- ID:
- ivo://CDS.VizieR/VII/225B
- Title:
- The Canada-France Redshift Survey (CFRS)
- Short Name:
- VII/225B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Canada-France Redshift Survey (CFRS) is a collaboration between astronomers in Canada and France: Simon Lilly (University of Toronto), Olivier Le Fevre and Francois Hammer (Observatoire de Paris Meudon), David Crampton (Dominion Astrophysical Observatory, Victoria), Laurence Tresse (Cambridge University), and David Schade and Dan Hudon (University of Toronto). The survey is based primarily on observations with the 3.6m Canada-France-Hawaii Telescope (CFHT) on Mauna Kea, Hawaii. The CFRS consists of spectra of over 1000 faint objects selected to have 17.5 < I(AB) < 22.5 in five regions of sky. The survey is providing the first systematic study of normal galaxies at redshifts z > 0.5, corresponding to look-back times of greater than 50% of the age of the Universe. Observations of CFRS galaxies have also been made with the Hubble Space Telescope and the survey will form the basis of future studies with a number of other ground-based and space facilities. We have written a lay-persons guide to the CFRS and the main scientific results that are emerging from it.
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18702. The 3C and 3CR Catalogues
- ID:
- ivo://CDS.VizieR/VIII/1A
- Title:
- The 3C and 3CR Catalogues
- Short Name:
- VIII/1A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 3C Catalog is the result of observations with the Cambridge four-element interferometer at a frequency of 159MHz, and contains 471 sources between declinations -22 and +71degrees, with a flux density larger than 8Jy. The Revised version of the 3C (3CR) is based on new observations at a frequency of 178MHz, and represents a survey of all sources North of -05degrees with a flux density brighter than 9Jy, except in the areas near the ridge of galactic emission. The original numbering system has been preserved.
- ID:
- ivo://CDS.VizieR/J/MNRAS/182/273
- Title:
- The 5C6 and 5C7 surveys of radio sources.
- Short Name:
- J/MNRAS/182/273
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains the 5C6 and 5C7 radio surveys at 408 and 1407 MHz done with the with the One-Mile telescope at Cambridge (UK). The 5C6 survey of radio sources, made at 408 MHz (HPBW 80"x151") and 1407 MHz (HPBW 23"x44") was centered on 02:14 +32:00' (B1950) and contains 297 sources stronger than 10 mJy at 408 MHz and 1.5 mJy at 1407 MHz. The flux densities are on the KPW scale (Kellermann et al. 1969ApJ...157....1K) and were based on 3C147 and 3C380. Positions, positional errors, flux density information, and descriptions of optical objects visible on the Palomar Sky Survey within about 20" of the radio sources are given. The 5C7 survey of radio sources, made at 408 MHz (HPBW 80"x176") and 1407 MHz (HPBW 23"x51") was centered at 08:17 +27:00 (B1950) and contains 281 sources stronger than 10 mJy at 408 MHz and 1.5 mJy at 1407 MHz. The flux densities are on the KPW scale (Kellermann et al. 1969ApJ...157....1K), and were based on 3C147 and 3C380. Positions, positional errors, flux density information, and descriptions of optical objects visible on the Palomar Sky Survey within about 20" of the radio sources are given.
- ID:
- ivo://CDS.VizieR/J/ApJ/808/16
- Title:
- The Cannon: a new approach to determine abundances
- Short Name:
- J/ApJ/808/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New spectroscopic surveys offer the promise of stellar parameters and abundances ("stellar labels") for hundreds of thousands of stars; this poses a formidable spectral modeling challenge. In many cases, there is a subset of reference objects for which the stellar labels are known with high(er) fidelity. We take advantage of this with The Cannon, a new data-driven approach for determining stellar labels from spectroscopic data. The Cannon learns from the "known" labels of reference stars how the continuum-normalized spectra depend on these labels by fitting a flexible model at each wavelength; then, The Cannon uses this model to derive labels for the remaining survey stars. We illustrate The Cannon by training the model on only 542 stars in 19 clusters as reference objects, with Teff, logg, and [Fe/H] as the labels, and then applying it to the spectra of 55000 stars from APOGEE DR10. The Cannon is very accurate. Its stellar labels compare well to the stars for which APOGEE pipeline (ASPCAP) labels are provided in DR10, with rms differences that are basically identical to the stated ASPCAP uncertainties. Beyond the reference labels, The Cannon makes no use of stellar models nor any line-list, but needs a set of reference objects that span label-space. The Cannon performs well at lower signal-to-noise, as it delivers comparably good labels even at one-ninth the APOGEE observing time. We discuss the limitations of The Cannon and its future potential, particularly, to bring different spectroscopic surveys onto a consistent scale of stellar labels.
