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281. Globular cluster system in M87
ID:
ivo://CDS.VizieR/J/ApJ/559/812
Title:
Globular cluster system in M87
Short Name:
J/ApJ/559/812
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive database of kinematic, photometric, and positional information for 352 objects in the field of M87 (NGC 4486), the central giant elliptical galaxy in the Virgo Cluster; the majority of the tracers are globular clusters associated with that galaxy. New kinematic information comes from multislit observations with the Multi-Object Spectrograph (MOS) of the Canada-France-Hawaii Telescope (CFHT), an investigation that has added 96 new velocities to and confirmed many of the earlier values in a preexisting data set of 256 velocities published elsewhere. The photometry, consisting of magnitudes and colors in the Washington (T_1_, C-T_1_) system, is based on CCD observations made at the Cerro Tololo Inter-American Observatory (CTIO) and the Kitt Peak National Observatory (KPNO).
282. Globular cluster system in M87
ID:
ivo://CDS.VizieR/J/ApJ/513/733
Title:
Globular cluster system in M87
Short Name:
J/ApJ/513/733
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have identified 1057 globular cluster candidates in a WFPC2 image of the inner region of M87. The globular cluster luminosity function (GCLF) can be well fitted by a Gaussian profile with a mean value of m^0^_V_=23.67+/-0.07mag and {sigma}=1.39+/-0.06mag. The GCLF in five radial bins is found to be statistically the same at all points, showing no clear evidence of dynamical destruction processes based on the luminosity function (LF). Similarly, there is no obvious trend between the half-light radius of the clusters and the galactocentric distance. The core radius of the globular cluster density distribution is R_c_=56", considerably larger than the core of the stellar component (R_c_=6.8"). The mean color of the cluster candidates is V-I=1.09mag, which corresponds to an average metallicity of Fe/H=-0.74dex. The color distribution is bimodal everywhere, with a blue peak at V-I=0.95mag and a red peak at V-I=1.20mag. The red population is only 0.1mag bluer than the underlying galaxy, indicating that these clusters formed late in the metal-enrichment history of the galaxy and were possibly created in a burst of star/cluster formation 3-6Gyr after the blue population. We also find that both the red and the blue cluster distributions have a more elliptical shape (Hubble type E3.5) than the nearly spherical galaxy. The average half-light radius of the clusters is ~2.5pc, which is comparable to the 3pc average effective radius of the Milky Way clusters, although the red clusters are ~20% smaller than the blue ones.
283. Globular Cluster System of NGC5846
ID:
ivo://CDS.VizieR/J/A+A/455/453
Title:
Globular Cluster System of NGC5846
Short Name:
J/A+A/455/453
Date:
21 Oct 2021
Publisher:
CDS
Description:
NGC 5846 is a giant elliptical galaxy with a previously well studied globular cluster system (GCS), known to have a bimodal colour distribution with a remarkably high red fraction. Here we revisit the central galaxy regions searching for new globular cluster (GC) candidates, and measure magnitudes, colours and sizes for them. We also search for their X-ray counterparts. Methods: We use archival Hubble Space Telescope WFPC2 images, from which we modelled and subtracted the host light distribution to increase the available sample of GCs. We performed photometry on the central objects, and measured sizes and coordinates for the entire GC system known in this galaxy. Results: We detect two dozen previously unknown GC candidates in the central reg ions. Reliable sizes are obtained for about 60 GCs; their typical effective radii are in the range 3-5pc. The largest clusters are located in the central regions. We find 7 X-ray counterparts to GCs, most of them in the central region. They are among the most luminous X-ray sources in NGC 5846. They are also optically luminous, compact and belong to the red subpopulation. Conclusions: The GCS of NGC 5846 is composed of relatively luminous X-ray sources.
