HST FOS spectroscopy of M87: Evidence for a disk of ionized gas around a massive black hole

Richard J. Harms, Holland C. Ford, Zlatan Tsvetanov, George F. Hartig, Linda L. Dressel, Gerard A. Kriss, Ralph Bohlin, Arthur F. Davidsen, Bruce Margon, Ajay K. Kochhar

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Using the Faint Object Spectrograph on the Hubble Space Telescope (HST) to observe the central region of M87, we have obtained spectra covering ∼4600-6800 Å at a spectral dispersion ∼4.4 Å per resolution element through the 0″.26 diameter entrance aperture. One spectrum was obtained centered on the nucleus of M87 and two centered 0″.25 off the nucleus at position angles of 21° and 201°, thus sampling the anticipated major axis of the disklike structure (described in a companion Letter) expected to he approximately perpendicular to the axis of the M87 jet. Pointing errors for these observations are estimated to be less than 0″.02. Radial velocities of the ionized gas in the two positions 0″.25 on either side of the nucleus are measured to be ≈ ± 500 km s-1 relative to the M87 systemic velocity. These observations plus emission-line spectra obtained at two additional locations near the nucleus show the ionized gas to be in Keplerian rotation about a mass M = (2.4 ± 0.7) × 109 M within the inner 0″.25 of M87. Our results provide strong evidence for the presence of a supermassive nuclear black hole in M87.

Original languageEnglish
JournalAstrophysical Journal
Issue number1 PART 2
Publication statusPublished - 1 Nov 1994
Externally publishedYes



  • Black hole physics
  • Galaxies: individual (M87)
  • Galaxies: kinematics and dynamics
  • Instrumentation: spectrographs

ASJC Scopus subject areas

  • Space and Planetary Science
  • Nuclear and High Energy Physics

Cite this

Harms, R. J., Ford, H. C., Tsvetanov, Z., Hartig, G. F., Dressel, L. L., Kriss, G. A., Bohlin, R., Davidsen, A. F., Margon, B., & Kochhar, A. K. (1994). HST FOS spectroscopy of M87: Evidence for a disk of ionized gas around a massive black hole. Astrophysical Journal, 435(1 PART 2).