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2431. H{alpha} surface photometry in nearby clusters
ID:
ivo://CDS.VizieR/J/A+A/446/839
Title:
H{alpha} surface photometry in nearby clusters
Short Name:
J/A+A/446/839
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the H{alpha} imaging observations of 273 late-type galaxies in the nearby rich galaxy clusters Virgo, A 1367, Coma, Cancer, Hercules and in the Great Wall, carried out primarily with the 2.1m telescope of the San Pedro Martir Observatory (SPM) and with the ESO/3.6m telescope. We derived the H{alpha}+[NII] fluxes and equivalent widths. The H{alpha} survey reached completion for an optically selected sample of nearby galaxies in and outside rich clusters. Taking advantage of the completeness of the data set, the dependence of H{alpha} properties on the Hubble type was determined for late-type galaxies in the Virgo cluster. Differences in the gaseous content partly account for the large scatter of the H{alpha} EW within each Hubble-type class. We studied the radial distributions of the H{alpha} EW around Coma+A 1367 and the Virgo clusters in two luminosity bins. Luminous galaxies show a decrease in their average H{alpha} EW in the inner ~1 virial radius, while low-luminosity galaxies do not show this trend. Description:
2432. H{alpha} surface photometry in Virgo
ID:
ivo://CDS.VizieR/J/A+A/396/449
Title:
H{alpha} surface photometry in Virgo
Short Name:
J/A+A/396/449
Date:
21 Oct 2021
Publisher:
CDS
Description:
H{alpha}+[NII] imaging observations of 369 late-type (spiral) galaxies in the Virgo cluster and in the Coma/A1367 supercluster are analyzed, covering 3 rich nearby clusters (A1367, Coma and Virgo) and nearly isolated galaxies in the Great-Wall. They constitute an optically selected sample (mp<16.0) observed with ~60% completeness. These observations provide us with the current (T<10^7^yrs) star formation properties of galaxies that we study as a function of the clustercentric projected distances (Theta). The expected decrease of the star formation rate (SFR), as traced by the H{alpha} equivalent width, with decreasing Theta is found only when galaxies brighter than Mp~19.5 are considered. Fainter objects show no or reverse trends. We also include in our analysis Near Infrared data, providing information on the old (T>10^9^yrs) stars. Put together, the young and the old stellar indicators give the ratio of currently formed stars over the stars formed in the past, or "birthrate" parameter b. For the considered galaxies we also determine the "global gas content" combining HI with CO observations. We define the "gas deficiency'' parameter as the logarithmic difference between the gas content of isolated galaxies of a given Hubble type and the measured gas content.
2433. H{alpha} survey in the ONC
ID:
ivo://CDS.VizieR/J/ApJS/208/28
Title:
H{alpha} survey in the ONC
Short Name:
J/ApJS/208/28
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from an H{alpha} emission line survey in a 1 deg^2^ area centered on the Orion Nebula Cluster, obtained with the Wide Field Grism Spectrograph 2 on the 2.2 m telescope of the University of Hawaii. We identified 587 stars with H{alpha} emission, 99 of which, located mainly in the outer regions of the observed area, have not appeared in previous H{alpha} surveys. We determined the equivalent width (EW) of the line and, based on this, classified 372 stars as classical T Tauri stars (CTTSs) and 187 as weak-line T Tauri stars (WTTSs). Simultaneous r', i' photometry indicates a limiting magnitude of r' ~ 20 mag, but the sample is incomplete at r' > 17 mag. The surface distribution of the H{alpha} emission stars reveals a clustered population and a dispersed population, the former consisting of younger and more massive young stars than the latter. Comparison of the derived EWs with those found in the literature indicates variability of the H{alpha} line. We found that the typical amplitudes of the variability are not greater than a factor of two to three in most cases. We identified a subgroup of low-EW stars with infrared signatures indicative of optically thick accretion disks. We studied the correlations between the EW and other properties of the stars. Based on literature data, we examined several properties of our CTTS and WTTS subsamples and found significant differences in mid-infrared color indices, average rotational periods, and spectral energy distribution characteristics of the subsamples.
