- ID:
- ivo://CDS.VizieR/J/MNRAS/407/2475
- Title:
- Ionized gas in E/S0 galaxies with dust lanes
- Short Name:
- J/MNRAS/407/2475
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of multicolour observations of 30 E/S0 galaxies with dust lanes. For each galaxy we obtained broad-band images and narrow-band images using interference filters isolating the H{alpha}+[NII] emission lines to derive the amount and morphology of dust and ionized gas. To improve the wavelength coverage we retrieved data from the Sloan Digital Sky Survey and Two Micron All Sky Survey and combined these with our data. Ionized gas is detected in 25 galaxies and shows in most cases a smooth morphology, although knots and filamentary structure are also observed in some objects.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/510/104
- Title:
- Ionizing Stars of Extragalactic H II Regions
- Short Name:
- J/ApJ/510/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Medium-resolution spectra from 3650 to 10000 {AA} are presented for 96 giant H II regions distributed in 20 spiral galaxies. In order to interpret the data, we have calculated two separate grids of photoionization models, adopting single-star atmospheres (Kurucz) and star clusters synthesized with different initial mass functions (IMFs) as ionizing sources. Additional models were computed with more recent non-LTE stellar atmospheres, in order to check the effects of different stellar ionizing fluxes. We use the radiation softness parameter {eta}'=([O II]/[O III])/([S II]/[S III]) of Vilchez & Pagel (1988MNRAS.231..257V) to test for a metallicity dependence of the effective temperatures of the ionizing stars. Our results are consistent with a significant decrease in mean stellar temperatures of the ionizing stars with increasing metallicity. The magnitude of the effect, combined with the behavior of the He I {lambda}5876/H{beta} ratio, suggest a smaller upper mass limit for star formation at abundances higher than solar, even when considering the effects of metallicity on stellar evolution and atmospheric line blanketing. However, the exact magnitudes of the stellar temperature and IMF variations are dependent on the choice of stellar atmosphere and evolution models used, as well as on uncertainties in the nebular abundance scale at high metallicities. Our results also constrain the systematic behavior of the ionization parameter and the N/O ratio in extragalactic H II regions. The observed spectral sequences are inconsistent with current stellar evolution models, which predict a luminous, hot W-R stellar population in evolved H II regions older than 2-3 Myr. This suggests either that the hardness of the emitted Lyman continuum spectrum has been overestimated in the models or that some mechanism disrupts the H II regions before the W-R phases become important.
- ID:
- ivo://CDS.VizieR/J/AJ/159/216
- Title:
- Ions density in the CGM of low mass galaxy groups
- Short Name:
- J/AJ/159/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore how environment affects the metallicity of the circumgalactic medium (CGM) using 13 low-mass galaxy groups (two to five galaxies) at <z_abs_>=0.25 identified near background quasars. Using quasar spectra from the Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) and from Keck/High Resolution Echelle Spectrometer (Keck/HIRES) or the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph (VLT/UVES), we measure column densities of or determine limits on CGM absorption lines. We use a Markov Chain Monte Carlo approach with Cloudy to estimate metallicities of cool (T~104K) CGM gas within groups and compare them to CGM metallicities of 47 isolated galaxies. Both group and isolated CGM metallicities span a wide range (-2<[Si/H]<0), where the mean group (-0.54{pm}0.22) and isolated (-0.77{pm}0.14) CGM metallicities are similar. Group and isolated environments have similar distributions of HI column densities as a function of impact parameter. However, contrary to isolated galaxies, we do not find an anticorrelation between HI column density and the nearest group galaxy impact parameter. We additionally divided the groups by member luminosity ratios (i.e., galaxy-galaxy and galaxy-dwarf groups). While there was no significant difference in their mean metallicities, a modest increase in sample size should allow one to statistically identify a higher CGM metallicity in galaxy-dwarf groups compared to galaxy-galaxy groups. We conclude that either environmental effects have not played an important role in the metallicity of the CGM at this stage and expect that this may only occur when galaxies are strongly interacting or merging or that some isolated galaxies have higher CGM metallicities due to past interactions. Thus, environment does not seem to be the cause of the CGM metallicity bimodality.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/185
- Title:
- IR-bright MSX sources in the SMC with Spitzer/IRS
- Short Name:
- J/ApJ/834/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Infrared Spectrograph (IRS) on the Spitzer Space Telescope to observe stars in the Small Magellanic Cloud (SMC) selected from the Point Source Catalog of the Midcourse Space Experiment (MSX). We concentrate on the dust properties of the oxygen-rich evolved stars. The dust composition has smaller contributions from alumina compared to the Galaxy. This difference may arise from the lower metallicity in the SMC, but it could be a selection effect, as the SMC sample includes more stars that are brighter and thus more massive. The distribution of the SMC stars along the silicate sequence looks more like the Galactic sample of red supergiants than asymptotic giant branch stars (AGBs). While many of the SMC stars are definitively on the AGB, several also show evidence of hot bottom burning. Three of the supergiants show PAH emission at 11.3{mu}m. Two other sources show mixed chemistry, with both carbon-rich and oxygen-rich spectral features. One, MSX SMC 134, may be the first confirmed silicate/carbon star in the SMC. The other, MSX SMC 049, is a candidate post-AGB star. MSX SMC 145, previously considered a candidate OH/IR star, is actually an AGB star with a background galaxy at z=0.16 along the same line of sight. We consider the overall characteristics of all the MSX sources, the most infrared-bright objects in the SMC, in light of the higher sensitivity and resolution of Spitzer, and compare them with the object types expected from the original selection criteria. This population represents what will be seen in more distant galaxies by the upcoming James Webb Space Telescope (JWST). Color-color diagrams generated from the IRS spectra and the mid-infrared filters on JWST show how one can separate evolved stars from young stellar objects (YSOs) and distinguish among different classes of YSOs.
