Anomalous HI in NGC 2997

Hess, Kelley M. ; Pisano, D. J. ; Wilcots, Eric M. ; Chengalur, Jayaram N. (2009) Anomalous HI in NGC 2997 The Astrophysical Journal, 699 (1). pp. 76-88. ISSN 0004-637X

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Official URL: http://iopscience.iop.org/0004-637X/699/1/76

Related URL: http://dx.doi.org/10.1088/0004-637X/699/1/76

Abstract

We present deep H I observations of the moderately inclined spiral galaxy, NGC 2997. The goal of these observations was to search for H I clouds in the vicinity of NGC 2997 analogous to the high-velocity clouds of the Milky Way and gain insight into their origins. We find evidence for the presence of a galactic fountain as well as the accretion of intragalactic material, however we do not identify any large clouds of H I far from the disk of the galaxy. NGC 2997 has a thick, lagging H I disk that is modeled with a vertical velocity gradient of 18-31 km s−1 kpc−1. Anomalous velocity H I clouds with masses of order 107 M, which cannot be explained by galactic fountain models allow us to estimate a lower limit to the accretion of extragalactic gas of 1.2 Myr−1. The number and mass of these clouds have implications for cosmological simulations of large-scale structure and the presence of dark matter halos. We have used values from the literature to estimate a star formation rate of 5 ± 1 M yr−1 and to derive a new distance to NGC 2997 of 12.2 ± 0.9 Mpc using published Tully-Fisher relations.

Item Type:Article
Source:Copyright of this article belongs to American Astronomical Society.
Keywords:Galaxies: Individual (NGC 2297); Galaxies: ISM; Galaxies: Kinematics and Dynamics; Galaxies: Structure
ID Code:63577
Deposited On:29 Sep 2011 04:11
Last Modified:29 Sep 2011 04:11

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