2434. H{alpha} survey of cluster galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/357/1337
Title:
H{alpha} survey of cluster galaxies
Short Name:
J/MNRAS/357/1337
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have extended our H{alpha} objective prism survey of eight low-redshift clusters (viz. Abell 262, 347, 400, 426, 569, 779, 1367 and 1656) to include a complete sample of early-type galaxies within 1.5 Abell radii of the cluster centres. Of the 379 galaxies surveyed, 3 per cent of E, E-S0 galaxies, 6 per cent of S0 galaxies, and 9 per cent of S0/a galaxies were detected in emission. From a comparison of cluster and supercluster field galaxies, we conclude that the frequency of emission-line galaxies (ELGs; W>=20{AA}) is similar for field and cluster early-type galaxies. A similar result has previously been obtained for galaxies of types Sa and later. Together, these results confirm the inference of Biviano et al. (1997A&A...321...84B) that the relative frequency of ELGs in clusters and the field can be entirely accounted for by the different mix of morphological types between the differing environments, and that, for galaxies of a given morphological type, the fraction of ELGs is independent of environment. Detected emission is classified as 'compact' or 'diffuse', identified as circumnuclear starburst or active galactic nucleus (AGN) emission and disc emission, respectively. By comparing spectroscopic data for cluster early-type ELGs with data for field galaxies from the Palomar spectroscopic survey of nearby galactic nuclei, we demonstrate that there is modest evidence for an enhancement of compact H II emission relative to AGN emission in the early-type cluster ELGs as compared to the field. For the cluster early-type galaxies, compact H II emission correlates strongly with a disturbed morphology. This suggests that, as for later-type cluster galaxies, this enhanced compact H II emission can readily be explained as an enhancement of circumnuclear starburst emission due to gravitational tidal interactions, most likely caused by subcluster merging and other on-going processes of cluster virialization.
2435. H{alpha}3 V. Coma cluster
ID:
ivo://CDS.VizieR/J/A+A/576/A16
Title:
H{alpha}3 V. Coma cluster
Short Name:
J/A+A/576/A16
Date:
21 Oct 2021
Publisher:
CDS
Description:
Neutral hydrogen represents the major observable baryonic constituent of galaxies that fuels the formation of stars through transformation of molecular hydrogen. The emission of the hydrogen recombination line H{alpha} is the most direct tracer of the process that transforms gas (fuel) into stars. We continue to present H{alpha}3 (acronym for H{alpha}-{alpha}{alpha}), an extensive H{alpha}+[NII] narrow-band imaging campaign of galaxies selected from the HI Arecibo Legacy Fast ALFA Survey (ALFALFA), using the instrumentation available at the San Pedro Martir (SPM) observatory (Mexico). In 48 nights since 2011 we were able to carry out the H{alpha} imaging observations of 724 galaxies in the region of the Coma supercluster 10h<RA<16h ; 24{deg}<Dec<28{deg} and 3900<cz<9000km/s. Of these, 603 are selected from the ALFALFA and constitute a 97% complete sample. They provide for the first time a complete census of the massive star formation properties of local gas-rich galaxies belonging to different environments (cluster vs. filaments), morphological types (spirals vs. dwarf Irr), over a wide range of stellar mass (~10^8^-10^11.5^M_{sun}_) in the Coma supercluster. The present Paper V provides H{alpha} data and derived star formation rates for the observed galaxies.
2436. h and chi Per UBVI,H{alpha} photometry
ID:
ivo://CDS.VizieR/J/AJ/122/248
Title:
h and chi Per UBVI,H{alpha} photometry
Short Name:
J/AJ/122/248
Date:
21 Oct 2021
Publisher:
CDS
Description:
UBVI and H{alpha} photometry is presented for 17319 stars in vicinity of the young double cluster h and {chi} Persei. Our photometry extends over a 37'x1{deg} field centered on the association. We construct reddening contours within the imaged field. We find that the two clusters share a common distance modulus of 11.75+/-0.05 and ages of log[age(yr)]=7.1+/-0.1. From the V-H{alpha} color, a measure of the H{alpha} emission strength, we conduct a survey for emission line objects within the association. We detect a sample of 33 Be stars, eight of which are new detections. We present a scenario of evolutionary enhancement of the Be phenomenon to account for the peak in Be fraction toward the top of the main sequence in the population of h and {chi} Persei and similar young clusters. UBVI and H{alpha} photometry was performed on five nights between 1999 August 17 and 25 at the San Diego State University Mount Laguna Observatory with the 1m telescope and a Loral 2048x2048 CCD.
2437. H and Ks photometry of Trumpler 14
ID:
ivo://CDS.VizieR/J/A+A/515/A26
Title:
H and Ks photometry of Trumpler 14
Short Name:
J/A+A/515/A26
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present adaptive optics (AO) near-infrared observations of the core of the Tr 14 cluster in the Carina region obtained with the ESO multi-conjugate AO demonstrator, MAD. Our campaign yields AO-corrected observations with an image quality of about 0.2' across the 2" field of view, which is the widest AO mosaic ever obtained. We detected almost 2000 sources spanning a dynamic range of 10 mag. The pre-main sequence (PMS) locus in the colour-magnitude diagram is well reproduced by Palla & Stahler isochrones with an age of 3 to 5x10^5^yr, confirming the very young age of the cluster. We derive a very high (deprojected) central density n_0_~4.5(+/-0.5)x10^4^pc^-3^ and estimate the total mass of the cluster to be about ~4.3^+3.3^_-1.5_x10^3^M_{sun}_, although contamination of the field of view might have a significant impact on the derived mass. We show that the pairing process is largely dominated by chance alignment so that physical pairs are difficult to disentangle from spurious ones based on our single epoch observation. Yet, we identify 150 likely bound pairs, 30% of these with a separation smaller than 0.5" (~1300AU). We further show that at the 2{sigma} level massive stars have more companions than lower-mass stars and that those companions are respectively brighter on average, thus more massive. Finally, we find some hints of mass segregation for stars heavier than about 10M_{sun}_. If confirmed, the observed degree of mass segregation could be explained by dynamical evolution, despite the young age of the cluster.
