- 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.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/122/81
- Title:
- HST snapshot survey of 3CR radio sources
- Short Name:
- J/ApJS/122/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and describe optical counterparts to 46 3CR radio galaxies of redshifts less than 0.1 that were imaged with the Hubble Space Telescope's (HST) WFPC2 camera through the broadband F702W filter as part of the 3CR Snapshot Survey. This is the fifth and last such paper describing the 252 radio galaxies of this R-band survey. At the 0.1'' resolution of the images, a wealth of detail is visible. Approximately 89% of the galaxies are ellipticals, and nearly all reside in groups or clusters of galaxies of various richness and compactness. Nearby elliptical companions of slightly smaller size and mass are common. Dust is prevalent in the cores of the 3C hosts; nearly half of the galaxies possess some type of dust structure, such as irregular dust lanes, filaments, or disks. Besides the well-known dust disks of 3C 264 and 3C 270, we have found five new candidates in 3C 31, 3C 40, 3C 296, 3C 449, and 3C 465, as well as in the central regions of the nearby neighbors of 3C 31 and 3C 465. Our sample includes six confirmed optical synchrotron jets in 3C 15, 3C 66B, 3C 78, 3C 264, 3C 274, and 3C 371, or approximately 13% of the sample. Unresolved nuclei, consistent with the point spread function of WFPC2, are found in 43%-54% of the galaxies and in the majority of galaxies with dust disks and optical jets.
- ID:
- ivo://CDS.VizieR/J/ApJS/195/16
- Title:
- HST survey for Lyman limit systems. I.
- Short Name:
- J/ApJS/195/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a set of 71 quasars observed in the near ultraviolet with the PR200L prism on the Advanced Camera for Surveys and the G280 grism on the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope. The quasars were selected from the Sloan Digital Sky Survey data to search for intervening Lyman limit system (LLS) absorption. The sample was subjected to the constraints that the quasars have AB magnitude g'<18.5, quasar emission redshift 2.3<z_em_<2.6, and lack strong BAL or z~z_em_ absorption. The median emission redshift of the sample is {bar}z=2.403. The data were all processed using custom data reduction pipelines, and the one-dimensional spectra have sufficient signal-to-noise ratio and resolution to easily identify absorption from LLS over the redshift range 1.2<z<2.5. The WFC3 data presented here are the first non-calibration spectra from the G280 grism.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/137
- Title:
- HST survey for Lyman limit systems. II.
- Short Name:
- J/ApJ/765/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first science results from our Hubble Space Telescope survey for Lyman limit absorption systems (LLS) using the low dispersion spectroscopic modes of the Advanced Camera for Surveys and the Wide Field Camera 3. Through an analysis of 71 quasars, we determine the incidence frequency of LLS per unit redshift and per unit path length, l(z) and l(X), respectively, over the redshift range 1<z<2.6, and find a weighted mean of l(X)=0.29+/-0.05 for 2.0<z<2.5 through a joint analysis of our sample and that of Ribaudo et al. (2011, J/ApJ/736/42). Through stacked spectrum analysis, we determine a median (mean) value of the mean free path to ionizing radiation at z=2.4 of {lambda}^912^_mfp_=243(252)h^-1^_72_Mpc, with an error on the mean value of +/-43h^-1^_72_Mpc. We also re-evaluate the estimates of {lambda}^912^_mfp_ from Prochaska et al. (2010, J/ApJ/718/392) and place constraints on the evolution of {lambda}^912^_mfp_ with redshift, including an estimate of the "breakthrough" redshift of z=1.6. Consistent with results at higher z, we find that a significant fraction of the opacity for absorption of ionizing photons comes from systems with N_HI_<=10^17.5^cm^-2^ with a value for the total Lyman opacity of {tau}^Lyman^_eff_=0.40+/-0.15. Finally, we determine that at minimum, a 5-parameter (4 power law) model is needed to describe the column density distribution function f(N_HI_,X) at z~2.4, find that f(N_HI_,X) undergoes no significant change in shape between z~2.4 and z~3.7, and provide our best fit model for f(N_HI_,X).
- ID:
- ivo://CDS.VizieR/J/AJ/127/1982
- Title:
- HST UBVI photometry of NGC 3081 inner regions
- Short Name:
- J/AJ/127/1982
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope Wide Field Planetary Camera 2 images of the inner regions of NGC 3081, an absolute magnitude M_B_=-20.0 early-type barred spiral having four well-defined resonance rings: a nuclear ring, an inner ring, an outer R_1_ ring, and an outer R'_2_ pseudoring. Here we focus on a photometric study of the inner ring, a feature likely associated with an inner 4:1 resonance near the ends of the bar. The ring is notable for its high contrast and sharp definition, which is due to a significant degree of active star formation. The ring is also notable for its significant intrinsic elongation and parallel alignment with the bar.
- ID:
- ivo://CDS.VizieR/J/AJ/107/1745
- Title:
- HST UVI photometry of M15. II.
- Short Name:
- J/AJ/107/1745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The projected density distribution of resolved stars near the center of M15 is shown to be consistent with either a power-law cusp N(r) ~ r^{alpha}^, with {alpha} ~ -0.85+/-0.2, or with a King model with a core of radius <~ 2" (best fit r(core)=1.3"). The inferred slope is in agreement with the theoretical value, {alpha}=-0.75, calculated by Bahcall and Wolf for the distribution of equal-mass stars surrounding a massive black hole and is also consistent with the radial profile expected from core collapse without a central black hole. The object AC 214 is a candidate for the central density cusp. Analysis of Monte Carlo simulations of the diffuse light indicates that, using current analysis techniques and available data, the residual light is not a reliable indicator of the true density distribution. This is contrary to earlier work. Photometric measurements in V and I of more than 5x10^3^ stars (and in U, V, and I of >~1500 stars) are used to construct color-magnitude diagrams in the central 1' of M15. Fourteen blue straggler candidates are identified in the inner 20". The central color gradient noticed by previous researchers is caused by a central depletion of bright red giant stars rather than an excess of blue stragglers or blue horizontal branch stars.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/707/1417
- Title:
- HST view of YSOs in the LMC
- Short Name:
- J/ApJ/707/1417
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used archival Hubble Space Telecope (HST) H{alpha} images to study the immediate environments of massive and intermediate-mass young stellar object (YSO) candidates in the Large Magellanic Cloud (LMC). The sample of YSO candidates, taken from Gruendl & Chu (2009, Cat. J/ApJS/184/172), was selected based on Spitzer IRAC and MIPS observations of the entire LMC and complementary ground-based optical and near-infrared observations. We found HST H{alpha} images for 99 YSO candidates in the LMC, of which 82 appear to be genuine YSOs. More than 95% of the YSOs are found to be associated with molecular clouds. YSOs are seen in three different kinds of environments in the H{alpha} images: in dark clouds, inside or on the tip of bright-rimmed dust pillars, and in small HII regions. Comparisons of spectral energy distributions for YSOs in these three different kinds of environments suggest that YSOs in dark clouds are the youngest, YSOs with small HII regions are the most evolved, and YSOs in bright-rimmed dust pillars span a range of intermediate evolutionary stages. This rough evolutionary sequence is substantiated by the presence of silicate absorption features in the Spitzer Infrared Spectrograph spectra of some YSOs in dark clouds and in bright-rimmed dust pillars, but not those of YSOs in small HII regions. We present a discussion on triggered star formation for YSOs in bright-rimmed dust pillars or in dark clouds adjacent to HII regions. As many as 50% of the YSOs are resolved into multiple sources in high-resolution HST images.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A25
- Title:
- HST WFC3 photometry of NGC 2419
- Short Name:
- J/A+A/624/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new deep imaging of the central regions of the remote globular cluster NGC 2419, obtained with the F343N and F336W filters of the Wide Field Camera 3 on board the Hubble Space Telescope. The new data are combined with archival imaging to constrain nitrogen and helium abundance variations within the cluster. We find a clearly bimodal distribution of the nitrogen-sensitive F336W-F343N colours of red giants, from which we estimate that about 55% of the giants belong to a population with about normal (field-like) nitrogen abundances (P1), while the remaining 45% belong to a nitrogen-rich population (P2). On average, the P2 stars are more He-rich than the P1 stars, with an estimated mean difference of {Delta}Y~=0.05, but the P2 stars exhibit a significant spread in He content and some may reach {Delta}Y~=0.13. A smaller He spread may also be present for the P1 stars. Additionally, stars with spectroscopically determined low Mg abundances ([Mg/Fe]<0) are generally associated with P2. We find the P2 stars to be slightly more centrally concentrated in NGC 2419 with a projected half-number radius of about 10% less than for the P1 stars, but the difference is not highly significant (p~=0.05). Using published radial velocities, we find evidence of rotation for the P1 stars, whereas the results are inconclusive for the P2 stars, which are consistent with no rotation as well as the same average rotation found for the P1 stars. Because of the long relaxation time scale of NGC 2419, the radial trends and kinematic properties of the populations are expected to be relatively unaffected by dynamical evolution. Hence, they provide constraints on formation scenarios for multiple populations, which must account not only for the presence of He spreads within sub-populations identified via CNO variations, but also for the relatively modest differences in the spatial distributions and kinematics of the populations.
- ID:
- ivo://CDS.VizieR/J/ApJ/548/127
- Title:
- Hubble Deep Field-South region
- Short Name:
- J/ApJ/548/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the galaxy-galaxy angular correlations as a function of photometric redshift in a deep, wide galaxy survey centered on the Hubble Deep Field-South (HDF-S). Images were obtained with the Big Throughput Camera on the Blanco 4-m telescope at CTIO, of 1/2 square degree in broadband uBVRI, reaching ~24mag. Approximately 40,000 galaxies are detected in the survey. We determine photometric redshifts using galaxy template fitting to the photometry.
