- ID:
- ivo://CDS.VizieR/J/A+AS/116/75
- Title:
- Region of the open cluster Tr 14
- Short Name:
- J/A+AS/116/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBVRI CCD imaging photometry down to approximately V=19mag in the area of the very young open cluster Tr 14. Our results confirm the existence of an anomalous extinction law in the area if it is interpreted in terms of the UBVRI photometry. According to our analysis the cluster distance is d=3100 (V_0_-M_V_=12.50mag) and its age is 1.5+/-.5x10^6^y. We want to draw the attention on stars which, from the observed magnitude-spread at constant color, could be stars in an early stage of evolution. In that case, the observed spread leads to assume that the process of star formation in Tr 14 is continuous whereas, from pre-main sequence evolutionary tracks, a duration of about 5x10^6^y is deduced for it. The computation of the cluster initial mass function reveals a flat slop e even though it still compares to a Salpeter law. At the same time, we found a spatial variation of the cluster IMF, which could be explained by mass segregation in the star formation process. The cluster youth and its compact appearance seem to confirm that it is far from virial equilibrium. The observed tot al cluster mass is around 2000M_{sun}_ and its core contains about 40% of the total.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/742/89
- Title:
- Relations between spectra and colors of SNe Ia
- Short Name:
- J/ApJ/742/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To understand how best to use observations of Type Ia supernovae (SNe Ia) to obtain precise and accurate distances, we investigate the relations between spectra of SNe Ia and their intrinsic colors. Using a sample of 1630 optical spectra of 255 SNe, based primarily on data from the CfA Supernova Program, we examine how the velocity evolution and line strengths of SiII(6355) and CaII H&K are related to the B-V color at peak brightness. We find that the maximum-light velocity of SiII6355 and CaII H&K and the maximum-light pseudo-equivalent width of SiII6355 are correlated with intrinsic color, with intrinsic color having a linear relation with the SiII6355 measurements. CaII H&K does not have a linear relation with intrinsic color, but lower-velocity SNe tend to be intrinsically bluer. Combining the spectroscopic measurements does not improve intrinsic color inference. The intrinsic color scatter is larger for higher-velocity SNe Ia - even after removing a linear trend with velocity - indicating that lower-velocity SNe Ia are more "standard crayons". Employing information derived from SN Ia spectra has the potential to improve the measurements of extragalactic distances and the cosmological properties inferred from them.
- ID:
- ivo://CDS.VizieR/J/ApJ/848/56
- Title:
- Relationships between SNe Ia and the host galaxies
- Short Name:
- J/ApJ/848/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a sample of 1338 spectroscopically confirmed and photometrically classified Type Ia supernovae (SNe Ia) sourced from Carnegie Supernova Project, Center for Astrophysics Supernova Survey, Sloan Digital Sky Survey-II, and SuperNova Legacy Survey SN samples to examine the relationships between SNe Ia and the galaxies that host them. Our results provide confirmation with improved statistical significance that SNe Ia, after standardization, are on average more luminous in massive hosts (significance >5{sigma}), and decline more rapidly in massive hosts (significance >9{sigma}) and in hosts with low specific star formation rates (significance >8{sigma}). We study the variation of these relationships with redshift and detect no evolution. We split SNe Ia into pairs of subsets that are based on the properties of the hosts and fit cosmological models to each subset. Including both systematic and statistical uncertainties, we do not find any significant shift in the best-fit cosmological parameters between the subsets. Among different SN Ia subsets, we find that SNe Ia in hosts with high specific star formation rates have the least intrinsic scatter ({sigma}_int_=0.08+/-0.01) in luminosity after standardization.
- 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/ApJ/887/196
- Title:
- REQUIEM survey. I. Ly{alpha} halos around QSOs
- Short Name:
- J/ApJ/887/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of quasars a few hundred megayears after the Big Bang represents a major challenge to our understanding of black holes as well as galaxy formation and evolution. Quasars' luminosity is produced by extreme gas accretion onto black holes, which have already reached masses of M_BH_>10^9^M_{sun}_ by z~6. Simultaneously, their host galaxies form hundreds of stars per year, using up gas in the process. To understand which environments are able to sustain the rapid formation of these extreme sources, we started a Very Large Telescope/Multi-Unit Spectroscopic Explorer (MUSE) effort aimed at characterizing the surroundings of a sample of 5.7<z<6.6 quasars, which we have dubbed the Reionization Epoch QUasar InvEstigation with MUSE (REQUIEM) survey. We here present results of our searches for extended Ly{alpha} halos around the first 31 targets observed as part of this program. Reaching 5{sigma} surface brightness limits of 0.1-1.1x10^-17^erg/s/cm^2^/arcsec^2^ over a 1arcsec^2^ aperture, we were able to unveil the presence of 12 Ly{alpha} nebulae, eight of which are newly discovered. The detected nebulae show a variety of emission properties and morphologies with luminosities ranging from 8x10^42^ to 2x10^44^erg/s, FWHMs between 300 and 1700km/s, sizes <30pkpc, and redshifts consistent with those of the quasar host galaxies. As the first statistical and homogeneous investigation of the circumgalactic medium of massive galaxies at the end of the reionization epoch, the REQUIEM survey enables the study of the evolution of the cool gas surrounding quasars in the first 3Gyr of the universe. A comparison with the extended Ly{alpha} emission observed around bright (M_1450_<~-25mag) quasars at intermediate redshift indicates little variations on the properties of the cool gas from z~6 to z~3, followed by a decline in the average surface brightness down to z~2.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/166
- Title:
- RESOLVE survey photometry catalog
- Short Name:
- J/ApJ/810/166
