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- ID:
- ivo://CDS.VizieR/J/ApJS/216/22
- Title:
- 3060-3700{AA} spectra analysis of early-type stars
- Short Name:
- J/ApJS/216/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive and sensitive unbiased survey of interstellar features in the near-UV range (3050-3700{AA}). We combined a large number of VLT/UVES archival observations of a sample of highly reddened early-type stars -typical diffuse interstellar band targets- and unreddened standards. We stacked the individual observations to obtain a reddened "superspectrum" in the interstellar rest frame with a signal-to-noise ratio exceeding 1500. We compared this to the analogous geocentric and stellar rest frame superspectra as well as to an unreddened superspectrum to find interstellar absorption features. We find 30 known features (11 atomic and 19 molecular) and tentatively detect up to 7 new interstellar absorption lines of unknown origin. Our survey is sensitive to narrow and weak features; telluric residuals preclude us from detecting broader features. For each sightline, we measured fundamental parameters (radial velocities, line widths, and equivalent widths) of the detected interstellar features. We also revisit upper limits for the column densities of small, neutral polycyclic aromatic hydrocarbon molecules that have strong transitions in this wavelength range.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/34
- Title:
- 3000-25000{AA} spectroscopy of nearby M dwarfs
- Short Name:
- J/ApJ/850/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies of the stellar population in the solar neighborhood (<20pc) suggest that there are undetected white dwarfs (WDs) in multiple systems with main-sequence companions. Detecting these hidden stars and obtaining a more complete census of nearby WDs is important for our understanding of stellar and galactic evolution, as well as the study of explosive phenomena. In an attempt to uncover these hidden WDs, we present intermediate resolution spectroscopy over the wavelength range of 3000-25000{AA} of 101 nearby M dwarfs (dMs), observed with the Very Large Telescope X-Shooter spectrograph. For each star we search for a hot component superimposed on the dM spectrum. X-Shooter has excellent blue sensitivity and thus can reveal a faint hot WD despite the brightness of its red companion. Visual examination shows no clear evidence of a WD in any of the spectra. We place upper limits on the effective temperatures of WDs that may still be hiding by fitting dM templates to the spectra and modeling the WD spectra. On average our survey is sensitive to WDs hotter than about 5300K. This suggests that the frequency of WD companions of Teff>~5300K with separation of the order of <~50 au among the local dM population is <3% at the 95% confidence level.
- ID:
- ivo://CDS.VizieR/J/ApJ/470/724
- Title:
- Abell 576 galaxies magnitude and velocities
- Short Name:
- J/ApJ/470/724
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the galaxy population and dynamics of the galaxy cluster A576; the observational constraints include 281 redshifts (230 new), R-band CCD galaxy photometry over a 2h^-1^Mpcx2h^-1^Mpc region centered on the cluster, an Einstein IPC X-ray image, and an Einstein MPC X-ray spectrum. We focus on an 86% complete magnitude-limited sample (R_23.5_<17) of 169 cluster galaxies. The cluster galaxies with emission lines in their spectra have a larger velocity dispersion and are significantly less clustered on this 2h^-1^Mpc scale than galaxies without emission lines. We show that excluding the emission-line galaxies from the cluster sample decreases the velocity dispersion by 18% and the virial mass estimate by a factor of 2. The central cluster region contains a non-emission galaxy population and an intracluster medium which is significantly cooler ({sigma}_core_=387^+250^_-105_km/s and T_X_=1.6-0.3/+0.4keV at 90% confidence) than the global populations ({sigma}=977^+124^_-96_km/s for the non-emission population and T_X_>4keV at 90% confidence). Because (1) the low-dispersion galaxy population is no more luminous than the global population and (2) the evidence for a cooling flow is weak, we suggest that the core of A576 may contain the remnants of a lower mass subcluster. We examine the cluster mass, baryon fraction, and luminosity function. The cluster virial mass varies significantly depending on the galaxy sample used. Consistency between the hydrostatic and virial estimators can be achieved if (1) the gas temperature at r~1h^-1^Mpc is T_X_~8keV (the best-fit value) and (2) several velocity outliers are excluded from the virial calculation. Although the best-fit Schechter function parameters and the ratio of galaxy to gas mass in A576 are typical of other clusters, the baryon fraction is relatively low. Using the consistent cluster binding mass, we show that the gas mass fraction is ~3h^-3/2^% and the baryon fraction is ~4%.
