- ID:
- ivo://CDS.VizieR/J/ApJ/681/311
- Title:
- Blue stragglers in NGC 2419
- Short Name:
- J/ApJ/681/311
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used a combination of ACS HST high-resolution and wide-field Subaru data in order to study the blue straggler star (BSS) population over the entire extension of the remote Galactic globular cluster NGC 2419. The BSS population presented here is among the largest ever observed in any stellar system, with more than 230 BSSs in the brightest portion of the sequence. The radial distribution of the selected BSSs is essentially the same as that of the other cluster stars.
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- ID:
- ivo://CDS.VizieR/J/ApJ/748/91
- Title:
- Blue straggler stars in M75
- Short Name:
- J/ApJ/748/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used a combination of multiband high-resolution and wide-field ground-based observations to image the Galactic globular cluster M75 (NGC 6864). The extensive photometric sample covers the entire cluster extension, from the very central regions out to the tidal radius, allowing us to determine the center of gravity and to construct the most extended star density profile ever published for this cluster. We also present the first detailed star counts in the very inner regions. The star density profile is well reproduced by a standard King model with core radius r_c_~5.4" and intermediate-high concentration c~1.75. The present paper presents a detailed study of the blue straggler star (BSS) population and its radial distribution. A total of 62 bright BSSs (with m_F255W_<~21, corresponding to m_F555W_<~20) have been identified, and they have been found to be highly segregated in the cluster core. No significant upturn in the BSS frequency has been observed in the outskirts of M75, in contrast to several other clusters studied with the same technique. This observational fact is quite similar to what has been found in M79 (NGC 1904) by Lanzoni et al. (2007ApJ...663.1040L). Indeed, the BSS radial distributions in the two clusters are qualitatively very similar, even if in M75 the relative BSS frequency seems to decrease significantly faster than in M79: it decreases by a factor of five (from 3.4 to 0.7) within 1r_c_. Such evidence indicates that the vast majority of the cluster heavy stars (binaries) have already sunk to the core.
- ID:
- ivo://CDS.VizieR/J/AJ/129/2663
- Title:
- B photometry of M31 variable star candidates
- Short Name:
- J/AJ/129/2663
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A search for variable stars is performed using two epochs of Hubble Space Telescope Advanced Camera for Surveys imaging data for a 9.28arcmin^2^ portion of M31. This data set reveals 254 sources that vary by at least 4{sigma} between epochs. The positions and two-epoch B-band (equivalent) photometry of these sources are presented.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/189
- Title:
- Brightest high-z galaxies in RELICS clusters
- Short Name:
- J/ApJ/889/189
- Date:
- 17 Jan 2022 00:21:16
- Publisher:
- CDS
- Description:
- Massive foreground galaxy clusters magnify and distort the light of objects behind them, permitting a view into both the extremely distant and intrinsically faint galaxy populations. We present here the z~6-8 candidate high-redshift galaxies from the Reionization Lensing Cluster Survey (RELICS), a Hubble and Spitzer Space Telescope survey of 41 massive galaxy clusters spanning an area of ~200arcmin^2^. These clusters were selected to be excellent lenses, and we find similar high-redshift sample sizes and magnitude distributions as the Cluster Lensing And Supernova survey with Hubble (CLASH). We discover 257, 57, and eight candidate galaxies at z~6, 7, and 8 respectively, (322 in total). The observed (lensed) magnitudes of the z~6 candidates are as bright as AB mag ~23, making them among the brightest known at these redshifts, comparable with discoveries from much wider, blank-field surveys. RELICS demonstrates the efficiency of using strong gravitational lenses to produce high-redshift samples in the epoch of reionization. These brightly observed galaxies are excellent targets for follow-up study with current and future observatories, including the James Webb Space Telescope.
- ID:
- ivo://CDS.VizieR/J/AJ/135/1567
- Title:
- Bright star clusters in M51
- Short Name:
- J/AJ/135/1567
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of star clusters with V_F555W_<23mag detected in the interacting spiral galaxy M51 system based on mosaic images taken with the Hubble Space Telescope Advanced Camera for Surveys by the Hubble Heritage Team. We have selected about 3600 clusters based on their morphological information through visual inspection. The final star cluster catalog includes 2224 clusters that are relatively well isolated and have a circular shape.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/176
- Title:
- BVI photometry of Cepheids in M81
- Short Name:
- J/ApJ/743/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify and phase a sample of 107 Cepheids with 10days<P<100days in M81 (NGC 3031) using the Large Binocular Telescope and calibrate their B, V, and I mean magnitudes with archival Hubble Space Telescope (HST) data. The use of a ground-based telescope to identify and phase the Cepheids and HST only for the final calibration reduces the demand on this highly oversubscribed spacecraft by nearly an order of magnitude and yields period-luminosity (PL) relations with dispersions comparable to the best LMC samples. We fit the sample using the OGLE-II LMC PL relations and are unable to find a self-consistent distance for different band combinations or radial locations within M81. We find a distance modulus for M81, relative to the LMC, of {mu}M_81_-{mu}_LMC_=9.39+/-0.14mag, including uncertainties due to the metallicity corrections. This corresponds to a distance to M81 of 3.6+/-0.2Mpc, assuming an LMC distance modulus of 18.41mag.
