- ID:
- ivo://CDS.VizieR/J/ApJ/712/1259
- Title:
- LCID project. II. Variables in IC1613
- Short Name:
- J/ApJ/712/1259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a new search for variable stars in the Local Group (LG) isolated dwarf galaxy IC 1613, based on 24 orbits of F475W and F814W photometry from the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope. We detected 259 candidate variables in this field, of which only 13 (all of them bright Cepheids) were previously known. Out of the confirmed variables, we found 90 RR Lyrae stars, 49 classical Cepheids (including 36 new discoveries), and 38 eclipsing binary stars for which we could determine a period. The RR Lyrae include 61 fundamental (RRab) and 24 first-overtone (FO, RRc) pulsators, and five pulsating in both modes simultaneously (RRd). As for the majority of LG dwarfs, the mean periods of the RRab and RRc (0.611 and 0.334 days, respectively) as well as the fraction of overtone pulsators (f_c_=0.28) place this galaxy in the intermediate regime between the Oosterhoff types. From their position on the period-luminosity diagram and light-curve morphology, we can unambiguously classify 25 and 14 Cepheids as fundamental and FO mode pulsators, respectively. Another two are clearly second-overtone Cepheids, the first ones to be discovered beyond the Magellanic Clouds. Among the remaining candidate variables, five were classified as {delta}-Scuti and five as long-period variables. Most of the others are located on the main sequence, the majority of them likely eclipsing binary systems, although some present variations similar to pulsating stars.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/432/3047
- Title:
- LCID project VIII. Cepheids of Leo A
- Short Name:
- J/MNRAS/432/3047
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a new search for variable stars in the Local Group dwarf galaxy Leo A, based on deep photometry from the Advanced Camera for Surveys onboard the Hubble Space Telescope. We detected 166 bona fide variables in our field, of which about 60% are new discoveries and 33 candidate variables. Of the confirmed variables, we found 156 Cepheids, but only 10 RR Lyrae stars despite nearly 100percent completeness at the magnitude of the horizontal branch. The RR Lyrae stars include seven fundamental and three first-overtone pulsators, with mean periods of 0.636 and 0.366d, respectively. From their position on the period-luminosity (PL) diagram and light-curve morphology, we classify 91, 58 and 4 Cepheids as fundamental, first-overtone and second-overtone mode Classical Cepheids (CC), respectively, and two as Population II Cepheids. However, due to the low metallicity of Leo A, about 90percent of the detected Cepheids have periods shorter than 1.5d. Comparison with theoretical models indicate that some of the fainter stars classified as CC could be Anomalous Cepheids. We estimate the distance to Leo A using the tip of the red giant branch (TRGB) and various methods based on the photometric and pulsational properties of the Cepheids and RR Lyrae stars. The distances obtained with the TRGB and RR Lyrae stars agree well with each other while that from the Cepheid PL relations is somewhat larger, which may indicate a mild metallicity effect on the luminosity of the short-period Cepheids. Due to its very low metallicity, Leo A thus serves as a valuable calibrator of the metallicity dependences of the variable star luminosities.
- ID:
- ivo://CDS.VizieR/J/ApJS/130/237
- Title:
- LCRS loose groups of galaxies
- Short Name:
- J/ApJS/130/237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A "friends-of-friends" percolation algorithm has been used to extract a catalog of {delta}n/n=80 density enhancements (groups) from the six slices of the Las Campanas Redshift Survey (LCRS). The full catalog contains 1495 groups and includes 35% of the LCRS galaxy sample. A clean sample of 394 groups has been derived by culling groups from the full sample that either are too close to a slice edge, have a crossing time greater than a Hubble time, have a corrected velocity dispersion of zero, or contain a 55"-'orphan' (a galaxy with a mock redshift that was excluded from the original LCRS redshift catalog due to its proximity to another galaxy, i.e., within 55").
- ID:
- ivo://CDS.VizieR/J/MNRAS/244/408
- Title:
- LDSS Deep Redshift Survey
- Short Name:
- J/MNRAS/244/408
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a multisplit spectrograph, LDSS, we have obtained intermediate dispersion spectroscopy for a new sample of 149 faint objects selected randomly from the magnitude range 21<=bJ<=22.5 in three high-latitude fields.
