- ID:
- ivo://CDS.VizieR/J/A+A/638/A111
- Title:
- HST/ACS photometry of KKH22 and KKH34
- Short Name:
- J/A+A/638/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations with the Advanced Camera for Surveys on the Hubble Space Telescope of the nearby dwarf spheroidal galaxy KKH 22 = LEDA 2807114 in the vicinity of massive spiral galaxy IC 342. We derived its distance of 3.12+/-0.19Mpc using the Tip of Red Giant Branch method. We also use the 6-m BTA spectroscopy to measure a heliocentric radial velocity of globular cluster in KKH 22 to be +30+/-10km/s. The dSph galaxy KKH 22 has the V-band absolute magnitude of -12.19mag and the central surface brightness {mu}_v,0_=24.1mag/arcsec^2^. Both the velocity and the distance of KKH 22 are consistent with the dSph galaxy being gravitationally bound to IC 342. Another nearby dIr galaxy, KKH 34, with a low heliocentric velocity of +106km/s has the TRGB distance of 7.28+/-0.36Mpc residing in the background respect to the IC 342 group. KKH 34 has surprisinly high negative peculiar velocity of -236+/-26km/s.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/507/1375
- Title:
- HST/ACS VI data of M31 globular clusters
- Short Name:
- J/A+A/507/1375
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the aim of increasing the sample of M31 clusters for which a colour-magnitude diagram is available, we searched the HST archive for ACS images containing objects included in the Revised Bologna Catalogue of M31 globular clusters (RBC Version 3.5 available at: http://www.bo.astro.it/M31). Sixty-three such objects were found. We used the ACS images to confirm or revise their classification and were able to obtain useful CMDs for 11 old globular clusters and 6 luminous young clusters. We obtained simultaneous estimates of the distance, reddening, and metallicity of old clusters by comparing their observed field-decontaminated CMDs with a grid of template clusters of the Milky Way. We estimated the age of the young clusters by fitting with theoretical isochrones.
- ID:
- ivo://CDS.VizieR/J/ApJ/865/33
- Title:
- HST and Chandra obs. of the GLIMPSE-C01 star cluster
- Short Name:
- J/ApJ/865/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of Hubble Space Telescope and Chandra X-Ray Observatory observations of the GLIMPSE-C01 (hereafter GC01) star cluster. Color-magnitude and color-color diagrams suggest a cluster age of >~2Gyr up to ~10Gyr (dependent on GC01's metallicity), a distance of 3.3-3.5kpc, and strong differential reddening with A_V_=14-22. After performing astrometric corrections, we find that nine of the 15 X-ray sources have at least one near-infrared (NIR) counterpart within the 2{sigma} Chandra positional error circles. However, given the very high density of NIR sources in the cluster, most of these counterparts are likely due to chance coincidence. We jointly analyze the X-ray and NIR properties to assess the likelihood of true associations. Based primarily on their X-ray properties, we identify a low-mass X-ray binary candidate (source X2), a cataclysmic variable (CV) candidate (source X1), and an active binary (AB) candidate (source X9). Source X11 is detected during an X-ray flaring episode with a flare luminosity (L_X_=2.1x10^33^erg/s) and has a quiescent luminosity L_X_<8.0x10^30^erg/s, in 0.5-8keV at the distance of GC01, suggesting that the source is either an AB or CV. We also discuss the limits on an intermediate-mass black hole at the center of GC01 and the challenges of X-ray source classification imposed by the limitations of the existing data and instrumentation along with future prospects in the James Webb Space Telescope era.
- ID:
- ivo://CDS.VizieR/J/ApJ/738/186
- Title:
- HST and DEIMOS measurements of NGC 2419 stars
- Short Name:
- J/ApJ/738/186
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of a kinematic data set of stars in the globular cluster NGC 2419, taken with the DEep Imaging Multi-Object Spectrograph at the Keck II telescope. Combined with a reanalysis of deep Hubble Space Telescope and Subaru Telescope imaging data, which provide an accurate luminosity profile of the cluster, we investigate the validity of a large set of dynamical models of the system, which are checked for stability via N-body simulations.
- ID:
- ivo://CDS.VizieR/J/AJ/152/195
- Title:
- HST and Magellan observations of Haumea system
- Short Name:
- J/AJ/152/195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hi'iaka is the larger outer satellite of the dwarf planet Haumea. Using relative photometry from the Hubble Space Telescope and Magellan and a phase dispersion minimization analysis, we have identified the rotation period of Hi'iaka to be ~9.8hr (double peaked). This is ~120 times faster than its orbital period, creating new questions about the formation of this system and possible tidal evolution. The rapid rotation suggests that Hi'iaka could have a significant obliquity and spin precession that could be visible in light curves within a few years. We then turn to an investigation of what we learn about the (currently unclear) formation of the Haumea system and family based on this unexpectedly rapid rotation rate. We explore the importance of the initial semimajor axis and rotation period in tidal evolution theory and find that they strongly influence the time required to despin to synchronous rotation, relevant to understanding a wide variety of satellite and binary systems. We find that despinning tides do not necessarily lead to synchronous spin periods for Hi'iaka, even if it formed near the Roche limit. Therefore, the short rotation period of Hi'iaka does not rule out significant tidal evolution. Hi'iaka's spin period is also consistent with formation near its current location and spin-up due to Haumea-centric impactors.
