- ID:
- ivo://CDS.VizieR/J/ApJ/875/51
- Title:
- Mass accretion rates of PMS stars. VI. LH95 in LMC
- Short Name:
- J/ApJ/875/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the accretion properties of low-mass stars in the LH 95 association within the Large Magellanic Cloud. Using noncontemporaneous wideband optical and narrowband H{alpha} photometry obtained with the Hubble Space Telescope, we identify 245 low-mass pre-main-sequence (PMS) candidates showing H{alpha} excess emission above the 4{sigma} level. We derive their physical parameters, including effective temperatures, luminosities, masses (M_*_), ages, accretion luminosities, and mass accretion rates (dM/dt_acc_). We identify two different stellar populations: younger than ~8Myr with median dM/dt_acc_~5.4x10^-8^M_{sun}_/yr (and M_*_~0.15-1.8M_{sun}_) and older than ~8Myr with median dM/dt_acc_~4.8x10^-9^M_{sun}_/yr (and M_*_~0.6-1.2M_{sun}_). We find that the younger PMS candidates are assembled in groups around Be stars, while older PMS candidates are uniformly distributed within the region without evidence of clustering. We find that dM/dt_acc_ in LH 95 decreases with time more slowly than what is observed in Galactic star-forming regions (SFRs). This agrees with the recent interpretation, according to which higher metallicity limits the accretion process in both rate and duration due to higher radiation pressure. The dM/dt_acc_-M_*_ relationship shows different behavior at different ages, becoming progressively steeper at older ages, indicating that the effects of mass and age on dM/dt_acc_ cannot be treated independently. With the aim to identify reliable correlations between mass, age, and dM/dt_acc_, we used a multivariate linear regression fit between these parameters for our PMS candidates. The comparison between our results and those obtained in other SFRs of our Galaxy and the Magellanic Clouds confirms the importance of the metallicity for the study of the dM/dt_acc_ evolution in clusters with different environmental conditions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/881/54
- Title:
- Masses of SNR progenitors in M83
- Short Name:
- J/ApJ/881/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine the ages of the young, resolved stellar populations at the locations of 237 optically identified supernova remnants in M83. These age distributions put constraints on the progenitor masses of the supernovae that produced 199 of the remnants. The other 38 show no evidence for having a young progenitor and are therefore good Type Ia SNR candidates. Starting from Hubble Space Telescope broadband imaging, we measured resolved stellar photometry of seven archival WFC3/UVIS fields in F336W, F438W, and F814W. We generate color-magnitude diagrams of the stars within 50pc of each SNR and fit them with stellar evolution models to obtain the population ages. From these ages we infer the progenitor mass that corresponds to the lifetime of the most prominent age within the past 50Myr. In this sample, there are 47 SNRs with best-fit progenitor masses >15M_{sun}_, and 5 of these are >15M_{sun}_ at 84% confidence. This is the largest collection of high-mass progenitors to date, including our highest-mass progenitor inference found so far, with a constraint of <8Myr. Overall, the distribution of progenitor masses has a power-law index of -3.0_-0.7_^+0.2^, steeper than Salpeter initial mass function (-2.35). It remains unclear whether the reason for the low number of high-mass progenitors is due to the difficulty of finding and measuring such objects or because only a fraction of very massive stars produce supernovae.
- ID:
- ivo://CDS.VizieR/J/MNRAS/404/325
- Title:
- Massive galaxy clusters lensing analyse
- Short Name:
- J/MNRAS/404/325
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a statistical analysis of a sample of 20 strong lensing clusters drawn from the Local Cluster Substructure Survey, based on high-resolution Hubble Space Telescope imaging of the cluster cores and follow-up spectroscopic observations using the Keck-I telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A83
- Title:
- 12 massive lensing clusters MUSE observations
- Short Name:
- J/A+A/646/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic surveys of massive galaxy clusters reveal the properties of faint background galaxies thanks to the magnification provided by strong gravitational lensing. We present a systematic analysis of integral-field- spectroscopy observations of 12 massive clusters, conducted with the Multi Unit Spectroscopic Explorer (MUSE). All data were taken under very good seeing conditions (~0.6") in effective exposure times between two and 15 hrs per pointing, for a total of 125 hrs. Our observations cover a total solid angle of ~23-arcmin^2^ in the direction of clusters, many of which were previously studied by the MAssive Clusters Survey (MACS), Frontier Fields (FFs), Grism Lens-Amplified Survey from Space (GLASS) and Cluster Lensing And Supernova survey with Hubble (CLASH) programmes. The achieved emission line detection limit at 5sigma for a point source varies between (0.77-1.5)x10^-18^erg/s/cm^2^ at 7000{AA}. We present our developed strategy to reduce these observational data, detect continuum sources and line emitters in the datacubes, and determine their redshifts. We constructed robust mass models for each cluster to further confirm our redshift measurements using strong-lensing constraints, and identified a total of 312 strongly lensed sources producing 939 multiple images. The final redshift catalogues contain more than 3300 robust redshifts, of which 40% are for cluster members and ~30% are for lensed Lyman-alpha emitters. Fourteen percent of all sources are line emitters that are not seen in the available HST images, even at the depth of the FFs (~29 AB). We find that the magnification distribution of the lensed sources in the high- magnification regime (mu=2-25) follows the theoretical expectation of N(z){prop.to}mu^-2^. The quality of this dataset, number of lensed sources, and number of strong-lensing constraints enables detailed studies of the physical properties of both the lensing cluster and the background galaxies. The full data products from this work, including the datacubes, catalogues, extracted spectra, ancillary images, and mass models, are made available to the community.
