- ID:
- ivo://CDS.VizieR/J/ApJS/179/306
- Title:
- Radio galaxy morphologies
- Short Name:
- J/ApJS/179/306
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a statistical study of 51 radio galaxies at the millijansky flux level selected from the Faint Images of the Radio Sky at Twenty cm survey, including their optical morphologies and structure obtained with the Hubble Space Telescope (HST). Our optical imaging is significantly deeper (~2mag) than previous studies with the superior angular resolution of space-based imaging. We that find 8/51 (16%) of the radio sources have no optically identifiable counterpart to AB~24mag. For the remaining 43 sources, only 25 are sufficiently resolved in the HST images to reliably assign a visual classification: 15 (60%) are elliptical galaxies, two (8%) are late-type spiral galaxies, one (4%) is an S0, three (12%) are pointlike objects (quasars), and four (16%) are merger systems. We find a similar distribution of optical types with measurements of the Sersic index.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/665/921
- Title:
- Redshift survey in the field of A1689
- Short Name:
- J/ApJ/665/921
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of the HST Advanced Camera for Surveys spectroscopic ground-based redshift survey in the field of A1689. We measure 98 redshifts, increasing the number of spectroscopically confirmed objects sixfold. We present two spectra from this catalog of the Sextet Arcs, images that arise from a strongly lensed Lyman break galaxy (LBG) at a redshift of z=3.038. Gravitational lensing by the cluster magnifies its flux by a factor of ~16 and produces six separate images with a total r-band magnitude of r_625_=21.7. The two spectra, each of which represents emission from different regions of the LBG, show HI and interstellar metal absorption lines at the systemic redshift.
- ID:
- ivo://CDS.VizieR/J/ApJ/884/85
- Title:
- RELICS: Reionization Lensing Cluster Survey
- Short Name:
- J/ApJ/884/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Large surveys of galaxy clusters with the Hubble Space Telescope (HST) and Spitzer, including the Cluster Lensing And Supernova survey with Hubble and the Frontier Fields, have demonstrated the power of strong gravitational lensing to efficiently deliver large samples of high-redshift galaxies. We extend this strategy through a wider, shallower survey named RELICS, the Reionization Lensing Cluster Survey, described here. Our 188-orbit Hubble Treasury Program observed 41 clusters at 0.182<=z<=0.972 with Advanced Camera for Surveys (ACS) and WFC3/IR imaging spanning 0.4-1.7{mu}m. We selected 21 of the most massive clusters known based on Planck PSZ2 estimates and 20 additional clusters based on observed or inferred lensing strength. RELICS observed 46 WFC3/IR pointings (~200arcmin^2^) each with two orbits divided among four filters (F105W, F125W, F140W, and F160W) and ACS imaging as needed to achieve single-orbit depth in each of three filters (F435W, F606W, and F814W). As previously reported by Salmon+ (2020ApJ...889..189S), we discovered over 300 z~6-10 candidates, including the brightest z~6 candidates known, and the most distant spatially resolved lensed arc known at z~10. Spitzer IRAC imaging (945hr awarded, plus 100 archival, spanning 3.0-5.0{mu}m) has crucially enabled us to distinguish z~10 candidates from z~2 interlopers. For each cluster, two HST observing epochs were staggered by about a month, enabling us to discover 11 supernovae, including 3 lensed supernovae, which we followed up with 20 orbits from our program.
- ID:
- ivo://CDS.VizieR/J/AJ/136/1703
- Title:
- Ridgelines of six intermediate-age SMC clusters
- Short Name:
- J/AJ/136/1703
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric analysis of the star clusters Lindsay 1, Kron 3, NGC 339, NGC 416, Lindsay 38, and NGC 419 in the Small Magellanic Cloud (SMC), observed with the Hubble Space Telescope Advanced Camera for Surveys (ACS) in the F555W and F814W filters. Our color-magnitude diagrams (CMDs) extend ~3.5mag deeper than the main-sequence turnoff points, deeper than any previous data. Cluster ages were derived using three different isochrone models: Padova, Teramo, and Dartmouth, which are all available in the ACS photometric system. Fitting observed ridgelines for each cluster, we provide a homogeneous and unique set of low-metallicity, single-age fiducial isochrones.
- ID:
- ivo://CDS.VizieR/J/AJ/141/171
- Title:
- RR Lyrae stars in six ultra-deep fields of M31
- Short Name:
- J/AJ/141/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present HST/ACS observations of RR Lyrae variable stars in six ultra-deep fields of the Andromeda galaxy (M31), including parts of the halo, disk, and giant stellar stream. Past work on the RR Lyrae stars in M31 has focused on various aspects of the stellar populations that make up the galaxy's halo, including their distances and metallicities. This study builds upon this previous work by increasing the spatial coverage (something that has been lacking in previous studies) and by searching for these variable stars in constituents of the galaxy not yet explored.
