1999MNRAS.308..302Z

Query : 1999MNRAS.308..302Z

1999MNRAS.308..302Z - Mon. Not. R. Astron. Soc., 308, 302-308 (1999/September-2)

ROSAT observations of the dwarf star-forming galaxy Holmberg II (UGC 4305).

ZEZAS A.L., GEORGANTOPOULOS I. and WARD M.J.

Abstract (from CDS):

We present ROSAT PSPC and HRI observations of the dwarf irregular galaxy Holmberg II (UGC 4305). This is one of the most luminous dwarf galaxies (LX∼1040erg.s–1) detected in the ROSAT All-Sky Survey. The X-ray emission comes from a single unresolved point source, coincident with a large Hii region that emits intense radio emission. The source is variable on both year and day time-scales, clearly favouring accretion into a compact object rather than a supernova remnant or a superbubble interpretation for the origin of the X-ray emission. However, its X-ray spectrum is well-fitted by a steep power law or alternatively by a Raymond-Smith spectrum with kT∼0.8keV, lower than the temperature of X-ray binaries in nearby spiral galaxies.

Abstract Copyright: 1999, Royal Astronomical Society

Journal keyword(s): galaxies: individual: Holmberg II (UGC 4305) - galaxies: starburst - X-rays: galaxies

Simbad objects: 17

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Number of rows : 17
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 IC 10 rG 00 20 17.33520 +59 18 13.6480   13.6 9.5     ~ 1185 1
2 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 3588 2
3 IC 342 AGN 03 46 48.514 +68 05 45.98   10.5       ~ 1579 1
4 NGC 1569 rG 04 30 49.186 +64 50 52.52 11.72 11.86 11.03     ~ 1297 3
5 NGC 1705 Sy2 04 54 13.4661493464 -53 21 39.471592428 12.32 12.96 12.56 12.58 12.9 ~ 692 1
6 UGC 4305 IG 08 19 04.9864630512 +70 43 13.086910452 12.06 11.72 11.39 11.11   ~ 812 2
7 MCG-04-21-005 AGN 08 36 15.190 -26 24 33.66 12.04 11.93 11.45 11.09 12.3 ~ 600 3
8 M 82 AGN 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 6156 6
9 IC 2574 AG? 10 28 23.6148831408 +68 24 43.440012756 11.70 11.07 10.87 10.74   ~ 703 1
10 Z 266-55 AGN 10 32 31.956 +54 24 03.53 13.29 13.66 13.13 12.71 12.27 ~ 381 1
11 NGC 4449 EmG 12 28 11.118 +44 05 36.81 10.11 9.98 9.64 9.45   ~ 1192 1
12 NGC 4961 EmG 13 05 47.5766802528 +27 44 03.247625004   13.5       ~ 196 0
13 M 51 Sy2 13 29 52.698 +47 11 42.93   9.26 8.36 8.40   ~ 4565 4
14 NGC 5408 EmG 14 03 20.907 -41 22 39.75   12.59   11.96 12.2 ~ 368 3
15 Granat 1915+105 HXB 19 15 11.55576 +10 56 44.9052           ~ 2810 0
16 Mrk 509 Sy1 20 44 09.7504483224 -10 43 24.727155528   13.35 13.12 10.7   ~ 1370 0
17 V* AR Lac RS* 22 08 40.8182089680 +45 44 32.107863120 7.09 6.83 6.11     K0IVe+G5IV 745 0

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