- ID:
- ivo://CDS.VizieR/J/AJ/160/199
- Title:
- Estimated distances for ~12000 galaxies with NED-D
- Short Name:
- J/AJ/160/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Numerous research topics rely on an improved cosmic distance scale (e.g., cosmology, gravitational waves) and the NASA/IPAC Extragalactic Database of Distances (NED-D) supports those efforts by tabulating multiple redshift-independent distances for 12000 galaxies (e.g., Large Magellanic Cloud (LMC) zero-point). Six methods for securing a mean estimate distance (MED) from the data are presented (e.g., indicator and Decision Tree). All six MEDs yield surprisingly consistent distances for the cases examined, including for the key benchmark LMC and M106 galaxies. The results underscore the utility of the NED-D MEDs in bolstering the cosmic distance scale and facilitating the identification of systematic trends.
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Search Results
- ID:
- ivo://org.gavo.dc/gdr2dist/q/cone
- Title:
- Estimated distances to 1.33 billion stars in Gaia DR2
- Short Name:
- gdr2dist scs
- Date:
- 15 Aug 2024 15:17:03
- Publisher:
- The GAVO DC team
- Description:
- This catalogue provides distances estimates (and uncertainties therein) for 1.33 billion stars over the whole sky brighter than about G=20.7. These have been estimated using the parallaxes (and their uncertainties) from Gaia DR2. A Bayesian procedure was used involving a prior with a single parameter L(l,b), which varies smoothly with Galactic longitude and latitude according to a Galaxy model. The posterior is summarized with a point estimate (usually the mode) and a confidence interval (usually the 68% highest density interval). The estimation procedure is described in detail in the `accompanying paper`_, which also analyses the catalogue content. .. _accompanying paper: http://www.mpia.de/homes/calj/gdr2_distances.html
- ID:
- ivo://CDS.VizieR/J/MNRAS/432/2112
- Title:
- Estimating gas masses from HI and CO data
- Short Name:
- J/MNRAS/432/2112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a method to estimate the total gas column density, dust-to-gas and dust-to-metal ratios of distant galaxies from rest-frame optical spectra. The technique exploits the sensitivity of certain optical lines to changes in depletion of metals on to dust grains and uses photoionization models to constrain these physical ratios along with the metallicity and dust column density. We compare our gas column density estimates with HI and CO gas mass estimates in nearby galaxies to show that we recover their total gas mass surface density to within a factor of 2 up to a total surface gas mass density of ~75M{sun}/pc^2^. Our technique is independent of the conversion factor of CO to H_2_ and we show that a metallicity-dependent X_CO_ is required to achieve good agreement between our measurements and that provided by CO and HI. However, we also show that our method cannot be reliably aperture corrected to total integrated gas mass. We calculate dust-to-gas ratios for all star-forming galaxies in the Sloan Digital Sky Survey Data Release 7 and show that the resulting dependence on metallicity agrees well with the trend inferred from modelling of the dust emission of nearby galaxies using far-IR data. We also present estimates of the variation of the dust-to-metal ratio with metallicity and show that this is poorly constrained at metallicities below 50% solar. We conclude with a study of the inventory of gas in the central regions, defined both in terms of a fixed physical radius and as a fixed fraction of the half-light radius, of ~70000 star-forming galaxies from the Sloan Digital Sky Survey. We show that their central gas content and gas depletion time are not accurately predicted by a single parameter, but in agreement with recent studies we find that a combination of the stellar mass and some measure of central concentration provides a good predictor of gas content in galaxies. We also identify a population of galaxies with low surface densities of stars and very long gas depletion times.
- ID:
- ivo://CDS.VizieR/J/AJ/117/981
- Title:
- Estimation of stellar metal abundance. II.
- Short Name:
- J/AJ/117/981
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have recalibrated a method for the estimation of stellar metal abundance, parameterized as [Fe/H], based on medium-resolution (1-2{AA}) optical spectra (the majority of which cover the wavelength range 3700-4500{AA}). The equivalent width of the Ca II K line (3933{AA}) as a function of [Fe/H] and broadband B-V color, as predicted from spectrum synthesis and model atmosphere calculations, is compared with observations of 551 stars with high-resolution abundances available from the literature (a sevenfold increase in the number of calibration stars that were previously available). A second method, based on the Fourier autocorrelation function technique first described by Ratnatunga & Freeman (1989, Cat. <V/65>), is used to provide an independent estimate of [Fe/H], as calibrated by comparison with 405 standard-star abundances.