- ID:
- ivo://CDS.VizieR/J/A+A/607/A131
- Title:
- Abell 520 galaxies redshifts
- Short Name:
- J/A+A/607/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mergers of galaxy clusters are the most energetic events in the universe after the Big Bang. An ever increasing fraction of local clusters exhibit signs of recent or past mergers. Our goal is to probe how these mergers affect the evolution and content of their member galaxies. We specifically aim to answer the following questions: Is the quenching of star formation in merging clusters enhanced when compared with relaxed clusters? Is the quenching accompanied by a (short lived) burst of star formation? We obtained optical spectroscopy of $>400$ galaxies in the field of the merging cluster Abell 520. We combine these observations with archival data to get a comprehensive picture of the state of star formation in the members of this merging cluster. Finally, we compare these observations with a control sample of 10 non-merging clusters at the same redshift from The Arizona Cluster Redshift Survey (ACReS). We split the member galaxies in passive, star forming or recently quenched depending on their spectra. The core of the merger shows a decreased fraction of star-forming galaxies compared to clusters in the non-merging sample. This region, dominated by passive galaxies, is extended along the axis of the merger. We find evidence of rapid quenching of the galaxies during the core passage with no signs of a star burst on the time scales of the merger. Additionally, we report the tentative discovery of an infalling group along the main filament feeding the merger, currently at ~2.5Mpc from the merger centre. This group contains a high fraction of star forming galaxies as well as ~2/3 of all the recently quenched galaxies in our survey.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/11
- Title:
- Absorption features in SDSS. I. MgII abs. doublets
- Short Name:
- J/ApJS/235/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for MgII{lambda}{lambda}2796,2803 narrow absorption doublets in the spectra data around MgII{lambda}2798 emission lines. We obtain 17316 MgII doublets, within the redshift range of 0.3299<=z_abs_<=2.5663. We find that a velocity offset of {upsilon}_r_<6000km/s is a safe boundary to constrain the vast majority of associated Mg ii systems, although we find some doublets at {upsilon}_r_>6000km/s. If associated Mg ii absorbers are defined by {upsilon}_r_<6000km/s, ~33.3% of the absorbers are supposed to be contaminants of intervening systems. Removing the 33.3% contaminants, ~4.5% of the quasars present at least one associated MgII system with W_r_^{lambda}2796^>=0.2{AA}. The fraction of associated MgII systems with high-velocity outflows correlates with the average luminosities of their central quasars, indicating a relationship between outflows and the quasar feedback power. The {upsilon}_r_ distribution of the outflow MgII absorbers is peaked at 1023km/s, which is smaller than the corresponding value of the outflow CIV absorbers. The redshift number density evolution of absorbers (dn/dz) limited by {upsilon}_r_{>}-3000km/s differs from that of absorbers constrained by {upsilon}_r_>2000km/s. Absorbers limited by {upsilon}_r_>2000km/s and higher values exhibit profiles similar to dn/dz. In addition, the dn/dz is smaller when absorbers are constrained with larger {upsilon}_r_. The distributions of equivalent widths, and the ratio of W_r_^{lambda}2796^/W_r_^{lambda}2803^, are the same for associated and intervening systems, and independent of quasar luminosity.