- ID:
- ivo://CDS.VizieR/J/AJ/162/82
- Title:
- IRD and HPF spectra of TRAPPIST-1b,e and f
- Short Name:
- J/AJ/162/82
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We obtained high-resolution spectra of the ultracool M-dwarf TRAPPIST-1 during the transit of its planet "b" using two high-dispersion near-infrared spectrographs, the Infrared Doppler (IRD) instrument on the Subaru 8.2m telescope, and the Habitable Zone Planet Finder (HPF) instrument on the 10m Hobby-Eberly Telescope. These spectroscopic observations are complemented by a photometric transit observation for planet "b" using the APO/ARCTIC, which assisted us in capturing the correct transit times for our transit spectroscopy. Using the data obtained by the new IRD and HPF observations, as well as the prior transit observations of planets "b," "e" and "f" from IRD, we attempt to constrain the atmospheric escape of the planet using the Hei triplet 10830{AA} absorption line. We do not detect evidence for any primordial extended H-He atmospheres in all three planets. To limit any planet-related absorption, we place an upper limit on the equivalent widths of <7.754m{AA} for planet "b," <10.458m{AA} for planet "e," <4.143m{AA} for planet "f" at 95% confidence from the IRD data, and <3.467m{AA} for planet "b" at 95% confidence from HPF data. Using these limits along with a solar- like composition isothermal Parker wind model, we attempt to constrain the mass-loss rates for the three planets. For TRAPPIST-1b, our models exclude the highest possible energy-limited rate for a wind temperature <5000K. This nondetection of extended atmospheres with low mean-molecular weights in all three planets aids in further constraining their atmospheric composition by steering the focus toward the search of high-molecular-weight species in their atmospheres.
- ID:
- ivo://CDS.VizieR/J/AJ/142/148
- Title:
- IR observations of galaxies in the Coma cluster
- Short Name:
- J/AJ/142/148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a thorough study of the specific star formation rates (sSFRs) for MIPS 24um selected galaxies in the Coma cluster. We build galaxy spectral energy distributions using optical (u', g', r', i', z'), near-infrared (J, H, Ks), and mid- to far-infrared (Infrared Array Camera and MIPS) photometry. New and archival spectra confirm 210 cluster members. Subsequently, the total infrared luminosity, galaxy stellar mass, and sSFR for the members are determined by measuring best-fit templates. Using an array of complementary diagnostics, we search for any contaminating active galactic nuclei, but find few. We compare obscured SFRs to unobscured rates derived from extinction-corrected H{alpha} emission line measurements. The agreement between these two values leads us to conclude that there is no evidence for an additionally obscured component. In our spectroscopic sample, complete to 80% for r'<19.5, we find that all starbursts are blue and are dwarfs, having masses <10^9^M_{sun}_. Examining the location of these starbursts within the cluster, we confirm that there is a lower fraction in the cluster core.
- ID:
- ivo://CDS.VizieR/J/ApJ/890/119
- Title:
- Iron element abundances in 3 very metal-poor stars
- Short Name:
- J/ApJ/890/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained new detailed abundances of the Fe-group elements Sc through Zn (Z=21-30) in three very metal-poor ([Fe/H]~-3) stars: BD+03 740, BD-13 3442, and CD-33 1173. High-resolution ultraviolet Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra in the wavelength range 2300-3050{AA} were gathered, and complemented by an assortment of optical echelle spectra. The analysis featured recent laboratory atomic data for a number of neutral and ionized species for all Fe-group elements except Cu and Zn. A detailed examination of scandium, titanium, and vanadium abundances in large-sample spectroscopic surveys indicates that they are positively correlated in stars with [Fe/H]<=-2. The abundances of these elements in BD+03 740, BD-13 3442, CD-33 1173, and HD 84937 (studied in a previous paper of this series) are in accord with these trends and lie at the high end of the correlations. Six elements have detectable neutral and ionized features, and generally their abundances are in reasonable agreement. For Cr we find only minimal abundance disagreement between the neutral (mean of [CrI/Fe]=+0.01) and ionized species (mean of [CrII/Fe]=+0.08), unlike most studies in the past. The prominent exception is Co, for which the neutral species indicates a significant overabundance (mean of [CoI/H]=-2.53), while no such enhancement is seen for the ionized species (mean of [CoII/H]=-2.93). These new stellar abundances, especially the correlations among Sc, Ti, and V, suggest that models of element production in early high-mass metal-poor stars should be revisited.
