C.D.S. - SIMBAD4 rel 1.7 - 2020.10.24CEST18:18:55

2007A&A...473..783R - Astronomy and Astrophysics, volume 473, 783-789 (2007/10-3)

X-ray emission from the stellar population in M32.


Abstract (from CDS):

Using Chandra observations, we study the X-ray emission of the stellar population in the compact dwarf elliptical galaxy M32. The proximity of M32 allows one to resolve all bright point sources with luminosities higher than 8x1033erg/s in the 0.5-7keV band. The remaining (unresolved) emission closely follows the galaxy's optical light and is characterized by an emissivity per unit stellar mass of ∼4.3x1027erg/s/M in the 2-10keV energy band. The spectrum of the unresolved emission above a few keV smoothly joins the X-ray spectrum of the Milky Way's ridge measured with RXTE and INTEGRAL. These results strongly suggest that weak discrete X-ray sources (accreting white dwarfs and active binary stars) provide the bulk of the ``diffuse'' emission of this gas-poor galaxy. Within the uncertainties, the average X-ray properties of the M32 stars are consistent with those of the old stellar population in the Milky Way. The inferred cumulative soft X-ray (0.5-2keV) emissivity is however smaller than is measured in the immediate Solar vicinity in our Galaxy. This difference is probably linked to the contribution of young (age ≪1Gyr) stars, which are abundant in the Solar neighborhood but practically absent in M32. Combining Chandra, RXTE and INTEGRAL data, we obtain a broad-band (0.5-60keV) X-ray spectrum of the old stellar population in galaxies.

Abstract Copyright:

Journal keyword(s): ISM: general - galaxies: dwarf - galaxies: individual: M32 - galaxies: general - galaxies: stellar content - X-rays: diffuse background

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
1 M 32 IG 00 42 41.825 +40 51 54.61 9.51 9.03 8.08     ~ 2022 2
2 CXOM32 J004242.5+405153 X 00 42 42.52 +40 51 52.6           ~ 4 0
3 HD 22468 RS* 03 36 47.2911034958 +00 35 15.938962144 7.09 6.63   5.4   K2:Vnk 1125 0
4 V* SU UMa DN* 08 12 28.2694633475 +62 36 22.428029272           B2 470 0
5 NAME Galactic Ridge ? ~ ~           ~ 432 1
6 NAME Galactic Bulge reg ~ ~           ~ 3459 0
7 NAME Local Group GrG ~ ~           ~ 7074 0

    Equat.    Gal    SGal    Ecl

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