1998A&A...332..189K

Query : 1998A&A...332..189K

1998A&A...332..189K - Astronomy and Astrophysics, volume 332189-193 (1998/4-1)

Evidence for massive white dwarfs in the M 31 supersoft sources.

KAHABKA P.

Abstract (from CDS):

Simulating ROSAT PSPC hardness ratios HR1 and HR2 and count rates for NLTE white dwarf atmosphere spectra one finds that the 15 supersoft sources in the spiral galaxy M 31 contain hot ≃3.0-4.5x105K white dwarfs. If they undergo steady nuclear burning and if they are located close to the stability line then they harbor massive white dwarfs MWD≃0.85-1.0M☉ in agreement with what has been found for the galactic supersoft sources. The recurrent supersoft transient RX J0045.4+4154 affords a very hot ≃8.4x105K white dwarf. If it is on the stability line then it has a white dwarf mass of ≃1.26M☉. Taking a mass distribution of steadily nuclear burning white dwarfs into account one expects that there exist at least about 650 supersoft sources in M 31. The spectral parameters of the so far most distant (D∼1.3Mpc) supersoft source found in the galaxy NGC 55 imply a hot (∼6x105K) and massive (MWD∼1.1M☉) white dwarf. The number of such sources seen in a galaxy at this distance is derived from a luminosity function of supersoft sources.

Abstract Copyright: ∼

Journal keyword(s): galaxies: individual: M 31 - galaxies: individual: NGC 55 - binaries: close - X-rays: stars - stars: evolution - white dwarfs

Simbad objects: 21

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Number of rows : 21
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 NGC 55 rG 00 14 53.602 -39 11 47.86 8.54 8.58 7.87 7.84   ~ 828 2
2 RX J0016.0-3914 X 00 16 01.5 -39 14 40           ~ 4 0
3 RX J003725.3+401516 X 00 37 25.3 +40 15 16           ~ 10 0
4 RX J0038.5+4014 X 00 38 32.1 +40 14 39           ~ 11 0
5 RX J0038.6+4019 X 00 38 40.55 +40 19 56.4           ~ 12 0
6 RX J003938.5+405409 X 00 39 38.5 +40 54 09           ~ 10 0
7 RX J0040.4+4009 X 00 40 26.3 +40 09 01           ~ 11 0
8 RX J004043.2+401518 X 00 40 43.2 +40 15 18           ~ 11 0
9 RX J004130.2+404004 X 00 41 30.2 +40 40 04           ~ 11 0
10 RX J004149.9+405921 X 00 41 49.9 +40 59 21           ~ 11 0
11 RX J004227.6+404432 X 00 42 27.6 +40 44 32           ~ 11 0
12 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
13 RX J004335.9+420730 X 00 43 35.9 +42 07 30           ~ 11 0
14 RX J004404.8+411820 No* 00 44 04.71 +41 18 21.7           ~ 18 0
15 RX J0045.4+4154 No* 00 45 28.80 +41 54 10.1           ~ 263 1
16 RX J0045.5+4206 X 00 45 31.8 +42 07 06           ~ 12 0
17 RX J0046.2+4144 X 00 46 15.6 +41 44 36           ~ 11 0
18 RX J004617.8+413848 X 00 46 17.8 +41 38 48           ~ 11 0
19 RX J0047.6+4205 X 00 47 38.5 +42 05 07           ~ 11 0
20 OGLE LMC-SC20 113500 EB* 05 46 46.5466334000 -71 08 53.755688443     19.163   18.886 ~ 263 0
21 RX J0925.7-4758 XB* 09 25 46.0017018216 -47 58 17.340963384   19.2       ~ 91 0

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