Hubble space telescope NICMOS imaging of the cores of M31 and M32

Michael R. Corbin, Earl O'Neil, Marcia J. Rieke

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


We present 1.1, 1.6, and 2.2 μm images of the cores of the Local Group galaxies M31 and M32 obtained with the Near Infrared Camera and Multi-Object Spectrometer of the Hubble Space Telescope (HST). These images are also compared with optical images of the galaxies obtained with the HST Wide Field Planetary Camera 2 (WFPC2). In M31, the nucleus remains distinctly asymmetric in all of the infrared bands, with no evidence of concentrated dust, although the distinction between the two nuclei, P1 and P2, is not as strong as in the WFPC2 and earlier WF/PC-1 images. This result is nonetheless consistent with the model of the nucleus as an eccentric stellar disk produced by the dynamical influence of a central supermassive black hole. Several individual M giant stars are detected within ∼3″ of the nuclei and may represent stars that have escaped from the disk and phase-mixed around the nuclear center of mass. In M32 we also do not find strong evidence of dust, and the brightness profiles within the central ∼1″ of the infrared images can be fitted by a power law of the same form as that fitted to the optical images. The infrared color profiles of the central few arcseconds of M32 show no strong gradients and indicate a population dominated by K giant stars. This is consistent with recent ground-based spectroscopy and photometry of the core region, which similarly show no strong gradients in age or metallicity within its stellar population.

Original languageEnglish (US)
Pages (from-to)2549-2556
Number of pages8
JournalAstronomical Journal
Issue number5
StatePublished - May 2001


  • Galaxies: individual (M31, M32)
  • Galaxies: nuclei
  • Galaxies: photometry
  • Infrared radiation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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