284. Globular cluster 47 Tuc Chandra studies
ID:
ivo://CDS.VizieR/J/MNRAS/472/3706
Title:
Globular cluster 47 Tuc Chandra studies
Short Name:
J/MNRAS/472/3706
Date:
21 Oct 2021
Publisher:
CDS
Description:
We combined Chandra ACIS observations of the globular cluster 47 Tucanae (47 Tuc) from 2000, 2002 and 2014-2015 to create a deeper X-ray source list, and study some of the faint radio millisecond pulsars (MSPs) present in this cluster. We have detected 370 X-ray sources within the half-mass radius (2.79 arcsec) of the cluster, 81 of which are newly identified, by including new data and using improved source detection techniques. The majority of the newly identified sources are in the crowded core region, indicating cluster membership. We associate five of the new X-ray sources with chromospherically active BY Dra or W UMa variables identified by Albrow et al. We present alternative positions derived from two methods, centroiding and image reconstruction, for faint, crowded sources. We are able to extract X-ray spectra of the recently discovered MSPs 47 Tuc aa, 47 Tuc ab, the newly timed MSP 47 Tuc Z, and the newly resolved MSPs 47 Tuc S and 47 Tuc F. Generally, they are well fitted by blackbody or neutron star atmosphere models, with temperatures, luminosities and emitting radii similar to those of other known MSPs in 47 Tuc, though 47 Tuc aa and 47 Tuc ab reach lower X-ray luminosities. We limit X-ray emission from the full surface of the rapidly spinning (542 Hz) MSP 47 Tuc aa, and use this limit to put an upper bound for amplitude of r-mode oscillations in this pulsar as {alpha}<2.5x10^-9^ and constrain the shape of the r-mode instability window.
285. Globulars in PGC 6510, PGC 10922, PGC 4287
ID:
ivo://CDS.VizieR/J/AJ/137/383
Title:
Globulars in PGC 6510, PGC 10922, PGC 4287
Short Name:
J/AJ/137/383
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of the globular cluster (GC) systems of four early-type poststarburst galaxies using deep g- and I-band images from the Advanced Camera for Surveys aboard the Hubble Space Telescope. All the galaxies feature shells distributed around their main bodies and are thus likely merger remnants. The color distribution of the GCs in all four galaxies shows a broad peak centered on g-I~1.4, while PGC 6240 and PGC 42871 show a significant number of GCs with g-I~1.0.
286. Globulars of M81
ID:
ivo://CDS.VizieR/J/AJ/109/1055
Title:
Globulars of M81
Short Name:
J/AJ/109/1055
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained photometric BVR, morphological, and astrometric information on 3774 objects located within a 25' radius of M81. This catalogue is complete for 15 <= V <= 21; it is used here to identify globular cluster candidates in M81 and as a database for a statistical analysis of the system as a whole. The M81 globular cluster system is revealed as a strong surface density excess of ~70 objects within an 11 kpc galactocentric radius. The total population is estimated at N_T = 210 +/- 30 globulars. The spatial, (B-V), and (V-R) distributions are very similar to those of the Milky Way and of M31. Small but significant systematic errors in Madore et al.'s [AJ, 106, 2243 (1993)] photometry could be responsible for an overestimate of the Cepheid distance to M81 [(m-M)0 = 27.8] and we propose a revised modulus of (m-M)0 = 27.5 +/- 0.3. The globular cluster luminosity function then reaches its maximum at M_V* = -7.5 +/- 0.4, as it does in the galaxy and in M31. There is suggestive evidence that 13 +/- 5 objects are globulars seen through the disk of M81; spectroscopy or high-resolution imaging will resolve this issue. Using the (B-R)0 index to trace [Fe/H], we notice a weak dependence of mean metallicity on galactocentric distance, as observed in the galaxy and in M31. This result argues in favour of in situ globular formation during the continuous collapse and self-enrichment of an early-type spiral host.
