Kinematics of the M82 Starburst

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Session 31 -- Star-Forming Galaxies
Display presentation, Tuesday, 9:30-6:30, Heller Lounge Room

[31.13] Kinematics of the M82 Starburst

Niall I. Gaffney \& Dan F. Lester (University of Texas/McDonald Observatory), C. M. Telesco (NASA MSFC)

We are continuing our study of the stellar kinematics in the starburst galaxy M82. We observed the 2.294 $\mu$m (2-0)$^{12}$CO stellar absorption band across the central 30 arcseconds of M82 at a resolution of 20000 with the CSHELL echelle spectrometer on the 3m NASA IRTF on UT 7, 8, and 9 April 1993. With these data, we have measured the stellar kinematics of the central r$<$200 pc along the starburst disk. The velocity dispersion measured in our initial study (Gaffney et al. 1993, Ap. J. Letters, 407, L57) demonstrated that the stellar population in the central r$<$7.5 pc of M82 has a mass-to-light ratio consistent with that of a normal bulge. We interpret this as a nuclear population of old bulge stars surrounded by a ring of newly formed massive stars. By extending the spatial range of our measurements, we measure the mass of the stellar population surrounding the nucleus directly. With this, we will determine whether old giants or young supergiants dominate the near infrared continuum in the starburst disk. In addition to the stellar kinematics, we have measured the kinematics of the gas using both the 2.166 $\mu$m Brackett $\gamma$ hydrogen recombination line and the 1.644 $\mu$m [FeII] emission line. By comparing the stellar kinematics with the Brackett $\gamma$ and [FeII], we determine what effect shock and large scale gas flows have on the gas kinematics and morphology across the starburst disk.

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