- ID:
- ivo://CDS.VizieR/J/AJ/138/332
- Title:
- LEDA CMD/tip of the red giant branch
- Short Name:
- J/AJ/138/332
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The color-magnitude diagrams/tip of the red giant branch (CMDs/TRGB) section of the Extragalactic Distance Database contains a compilation of observations of nearby galaxies from the Hubble Space Telescope. Approximately 250 (and increasing) galaxies in the Local Volume have CMDs and the stellar photometry tables used to produce them available through the Web. Various stellar populations that make up a galaxy are visible in the CMDs, but our primary purpose for collecting and analyzing these galaxy images is to measure the TRGB in each. We can estimate the distance to a galaxy by using stars at the TRGB as standard candles. In this paper, we describe the process of constructing the CMDs and make the results available to the public.
- ID:
- ivo://CDS.VizieR/VII/242
- Title:
- LEDA galaxies with DENIS measurements catalog
- Short Name:
- VII/242
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of near-infrared properties of LEDA galaxies, using the full resolution images from the DENIS survey. The fluxes are integrated in eight homothetic ellipses defined by their proper axis ratio, position angle and major axis (up to twice the blue diameter at the isophote 25mag/arcsec^2^) extracted from the LEDA database. From the curves of growth in I, J and K_ms_ photometric bands, we estimated different apparent magnitudes and diameters ("total", "Kron" and "isophotal"). Isophotal parameters refer to the limiting surface brightnesses : 22.5(Imag)/arcsec^2^, 21.0(Jmag)/arcsec^2^ and 20.0(K_ms_mag)/arcsec^2^ for the three photometric bands, respectively. The result is a catalog of 753 153 objects (among which there are 508 224 galaxies, 34 449 probable galaxies and 210 480 galaxies to be confirmed). The catalog gives about (the figures vary, depending on the considered magnitude or diameter) : 668 000 I-band magnitudes, 576 000 J-band magnitudes, 357 000 K_ms_-band magnitudes and 452 000 I-band diameters, 299 000 J-band diameters, 114 000 K_ms_-band diameters. The typical standard deviations for I, J and K_ms_ magnitudes are 0.14, 0.15 and 0.25, respectively, for magnitudes limited at I=16, J=15 and K_ms_=14. The contamination by superimposed objects probably remains the major source of problems and could require future improvement. The completeness limits in magnitude are about : 15.5, 14.5 and 13 in I, J and K_ms_, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJS/239/27
- Title:
- LEGA-C DR2: galaxies in the COSMOS field
- Short Name:
- J/ApJS/239/27
- Date:
- 01 Mar 2022
- Publisher:
- CDS
- Description:
- We present the second data release of the Large Early Galaxy Astrophysics Census (LEGA-C), an ESO 130-night public spectroscopic survey conducted with VIMOS on the Very Large Telescope. We release 1988 spectra with typical continuum S/N~20{AA}^-1^ of galaxies at 0.6<~z<~1.0, each observed for ~20hr and fully reduced with a custom-built pipeline. We also release a catalog with spectroscopic redshifts, emission-line fluxes, Lick/IDS indices, and observed stellar and gas velocity dispersions that are spatially integrated quantities, including both rotational motions and genuine dispersion. To illustrate the new parameter space in the intermediate-redshift regime probed by LEGA-C, we explore relationships between dynamical and stellar population properties. The star-forming galaxies typically have observed stellar velocity dispersions of ~150km/s and strong H{delta} absorption (H{delta}_A_~5{AA}), while passive galaxies have higher observed stellar velocity dispersions (~200km/s) and weak H{delta} absorption (H{delta}_A_~0{AA}). Strong [OIII]5007/H{beta} ratios tend to occur mostly for galaxies with weak H{delta}_A_ or galaxies with higher observed velocity dispersion. Beyond these broad trends, we find a diversity of possible combinations of rest-frame colors, absorption-line strengths, and emission-line detections, illustrating the utility of spectroscopic measurements to more accurately understand galaxy evolution.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/23
- Title:
- LEGUS galaxies1 observations
- Short Name:
