UIT Observations of the Halo of NGC 891
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Session 19 -- Gas and Star Formation in Spiral Galaxies
Display presentation, Wednesday, January 12, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[19.08] UIT Observations of the Halo of NGC 891

J. V. Brinkmann (Astronomy Department, University of Virginia), R. C. Bohlin (Space Telescope Science Institute), K.- P. Cheng (Goddard Space Flight Center), P. M. Hintzen (Department of Physics and Astronomy, University of Nevada, Las Vegas), R. W. O'Connell (Astronomy Department, University of Virginia), M. S. Roberts (National Radio Astronomy Observatory), A. M. Smith (Goddard Space Flight Center), E. P. Smith (Goddard Space Flight Center), T. P. Stecher (Goddard Space Flight Center)


We present an observation of the edge-on Sb galaxy NGC 891 taken by Ultraviolet Imaging Telescope during the ASTRO 1 mission with a broad mid-UV filter with half power points at 1800 \AA\ and 3100 \AA. We compare the emission seen in this image with the emission seen in the ground--based optical H$\alpha$ and [S II] $\lambda\lambda$6717,6731 images of Rand, Kulkarni and Hester (ApJ 362 , L1--L4).

The mid-UV emission is brightest along a thin plane corresponding to the major axis of the galaxy. The mid-UV surface brightness of the disk, measured with the center of the galaxy masked out, has a scale height of 0.6 kpc. Emission in the disk is asymetrically concentrated to the NE of the galaxy center, in rough correspondence with the H$\alpha$ emission from young star forming regions.

Diffuse mid-UV emission is detectable in the halo; there are no obvious discrete features, although the signal to noise is low. The emission in the bulge has a scale height of 1.7 kpc, which is in good agreement with the H$\alpha$ scale neight of 1.4 kpc. There are no strong emission lines in the mid-UV band, however, so the radiation here is probably dominated by dust scattering of light from the disk. The halo gas appears to contain significant amounts of dust.

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