M87

A misaligned BL lacertae object?

Zlatan I. Tsvetanov, George F. Hartig, Holland C. Ford, Michael A. Dopita, Gerard A. Kriss, Yichuan C. Pei, Linda L. Dressel, Richard J. Harms

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

The nuclear region of M87 was observed with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) at six epochs, spanning 18 months, after the HSTimage quality was improved with the deployment of the corrective optics (COSTAR) in 1993 December. From the FOS target acquisition data, we have established that the flux from the optical nucleus of M87 varies by a factor of ∼2 on timescales of ∼2.5 months and by as much as 25% over 3 weeks and remains unchanged (≲2.5%) on timescales of ∼1 day. The changes occur in an unresolved central region ≲5 pc in diameter, with the physical size of the emitting region limited by the observed timescales to a few hundred gravitational radii. The featureless continuum spectrum becomes bluer as it brightens while emission lines remain unchanged. This variability, combined with the observations of the continuum spectral shape, strong relativistic boosting, and the detection of significant superluminal motions in the jet, strongly suggest that M87 belongs to the class of BL Lac objects but is viewed at an angle too large to reveal the classical BL Lac properties.

Original languageEnglish
JournalAstrophysical Journal
Volume493
Issue number2 PART II
Publication statusPublished - 1998
Externally publishedYes

Fingerprint

BL Lacertae objects
faint objects
spectrographs
continuums
timescale
target acquisition
Hubble Space Telescope
time measurement
optics
data acquisition
nuclei
radii

Keywords

  • BL Lacertae objects: general
  • Galaxies: active
  • Galaxies: individual (M87)
  • Galaxies: nuclei

ASJC Scopus subject areas

  • Space and Planetary Science
  • Nuclear and High Energy Physics

Cite this

Tsvetanov, Z. I., Hartig, G. F., Ford, H. C., Dopita, M. A., Kriss, G. A., Pei, Y. C., ... Harms, R. J. (1998). M87: A misaligned BL lacertae object? Astrophysical Journal, 493(2 PART II).

M87 : A misaligned BL lacertae object? / Tsvetanov, Zlatan I.; Hartig, George F.; Ford, Holland C.; Dopita, Michael A.; Kriss, Gerard A.; Pei, Yichuan C.; Dressel, Linda L.; Harms, Richard J.

In: Astrophysical Journal, Vol. 493, No. 2 PART II, 1998.

Research output: Contribution to journalArticle

Tsvetanov, ZI, Hartig, GF, Ford, HC, Dopita, MA, Kriss, GA, Pei, YC, Dressel, LL & Harms, RJ 1998, 'M87: A misaligned BL lacertae object?', Astrophysical Journal, vol. 493, no. 2 PART II.
Tsvetanov ZI, Hartig GF, Ford HC, Dopita MA, Kriss GA, Pei YC et al. M87: A misaligned BL lacertae object? Astrophysical Journal. 1998;493(2 PART II).
Tsvetanov, Zlatan I. ; Hartig, George F. ; Ford, Holland C. ; Dopita, Michael A. ; Kriss, Gerard A. ; Pei, Yichuan C. ; Dressel, Linda L. ; Harms, Richard J. / M87 : A misaligned BL lacertae object?. In: Astrophysical Journal. 1998 ; Vol. 493, No. 2 PART II.
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