- J/ApJS/235/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Legacy ExtraGalactic UV Survey (LEGUS) is a multiwavelength Cycle 21 Treasury program on the Hubble Space Telescope. It studied 50 nearby star-forming galaxies in 5 bands from the near-UV to the I-band, combining new Wide Field Camera 3 observations with archival Advanced Camera for Surveys data. LEGUS was designed to investigate how star formation occurs and develops on both small and large scales, and how it relates to the galactic environments. In this paper we present the photometric catalogs for all the apparently single stars identified in the 50 LEGUS galaxies. We present optical and near-UV color-magnitude diagrams for all the galaxies. For each galaxy we derived the distance from the tip of the red giant branch. We then used the NUV color-magnitude diagrams to identify stars more massive than 14M_{sun}_, and compared their number with the number of massive stars expected from the GALEX FUV luminosity. Our analysis shows that the fraction of massive stars forming in star clusters and stellar associations is about constant with the star formation rate. This lack of a relation suggests that the timescale for evaporation of unbound structures is comparable or longer than 10Myr. At low star formation rates this translates to an excess of mass in clustered environments as compared to model predictions of cluster evolution, suggesting that a significant fraction of stars form in unbound systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/154
- Title:
- LEGUS & Ha-LEGUS obs. of NGC4449 star clusters
- Short Name:
- J/ApJ/889/154
- Date:
- 17 Jan 2022 11:55:48
- Publisher:
- CDS
- Description:
- We present a new catalog and results for the cluster system of the starburst galaxy NGC 4449, based on multiband imaging observations taken as part of the LEGUS and H_{alpha}_-LEGUS surveys. We improve the spectral energy fitting method used to estimate cluster ages, and find that the results, particularly for older clusters, are in better agreement with those from spectroscopy. The inclusion of H{alpha} measurements, the role of stochasticity for low-mass clusters, the assumptions about reddening, and the choices of SSP model and metallicity all have important impacts on the age dating of clusters. A comparison with ages derived from stellar color-magnitude diagrams for partially resolved clusters shows reasonable agreement, but large scatter in some cases. The fraction of light found in clusters relative to the total light (i.e., T_L_) in the U, B, and V filters in 25 different ~kiloparsec-size regions throughout NGC 4449 correlates with both the specific region luminosity, R_L_, and the dominant age of the underlying stellar population in each region. The observed cluster age distribution is found to decline over time as dN/d{tau}{propto}{tau}^{gamma}^, with {gamma}=-0.85+/-0.15, independent of cluster mass, and is consistent with strong, early cluster disruption. The mass functions of the clusters can be described by a power law with dN/dM{propto}M^{beta}^ and {beta}=-1.86+/-0.2, independent of cluster age. The mass and age distributions are quite resilient to differences in age-dating methods. There is tentative evidence for a factor of 2-3 enhancement in both the star and cluster formation rate ~100-300Myr ago, indicating that cluster formation tracks star formation generally. The enhancement is probably associated with an earlier interaction event.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/76
- Title:
- Lensed z~6-8 galaxies behind CLASH clusters
- Short Name:
- J/ApJ/792/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We utilize 16 band Hubble Space Telescope (HST) observations of 18 lensing clusters obtained as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) Multi-Cycle Treasury program to search for z ~ 6-8 galaxies. We report the discovery of 204, 45, and 13 Lyman-break galaxy candidates at z ~ 6, z ~ 7, and z ~ 8, respectively, identified from purely photometric redshift selections. This large sample, representing nearly an order of magnitude increase in the number of magnified star-forming galaxies at z ~ 6-8 presented to date, is unique in that we have observations in four WFC3/UVIS UV, seven ACS/WFC optical, and all five WFC3/IR broadband filters, which enable very accurate photometric redshift selections. We construct detailed lensing models for 17 of the 18 clusters to estimate object magnifications and to identify two new multiply lensed z >~ 6 candidates. The median magnifications over the 17 clusters are 4, 4, and 5 for the z ~ 6, z ~ 7, and z ~ 8 samples, respectively, over an average area of 4.5 arcmin^2^ per cluster. We compare our observed number counts with expectations based on convolving "blank" field UV luminosity functions through our cluster lens models and find rough agreement down to ~27 mag, where we begin to suffer significant incompleteness. In all three redshift bins, we find a higher number density at brighter observed magnitudes than the field predictions, empirically demonstrating for the first time the enhanced efficiency of lensing clusters over field surveys. Our number counts also are in general agreement with the lensed expectations from the cluster models, especially at z ~ 6, where we have the best statistics.
