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25211. X-ray Sources in Molecular Clouds
ID:
ivo://CDS.VizieR/J/A+AS/128/331
Title:
X-ray Sources in Molecular Clouds
Short Name:
J/A+AS/128/331
Date:
21 Oct 2021
Publisher:
CDS
Description:
Figure 9: Finding charts for the objects where spectra were taken, based on the APM data base. The cross is centered at the X-ray position. 30 arcsec radius error circles are shown and arrows mark the objects with the available spectra. North is up and East to the left in all charts. Figure 10: Deep CCD images of the X-ray source fields with faint optical counterparts. Circles with 30 arcsec radius are centered on the X-ray position. Capital letters identify the brightest object next to them (see Table 3 for remarks on identification). The filter used and the exposure time are shown above each image in brackets.
25212. X-ray sources in NGC 188
ID:
ivo://CDS.VizieR/J/A+A/438/291
Title:
X-ray sources in NGC 188
Short Name:
J/A+A/438/291
Date:
21 Oct 2021
Publisher:
CDS
Description:
I present the analysis results from XMM-Newton observations of the old open stellar cluster NGC 188, which has an age of about 7Gyr and a near solar metallicity. 58 X-ray sources were detected in the field of view of the EPIC MOS and PN cameras, and 46 sources are new X-ray detections. Visible counterparts were found for 20 sources including the variable star WV 28, the W UMa-type binaries V371 Cep and V372 Cep, and the red giant V11. 9 X-ray sources are identified with probable cluster non-members, while 43 X-ray sources are of unknown membership. X-ray emission was detected from 6 stars with high membership probability above a luminosity threshold of 10^30^erg/s.
25213. X-ray sources in NGC 5775
ID:
ivo://CDS.VizieR/J/MNRAS/390/59
Title:
X-ray sources in NGC 5775
Short Name:
J/MNRAS/390/59
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the edge-on galaxy NGC 5775, utilizing a 58.2ks Chandra ACIS-S observation together with complementary Hubble Space Telescope (HST) ACS, Spitzer IRAC and other multi-wavelength data sets. This edge-on galaxy, with its disc-wide active star formation, is particularly well suited for studying the disc/halo interaction on subgalactic scales. We detect 27 discrete X-ray sources within the D_25_ region of the galaxy, including an ultra-luminous source with a 0.3-7keV luminosity of ~7x10^40^erg/s.
25214. X-ray sources in NGC 5866
ID:
ivo://CDS.VizieR/J/ApJ/706/693
Title:
X-ray sources in NGC 5866
Short Name:
J/ApJ/706/693
Date:
21 Oct 2021
Publisher:
CDS
Description:
S0 galaxies are often thought to be passively evolved from spirals after star formation is quenched. To explore what is actually occurring in such galaxies, we present a multi-wavelength case study of NGC 5866 - a nearby edge-on S0 galaxy in a relatively isolated environment. This study shows strong evidence for dynamic activities in the interstellar medium, which are most likely driven by supernova explosions in the galactic disk and bulge. Understanding these activities can have strong implications for studying the evolution of such galaxies. We utilize Chandra, Hubble Space Telescope, and Spitzer data as well as ground-based observations to characterize the content, structure, and physical state of the medium and its interplay with the stellar component in NGC 5866. We reveal the presence of diffuse X-ray-emitting hot gas, which extends as far as 3.5kpc away from the galactic plane and can be heated easily by Type Ia SNe in the bulge.
25215. X-ray sources in NGC 1600
ID:
ivo://CDS.VizieR/J/ApJ/617/262
Title:
X-ray sources in NGC 1600
Short Name:
J/ApJ/617/262
Date:
21 Oct 2021
Publisher:
CDS
Description:
We observed the X-ray-bright E3 galaxy NGC 1600 and nearby members of the NGC 1600 group with the Chandra X-Ray Observatory ACIS-S3 to study their X-ray properties. Unresolved emission dominates the observation; however, we resolved some of the emission into 71 sources, most of which are low-mass X-ray binaries associated with NGC 1600. Twenty-one of the sources have L_X_>2x10^39^ergs/s (0.3-10.0keV; assuming they are at the distance of NGC 1600), marking them as ultraluminous X-ray point source (ULX) candidates; we expect that only 11+/-2 are unrelated foreground/background sources.
