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2701. Star formation in E/S0 galaxies
ID:
ivo://CDS.VizieR/J/ApJ/708/841
Title:
Star formation in E/S0 galaxies
Short Name:
J/ApJ/708/841
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recent work has identified a population of low-redshift E/S0 galaxies that lie on the blue sequence in color versus stellar mass parameter space, where spiral galaxies typically reside. While high-mass blue-sequence E/S0s often resemble young merger or interaction remnants likely to fade to the red sequence, we focus on blue-sequence E/S0s with lower stellar masses (M_*_<a fewx10^10^M_{sun}_), which are characterized by fairly regular morphologies and low-density field environments where fresh gas infall is possible. This population may provide an evolutionary link between early-type galaxies and spirals through disk regrowth. Focusing on atomic gas reservoirs, we present new GBT HI data for 27 E/S0s on both sequences as well as a complete tabulation of archival HI data for other galaxies in the Nearby Field Galaxy Survey. Normalized to stellar mass, the atomic gas masses for 12 of the 14 blue-sequence E/S0s range from 0.1 to >1.0, demonstrating that morphological transformation is possible if the detected gas can be converted into stars. These gas-to-stellar mass ratios are comparable to those of spiral and irregular galaxies and have a similar dependence on stellar mass.
2702. Star formation in the blue compact dwarf Mrk 900
ID:
ivo://CDS.VizieR/J/A+A/634/A95
Title:
Star formation in the blue compact dwarf Mrk 900
Short Name:
J/A+A/634/A95
Date:
21 Oct 2021
Publisher:
CDS
Description:
Low-luminosity, active star-forming blue compact galaxies (BCGs) are excellent laboratories for investigating the process of star formation on galactic scales and probing the interplay between massive stars and the surrounding interstellar (or intergalactic) medium. We investigated the morphology, structure, and stellar content of the Blue Compact Galaxy Mrk 900, combining optical integral field observations obtained with VIMOS at the VLT and deep broad-band photometry taken at the 2.5 m NOT telescope. From the integral field data, we built continuum, emission, and diagnostic line ratio maps and produced velocity and velocity dispersion maps. We also generated the integrated spectrum of the major HII regions and the nuclear area to determine reliable physical parameters and oxygen abundances. The broad-band data, tracing the galaxy up to radius 4 kpc, allowed us to investigate the properties of the low surface brightness underlying stellar host. We disentangle two different stellar components in Mrk 900: a young population, which resolves into individual stellar clusters with ages ~5.5-6.6Myr and extends about 1 kpc along the galaxy minor axis, is placed on top of a rather red and regular shaped underlying stellar host, several Gyr old. We find evidence of a substantial amount of dust and an inhomogeneous extinction pattern, with a dust lane crossing the central starburst. Mrk 900 displays overall rotation, although distorted in the central, starburst regions; the dispersion velocity map is highly inhomogeneous, with values increasing up to 60km/s at the periphery of the SF regions, where we also find hints of the presence of shocks. Our observational results point to an interaction or merger with a low-mass object or infalling gas as plausible trigger mechanisms for the present starburst event.
2703. Star formation in z~1.5 quiescent galaxies
ID:
ivo://CDS.VizieR/J/A+A/599/A95
Title:
Star formation in z~1.5 quiescent galaxies
Short Name:
J/A+A/599/A95
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a sample of 34 spectroscopically confirmed BzK-selected ~10^11^M_{sun}_ quiescent galaxies (pBzK) in the COSMOS field. The targets were initially observed with VIMOS on the VLT to facilitate the calibration of the photometric redshifts of massive galaxies at z>~1.5. Here we describe the reduction and analysis of the data, and the spectrophotometric properties of these pBzK galaxies. In particular, using a spatially resolved median 2D spectrum, we find that the fraction of stellar populations with ages <1Gyr is at least 3 times higher in the outer regions of the pBzK galaxies than in their cores. This results in a mild age gradient of {DELTA}age<=0.4Gyr over ~6kpc and suggests either the occurrence of widespread rejuvenation episodes or that inside-out quenching played a role in the passivization of this galaxy population. We also report on low-level star formation rates derived from the [OII]3727{AA} emission line, with SFR_OII_~3.7-4.5M_{sun}_/yr. This estimate is confirmed by an independent measurement on a separate sample of similarly-selected quiescent galaxies in the COSMOS field, using stacked far-infrared data (SFR_FIR_~2-4M_{sun}_/yr). This second, photometric sample also displays significant excess at 1.4GHz, suggestive of the presence of radio-mode AGN activity.
