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NGC 5135

As in NGC 7130, the highest surface brightness of the UV continuum emission is in the inner 2 arcsec. This inner structure is sprinkled with about a dozen prominent knots, much like those seen in ``normal'' starburst galaxies (Meurer et al. 1995). A few fainter knots are also detected in the spiral-arm-like segments near the center in the South-North direction and two other knots in the North-South direction (Figure 5). The adopted origin of our coordinate system is the knot with the hightest surface brightness emission. However, the maximum surface brightness in the optical light is in the knot located at 1.05 arcsec North and 0.4 arcsec East of the zero point (Figure 6a). This knot at the UV light seems to be surrounded by diffuse extended emission in the South-West direction that comprises two other knots (Figure 6b). The symmetry of the two inner spiral segments suggests that this knot is the center and nucleus of the galaxy (see Figure 1b). The morphology of the inner 2 arcsec in the UV and WFPC images is very similar. The brightest knots in the UV seem to be formed at the end of the spiral arm segment that runs from North to South to North.

The total UV emission detected in the 23#23 FOC image is 70% as large as the flux detected by IUE at 2150 Å. The flux detected in the inner 32#32 arcsec ( 33#33 pc) is 34#34 erg s-1cm-2 Å-1, which represents about 70% of the total FOC flux. The flux of the brightest knot is 35#35 erg s-1 cm-2Å-1, 7% of the total emission. The flux of the presumed nucleus is difficult to measure accurately due to the extended emission around it, but it is about 36#36 erg s-1 cm-2 Å-1, and amounts to only 3% of the total emission.

The starburst has an outer radius of 1.67'' yielding re = 0.75 arcsec (200 pc) and 37#37 STmag arcsec-2 at 2150 Å. The Galactic extinction derived from an HI column density of 38#38 cm-2is E(B-V)=0.094. This implies an extinction of 0.92 mag at 2150 Å due to our galaxy alone.


next up previous
Next: IC 3639 Up: HST-UV imaging: results and Previous: NGC 7130
Rosa Gonzalez
1998-06-20