Astronomical Applications Department, U.S. Naval Observatory thesis Page 49
35
center, the average value is
F
U
V
=21.2 mag arcsec
,2
0
:
03. Surface brightness
maps of the galaxy indicate that the highest levels of activity lie in the region
responsible for this peak. The brightest knot in the center of the star forming
arc has the highest levels,
F
U
V
18.9 mag arcsec
,2
in a resolution element 5
00
.
Following the peak, the pro le exhibits somewhat exponential behavior until r
2
0
,
where it takes a constant value of
F
U
V
22.4 mag arcsec
,2
. The attening of the
pro le is due to ux from the group of regions on the eastern side of the central
star forming arc. second, yet relatively small peak occurs at r
2.7
0
, after which
it falls o sharply. The second peak can be accounted for by the di use patches
of emission in the northern part of the galaxy.
0
1
2
3
4
Radius (arcminutes)
25
24
23
22
21
µ
FUV
(mag arcsec
-2
)
Fig. 4.1. The FUV surface brightness pro le of Holmberg II
Like the HoII pro le, the IC2574 FUV surface brightness pro le shown in Fig.
4.2 is similarly double peaked. However, in this case, the pro le peaks at the