- ID:
- ivo://CDS.VizieR/J/AJ/132/378
- Title:
- HST and UV photometry of NGC 6822
- Short Name:
- J/AJ/132/378
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope WFPC2 and STIS imaging of the low-metallicity galaxy NGC 6822, performed as part of a study of the young stellar populations in the galaxies of the Local Group. Eleven WFPC2 pointings, with some overlap, cover two regions extending over 19 and 13arcmin^2^, respectively, off the galaxy center. The filters used are F170W, F255W, F336W, F439W, and F555W. One 25x25 field observed with the STIS FUV- and NUV-MAMA includes Hodge's OB 8 association and the HII region Hubble V, contained in field 1 of Bianchi et al. (2001, Cat. <J/AJ/121/2020>); this previous study provides additional WFPC2 four-band photometry. We derive the physical parameters of the stars in the fields and the extinction by comparing the photometry to grids of model magnitudes.
- ID:
- ivo://CDS.VizieR/J/AJ/125/3302
- Title:
- HST binary very low mass stars and brown dwarfs
- Short Name:
- J/AJ/125/3302
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present analysis of Hubble Space Telescope (HST) images of 82 nearby field late M and L dwarfs. We resolve 13 of these systems into double M/L dwarf systems and identify an additional possible binary.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/2937
- Title:
- HST BVI catalogue of star clusters in 5 HCGs
- Short Name:
- J/MNRAS/449/2937
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric catalogue of star cluster candidates in Hickson compact groups (HCGs) 7, 31, 42, 59, and 92, based on observations with the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope. The catalogue contains precise cluster positions (right ascension and declination), magnitudes, and colours in the BVI filters. The number of detected sources ranges from 2200 to 5600 per group, from which we construct the high-confidence sample by applying a number of criteria designed to reduce foreground and background contaminants. Furthermore, the high-confidence cluster candidates for each of the 16 galaxies in our sample are split into two subpopulations: one that may contain young star clusters and one that is dominated by globular older clusters. The ratio of young star cluster to globular cluster candidates varies from group to group, from equal numbers to the extreme of HCG 31 which has a ratio of 8 to 1, due to a recent starburst induced by interactions in the group. We find that the number of blue clusters with M_V_<-9 correlates well with the current star formation rate in an individual galaxy, while the number of globular cluster candidates with M_V_<-7.8 correlates well (though with large scatter) with the stellar mass. Analyses of the high-confidence sample presented in this paper show that star clusters can be successfully used to infer the gross star formation history of the host groups and therefore determine their placement in a proposed evolutionary sequence for compact galaxy groups.
- ID:
- ivo://CDS.VizieR/J/AJ/122/1330
- Title:
- HST BVI photometry of M 81 star clusters
- Short Name:
- J/AJ/122/1330
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present the discovery of 114 compact star clusters in the nearby spiral galaxy M81 from B-, V-, and I-band Hubble Space Telescope Wide Field Planetary Camera 2 imaging in eight fields, covering a total area of ~40arcmin^2^. The fields sample a variety of environments (both spiral and interarm regions), as well as a range of projected galactocentric distances from 2 to 12kpc. The sample is complete to V~22, deeper by ~1mag than any previous cluster survey in M81. We present details of the separation of clusters from both stellar sources and background galaxies, which has been based solely on structural parameters and morphology and not using any color cuts, as is necessary for ground-based surveys. We present magnitudes and colors of detected clusters. Surface brightness profiles are compared with single-mass King models, giving a range of core radii for the clusters in our sample between 0.2 and 7pc.
- ID:
- ivo://CDS.VizieR/J/ApJ/499/112
- Title:
- HST CFRS and LDSS redshift surveys. I.
- Short Name:
- J/ApJ/499/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze Hubble Space Telescope images of a complete sample of 341 galaxies drawn from the Canada-France Redhsift Survey (CFRS) and Low-Dispersion Survey Spectrograph (LDSS) ground-based redshift surveys. In this, the first paper in the series, each galaxy has been morphologically classified according to a scheme similar to that developed for the Medium Deep Survey. We discuss the reproducibility of these classifications and quantify possible biases that may arise from various redshift-dependent effects. We then discuss automated classifications of the sample and conclude, from several tests, that we can expect an apparent migration with redshift to later Hubble types that corresponds to a misclassification in our adopted machine classification system of ~24%+/-11 of the true "spirals" as "peculiars" at a redshift z~=0.9. After allowing for such biases, the redshift distribution for normal spirals, together with their luminosity function derived as a function of redshift, indicates approximately 1mag of luminosity evolution in B_AB_ by z~=1. The elliptical sample is too small for precise evolutionary constraints. However, we find a substantial increase in the proportion of galaxies with irregular morphology at large redshift from 9%+/-3% for 0.3<=z<=0.5 to 32%+/-12% for 0.7<=z<=0.9. These galaxies also appear to be the dominant cause of the rapid rise with redshift in the blue luminosity density identified in the redshift surveys. Although galaxies with irregular morphology may well comprise a mixture of different physical systems and might not correspond to present-day irregulars, it is clear that the apparently declining abundance and luminosities of our distant "irregulars" holds an important key to understanding recent evolution in the star formation history of normal galaxies.