- ID:
- ivo://CDS.VizieR/J/AJ/133/917
- Title:
- HST photometry of two NGC 4214 clusters
- Short Name:
- J/AJ/133/917
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the data and methods that we have used to perform a detailed UV-optical study of the nearby dwarf starburst galaxy NGC 4214 using multifilter Hubble Space Telescope WFPC2 and STIS photometry. We explain the process followed to obtain high-quality photometry and astrometry of the stellar and cluster populations of this galaxy. We describe the procedure used to transform magnitudes and colors into physical parameters using spectral energy distributions. The data show the existence of both young and old stellar populations that can be resolved at the distance of NGC 4214 (2.94Mpc), and we perform a general description of those populations.
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- ID:
- ivo://CDS.VizieR/J/AJ/144/142
- Title:
- HST photometry of young stellar populations in M31
- Short Name:
- J/AJ/144/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We studied the young stellar populations of 22 star-forming regions in the Andromeda galaxy (M31), with Hubble Space Telescope (HST) multi-band imaging from far-UV to I. The regions were selected from Galaxy Evolution Explorer (GALEX) wide-field far-UV imaging; they sample different environments and galactocentric distances from 6 to 22kpc. They were imaged with 30 HST fields (360 distinct images, in six bandpasses), with a pixel scale of 0.38pc projected on the sky, at the distance of M31. This study is part of HST treasury survey program HST-GO-11079, which includes star-forming regions in eight Local Group galaxies. We provide a merged catalog of six-band stellar photometry in the 30 M31 fields, containing 118036 sources brighter than V and B~23mag. Each HST field covers about 0.3kpc^2^ in M31, and contains up to ~7000 stars, of which the number varies by a factor of >7 among the target regions; a large fraction of the sample are hot massive stars, due to our choice of filters and exposures. We derived stellar physical parameters and interstellar extinction for individual sources by spectral energy distribution analysis with model-atmosphere colors, and used the results to infer ages, massive stars content, and extinction of the star-forming regions. Reddening is up to E(B-V)<~0.6mag in some OB associations, and lowest in the outermost regions (average of <~0.12mag in OB184 at 21.9kpc). We examined the spatial distribution (clustering) of the hot massive stars, and defined OB associations on various spatial scales from compact to wider, more spread out ones. A hierarchical structuring is observed, with small compact groups arranged within large complexes. Their areas vary from less than 10 to 10^5^pc^2^, and masses are up to {approx}10^5^M_{sun}_, in the scales sampled by our analysis. Their cumulative mass distribution follows a power law, at least in part of the sampled regime. Hot-star counts in the young regions compare very well with integrated measurements of UV flux from GALEX.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/99
- Title:
- HSTPROMO cat. VI. Improved analysis of NGC362
- Short Name:
- J/ApJ/861/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an improved data-reduction technique to obtain high-precision proper motions (PMs) of globular clusters (GCs) using Hubble Space Telescope data. The new reduction is superior to the one presented in the first paper of this series for the faintest sources in very crowded fields. We choose the GC NGC 362 as a benchmark to test our new procedures. We measure PMs of 117450 sources in the field, showing that we are able to obtain a PM precision better than 10{mu}as/yr for bright stars. We make use of this new PM catalog of NGC 362 to study the cluster's internal kinematics. We investigate the velocity dispersion profiles of the multiple stellar populations hosted by NGC 362 and find new pieces of information on the kinematics of first- and second- generation stars. We analyze the level of energy equipartition of the cluster and find direct evidence for its post-core-collapsed state from kinematic arguments alone. We refine the dynamical mass of the blue stragglers (BSs) and study possible kinematic differences between BSs formed by collisions and mass transfer. We also measure no significant cluster rotation in the plane of the sky. Finally, we measure the absolute PM of NGC 362 and of the background stars belonging to the Small Magellanic Cloud, finding a good agreement with previous estimates in the literature. We make the PM catalog publicly available.
