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J. L. Turner, L. P. Crosthwaite, D. S. Meier (UCLA), S. C. Beck (Tel Aviv)
We present high spectral (R~25,000) and spatial resolution near-infrared spectra of the starburst in the dwarf galaxy NGC 5253. The data were obtained with the NIRSPEC spectrometer on the Keck Telescope.
The spectra confirm the presence of the bright IR and radio ``supernebula'' discovered by Beck et al. (1996 ApJ, 457, 610) and Turner et al. (1998, AJ, 116, 1212; 2000 ApJ, 532, L109), which contains the ionization equivalent of 4000 O7 stars within a 1-2 pc region. The supernebula is detected in both Brackett \alpha at 4.05\mu m and Brackett \gamma at 2.17\mu m. The linewidths of the Brackett lines are large for the ~1\prime\prime centered on the supernebula: roughly 160-170 km/s FWZI for both lines. The broad linewidths for this small (<10 pc) region are not due to galactic rotation, but probably indicate the presence of winds from the large young stellar population, estimated at a million stars. The nebula overwhelmingly dominates the Brackett line emission from the 20-30\prime\prime starburst region, in agreement with the mid-infrared continuum emission (Gorjian, Turner, & Beck 2001).
This research is supported by NSF grant AST-0071276, the US-Israel Binational Science Foundation grant 94-00303, and Sigma Xi Grants-in-Aid of Research.