- ID:
- ivo://CDS.VizieR/J/A+A/594/A106
- Title:
- eta Car velocity-resolved imaging
- Short Name:
- J/A+A/594/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mass loss from massive stars is not understood well. eta Carinae is a unique object for studying the massive stellar wind during the luminous blue variable phase. It is also an eccentric binary with a period of 5.54yr. The nature of both stars is uncertain, although we know from X-ray studies that there is a wind-wind collision whose properties change with orbital phase. We want to investigate the structure and kinematics of eta Car's primary star wind and wind-wind collision zone with a high spatial resolution of ~6mas (~14au) and high spectral resolution of R=12000. Observations of eta Car were carried out with the ESO Very Large Telescope Interferometer (VLTI) and the AMBER instrument between approximately five and seven months before the August 2014 periastron passage. Velocity-resolved aperture-synthesis images were reconstructed from the spectrally dispersed interferograms. Interferometric studies can provide information on the binary orbit, the primary wind, and the wind collision.
- ID:
- ivo://nasa.heasarc/etachamain
- Title:
- Eta Chamaeleontis eROSITA EDR Field X-Ray (0.2-2.3 keV) Source Catalog
- Short Name:
- ETACHAMAIN
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table contains the "main" (0.2-2.3 keV) catalog of the X-ray sources in the eta Chamaeleontis field scan eROSITA observation (OBSID 300004; see Robrade et al., 2022). The nearby young open cluster eta Chamaeleontis was observed by eROSITA/SRG during its CalPV phase for 150 ks. The eROSITA data were taken in the field-scan mode, an observing mode of Spectrum-Roentgen-Gamma (SRG) that follows a rectangular grid-like pattern, covering a 5x5 deg field with an exposure depth of about 5 ks. The authors studied the known members in X-rays and searched for potential new members of the anticipated dispersed low-mass cluster population. Detected sources were identified by cross-matching X-ray sources with Gaia and 2MASS, and young stars were identified by their X-ray activity, by their position in the color-magnitude diagram, and by their astrometric and kinematic properties. X-ray luminosities, light curves, and spectra of cluster members were obtained and compared with previous X-ray data. Literature results of other member searches were used to verify the new member candidates in the observed field. The authors determined X-ray properties of virtually all known eta Cha members and identified five additional stellar systems that showed basically identical characteristics, but are more dispersed. Four of them were previously proposed as potential members; this status is supported by this X-ray study. Based on their spatial distribution, further members are expected beyond the sky region surveyed. The identified stellar systems very likely belong to the ejected halo population, which brings the total number of eta Cha cluster members to at least 23. <a href="/W3Browse/erosita/etachahard.html">ETACHAHARD</a> is the related catalog of hard band (2.3-5.0 keV) sources. This database table was ingested by the HEASARC in August 2022 and is based upon a file downloaded from the eROSITA-DE Early Data Release <a href="https://erosita.mpe.mpg.de/edr/eROSITAObservations/Catalogues/">catalogs web page</a>. In some cases, the HEASARC has altered the original field names, as per HEASARC conventions, and provides the original field names in square brackets. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/etachahard
- Title:
- Eta Chamaeleontis eROSITA EDR Field X-Ray (2.3-5.0 keV) Source Catalog
- Short Name:
- ETACHAHARD
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table contains the catalog of the X-ray sources in the eta Chamaeleontis field scan eROSITA observation (OBSID 300004; see Robrade et al., 2022) in the hard (2.3-5.0 keV) band. The nearby young open cluster eta Chamaeleontis was observed by eROSITA/SRG during its CalPV phase for 150 ks. The eROSITA data were taken in the field-scan mode, an observing mode of Spectrum-Roentgen-Gamma (SRG) that follows a rectangular grid-like pattern, covering a 5x5 deg field with an exposure depth of about 5 ks. The authors studied the known members in X-rays and searched for potential new members of the anticipated dispersed low-mass cluster population. Detected sources were identified by cross-matching X-ray sources with Gaia and 2MASS, and young stars were identified by their X-ray activity, by their position in the color-magnitude diagram, and by their astrometric and kinematic properties. X-ray luminosities, light curves, and spectra of cluster members were obtained and compared with previous X-ray data. Literature results