UIT Imagery of the Field of N49 in the LMC

Previous abstract Next abstract

Session 32 -- Local Group Galaxies
Display presentation, Tuesday, 9:30-6:30, Heller Lounge Room

[32.01] UIT Imagery of the Field of N49 in the LMC

Robert S. Hill (Hughes STX Corp.), Andrew M. Smith, K.-P. Cheng (Laboratory for Astronomy and Solar Physics, NASA/GSFC), Ralph C. Bohlin (STSciI), Robert W. O'Connell (U. of Virginia), Morton S. Roberts (NRAO), Theodore P. Stecher (Laboratory for Astronomy and Solar Physics, NASA/GSFC)

On the Astro-1\/ Space Shuttle mission in 1990 December, the Ultraviolet Imaging Telescope obtained an image at 1550\AA\ of the $40'$ field containing the supernova remnant (SNR) N49 in the Large Magellanic Cloud (LMC). This field is an excellent prototype of a Magellanic Cloud survey field, as it contains not only N49, but also another SNR, a globular cluster, several open clusters, H{\sc ii} regions, and two large stellar associations. The UIT image of the field is compared to the Hodge \& Wright LMC atlas print. The morphology of the entire region is compared to infrared imagery from IRAS.

N49 is compared to optical data obtained by Vancura et al. with respect to emission-line and continuum morphology. Emission from N49 in the bandpass observed by UIT includes C{\sc iv} $\lambda 1550$, He{\sc ii} $\lambda 1640$, O{\sc iii}]$\lambda 1663$, and hydrogen two-photon continuum. A map of the ratio of [O{\sc iii}]$\lambda 5007$ to continuum-subtracted UV shows a general coincidence of these two types of emission, including the high-excitation ``ring'' detected by Vancura et al. Several enhancements of this ratio are seen along the southern and eastern periphery, possibly because of reddening variation on scales of a few arcsec or optical depth effects in the C{\sc iv} UV resonance line. Optical and UV images are also compared to archive data from the {\it Einstein} High Resolution Imager (HRI). An x-ray bright spot is displaced from bright UV and [O{\sc iii}]$\lambda 5007$ emission by $4.5''$ ($\sim 1$ pc) and fits into an apparent notch in the southeast edge of the UV and optical SNR.

UV-optical color-magnitude diagrams (CMDs) of the associations LH52 and LH53 are presented. The CMD of LH53, which surrounds N49 in projection, appears to be almost unreddened, as compared to $E(B-V)=0.37$ deduced by Vancura et al. for N49 itself.

Tuesday program listing