The Distance of BL Lacertae
Abstract
The extended object around BL Lacertae has been observed spectrophotometrically, with the use of both an annulus and round apertures. The annulus spectrum shows the absorption lines normally seen in spectra of ordinary giant galaxies; these lines yield a redshift z = 0.07. It is also shown that (1) the central source is a power-law spectrum with a = - 1.55(2) the underlying galaxy energy distribution is consistent with that of a normal giant elliptical galaxy; (3) the interstellar extinction corresponds to = 0.28; (4) if H8 = 60 km 1 is used, the absolute visual magnitude of the galaxy is -22.9 and the distance is 350 Mpc (the central source at the brightest we have observed it is 7 times as bright as the galaxy); (S) on the assumption that the redshift z = 0.07, the central source is similar in spectral index and luminosity to quasars such as 3C 48, 3C 279, and 3C 345, provided a cosmological distance is assumed for these latter quasars. Subject headings: quasi-stellar sources - spectrophotometry - redshifts
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1974
- DOI:
- 10.1086/181450
- Bibcode:
- 1974ApJ...189L...5O