- ID:
- ivo://CDS.VizieR/J/AJ/146/114
- Title:
- Massive stars in M101. I. HST BVI photometry
- Short Name:
- J/AJ/146/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An increasing number of non-terminal giant eruptions are being observed by modern supernova and transient surveys. But very little is known about the origin of these giant eruptions and their progenitors, many of which are presumably very massive, evolved stars. Motivated by the small number of progenitors positively associated with these giant eruptions, we have begun a survey of the evolved massive star populations in nearby galaxies. The nearby, nearly face-on, giant spiral M101 is an excellent laboratory for studying a large population of very massive stars. In this paper, we present BVI photometry obtained from archival HST/ACS Wide Field Camera images of M101. We have produced a catalog of luminous stars with photometric errors <10% for V<24.5 and 50% completeness down to V~26.5 even in regions of high stellar crowding. Using color and luminosity criteria, we have identified candidate luminous OB-type stars and blue supergiants, yellow supergiants, and red supergiants for future observation. We examine their spatial distributions across the face of M101 and find that the ratio of blue to red supergiants decreases by two orders of magnitude over the radial extent of M101 corresponding to 0.5 dex in metallicity. We discuss the resolved stellar content in the giant star-forming complexes NGC 5458, 5453, 5461, 5451, 5462, and 5449 and discuss their color-magnitude diagrams in conjunction with the spatial distribution of the stars to determine their spatio-temporal formation histories.
- ID:
- ivo://CDS.VizieR/J/ApJ/799/144
- Title:
- M31 Cepheids in near-IR
- Short Name:
- J/ApJ/799/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the largest M31 near-infrared (F110W (close to J band), F160W (H band)) Cepheid sample so far. The sample consists of 371 Cepheids with photometry obtained from the HST PHAT program. The sample of 319 fundamental mode Cepheids, 16 first overtone Cepheids and 36 type II Cepheids, was identified using the median absolute deviation (MAD) outlier rejection method we develop here. This method does not rely on priors and allows us to obtain this clean Cepheid sample without rejecting a large fraction of Cepheids. The obtained Period-Luminosity relations (PLRs) have a very small dispersion, i.e. 0.155mag in F160W, despite using random phased observations. This remarkably small dispersion allows us to determine that the PLRs are significantly better described by a broken slope at ten days than a linear slope. The use of our sample as an anchor to determine the Hubble constant gives a 3.2% larger Hubble constant compared to the Riess et al. (2012ApJ...745..156R, Cat. J/ApJ/745/156) sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/745/156
- Title:
- M31 Cepheids with HST/WFC3
- Short Name:
- J/ApJ/745/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of 68 classical Cepheids, most detected from the Canada-France-Hawaii Telescope POMME Survey, with periods from 10 to 78 days observed in the near-infrared by the Panchromatic Hubble Andromeda Treasury Program using the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). The combination of HST's resolution and the use of near-infrared measurements provide a dramatic reduction in the dispersion of the period-luminosity relation over the present optical, ground-based data. Even using random phase magnitudes we measure a dispersion of just 0.17mag, implying a dispersion of just 0.12mag for mean magnitudes. The error in the mean for this relation is 1% in distance. Combined with similar observations of Cepheids in other hosts and independent distance determinations, we measure a distance to M31 of {mu}_0_=24.38+/-0.06(statistical)+/-0.03(systematic), 752+/-27kpc, in good agreement with past measurements though with a better, 3% precision here. The result is also in good agreement with independent distance determinations from two detached eclipsing binaries allowing for an independent calibration of the Cepheid luminosities and a determination of the Hubble constant.