- ID:
- ivo://CDS.VizieR/J/AJ/138/184
- Title:
- RR Lyrae variables in 2 fields in M31 spheroid
- Short Name:
- J/AJ/138/184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope observations taken with the Advanced Camera for Surveys Wide Field Channel of two fields near M32 - between 4 and 6kpc from the center of M31. The data cover a time baseline sufficient for the identification and characterization of 681 RR Lyrae variables of which 555 are ab-type and 126 are c-type.
- ID:
- ivo://CDS.VizieR/J/ApJ/708/817
- Title:
- RR Lyrae variables in M32 and M31
- Short Name:
- J/ApJ/708/817
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed two fields near M32 with the Advanced Camera for Surveys/High Resolution Channel (ACS/HRC) on board the Hubble Space Telescope. The main field, F1, is 1.8' from the center of M32; the second field, F2, constrains the M31 background, and is 5.4' distant. Each field was observed for 16 orbits in each of the F435W (narrow B) and F555W (narrow V) filters. The duration of the observations allowed RR Lyrae stars to be detected. A population of RR Lyrae stars determined to belong to M32 would prove the existence of an ancient population in that galaxy, a subject of some debate. We detected 17 RR Lyrae variables in F1 and 14 in F2. A 1{sigma} upper limit of 6 RR Lyrae variables belonging to M32 is inferred from these two fields alone. Use of our two ACS/WFC parallel fields provides better constraints on the M31 background, however, and implies that 7^+4^_-3_ (68% confidence interval) RR Lyrae variables in F1 belong to M32. We have therefore found evidence for an ancient population in M32. It seems to be nearly indistinguishable from the ancient population of M31. The RR Lyrae stars in the F1 and F2 fields have indistinguishable mean V-band magnitudes, mean periods, distributions in the Bailey diagram, and ratios of RRc to RRtotal types. However, the color distributions in the two fields are different, with a population of red RRab variables in F1 not seen in F2. We suggest that these might be identified with the detected M32 RR Lyrae population, but the small number of stars rules out a definitive claim.
- ID:
- ivo://CDS.VizieR/J/ApJ/724/799
- Title:
- RR Lyrae variables in M33. II.
- Short Name:
- J/ApJ/724/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an extensive survey of RR Lyrae (RRL) stars in three fields along the major axis of the Triangulum Galaxy (M33). From images taken with the Advanced Camera for Surveys (ACS) Wide Field Channel on board the Hubble Space Telescope through two passbands (F606W and F814W), we have identified and characterized a total of 119 RRL variables (96 RRab (RR0) and 23 RRc (RR1)) in M33. Using the properties of 83 RRL stars (65 RRab and 18 RRc) in the innermost ACS field (hereafter DISK2), we find mean periods of <P_ab_>=0.553+/-0.008(error1)+/-0.05(error2) and <P_c_>=0.325+/-0.008(error1)+/-0.05(error2), where the "error1" value represents the standard error of the mean and the "error2" value is based on the error of an individual RRL period calculated from our synthetic light curve simulations. The VI minimum-light colors of the RRab stars are used to calculate a mean line-of-sight reddening toward the DISK2 field of <E(V-I)>=0.175.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1500
- Title:
- RR Lyrae variables in the central region of M54
- Short Name:
- J/AJ/140/1500
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analyzed archival Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations of the central region of the globular cluster M54. The 12 irregularly timed observations (6 F555W, 6 F814W) were reduced using the HSTphot stellar photometry package. Our statistical analysis of the HSTphot photometry yielded 50 variable stars that are likely RR Lyrae candidates. These candidates were missed by previous ground-based searches for RR Lyraes due to the extreme crowding in the core of M54. We performed two checks on our sample of RR Lyrae candidates to determine how different they were from the other variable candidates.
- ID:
- ivo://CDS.VizieR/J/A+A/539/A138
- Title:
- RR Lyr variable stars in M32
- Short Name:
- J/A+A/539/A138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using archival multi-epoch ACS/WFC images in the F606W and F814W filters of a resolved stellar field in Local Group dwarf elliptical galaxy M 32 we have made an accurate Colour-Magnitude Diagram and a careful search for RR Lyr variable stars. We identified 416 bona fide RR Lyr stars over our field of view, and their spatial distribution shows a rising number density towards the centre of M 32. These new observations clearly confirm the tentative result of Fiorentino et al. (2010ApJ...708..817F), on a much smaller field of view, associating an ancient population of RR Lyr variables to M 32. We associate at least 83 RR Lyr stars in our field to M 32.