- ID:
- ivo://CDS.VizieR/J/ApJ/797/115
- Title:
- HSTPROMO I. Observations and NGC7078 results
- Short Name:
- J/ApJ/797/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first study of high-precision internal proper motions (PMs) in a large sample of globular clusters, based on Hubble Space Telescope (HST) data obtained over the past decade with the ACS/WFC, ACS/HRC, and WFC3/UVIS instruments. We determine PMs for over 1.3 million stars in the central regions of 22 clusters, with a median number of ~60000 stars per cluster. These PMs have the potential to significantly advance our understanding of the internal kinematics of globular clusters by extending past line-of-sight (LOS) velocity measurements to two- or three-dimensional velocities, lower stellar masses, and larger sample sizes. We describe the reduction pipeline that we developed to derive homogeneous PMs from the very heterogeneous archival data. We demonstrate the quality of the measurements through extensive Monte Carlo simulations. We also discuss the PM errors introduced by various systematic effects and the techniques that we have developed to correct or remove them to the extent possible. We provide in electronic form the catalog for NGC 7078 (M 15), which consists of 77837 stars in the central 2.4'. We validate the catalog by comparison with existing PM measurements and LOS velocities and use it to study the dependence of the velocity dispersion on radius, stellar magnitude (or mass) along the main sequence, and direction in the plane of the sky (radial or tangential).
- ID:
- ivo://CDS.VizieR/J/ApJ/839/L11
- Title:
- HST strong lensing analysis of PLCKG287.0+32.9
- Short Name:
- J/ApJ/839/L11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since galaxy clusters sit at the high end of the mass function, the number of galaxy clusters both massive and concentrated enough to yield particularly large Einstein radii poses useful constraints on cosmological and structure formation models. To date, less than a handful of clusters are known to have Einstein radii exceeding ~40" (for a source at z_s_~2, nominally). Here, we report an addition to that list of the Sunyaev-Zel'dovich (SZ) selected cluster, PLCKG287.0+32.9 (z=0.38), the second-highest SZ-mass (M500) cluster from the Planck catalog. We present the first strong-lensing analysis of the cluster, identifying 20 sets of multiply imaged galaxies and candidates in new Hubble Space Telescope (HST) data, including a long, l~22" giant arc, as well as a quadruply imaged, apparently bright (magnified to J_F110W_=25.3 AB), likely high-redshift dropout galaxy at z_phot_=6.90 [6.13-8.43] (95% C.I.). Our analysis reveals a very large critical area (1.55arcmin^2^, z_s_~2), corresponding to an effective Einstein radius of {theta}_E_~42". The model suggests the critical area will expand to 2.58arcmin^2^ ({theta}_E_~54") for sources at z_s_~10. Our work adds to recent efforts to model very massive clusters toward the launch of the James Webb Space Telescope, in order to identify the most useful cosmic lenses for studying the early universe. Spectroscopic redshifts for the multiply imaged galaxies and additional HST data will be necessary for refining the lens model and verifying the nature of the z~7 dropout.
- ID:
- ivo://CDS.VizieR/J/ApJS/227/1
- Title:
- HST survey for novae in M87. I. VI LCs
- Short Name:
- J/ApJS/227/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae (CNe) and nine fainter, likely very slow, and/or symbiotic novae. In this first paper of a series, we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae follows the light of the galaxy, suggesting that novae accreted by M87 during cannibalistic episodes are well-mixed. Conservatively using only the 32 brightest CNe we derive a nova rate for M87: 363_-45_^+33^ novae yr^-1^. We also derive the luminosity-specific classical nova rate for this galaxy, which is 7.88_-2.6_^+2.3^yr^-1^/10^10^L_{sun},K_. Both rates are 3-4 times higher than those reported for M87 in the past, and similarly higher than those reported for all other galaxies. We suggest that most previous ground-based surveys for novae in external galaxies, including M87, miss most faint, fast novae, and almost all slow novae near the centers of galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJS/177/148
- Title:
- HST survey of 3CR radio source counterparts. II.
- Short Name:
- J/ApJS/177/148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second part of an H-band (1.6um) "atlas" of z<0.3 3CR radio galaxies, using the Hubble Space Telescope Near Infrared Camera and Multi-Object Spectrometer (HST NICMOS2). We present new imaging for 21 recently acquired sources and host galaxy modeling for the full sample of 101 (including 11 archival) - an 87% completion rate. Two different modeling techniques are applied, following those adopted by the galaxy morphology and the quasar host galaxy communities. Results are compared and found to be in excellent agreement, although the former breaks down in the case of sources with strong active galactic nuclei (AGNs). Companion sources are tabulated, and the presence of mergers, tidal features, dust disks, and jets are cataloged. The tables form a catalog for those interested in the structural and morphological dust-free host galaxy properties of the 3CR sample, and for comparison with morphological studies of quiescent galaxies and quasar host galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/138/1667
- Title:
- HST survey of young clusters in M31. III.