- ID:
- ivo://CDS.VizieR/J/ApJ/788/L21
- Title:
- Measured photometry of SN 2014J from HST
- Short Name:
- J/ApJ/788/L21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The wavelength dependence of the extinction of Type Ia SN 2014J in the nearby galaxy M82 has been measured using UV to near-IR photometry obtained with the Hubble Space Telescope, the Nordic Optical Telescope, and the Mount Abu Infrared Telescope. This is the first time that the reddening of an SN Ia is characterized over the full wavelength range of 0.2-2 {mu}m. A total-to-selective extinction, R_V_>= 3.1, is ruled out with high significance. The best fit at maximum using a Galactic type extinction law yields R_V_=1.4+/-0.1. The observed reddening of SN 2014J is also compatible with a power-law extinction, A_{lambda}_/A_V_=({lambda}/{lambda}_V_)^p^ as expected from multiple scattering of light, with p=-2.1+/-0.1. After correcting for differences in reddening, SN 2014J appears to be very similar to SN 2011fe over the 14 broadband filter light curves used in our study.
- ID:
- ivo://CDS.VizieR/J/AJ/148/137
- Title:
- Merging galaxies in COSMOS to z~1
- Short Name:
- J/AJ/148/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The role of major mergers in galaxy and black hole formation is not well-constrained. To help address this, we develop an automated method to identify late-stage galaxy mergers before coalescence of the galactic cores. The resulting sample of mergers is distinct from those obtained using pair-finding and morphological indicators. Our method relies on median-filtering of high-resolution images to distinguish two concentrated galaxy nuclei at small separations. This method does not rely on low surface brightness features to identify mergers, and is therefore reliable to high redshift. Using mock images, we derive statistical contamination and incompleteness corrections for the fraction of late-stage mergers. The mock images show that our method returns an uncontaminated (<10%) sample of mergers with projected separations between 2.2 and 8kpc out to z~1. We apply our new method to a magnitude-limited (m_FW814_<23) sample of 44164 galaxies from the COSMOS HST/ACS catalog. Using a mass-complete sample with log M_{star}_/M_{sun}_>10.6 and 0.25<z<=1.00, we find ~5% of systems are late-stage mergers. Correcting for incompleteness and contamination, the fractional merger rate increases strongly with redshift as {\bf R}_merge_\propto(1+z)^3.8+/-0.9^, in agreement both with earlier studies and with dark matter halo merger rates. Separating the sample into star-forming and quiescent galaxies shows that the merger rate for star-forming galaxies increases strongly with redshift, (1+z)^4.5+/-1.3^, while the merger rate for quiescent galaxies is consistent with no evolution, (1+z)^1.1+/-1.2^. The merger rate also becomes steeper with decreasing stellar mass. Limiting our sample to galaxies with spectroscopic redshifts from zCOSMOS, we find that the star formation rates and X-ray selected active galactic nucleus (AGN) activity in likely late-stage mergers are higher by factors of ~2 relative to those of a control sample. Combining our sample with more widely separated pairs, we find that 8+/-5% of star formation and 20+/-8% of AGN activity are triggered by close encounters (<143kpc) or mergers, providing additional evidence that major mergers are not the only channels for star formation and black hole growth.
- ID:
- ivo://CDS.VizieR/J/ApJ/832/90
- Title:
- Merging galaxies with tidal tails in COSMOS to z=1
- Short Name:
- J/ApJ/832/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tidal tails are created in major mergers involving disk galaxies. It remains to be explored how the tidal tails trace the assembly history of massive galaxies. We identify a sample of 461 merging galaxies with long tidal tails, from 35076 galaxies mass-complete at M*>=10^9.5^M_{sun}_ and 0.2<=z<=1, based on Hubble Space Telescope/ACS F814W imaging data and public catalogs of the COSMOS field. The long tails refer to those with length equal to or greater than the diameter of their host galaxies. The mergers with tidal tails are selected using our novel A_O_-D_O_ technique for strong asymmetric features, along with visual examination. Our results show that the fraction of tidal-tailed mergers evolves mildly with redshift, as ~(1+z)^2.0+/-0.4^, and becomes relatively higher in less-massive galaxies, out to z=1. With a timescale of 0.5Gyr for the tidal-tailed mergers, we obtain that the occurrence rate of such mergers follows 0.01+/-0.007(1+z)^2.3+/-1.4^Gyr^-1^, and corresponds to ~0.3 events since z=1, as well as roughly one-third of the total budget of major mergers from the literature. For disk-involved major mergers, nearly half of them have undergone a phase with long tidal tails.