25216. X-ray sources in NGC 4261
ID:
ivo://CDS.VizieR/J/ApJ/634/272
Title:
X-ray sources in NGC 4261
Short Name:
J/ApJ/634/272
Date:
21 Oct 2021
Publisher:
CDS
Description:
Chandra images of the elliptical galaxy NGC 4261 have revealed an anisotropy in the spatial distribution of the off-nuclear X-ray sources, interpreted by Zezas et al. (2003ApJ...599L..73Z) as evidence of an association with a young stellar population. Our independent analysis of archive X-ray (Chandra) and optical (INT and HST) observations confirms the anisotropy of the X-ray sources but conducts to a different interpretation for their origin.
25217. X-ray sources in NGC 3379
ID:
ivo://CDS.VizieR/J/ApJ/635/1053
Title:
X-ray sources in NGC 3379
Short Name:
J/ApJ/635/1053
Date:
21 Oct 2021
Publisher:
CDS
Description:
A Chandra observation of the intermediate-luminosity (M_B_=-20) elliptical galaxy NGC 3379 resolves 75% of the X-ray emission within the central 5kpc into point sources. Spectral analysis of the remaining unresolved emission within the central 770pc indicates that 90% of the emission probably arises from undetected point sources, while 10% arises from thermal emission from kT=0.6keV gas.
25218. X-ray sources in NGC 752
ID:
ivo://CDS.VizieR/J/A+A/490/113
Title:
X-ray sources in NGC 752
Short Name:
J/A+A/490/113
Date:
21 Oct 2021
Publisher:
CDS
Description:
While observational evidence shows that most of the decline in a star's X-ray activity occurs between the age of the Hyades (~8x10^8yr) and that of the Sun, very little is known about the evolution of stellar activity between these ages. To gain information on the typical level of coronal activity at a star's intermediate age, we studied the X-ray emission from stars in the 1.9Gyr old open cluster NGC 752. We analysed a ~140ks Chandraobservation of NGC 752 and a ~50ks XMM-Newtonobservation of the same cluster. We detected 262 X-ray sources in the Chandra data and 145 sources in the XMM-Newton observation. Around 90% of the catalogued cluster members within Chandra's field-of-view are detected in the X-ray. The X-ray luminosity of all observed cluster members (28 stars) and of 11 cluster member candidates was derived.
25219. X-ray sources in NGC 4194 and NGC 7541
ID:
ivo://CDS.VizieR/J/ApJ/682/1020
Title:
X-ray sources in NGC 4194 and NGC 7541
Short Name:
J/ApJ/682/1020
Date:
21 Oct 2021
Publisher:
CDS
Description:
We examine the X-ray point-source population and 2-10keV luminosity for two galaxies with high star formation rates (SFRs), NGC 4194 and NGC 7541 and combined our results with a sample of galaxies with SFRs above 1M_{sun}_/yr.
25220. 233 X-ray sources in omega Centauri
ID:
ivo://CDS.VizieR/J/MNRAS/479/2834
Title:
233 X-ray sources in omega Centauri
Short Name:
J/MNRAS/479/2834
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identify 233 X-ray sources, of which 95 are new, in a 222ks exposure of omega Centauri with the Chandra X-ray Observatory's Advanced CCD Imaging Spectrometer detector. The limiting unabsorbed flux in the core is fX(0.5-6.0keV)~=3x10^-16^erg/s/cm^2^ (Lx~=1x10^30^erg/s at 5.2kpc). We estimate that ~60+/-20 of these are cluster members, of which ~30 lie within the core (r_c_=155-arcsec), and another ~30 between 1-2 core radii. We identify four new optical counterparts, for a total of 45 likely identifications. Probable cluster members include 18 cataclysmic variables (CVs) and CV candidates, one quiescent low-mass X-ray binary, four variable stars, and five stars that are either associated with omega Cen's anomalous red giant branch or are sub-subgiants. We estimate that the cluster contains 40+/-10 CVs with Lx>10^31^erg/s, confirming that CVs are underabundant in omega Cen relative to the field. Intrinsic absorption is required to fit X-ray spectra of six of the nine brightest CVs, suggesting magnetic CVs, or high-inclination systems. Though no radio millisecond pulsars (MSPs) are currently known in omega Cen, more than 30 unidentified sources have luminosities and X-ray colours like those of MSPs found in other globular clusters; these could be responsible for the Fermi-detected gamma-ray emission from the cluster. Finally, we identify a CH star as the counterpart to the second brightest X-ray source in the cluster and argue that it is a symbiotic star. This is the first such giant/white dwarf binary to be identified in a globular cluster.

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