2438. HAPLESS galaxies sample
ID:
ivo://CDS.VizieR/J/MNRAS/452/397
Title:
HAPLESS galaxies sample
Short Name:
J/MNRAS/452/397
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the properties of the first 250 {mu}m blind sample of nearby galaxies (15<D<46Mpc) containing 42 objects from the Herschel Astrophysical Terahertz Large Area Survey. Herschel's sensitivity probes the faint end of the dust luminosity function for the first time, spanning a range of stellar mass (7.4<M*<11.3log10M_{sun}_), star formation activity (-11.8<SSFR<-8.9log10yr^-1^), gas fraction (3-96 per cent), and colour (0.6<FUV-K_S_<7.0mag). The median cold dust temperature is 14.6K, colder than in the Herschel Reference Survey (18.5K) and Planck Early Release Compact Source Catalogue (17.7K). The mean dust-to-stellar mass ratio in our sample is higher than these surveys by factors of 3.7 and 1.8, with a dust mass volume density of (3.7+/-0.7)x10^5^M_{sun}_/Mpc^3^. Counter-intuitively, we find that the more dust rich a galaxy, the lower its UV attenuation. Over half of our dust-selected sample are very blue in FUV-K_S_ colour, with irregular and/or highly flocculent morphology; these galaxies account for only 6 per cent of the sample's stellar mass but contain over 35 per cent of the dust mass. They are the most actively star-forming galaxies in the sample, with the highest gas fractions and lowest UV attenuation. They also appear to be in an early stage of converting their gas into stars, providing valuable insights into the chemical evolution of young galaxies.
2439. HAQ survey: red QSO candidates follow-up
ID:
ivo://CDS.VizieR/J/ApJS/217/5
Title:
HAQ survey: red QSO candidates follow-up
Short Name:
J/ApJS/217/5
Date:
21 Oct 2021
Publisher:
CDS
Description:
Quasi-stellar objects (QSOs) whose spectral energy distributions (SEDs) are reddened by dust either in their host galaxies or in intervening absorber galaxies are to a large degree missed by optical color selection criteria like the ones used by the Sloan Digital Sky Survey (SDSS). To overcome this bias against red QSOs, we employ a combined optical and near-infrared (near-IR) color selection. In this paper, we present a spectroscopic follow-up campaign of a sample of red candidate QSOs which were selected from the SDSS and the UKIRT Infrared Deep Sky Survey (UKIDSS). The spectroscopic data and SDSS/UKIDSS photometry are supplemented by mid-infrared photometry from the Wide-field Infrared Survey Explorer. In our sample of 159 candidates, 154 (97%) are confirmed to be QSOs. We use a statistical algorithm to identify sightlines with plausible intervening absorption systems and identify nine such cases assuming dust in the absorber similar to Large Magellanic Cloud sightlines. We find absorption systems toward 30 QSOs, 2 of which are consistent with the best-fit absorber redshift from the statistical modeling. Furthermore, we observe a broad range in SED properties of the QSOs as probed by the rest-frame 2{mu}m flux. We find QSOs with a strong excess as well as QSOs with a large deficit at rest-frame 2{mu}m relative to a QSO template. Potential solutions to these discrepancies are discussed. Overall, our study demonstrates the high efficiency of the optical/near-IR selection of red QSOs.
2440. HATLAS candidate lensed galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/465/3558
Title:
HATLAS candidate lensed galaxies
Short Name:
J/MNRAS/465/3558
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a sample of 80 candidate strongly lensed galaxies with flux density above 100mJy at 500{mu}m extracted from the Herschel Astrophysical Terahertz Large Area Survey, over an area of 600deg^2^. Available imaging and spectroscopic data allow us to confirm the strong lensing in 20 cases and to reject it in one case. For other eight objects, the lensing scenario is strongly supported by the presence of two sources along the same line of sight with distinct photometric redshifts. The remaining objects await more follow-up observations to confirm their nature. The lenses and the background sources have median redshifts z_L_=0.6 and z_S_=2.5, respectively, and are observed out to z_L_=1.2 and z_S_=4.2. We measure the number counts of candidate lensed galaxies at 500{mu}m and compare them with theoretical predictions, finding a good agreement for a maximum magnification of the background sources in the range 10-20. These values are consistent with the magnification factors derived from the lens modelling of individual systems. The catalogue presented here provides sub-mm bright targets for follow-up observations aimed at exploiting gravitational lensing, to study with unprecedented details the morphological and dynamical properties of dusty star-forming regions in z>=1.5 galaxies.