2704. Star Formation Rate of NFGS galaxies
ID:
ivo://CDS.VizieR/J/AJ/127/2002
Title:
Star Formation Rate of NFGS galaxies
Short Name:
J/AJ/127/2002
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the [O II] emission line as a star formation rate (SFR) indicator using integrated spectra of 97 galaxies from the Nearby Field Galaxies Survey (NFGS). The sample includes all Hubble types and contains SFRs ranging from 0.01 to 100M_{sun}_/yr.
2705. Star formation rates of blue compact galaxies
ID:
ivo://CDS.VizieR/J/A+A/425/417
Title:
Star formation rates of blue compact galaxies
Short Name:
J/A+A/425/417
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using Halpha, [OII]3727, infrared (IR), radio (1.4GHz) luminosities and neutral hydrogen (HI) gas masses, we estimated star formation rates and gas depletion timescales of 72 star-forming blue compact galaxies (BCGs) To assess the possible systematic differences among different star formation rate indicators, we compared the star formation rates derived from Halpha, [OII]3727, IR, and radio luminosities, and investigated the effects from underlying stellar absorption and dust extinction. We found that subtracting underlying stellar absorption is very important to calculate both dust extinction and star formation rate of galaxies. Otherwise, the intrinsic extinction will be overestimated, the star formation rates derived from [OII]3727 and Halpha will be underestimated (if the underlying stellar absorption and the internal extinction were not corrected from the observed luminosity) or overestimated (if an overestimated internal extinction were used for extinction correction). After both the underlying stellar absorption and the dust extinction were corrected, a remarkably good correlation emerges among Halpha, [OII]3727, IR and radio star formation rate indicators.
2706. Star-forming dwarfs at intermediate-z in VUDS
ID:
ivo://CDS.VizieR/J/A+A/601/A95
Title:
Star-forming dwarfs at intermediate-z in VUDS
Short Name:
J/A+A/601/A95
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present emission line measurements and the main physical properties of a sample of 164 star-forming dwarf galaxies (SFDGs) in the VIMOS Ultra Deep Survey (VUDS, Le Fevre et al., 2015A&A...576A..79L). VUDS is one of the largest programs on the ESO-VLT with 640 hours of observing time, and covers a total of one square degree in three separate fields: COSMOS, ECDFS, and VVDS-02h. The spectroscopic observations were carried out at the VLT with the VIMOS Multi-Object Spectrograph (MOS) with two grisms (LRBLUE and LRRED) covering a wavelength range of 365<lambda<935nm at uniform spectral resolution of R=180 and R=210, respectively. The integration time (on-source) is ~14-hours per target for each grism, which allows to detect the continuum at 850nm for i_AB_=25, and emission lines with an observed flux limit F=1.5*10^-18^erg/s/cm2 at S/N~5. Redshift measurements in VUDS were performed using the EZ code (Garilli et al., 2010PASP..122..827G), both in automatic and manual modes (by two persons independently) for each spectrum. The overall redshift accuracy is dz/(1+z)=0.0005-0.0007. The spectra had already been fully calibrated in wavelength and flux by the VUDS team, which also did the sky subtraction. Emission lines fluxes and equivalent widths are measured manually on a one-by- one basis using the task 'splot' of IRAF by direct integration of the line profile after linear subtraction of the continuum. These fluxes are given in units of 10^-18^erg/s/cm^2^. The uncertainties in the line measurements were computed from the dispersion of values provided by multiple measurements adopting different possible band-passes (free of lines and strong residuals from sky subtraction) for the local continuum determination, which is fitted using a second order polynomial. No extinction correction has been applied to these fluxes. The EW measurements of H{gamma}, H{beta} and H{alpha} lines have been already corrected for absorption by +0.1nm for all galaxies, following Ly et al. (2014ApJ...780..122L). For each galaxy the reddening constant, c(H{beta}), is presented. These values and their uncertainties have been derived from the H{alpha}/H{beta} or H{gamma}/H{beta} ratios, whenever possible. We adopted the reddening constant from the best-fit SED, using the relations of Calzetti et al. (2000ApJ...533..682C), for (a) galaxies where the computation of c(H{beta}) from emission lines is not possible because the lines are not present, or (b) the line ratios give a negative extinction correction (i.e., H{alpha}/H{beta}<2.82 or H{gamma}/H{beta}<0.47, assuming Case B recombination with Te=2*10^4^K, ne=100cm^-3^).