of other member searches were used to verify the new member candidates in the observed field. The authors determined X-ray properties of virtually all known eta Cha members and identified five additional stellar systems that showed basically identical characteristics, but are more dispersed. Four of them were previously proposed as potential members; this status is supported by this X-ray study. Based on their spatial distribution, further members are expected beyond the sky region surveyed. The identified stellar systems very likely belong to the ejected halo population, which brings the total number of eta Cha cluster members to at least 23. <a href="/W3Browse/erosita/etachamain.html">ETACHAMAIN</a> is the related catalog of main (0.2-2.3 keV) sources. This database table was ingested by the HEASARC in August 2022 and is based upon a file downloaded from the eROSITA-DE Early Data Release <a href="https://erosita.mpe.mpg.de/edr/eROSITAObservations/Catalogues/">catalogs web page</a>. In some cases, the HEASARC has altered the original field names, as per HEASARC conventions, and provides the original field names in square brackets. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJ/810/138
- Title:
- ETGs sample for the Coma cluster
- Short Name:
- J/ApJ/810/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the properties of early-type galaxies (ETGs), including ellipticals (E) and lenticulars (S0), in rich environments, such as clusters of galaxies (Virgo and Coma). The L_24_/L_K_ distribution of ETGs in both Virgo and Coma clusters shows that some S0s have a much larger L_24_/L_K_ ratio (0.5 to ~2 dex) than the bulk of the ETG population. This could be interpreted as an enhanced star formation rate in these lenticulars. We compare the optical colors of galaxies in these two clusters and investigate the nature of these sources with a large L_24_/L_K_ ratio by looking at their spatial distribution within the cluster, analyzing their optical spectra, and looking at their optical colors compared to late-types. We obtain 10 Coma and 3 Virgo early-type sources with larger L_24_/L_K_ ratios than the bulk of their population. We call these sources mid-infrared enhanced galaxies (MIEGs). In Coma, they are mostly located in the southwest part of the cluster where a substructure is falling onto the main cluster. MIEGs present a lower g-r color than the rest of the ETG sample because of a blue continuum. We interpret the excess L_24_/L_K_ ratio as evidence for enhanced star formation induced as a consequence of their infall into the main cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/381/500
- Title:
- Eu abundances in F and G disk stars
- Short Name:
- J/A+A/381/500
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Europium abundances for 74 F and G dwarf stars of the galactic disk have been determined. The stars were selected from the sample of Edvardsson et al. (1993, Cat. <J/A+A/275/101>) and [Eu/Fe] shows a smaller scatter and a slightly weaker trend with [Fe/H] than found by Woolf et al. (1995ApJ...453..660W). The data of the two analyses are homogeneized and merged.
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/744
- Title:
- EUADP sample. [N/{alpha}] distribution
- Short Name:
- J/MNRAS/444/744
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report here a study of nitrogen and {alpha}-capture element (O, S, and Si) abundances in 18 damped Ly{alpha} absorbers (DLAs) and sub-DLAs drawn from the European Southern Observatory's Ultraviolet Visual Echelle Spectrograph (ESO-UVES) Advanced Data Products (EUADP) data base. We report nine new measurements, five upper and four lower limits of nitrogen that when compiled with available nitrogen measurements from the literature makes a sample of 10^8^ systems. The extended sample presented here confirms the [N/{alpha}] bimodal behaviour suggested in previous studies. Three-quarter of the systems show <[N/{alpha}]>=-0.85 (+/-0.20dex) and one-quarter of the systems show that ratios are clustered at <[N/{alpha}]>=-1.41 (+/-0.14dex). The high [N/{alpha}] plateau is consistent with the Hii regions of dwarf irregular and blue compact dwarf galaxies although extended to lower metallicities and could be interpreted as the result of a primary nitrogen production by intermediate mass stars. The low [N/{alpha}] values are the lowest ever observed in any astrophysical site. In spite of this fact, even lower values could be measured with the present instrumentation, but we do not find them below [N/{alpha}]~-1.7. This suggests the presence of a floor in [N/{alpha}] abundances, which along with the lockstep increase of N and Si may indicate a primary nitrogen production from fast rotating, massive stars in relatively young or unevolved systems.