- Short Name:
- J/AJ/138/1667
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Surface brightness profiles for 23 M31 star clusters were measured using images from the Wide Field Planetary Camera 2 on the Hubble Space Telescope, and fitted to two types of models to determine the clusters' structural properties. The clusters are primarily young (~108yr) and massive (~104.5M_{sun}_), with median half-light radius 7pc and dissolution times of a few Gyr. The properties of the M31 clusters are comparable to those of clusters of similar age in the Magellanic Clouds. Simulated star clusters are used to derive a conversion from statistical measures of cluster size to half-light radius so that the extragalactic clusters can be compared to young massive clusters in the Milky Way. All three sets of star clusters fall approximately on the same age-size relation. The young M31 clusters are expected to dissolve within a few Gyr and will not survive to become old, globular clusters. However, they do appear to follow the same fundamental plane (FP) relations as old clusters; if confirmed with velocity dispersion measurements, this would be a strong indication that the star cluster FP reflects universal cluster formation conditions.
- ID:
- ivo://CDS.VizieR/J/ApJS/207/10
- Title:
- HST Treasury Program on the ONC
- Short Name:
- J/ApJS/207/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Space Telescope (HST) Treasury Program on the Orion Nebula Cluster (ONC) has used 104 orbits of HST time to image the Great Orion Nebula region with the Advanced Camera for Surveys (ACS), the Wide-Field/Planetary Camera 2 (WFPC2), and the Near-Infrared Camera and Multi-Object Spectrograph (NICMOS) instrument in 11 filters ranging from the U band to the H band equivalent of HST. The program has been intended to perform the definitive study of the stellar component of the ONC at visible wavelengths, addressing key questions like the cluster initial mass function, age spread, mass accretion, binarity, and circumstellar disk evolution. The scanning pattern allowed us to cover a contiguous field of approximately 600 arcmin2 with both ACS and WFPC2, with a typical exposure time of approximately 11 minutes per ACS filter, corresponding to a point source depth AB(F435W) = 25.8 and AB(F775W) = 25.2 with 0.2 mag of photometric error. We describe the observations, data reduction, and data products, including images, source catalogs, and tools for quick look preview. In particular, we provide ACS photometry for 3399 stars, most of them detected at multiple epochs; WFPC2 photometry for 1643 stars, 1021 of them detected in the U band; and NICMOS JH photometry for 2116 stars. We summarize the early science results that have been presented in a number of papers.
- ID:
- ivo://CDS.VizieR/J/ApJ/848/37
- Title:
- HST UV-IR photometry in CLASH galaxy clusters
- Short Name:
- J/ApJ/848/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new method for photometering objects in galaxy clusters. We introduce a mode-filtering technique for removing spatially variable backgrounds, improving both detection and photometric accuracy (roughly halving the scatter in the red sequence compared to previous catalogs of the same clusters). This method is based on robustly determining the distribution of background pixel values and should provide comparable improvement in photometric analysis of any crowded fields. We produce new multiwavelength catalogs for the 25 CLASH cluster fields in all 16 bandpasses from the UV through the near-IR, as well as rest-frame magnitudes. A comparison with spectroscopic values from the literature finds a ~30% decrease in the redshift deviation from previously released CLASH photometry. This improvement in redshift precision, in combination with a detection scheme designed to maximize purity, yields a substantial upgrade in cluster member identification over the previous CLASH galaxy catalog. We construct luminosity functions for each cluster, reliably reaching depths of at least 4.5mag below M* in every case, and deeper still in several clusters. We measure M* , {alpha}, and their redshift evolution, assuming the cluster populations are coeval, and find little to no evolution of {alpha}{<~}-0.9<~{alpha}{<~}-0.8, and M* values consistent with passive evolution. We present a catalog of galaxy photometry, photometric and spectroscopic redshifts, and rest-frame photometry for the full fields of view of all 25 CLASH clusters. Not only will our new photometric catalogs enable new studies of the properties of CLASH clusters, but mode-filtering techniques, such as those presented here, should greatly enhance the data quality of future photometric surveys of crowded fields.