287. Globulars with X-ray sources in NGC 5128
ID:
ivo://CDS.VizieR/J/ApJ/682/199
Title:
Globulars with X-ray sources in NGC 5128
Short Name:
J/ApJ/682/199
Date:
21 Oct 2021
Publisher:
CDS
Description:
We detect 353 X-ray point sources, mostly low-mass X-ray binaries (LMXBs), in four Chandra observations of Centaurus A (NGC 5128), the nearest giant early-type galaxy, and correlate this point-source population with the largest available ensemble of confirmed and likely globular clusters (GCs) associated with this galaxy. Of the X-ray sources, 31 are coincident with 30 GCs that are confirmed members of the galaxy by radial velocity measurement (two X-ray sources match one GC within our search radius), while one X-ray source coincides with a GC resolved by Hubble Space Telescope (HST) images. Another 36 X-ray point sources match probable, but spectroscopically unconfirmed, GC candidates.
288. griz and CT1 photometry in M87
ID:
ivo://CDS.VizieR/J/MNRAS/431/1405
Title:
griz and CT1 photometry in M87
Short Name:
J/MNRAS/431/1405
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Gemini griz' photometry for 521 globular cluster (GC) candidates in a 5.5x5.5arcmin^2^ field centred 3.8-arcmin to the south and 0.9-arcmin to the west of the centre of the giant elliptical galaxy NGC 4486. All these objects have previously published (C-T1) photometry. We also present new (C-T1) photometry for 338 globulars, within 1.7-arcmin in galactocentric radius, which have (g-z) colours in the photometric system adopted by the Virgo Cluster Survey of the Advanced Camera for Surveys of the Hubble Space Telescope (HST). These photometric data are used to define a self-consistent multicolour grid (avoiding polynomial fits) and preliminarily calibrated in terms of two chemical abundance scales. The resulting multicolour colour-chemical abundance relations are used to test GC chemical abundance distributions. This is accomplished by modelling the 10 GC colour histograms that can be defined in terms of the Cgriz' bands. Our results suggest that the best fit to the GC observed colour histograms is consistent with a genuinely bimodal chemical abundance distribution N_GC_(Z). On the other side, each ('blue' and 'red') GC subpopulation follows a distinct colour-colour relation.
289. Ground-based proper motion of 12 nearby GC
ID:
ivo://CDS.VizieR/J/MNRAS/471/1446
Title:
Ground-based proper motion of 12 nearby GC
Short Name:
J/MNRAS/471/1446
Date:
21 Oct 2021
Publisher:
CDS
Description:
We derive relative proper motions of stars in the fields of the globular clusters M12, NGC 6362, M4, M55, M22, NGC 6752, NGC 3201, M30, M10, NGC 362, M5 and 47 Tucanae based on data collected between 1997 and 2015 with the 1-m Swope telescope of Las Campanas Observatory. We determine membership class and membership probability for over 446000 objects, and show that these are efficient methods for separating field stars from members of the cluster. In particular, membership probabilities of variable stars and blue/yellow/red stragglers are determined. Finally, we find absolute proper motions for six globular clusters from our sample: M55, NGC 3201, M10, NGC 362, M5 and 47 Tuc. An electronic catalogue of the derived proper motions is publicly available via the internet.
290. gr photometry of stars in Kim 2
ID:
ivo://CDS.VizieR/J/ApJ/803/63
Title:
gr photometry of stars in Kim 2
Short Name:
J/ApJ/803/63
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of a new, low-luminosity star cluster in the outer halo of the Milky Way. High-quality gr photometry is presented, from which a color-magnitude diagram is constructed, and estimates of age, [Fe/H], [{alpha}/Fe], and distance are derived. The star cluster, which we designate as Kim 2, lies at a heliocentric distance of ~105kpc. With a half-light radius of ~12.8pc and ellipticity of {epsilon}~0.12, it shares the properties of outer halo globular clusters, except for at higher metallicity ([Fe/H]~-1.0) and lower luminosity (M_v_~-1.5). These parameters are similar to those for the globular cluster AM 4, which is considered to be associated with the Sagittarius dwarf spheroidal galaxy. We find evidence of dynamical mass segregation and the presence of extra-tidal stars that suggests that Kim 2 is most likely a star cluster. Spectroscopic observations for radial-velocity membership and chemical abundance measurements are needed to further understand the nature of the object.

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