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present custom-processed ultraviolet, optical, and near-infrared photometry for the REsolved Spectroscopy of a Local VolumE (RESOLVE) survey, a volume-limited census of stellar, gas, and dynamical mass within two subvolumes of the nearby universe (RESOLVE-A and RESOLVE-B). RESOLVE is complete down to baryonic mass ~10^9.1-9.3^M_{sun}_, probing the upper end of the dwarf galaxy regime. In contrast to standard pipeline photometry (e.g., SDSS), our photometry uses optimal background subtraction, avoids suppressing color gradients, and employs multiple flux extrapolation routines to estimate systematic errors. With these improvements, we measure brighter magnitudes, larger radii, bluer colors, and a real increase in scatter around the red sequence. Combining stellar mass estimates based on our optimized photometry with the nearly complete HI mass census for RESOLVE-A, we create new z=0 volume-limited calibrations of the photometric gas fractions (PGF) technique, which predicts gas-to-stellar mass ratios (G/S) from galaxy colors and optional additional parameters. We analyze G/S-color residuals versus potential third parameters, finding that axial ratio is the best independent and physically meaningful third parameter. We define a "modified color" from planar fits to G/S as a function of both color and axial ratio. In the complete galaxy population, upper limits on G/S bias linear and planar fits. We therefore model the entire PGF probability density field, enabling iterative statistical modeling of upper limits and prediction of full G/S probability distributions for individual galaxies. These distributions have two-component structure in the red color regime. Finally, we use the RESOLVE-B 21cm census to test several PGF calibrations, finding that most systematically under- or overestimate gas masses, but the full probability density method performs well.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/42
- Title:
- Reverberation mapping & opt. spectra data of AGNs
- Short Name:
- J/ApJ/886/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The radius-luminosity (R_H{beta}_-L_5100_) relationship of active galactic nuclei (AGNs) established by the reverberation mapping (RM) observations has been widely used as a single-epoch black hole mass estimator in the research of large AGN samples. However, the recent RM campaigns discovered that the AGNs with high-accretion rates show shorter time lags by factors of a few comparing with the predictions from the R_H{beta}_-L_5100_ relationship. The explanation of the shortened time lags has not been finalized yet. We collect eight different single-epoch spectral properties to investigate how the shortening of the time lags correlates with those properties and to determine the origin of the shortened lags. We find that the flux ratio between FeII and H{beta} emission lines shows the most prominent correlation, thus confirming that accretion rate is the main driver for the shortened lags. In addition, we establish a new scaling relation including the relative strength of FeII emission. This new scaling relation can provide less biased estimates of the black hole mass and accretion rate from the single-epoch spectra of AGNs.
- ID:
- ivo://CDS.VizieR/V/143
- Title:
- Revised Bologna Catalog of M31 clusters, V.5
- Short Name:
- V/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The dataset lists all the confirmed globular clusters (GC), all the known candidates GCs, and also all the objects that were identified as candidate GCs in the past and were subsequently recognised not to be genuine clusters, each entry being properly classified (GC, candidate GC, foreground star, background galaxy, HII region, etc.). The latter entries are maintained in the catalogue to avoid re-discoveries of objects that may look like M31 GCs and have been already classified as non-GCs. Please take into account the classification flag(s) when you use the RBC.
- ID:
- ivo://CDS.VizieR/J/A+A/416/917
- Title:
- Revised Bologna Catalog of M31 globular clusters
- Short Name:
- J/A+A/416/917
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified in the 2MASS database 693 known and candidate globular clusters in M31. The 2MASS J,H,K magnitudes of these objects have been transformed to the same homogeneous photometric system of existing near infrared photometry of M31 globulars, finally yielding J,H,K integrated photometry for 279 confirmed M31 clusters, 406 unconfirmed candidates and 8 objects with controversial classification. Of these objects 529 lacked any previous estimate of their near infrared magnitudes. The newly assembled near infrared dataset has been implemented into a revised version of the Bologna Catalogue of M31 globulars, with updated optical (UBVRI) photometry taken, when possible, from the most recent sources of CCD photometry available in the literature and transformed to a common photometric system. The final Revised Bologna Catalogue (table 2) most comprehensive list presently available of confirmed and candidate M31 globular clusters, with a total of 1164 entries. In particular, it includes 337 confirmed GCs, 688 GC candidates, 10 objects with controversial classification, 70 confirmed galaxies, 55 confirmed stars, and 4 HII regions. Using the newly assembled database we show that the V-K color provides a powerful tool to discriminate between M31 clusters and background galaxies, and we identify a sample of 83 globular cluster candidates, which is not likely to be contaminated by misclassified galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/403/993
- Title:
- Revised HIP periods for long-period variables
- Short Name:
- J/A+A/403/993
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the K-band luminosities of a sample of galactic long-period variables using parallaxes measured by the Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from measurements by COBE, and are corrected for interstellar and circumstellar extinction. The sample contains stars of several spectral types: M, S and C, and of several variability classes: Mira, semiregular SRa, and SRb. We find that the distribution of stars in the period-luminosity plane is independent of circumstellar chemistry, but that the different variability types have different P-L distributions. Both the Mira variables and the SRb variables have reasonably well-defined period-luminosity relationships, but with very different slopes. The SRa variables are distributed between the two classes, suggesting that they are a mixture of Miras and SRb, rather than a separate class of stars. New period-luminosity relationships are derived based on our revised Hipparcos parallaxes. The Miras show a similar period-luminosity relationship to that found for Large Magellanic Cloud Miras by Feast et al. (1989MNRAS.241..375F).
