AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 71. Between the Stars II: The ISM, Galactic and Extragalactic
Display, Wednesday, June 2, 1999, 10:00am-6:30pm, Southwest Exhibit Hall

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[71.17] First Results from Abu on SPIREX: Wide-Field Imaging of NGC 6334

J. M. Jackson, K. E. Kraemer (Boston University), I. Gatley (RIT), A. Fowler, K. M. Merrill, N. Sharp (NOAO), R. Evans, D. A. Harper, R. F. Loewenstein, F. Mrozek (University of Chicago), R. Marks (UNSW/U. Chicago), M. C. B. Ashley, M. G. Burton, J. W. V. Storey (UNSW)

We present the first results of the Abu instrument on the SPIREX facility at the South Pole. Abu uses a 1024\times 1024 InSb detector array with a 10.2'\times10.2' field-of-view and 0.6'' pixels. Using the 60 cm SPIREX telescope with the Abu camera, during the 1998 austral winter we detect L=13.5 mag (S/N=10 in 1 hour). Engineering improvements to reduce the thermal background should allow even better performance this season. Abu/SPIREX offers the best currently available wide-field 3-5 \mum imaging and pioneers a future capability which can effectively complement SIRTF, Gemini, and SOFIA.

We have imaged NGC 6334, a southern massive star formation region, in Br \alpha, the 3.3 \mum PAH feature, and in L-band continuum. The 3.3 \mum PAH emission matches the spatial distribution of the [C II] 158 \mum emission, a tracer of photodissociation regions (PDRs). The 3.3 \mum PAH imaging of NGC 6334 therefore reveals the structure of its various PDRs in unprecedented angular resolution (~''), more than an order of magnitude better than traditional FIR (~') tracers of the PDRs. The bubbles and loops carved out by the winds from the young stars show that PDRs are clumpy and filamentary. With this detailed structure, we can now compare the PDR distribution with the other components of the ISM (ionized gas, dust, molecular gas) at comparable angular resolution. A preliminary examination of these data shows an anti-correlation between the 3.3 \mum feature and the ionized gas (traced by radio and Br \alpha). The distribution of molecular gas (traced by the extinction), of photodissociated gas (traced by the 3.3 \mum emission), and of ionized gas (traced by the Br \alpha emission), is precisely that expected for a photodissociation region: the ionized gas lies on the interior of the shell, the photodissociated gas just outside the ionized gas, and the molecular gas just outside the photodissociated gas. There are also a few remarkably red objects that suggest deeply embedded protostellar sources.

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