- ID:
- ivo://CDS.VizieR/J/ApJS/221/11
- Title:
- CANDELS visual classifications for GOODS-S
- Short Name:
- J/ApJS/221/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have undertaken an ambitious program to visually classify all galaxies in the five CANDELS fields down to H<24.5 involving the dedicated efforts of over 65 individual classifiers. Once completed, we expect to have detailed morphological classifications for over 50000 galaxies spanning 0<z<4 over all the fields, with classifications from 3 to 5 independent classifiers for each galaxy. Here, we present our detailed visual classification scheme, which was designed to cover a wide range of CANDELS science goals. This scheme includes the basic Hubble sequence types, but also includes a detailed look at mergers and interactions, the clumpiness of galaxies, k-corrections, and a variety of other structural properties. In this paper, we focus on the first field to be completed --GOODS-S, which has been classified at various depths. The wide area coverage spanning the full field (wide+deep+ERS) includes 7634 galaxies that have been classified by at least three different people. In the deep area of the field, 2534 galaxies have been classified by at least five different people at three different depths. With this paper, we release to the public all of the visual classifications in GOODS-S along with the Perl/Tk GUI that we developed to classify galaxies. We present our initial results here, including an analysis of our internal consistency and comparisons among multiple classifiers as well as a comparison to the Sersic index. We find that the level of agreement among classifiers is quite good (>70% across the full magnitude range) and depends on both the galaxy magnitude and the galaxy type, with disks showing the highest level of agreement (>50%) and irregulars the lowest (<10%). A comparison of our classifications with the Sersic index and rest-frame colors shows a clear separation between disk and spheroid populations. Finally, we explore morphological k-corrections between the V-band and H-band observations and find that a small fraction (84 galaxies in total) are classified as being very different between these two bands. These galaxies typically have very clumpy and extended morphology or are very faint in the V-band.
- ID:
- ivo://CDS.VizieR/J/ApJ/790/164
- Title:
- Candidate bulge WDs in the SWEEPS field
- Short Name:
- J/ApJ/790/164
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope data of the low-reddening Sagittarius window in the Galactic bulge. The Sagittarius Window Eclipsing Extrasolar Planet Search field (~3'x3'), together with three more Advanced Camera for Surveys and eight Wide-Field Camera 3 fields, were observed in the F606W and F814W filters, approximately every two weeks for 2 yr, with the principal aim of detecting a hidden population of isolated black holes and neutron stars through astrometric microlensing. Proper motions were measured with an accuracy of ~0.1 mas/yr (~4 km/s) at F606W ~25.5 mag, and better than ~0.5 mas/yr (~20 km/s) at F606W ~28 mag, in both axes. Proper-motion measurements allowed us to separate disk and bulge stars and obtain a clean bulge color-magnitude diagram. We then identified for the first time a white dwarf (WD) cooling sequence in the Galactic bulge, together with a dozen candidate extreme horizontal branch stars. The comparison between theory and observations shows that a substantial fraction of the WDs (~30%) are systematically redder than the cooling tracks for CO-core H-rich and He-rich envelope WDs. This evidence would suggest the presence of a significant number of low-mass WDs and WD-main-sequence binaries in the bulge. This hypothesis is further supported by the finding of two dwarf novae in outburst, two short-period (P <~ 1 day) ellipsoidal variables, and a few candidate cataclysmic variables in the same field.
- ID:
- ivo://CDS.VizieR/J/MNRAS/403/429
- Title:
- Candidate globular clusters in NGC 5170
- Short Name:
- J/MNRAS/403/429
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here, we present Hubble Space Telescope/Advanced Camera for Surveys (ACS) imaging, in the B and I bands, of the edge-on Sb/Sc galaxy NGC 5170. Excluding the central disc region, we detect 142 objects with colours and sizes typical of globular clusters (GCs). Our main result is the discovery of a "blue tilt" (a mass-metallicity relation), at the 3{sigma} level, in the metal-poor GC subpopulation of this Milky Way like galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/750/140
- Title:
- Candidate globular clusters in NGC 1316
- Short Name:
- J/ApJ/750/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study mass functions of globular clusters derived from Hubble Space Telescope/Advanced Camera for Surveys images of the early-type merger remnant galaxy NGC 1316, which hosts a significant population of metal-rich globular clusters of intermediate age (~3Gyr). For the old, metal-poor ("blue") clusters, the peak mass of the mass function M_p_ increases with internal half-mass density {rho}_h_ as M_p_{prop.to}{rho}_h_^0.44^, whereas it stays approximately constant with galactocentric distance R_gal_. The mass functions of these clusters are consistent with a simple scenario in which they formed with a Schechter initial mass function and evolved subsequently by internal two-body relaxation. For the intermediate-age population of metal-rich ("red") clusters, the faint end of the previously reported power-law luminosity function of the clusters with R_gal_>9kpc is due to many of those clusters having radii larger than the theoretical maximum value imposed by the tidal field of NGC 1316 at their R_gal_. This renders disruption by two-body relaxation ineffective. Only a few such diffuse clusters are found in the inner regions of NGC 1316. Completeness tests indicate that this is a physical effect. Using comparisons with star clusters in other galaxies and cluster disruption calculations using published models, we hypothesize that most red clusters in the low-{rho}_h_ tail of the initial distribution have already been destroyed in the inner regions of NGC 1316 by tidal shocking, and that several remaining low-{rho}_h_ clusters will evolve dynamically to become similar to "faint fuzzies" that exist in several lenticular galaxies. Finally, we discuss the nature of diffuse red clusters in early-type galaxies.