- ID:
- ivo://CDS.VizieR/J/ApJS/136/631
- Title:
- IUE absorption toward 164 early-type stars
- Short Name:
- J/ApJS/136/631
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of Galactic interstellar AlIII, SiIV, and CIV absorption recorded in high-resolution archival ultraviolet spectra of 164 hot early-type stars observed by the International Ultraviolet Explorer (IUE) satellite. The objects studied were drawn from the list of hot stars scheduled to be observed with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite as part of observing programs designed to investigate absorption by OVI in the Galactic disk and halo. Multiple IUE echelle-mode integrations have been combined to produce a single ultraviolet (1150-1900{AA}) spectrum of each star with a spectral resolution of ~25km/s (FWHM). Selected absorption-line profiles are presented for each star along with plots of the apparent column density per unit velocity for each line of the AlIII, SiIV, and CIV doublets. We report absorption-line equivalent widths, absorption velocities, and integrated column densities based on the apparent optical depth method of examining interstellar absorption lines. We also determine column densities and Doppler parameters from single-component curve-of-growth analyses. The scientific analysis of these observations will be undertaken after the FUSE satellite produces similar measurements for absorption by interstellar OIV, FeIII, SIII, and other ions.
- ID:
- ivo://CDS.VizieR/J/ApJS/237/14
- Title:
- KASI-Yonsei Deep Imaging Survey of Clusters (KYDISC)
- Short Name:
- J/ApJS/237/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the KASI-Yonsei Deep Imaging Survey of Clusters targeting 14 clusters at 0.015<~z<~0.144 using the Inamori Magellan Areal Camera and Spectrograph on the 6.5m Magellan Baade telescope and the MegaCam on the 3.6m Canada-France-Hawaii Telescope. We provide a catalog of cluster galaxies that lists magnitudes, redshifts, morphologies, bulge-to-total ratios, and local density. Based on the 1409 spectroscopically confirmed cluster galaxies brighter than -19.8 in the r band, we study galaxy morphology, color, and visual features generated by galaxy mergers. We see a clear trend between morphological content and cluster velocity dispersion, which was not presented by previous studies using local clusters. Passive spirals are preferentially found in a highly dense region (i.e., cluster center), indicating that they have gone through environmental quenching. In deep images ({mu}_r'_~27mag/arcsec^2^), 20% of our sample shows signatures of recent mergers, which is not expected from theoretical predictions and a low frequency of ongoing mergers in our sample (~4%). Such a high fraction of recent mergers in the cluster environment supports a scenario that the merger events that made the features have preceded the galaxy accretion into the cluster environment. We conclude that mergers affect a cluster population mainly through the preprocessing of recently accreted galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/869/123
- Title:
- Keck Lyman continuum spectroscopic survey (KLCS)
- Short Name:
- J/ApJ/869/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a deep spectroscopic survey quantifying the statistics of the escape of ionizing radiation from star-forming galaxies at z~3. We measure the ratio of ionizing to non-ionizing UV flux density <f_900_/f_1500_>_obs_, where f_900_ is the mean flux density evaluated over the range [880,910]{AA}. We quantify the emergent ratio of ionizing to non-ionizing UV flux density by analyzing high signal-to-noise ratio composite spectra formed from subsamples with common observed properties and numbers sufficient to reduce the statistical uncertainty in the modeled IGM+CGM correction to obtain precise values of <f_900_/f_1500_>_out_, including a full-sample average <f_900_/f_1500>_out_=0.057{+/-}0.006. We show that <f_900_/f_1500_>_out_ increases monotonically with W_{lambda}_(Ly{alpha}), inducing an inverse correlation with UV luminosity as a by-product. We fit the composite spectra using stellar spectral synthesis together with models of the ISM in which a fraction f_c_ of the stellar continuum is covered by gas with column density N_HI_. We show that the composite spectra simultaneously constrain the intrinsic properties of the stars (L_900_/L_1500_)_int_ along with f_c_, N_HI_, E(B-V), and f_esc,abs_, the absolute escape fraction of ionizing photons. We find a sample-averaged f_esc,abs_=0.09{+/-}0.01, with subsamples falling along a linear relation <f_esc,abs_>~0.75[W_{lambda}_(Ly{alpha})/110{AA}]. Using the far-UV luminosity function, the distribution function n(W(Ly{alpha})), and the relationship between W_{lambda}_(Ly{alpha}) and <f_900_/f_1500_>_out_, we estimate the total ionizing emissivity of z~3 star-forming galaxies with M_uv_<=-19.5, which exceeds the contribution of quasi-stellar objects by a factor of ~3, and accounts for ~50% of the total {epsilon}LyC at z~3 estimated using indirect methods.