2707. Star-forming galaxies in ACO 2029
ID:
ivo://CDS.VizieR/J/ApJ/773/86
Title:
Star-forming galaxies in ACO 2029
Short Name:
J/ApJ/773/86
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dense environments are known to quench star formation in galaxies, but it is still unknown what mechanism(s) are directly responsible. In this paper, we study the star formation of galaxies in A2029 and compare it to that of Coma, combining indicators at 24{mu}m, H{alpha}, and UV down to rates of 0.03M_{sun}_/yr. We show that A2029's star-forming galaxies follow the same mass-SFR relation as the field. The Coma cluster, on the other hand, has a population of galaxies with star formation rates (SFRs) significantly lower than the field mass-SFR relation, indicative of galaxies in the process of being quenched. Over half of these galaxies also host active galactic nuclei. Ram-pressure stripping and starvation/strangulation are the most likely mechanisms for suppressing the star formation in these galaxies, but we are unable to disentangle which is dominating. The differences we see between the two clusters' populations of star-forming galaxies may be related to their accretion histories, with A2029 having accreted its star-forming galaxies more recently than Coma. Additionally, many early-type galaxies in A2029 are detected at 24{mu}m and/or in the far-UV, but this emission is not directly related to star formation. Similar galaxies have probably been classified as star forming in previous studies of dense clusters, possibly obscuring some of the effects of the cluster environment on true star-forming galaxies.
2708. Star-forming regions deuteration
ID:
ivo://CDS.VizieR/J/A+A/579/A80
Title:
Star-forming regions deuteration
Short Name:
J/A+A/579/A80
Date:
21 Oct 2021
Publisher:
CDS
Description:
The chemical evolution in high-mass star-forming regions is still poorly constrained. Studying the evolution of deuterated molecules allows distinguishing between subsequent stages of high-mass star formation regions based on the strong temperature dependence of deuterium isotopic fractionation. We observed a sample of 59 sources including 19 infrared dark clouds, 20 high-mass protostellar objects, 11 hot molecular cores and 9 ultra-compact HII regions in the (3-2) transitions of the four deuterated molecules, DCN, DNC, DCO^+^, and N_2_D^+^ as well as their non-deuterated counterparts. The overall detection fraction of DCN, DNC, and DCO^+^ is high and exceeds 50% for most of the stages. N_2_D^+^ was only detected in a few infrared dark clouds and high-mass protostellar objects. This may be related to problems in the bandpass at the transition frequency and to low abundances in the more evolved, warmer stages. We find median D/H ratios of 0.02 for DCN, 0.005 for DNC, 0.0025 for DCO^+^, and 0.02 for N_2_D^+^. While the D/H ratios of DNC, DCO^+^, and N_2_D^+^ decrease with time, DCN/HCN peaks at the hot molecular core stage. We only found weak correlations of the D/H ratios for N_2_D^+^ with the luminosity of the central source and the FWHM of the line, and no correlation with the H_2_ column density. In combination with a previously observed set of 14 other molecules (Paper I), we fitted the calculated column densities with an elaborate 1D physico-chemical model with time-dependent D-chemistry including ortho- and para-H_2_ states. Good overall fits to the observed data were obtained with the model. This is one of the first times that observations and modeling were combined to derive chemically based best-fit models for the evolution of high-mass star formation including deuteration.
2709. Star-forming z~2.1 galaxy metallicities
ID:
ivo://CDS.VizieR/J/ApJ/817/10
Title:
Star-forming z~2.1 galaxy metallicities
Short Name:
J/ApJ/817/10
Date:
21 Oct 2021
Publisher:
CDS
Description:
We explore the evolution of the Stellar Mass-Star Formation Rate (SFR)-Metallicity relation using a set of 256 COSMOS and GOODS galaxies in the redshift range 1.90<z<2.35. We present the galaxies' rest-frame optical emission-line fluxes derived from IR-grism spectroscopy with the Hubble Space Telescope and combine these data with SFRs and stellar masses obtained from deep, multi-wavelength (rest-frame UV to IR) photometry. We then compare these measurements to those for a local sample of galaxies carefully matched in stellar mass (7.5<~log(M_{star}_/M_{sun}_<~10.5) and SFR (-0.5<~log(SFR)<~2.5 in M_{sun}_/yr). We find that the distribution of z~2.1 galaxies in stellar mass-SFR-metallicity space is clearly different from that derived for our sample of similarly bright (L_H{beta}_>3x10^40^erg/s) local galaxies, and this offset cannot be explained by simple systematic offsets in the derived quantities. At stellar masses above ~10^9^M_{sun}_ and SFRs above ~10M_{sun}_/yr, the z~2.1 galaxies have higher oxygen abundances than their local counterparts, while the opposite is true for lower-mass, lower-SFR systems.
2710. Stark broadening
ID:
ivo://CDS.VizieR/J/A+AS/113/579
Title:
Stark broadening
Short Name:
J/A+AS/113/579
Date:
21 Oct 2021
Publisher:
CDS
Description:
Tables of Stark broadening profiles for the N V 6f, g, h-7f, g, h, i line complex at 4945A have been generated. Modern close-coupling techniques are used for the electron broadening while the important influence of perturbing ions is included within the framework of the model microfield method. Comparison has been made with the results of line formation calculations using approximate formulae for the Stark profiles.

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