Evidence of a Starburst within 9 Parsecs of the Active Nucleus of NGC 1097

Abstract

We report evidence of a recent burst of star formation located within 9 pc of the active nucleus of NGC 1097. The observational signatures of the starburst include UV absorption lines and continuum emission from young stars observed in a small-aperture Hubble Space Telescope spectrum. The burst is <= a few × 10⁶ yr old, has a mass of ~10⁶ M_solar, an observed luminosity of 1.5×10⁷ L_solar, and is obscured by A_V~3 mag. The importance of this finding is twofold: (1) the proximity of the starburst to the active nucleus and thus its possible association with it, and (2) its obscuration by and apparent association with a dusty absorbing medium, while the broad emission lines appear unobscured, suggesting that the starburst could be embedded in a circumnuclear torus as predicted in the unified model of active galactic nuclei.

Based on observations with the NASA/ESA Hubble Space Telescope at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.