- ID:
- ivo://CDS.VizieR/J/MNRAS/386/715
- Title:
- Absorption-line strengths in Coma galaxies
- Short Name:
- J/MNRAS/386/715
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present stellar population parameters of 12 elliptical and S0 galaxies in the Coma cluster around and including the cD galaxy NGC 4874, based on spectra obtained using the Low Resolution Imaging Spectrograph on the Keck II Telescope. Our data are among the most precise and accurate absorption-line strengths yet obtained for cluster galaxies, allowing us to examine in detail the zero-point and scatter in the stellar population properties of Coma cluster early-type galaxies (ETGs).
- ID:
- ivo://CDS.VizieR/J/A+A/412/707
- Title:
- Absorption-line systems in QSO spectra - CoALS
- Short Name:
- J/A+A/412/707
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Absorption lines and absorption-line systems (ALSs) observed in the spectra of QSOs contain fundamental information on distribution of matter between the observer and the QSO, and on physical processes in the Universe in different epochs of the cosmological evolution. The presented catalog contains a compilation of basic information on absorption-line systems (ALSs) in QSO spectra. The data are taken from publications available to the authors up to January 2002. The catalog includes, in particular, all the data of the catalogs by Junkkarinen et al. (1991ApJS...77..203J) and York et al. (1991MNRAS.250...24Y ). The catalog consists of table1.dat, table2.txt and the list of references in refs.dat file. The present catalog is also available at the site of the Dept. of Theor. Astrophys. of the Ioffe Physical Technical Institute: <www.ioffe.ru/astro/QC>
- ID:
- ivo://CDS.VizieR/J/ApJ/845/85
- Title:
- Absorption velocities for 21 super-luminous SNe Ic
- Short Name:
- J/ApJ/845/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Super-luminous supernovae (SLSNe) are tremendously luminous explosions whose power sources and progenitors are highly debated. Broad-lined SNe Ic (SNe Ic-bl) are the only type of SNe that are connected with long-duration gamma-ray bursts (GRBs). Studying the spectral similarity and difference between the populations of hydrogen-poor SLSNe (SLSNe Ic) and of hydrogen-poor stripped-envelope core-collapse SNe, in particular SNe Ic and SNe Ic-bl, can provide crucial observations to test predictions of theories based on various power source models and progenitor models. In this paper, we collected all of the published optical spectra of 32 SLSNe Ic, 21 SNe Ic-bl, as well as 17 SNe Ic, quantified their spectral features, constructed average spectra, and compared them in a systematic way using new tools we have developed. We find that SLSNe Ic and SNe Ic-bl, including those connected with GRBs, have comparable widths for their spectral features and average absorption velocities at all phases. Thus, our findings strengthen the connection between SLSNe Ic and GRBs. In particular, SLSNe Ic have average FeII{lambda}5169 absorption velocities of -15000+/-2600km/s at 10 days after peak, which are higher than those of SNe Ic by ~7000km/s on average. SLSNe Ic also have significantly broader FeII{lambda}5169 lines than SNe Ic. Moreover, we find that such high absorption and width velocities of SLSNe Ic may be hard to explain with the interaction model, and none of the 13 SLSNe Ic with measured absorption velocities spanning over 10 days has a convincing flat velocity evolution, which is inconsistent with the magnetar model in one dimension. Lastly, we compare SN 2011kl, the first SN connected with an ultra-long GRB, with the mean spectrum of SLSNe Ic and of SNe Ic-bl.
- ID:
- ivo://CDS.VizieR/J/ApJS/162/346
- Title:
- Abundance gradients in the Galaxy
- Short Name:
- J/ApJS/162/346
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Six HII regions at galactocentric distances of R=10-15kpc have been observed in the far-IR emission lines of [OIII] (52{mu}m, 88{mu}m), [NIII] (57{mu}m), and [SIII] (19{mu}m) using the Kuiper Airborne Observatory. These observations have been combined with Very Large Array radio continuum observations of these sources to determine the abundances of O++, N++, and S++ relative to hydrogen. In addition, eight of the most recent sets of measurements of ionic line strengths in HII regions have been reanalyzed in order to attempt to reconcile differences in optical versus far-IR abundance determinations. We have in total 168 sets of observations of 117 HII regions in our analysis.
