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The redshift of the highly variable BL Lac object H0323+022

Filippenko, Alexei V. and Djorgovski, S. and Spinrad, Hyron and Sargent, Wallace L. W. (1986) The redshift of the highly variable BL Lac object H0323+022. Astronomical Journal, 91 (1). pp. 49-55. ISSN 0004-6256. doi:10.1086/113977.

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New optical spectra are used to derive the redshift of H0323 + 022, a bright, highly variable x-ray source whose nature has been the subject of controversy. Most of the spectra are dominated by a featureless nonstellar continuum, as found in BL Lac objects. Photometric variations of ≳2 mag have been seen over a time interval of only 2 days. The nonstellar light is sometimes faint enough to allow the detection of absorption lines at a redshift z = 0.1471 + 0.0005. These lines are clearly due to stars in the host galaxy, which is easily visible in deep images of the object. The galaxy is probably a relatively normal elliptical with M_v ≈ -21 to -22, except that a noticeable extension is evident in one quadrant. On 24.15 February 1985 UT, the nonstellar continuum could be described by a power law of index a ≈ 0.6 (where f_v ∝ v -α); its relative strength in the nucleus (2" X 5.2") was ~62% at 5460 Å, while M_v ≈ -22 to -23. When the power-law component fades, its slope appears to steepen. There is now no doubt that H0323 + 022 is a BL Lac object, rather than a peculiar Galactic star. As discussed by Feigelson et al. (1986), its extremely rapid variability (ΔL ≈ 1 X 10^(45) erg s^(-1) in Δt ≈ 30 s) is matched only by that of OJ 287, and the hard x rays must come from a region roughly a factor of 10^4 smaller than that which produces the radio emission.

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Filippenko, Alexei V.0000-0003-3460-0103
Djorgovski, S.0000-0002-0603-3087
Additional Information:© 1986 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 7August 1985; revised 4 September 1985. Based in part on research done at Lick Observatory, University of California. We thank M. Doyle, J. Henning, S. Staples, and D. Tennant for their assistance at Palomar Observatory, as well as B. Alcott, K. Baker, C. Clark, W. Earthman, J. Morey, and M. Owens at Lick Observatory. Dr. H. E. Smith and R. P. S. Stone provided useful information for operating the Lick ITS. Drs. H. Bradt and C. M. Urry aroused our initial interest in H0323 + 022, and Dr. W. Romanishin communicated results prior to publication. Valuable conversations with R. M. Rich and Dr. J. P. Halpern are gratefully acknowledged. This work was supported by the Miller Institute for Basic Research in Science (A. V. F.), a University of California Regents Fellowship (S.D.), NSF Grant No. AST 84-01788 (H.S.), and NSF Grant No. AST 84-16704 (W.L.W.S).
Funding AgencyGrant Number
Miller Institute for Basic Research in ScienceUNSPECIFIED
University of CaliforniaUNSPECIFIED
NSFAST 84-01788
NSFAST 84-16704
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ID Code:97558
Deposited By: Tony Diaz
Deposited On:01 Aug 2019 17:09
Last Modified:16 Nov 2021 17:32

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