We have obtained optical long-slit spectroscopy of the nucleus of M32 using the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. The stellar rotation velocity and velocity dispersion, as well as the full line-of-sight velocity distribution (LOSVD), were determined as a function of position along the slit using two independent spectral deconvolution algorithms. We see three clear kinematical signatures of the nuclear black hole: a sudden upturn, at ∼ 0.3′′ from the center, in the stellar velocity dispersions; a flat or rising rotation curve into the center; and strong, non-Gaussian wings on the central LOSVD. The central velocity dispersion is ∼ 130 km s−1 (Gaussian fit) or >∼ 175 km s−1 (corrected for the wings). Both the velocity dispersion spike and the shape of the central LOSVD are consistent with the presence of a supermassive compact object in M32 with a mass in the range 2 − 5 × 106M⊙. These data are a significant improvement on previous stellar kinematical data, making M32 the first galaxy for which the imprint of the black hole’s gravitation on the stellar velocities has been observed with a resolution comparable to that of gas-dynamical studies. (Refer to PDF file for exact formulas).

Publication Date



Archived in: arXiv:astro-ph/0005530 v2 28 May 2000 AND Rutgers Astrophysics Preprint Series No. 273 This work was supported by NASA grants NAG 5-3158 and NAG 5-6037, by NSF grant AST 96-17088, and by STIS GTO funding. Data presented here were based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under NASA contract NAS5-26555.ISSN:1538-4357 Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus