- ID:
- ivo://CDS.VizieR/J/ApJ/703/42
- Title:
- HST photometry of M87 globular clusters
- Short Name:
- J/ApJ/703/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the M87 GC system using deep, archival HST/ACS imaging with the F606W and F814W filters, in which we find a significant color-magnitude relation for the metal-poor globular clusters (GCs). The slope of this relation in the I versus V-I color-magnitude diagram ({gamma}_I_=-0.024+/-0.006) is perfectly consistent with expectations based on previously published results using data from the ACS Virgo Cluster Survey. We show that previously measured half-light radii of M87 GCs from best-fit PSF-convolved King models are consistent with the more accurate measurements in this study, and we also explain how the color-magnitude relation for metal-poor GCs is real and cannot be an artifact of the photometry. We fit Gaussian and evolved Schechter functions to the luminosity distribution of GCs across all colors, as well as divided into blue and red subpopulations, finding that the blue GCs have a brighter mean luminosity and a narrower distribution than the red GCs. Finally, we present a catalog of astrometry and photometry for 2250 M87 GCs.
Number of results to display per page
Search Results
- 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/896/81
- Title:
- HST survey of ONC in H2O 1.4um abs. band. III.
- Short Name:
- J/ApJ/896/81
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We present new results concerning the substellar binary population in the Orion Nebula Cluster (ONC). Using the Karhunen-Loeve Image Projection algorithm, we have reprocessed images taken with the IR channel of the Wide Field Camera 3 mounted on the Hubble Space Telescope to unveil faint, close companions in the wings of the stellar point-spread functions. Starting with a sample of 1392 bona fide unsaturated cluster members, we detect 39 close-pair cluster candidates with separation 0.16"-0.77". The primary masses span a range Mp~0.015-1.27M_{sun}_, whereas for the companions we derive Mc~0.004-0.54M_{sun}_. Of these 39 binary systems, 18 were already known, while the remaining 21 are new detections. Correcting for completeness and combining our catalog with previously detected ONC binaries, we obtain an overall binary fraction of 11.5%+/-0.9%. Compared to other star-forming regions, our multiplicity function is ~2 times smaller than, for example, Taurus, while compared to the binaries in the field we obtain comparable values. We analyze the mass functions of the binaries, finding differences between the mass distributions of binaries and single stars and between primary and companion mass distributions. The mass ratio shows a bottom-heavy distribution with median value Mc/Mp~0.25. Overall, our results suggest that ONC binaries may represent a template for the typical population of field binaries, supporting the hypothesis that the ONC may be regarded as a most typical star-forming region in the Milky Way.
- ID:
- ivo://CDS.VizieR/J/ApJ/896/79
- Title:
- HST survey of ONC in H20 1.4um abs. band. I.
- Short Name:
- J/ApJ/896/79
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- In order to obtain a complete census of the stellar and substellar population, down to a few M_Jup_ in the ~1Myr old Orion Nebula Cluster, we used the infrared channel of the Wide Field Camera 3 of the Hubble Space Telescope with the F139M and F130N filters. These bandpasses correspond to the 1.4{mu}m H2O absorption feature and an adjacent line-free continuum region. Out of 4504 detected sources, 3352 (about 75%) appear fainter than m130=14 (Vega mag) in the F130N filter, a brightness corresponding to the hydrogen- burning limit mass (M~0.072M_{sun}_) at ~1Myr. Of these, however, only 742 sources have a negative F130M-F139N color index, indicative of the presence of H2O vapor in absorption, and can therefore be classified as bona fide M and L dwarfs, with effective temperatures T<~2850K at an assumed 1Myr cluster age. On our color-magnitude diagram (CMD), this population of sources with H2O absorption appears clearly distinct from the larger background population of highly reddened stars and galaxies with positive F130M-F139N color index and can be traced down to the sensitivity limit of our survey, m130~21.5, corresponding to a 1Myr old ~3M_Jup_ planetary-mass object under about 2mag of visual extinction. Theoretical models of the BT-Settl family predicting substellar isochrones of 1, 2, and 3 Myr down to ~1M_Jup_ fail to reproduce the observed H2O color index at M<~20M_Jup_. We perform a Bayesian analysis to determine extinction, mass, and effective temperature of each substellar member of our sample, together with its membership probability.
- 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/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/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/743/146
- Title:
- HST/WFC3 observations in HUDF and GOODS-S
- Short Name:
- J/ApJ/743/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the high angular resolution in the near-infrared of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope to determine YHVz color-color-selection criteria to identify and characterize 1.5<z<3.5 galaxies in the Hubble Ultra Deep Field 2009 (HUDF09) and Early Release Science (GOODS-South) fields. The WFC3 NIR images reveal galaxies at these redshifts that were undetected in the rest-frame UV HUDF/GOODS images, as well as true centers and regular disks in galaxies classified as highly irregular in rest-frame UV light. Across the 1.5<z<2.15 redshift range, regular disks are unveiled in the WFC3 images of ~25% of both intermediate and high mass galaxies, i.e., above 10^10^M_{sun}_. Meanwhile, galaxies maintaining diffuse and/or irregular morphologies in the rest-frame optical light - i.e., not yet dynamically settled - at these epochs are almost entirely restricted to masses below 10^11^M_{sun}_. In contrast at 2.25<z<3.5 these diffuse and/or irregular structures overwhelmingly dominate the morphological mix in both the intermediate and high mass regimes, while no regular disks, and only a small fraction (~25%) of smooth spheroids, are evident above 10^11^M_{sun}_. Strikingly, by 1.5<z<2.25 roughly two out of every three galaxies at the highest masses are spheroids. In our small sample, the fraction of star-forming galaxies at these mass scales decreases concurrently from ~60% to ~5%. If confirmed, this indicates that z~2 is the epoch of both the morphological transformation and quenching of star formation which assemble the first substantial population of massive ellipticals.
- 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/730/78
- Title:
- Hubble and Spitzer photometry of NGC 602
- Short Name:
- J/ApJ/730/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the photometric catalogs for the star-forming cluster NGC 602 in the wing of the Small Magellanic Cloud covering a range of wavelengths from optical (HST/ACS F555W, F814W, and SMARTS/ANDICAM V, I) to infrared (Spitzer/IRAC 3.6, 4.5, 5.8, and 8um and MIPS 24um). Combining this with Infrared Survey Facility near-infrared photometry (J, H, Ks), we compare the young main sequence (MS) and pre-main sequence (PMS) populations prominent in the optical with the current young stellar object (YSO) populations revealed by the infrared. We analyze the MS and PMS population with isochrones in color-magnitude diagrams to derive ages and masses. The optical data reveal ~565 PMS candidates, low-mass Stage III YSOs. We characterize ~40 YSOs by fitting their spectral energy distributions to a grid of models (Robitaille et al. 2007ApJS..169..328R) to derive luminosities, masses, and evolutionary phase (Stages I-III). The higher resolution HST images reveal that ~70% of the YSO candidates are either multiples or protoclusters. For YSOs and PMS sources found in common, we find a consistency in the masses derived. We use the YSO mass function to derive a present-day star formation rate of ~0.2-1.0M_{sun}_/yr/kpc^2^, similar to the rate derived from the optical star formation history suggesting a constant star formation rate for this region.
