luminosity Functions ◽  
Quasi Stellar Objects

Counts of quasi-stellar objects selected by their optical properties imply evolutionary properties similar to those found by examining the radio-selected objects. The optical luminosity functions of the 3CR and optically-selected quasi-stellar objects are compared. Data on the radio emission and optical variability of the optically-selected sample are presented.

The properties of the dusty inner regions of nearby QSOs

2019 ◽  
Vol 15 (S356) ◽  
pp. 95-95
Author(s):  
Itziar Aretxaga
Keyword(s):  
Star Formation ◽  
Polycyclic Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbon ◽  
Stellar Objects ◽  
X Ray ◽  
Mir Spectroscopy ◽  
Polycyclic Aromatic ◽  
Quasi Stellar Objects

AbstractWe present MIR spectroscopy and photometry obtained with CanariCam on the 10.4 m Gran Telescopio CANARIAS for a sample of 20 nearby, MIR bright and X-ray luminous quasi-stellar objects (QSOs). We find that for the majority of QSOs the MIR emission is unresolved at angular scales ∼0.3 arcsec. We derive the properties of the dusti tori that surround the nucleus based on these observations and find significant differences in the parameters compared with a sample of Seyfert 1 and 2 nuclei. We also find evidence for polycyclic aromatic hydrocarbon (PAH) features in the spectra, indicative of star formation, more centrally peaked (on scales of a few hundred pc) than previously believed.

scholarly journals Classification of Compact Objects: QSS, QSOs, N-Type and Compact Galaxies, Seyfert and Galactic Nuclei

1972 ◽  
Vol 44 ◽  
pp. 97-103
Author(s):  
W. W. Morgan
Keyword(s):  
Galactic Nuclei ◽  
Seyfert Galaxy ◽  
Classification Criteria ◽  
Compact Objects ◽  
Stellar Objects ◽  
Quasi Stellar Objects ◽  
Compact Galaxies

Some methods currently in use for the classification of the optical forms of the ‘compact’ galaxies and quasi-stellar objects are reviewed. It is shown that the category ‘Seyfert Galaxy’ is basically a spectroscopic (rather than a form) classification.An optical form-classification is described which is, in principle, identical with published classification criteria for QSO, N-type, and compact objects. The importance of maintaining rigid form-standards is emphasized.

On the Space Distribution of Identified Quasi-stellar Objects and Radiogalaxies

Nature ◽  
1967 ◽  
Vol 216 (5113) ◽  
pp. 351-352 ◽  
Author(s):  
G. R. BURBIDGE ◽  
F. HOYLE
Keyword(s):  
Space Distribution ◽  
Stellar Objects ◽  
Quasi Stellar Objects

Nature of strong radio emission from quasi-stellar objects

1964 ◽  
Vol 9 (2) ◽  
pp. 138-139 ◽  
Author(s):  
L. Gold ◽  
J.W. Moffat
Keyword(s):  
Radio Emission ◽  
Stellar Objects ◽  
Quasi Stellar Objects

scholarly journals THE HIGH A V Quasar Survey: Reddened Quasi-Stellar Objects selected from optical/near-infrared photometry. II.

2015 ◽  
Vol 217 (1) ◽  
pp. 5 ◽  
Author(s):  
J.-K. Krogager ◽  
S. Geier ◽  
J. P. U. Fynbo ◽  
B. P. Venemans ◽  
C. Ledoux ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Photometry ◽  
Stellar Objects ◽  
Quasi Stellar Objects

scholarly journals The Origin of Absorption Spectra in Quasi-Stellar Objects

1980 ◽  
Vol 92 ◽  
pp. 107-117 ◽  
Author(s):  
Ray J. Weymann
Keyword(s):  
Absorption Line ◽  
Absorption Spectra ◽  
Classification Scheme ◽  
Spectral Characteristics ◽  
Type A ◽  
Galactic Halos ◽  
Evolutionary Sequence ◽  
Rich Cluster ◽  
Stellar Objects ◽  
Quasi Stellar Objects

A classification scheme for QSO absorption line spectra is described which ascribes the origin of the lines to at least four mechanisms: (A) Explosive ejection of material at speeds up to 0.1 c. (B) Absorption by highly ionized material moving in a rich cluster in which the QSO is embedded. (C-1) Cosmologically distant intervening material with ‘normal’ abundances, probably associated with large galactic halos. (C-2) Cosmologically distant intervening material consisting of primordial uncondensed gas. Examples of each type of spectra are given and their ionization and other spectral characteristics discussed. The similarity between the development of novae spectra and a possible evolutionary sequence of the explosive ejecta of type A is striking and suggestive. Several difficulties and unsolved problems involving this scheme are noted. Finally, we speculate on the interpretation of two interesting objects (PKS 0237-23 and the ‘twin quasars’ 0957+56A,B) in the context of this scheme.

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