- ID:
- ivo://CDS.VizieR/J/ApJ/823/114
- Title:
- The Cannon: a new approach to determine masses
- Short Name:
- J/ApJ/823/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mass of a star is arguably its most fundamental parameter. For red giant stars, tracers luminous enough to be observed across the Galaxy, mass implies a stellar evolution age. It has proven to be extremely difficult to infer ages and masses directly from red giant spectra using existing methods. From the Kepler and APOGEE surveys, samples of several thousand stars exist with high-quality spectra and asteroseismic masses. Here we show that from these data we can build a data-driven spectral model using The Cannon, which can determine stellar masses to ~0.07dex from APOGEE DR12 spectra of red giants; these imply age estimates accurate to ~0.2dex (40%). We show that The Cannon constrains these ages foremost from spectral regions with CN absorption lines, elements whose surface abundances reflect mass-dependent dredge-up. We deliver an unprecedented catalog of 70000 giants (including 20000 red clump stars) with mass and age estimates, spanning the entire disk (from the Galactic center to R~20kpc). We show that the age information in the spectra is not simply a corollary of the birth-material abundances [Fe/H] and [{alpha}/Fe], and that, even within a monoabundance population of stars, there are age variations that vary sensibly with Galactic position. Such stellar age constraints across the Milky Way open up new avenues in Galactic archeology.
18706. The Carina Dwarf
- ID:
- ivo://CDS.VizieR/J/AJ/114/1458
- Title:
- The Carina Dwarf
- Short Name:
- J/AJ/114/1458
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our analysis of Hubble Space Telescope Wide Field Planetary Camera 2 observations in F555W (~V) and F814W (~I) of the Carina dwarf spheroidal galaxy. The resulting V vs V-I color-magnitude diagrams reach V~27.1mag. The reddening of Carina is estimated to be E(V-I)=0.08+/-0.02 mag. A new estimate of the distance modulus of Carina, (m-M)0=19.87+/-0.11mag, has been derived primarily from existing photometry in the literature. The apparent distance moduli in V and I were determined to be (m-M)V=20.05+/-0.11mag and (m-M)I=19.98+/-0.12mag, respectively. These determinations assumed that Carina has a metallicity of [Fe/H]=-1.9+/-0.2dex. This space-based observation, when combined with previous ground-based observations, is consistent with (but does not necessarily prove) the following star formation scenario. The Carina dwarf spheroidal galaxy formed its old stellar population in a short burst (<~3Gyr) at about the same time the Milky Way formed its globular clusters. The dominant burst of intermediate-age star formation then began in the central region of the galaxy where stars formed for several billion years before the process of star formation became efficient enough in the outer regions of the galaxy to allow for the formation of large numbers of stars. There has been negligible star formation during the last few billion years. This observation provides evidence that at least some dwarf galaxies can have complex global star formation histories with local variations of the rate of star formation as a function of time and position within the galaxy. (c) 1997 American Astronomical Society.
- ID:
- ivo://CDS.VizieR/J/AJ/126/197
- Title:
- The Carina projects. I. Bright variables stars
- Short Name:
- J/AJ/126/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new BV time series data of the Carina dwarf spheroidal galaxy (dSph). Current data cover an area of ~0.3deg^2^ around the center of the galaxy and allow us to identify 92 variables. Among them 75 are RR Lyrae stars, 15 are bona fide anomalous Cepheids, one might be a Galactic field RR Lyrae star, and one is located along the Carina red giant branch. Expanding upon the seminal photographic investigation by Saha, Monet, & Seitzer (1986AJ.....92..302S) we supply, for the first time, accurate estimates of their pulsation parameters (periods, amplitudes, mean magnitudes, and colors) on the basis of CCD photometry. Approximately 50% of both RR Lyrae stars and anomalous Cepheids are new identifications. Among the RR Lyrae sample, six objects are new candidate double-mode (RRd) variables. On the basis of their pulsation properties we estimate that two variables (V158, V182) are about 50% more massive than typical RR Lyrae stars, while the bulk of the anomalous Cepheids are roughly a factor of 2 more massive than fundamental-mode (RRab) RR Lyrae stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/830/126
- Title:
- The Carina project. X. Radial velocities
- Short Name:
- J/ApJ/830/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocity (RV) measurements of old (horizontal branch) and intermediate-age (red clump) stellar tracers in the Carina dwarf spheroidal. They are based on more than 2200 low-resolution spectra collected with VIMOS at Very Large Telescope (VLT). The targets are faint (20<~V<~21.5mag), but the accuracy at the faintest limit is <=9km/s. These data were complemented with RV measurements either based on spectra collected with FORS2 and FLAMES/GIRAFFE at VLT or available in the literature. We ended up with a sample of 2748 stars and among them, 1389 are candidate Carina stars. We found that the intermediate-age stellar component shows a well-defined rotational pattern around the minor axis. The western and the eastern side of the galaxy differ by +5 and -4km/s when compared with the main RV peak. The old stellar component is characterized by a larger RV dispersion and does not show evidence of the RV pattern. We compared the observed RV distribution with N-body simulations for a former disky dwarf galaxy orbiting a giant Milky Way-like galaxy. We rotated the simulated galaxy by 60{deg} with respect to the major axis, we kept the observer on the orbital plane of the dwarf and extracted a sample of stars similar to the observed one. Observed and predicted V_rot_/{sigma} ratios across the central regions are in remarkable agreement. This evidence indicates that Carina was a disky dwarf galaxy that experienced several strong tidal interactions with the Milky Way. Owing to these interactions, Carina transformed from a disky to a prolate spheroid and the rotational velocity transformed into random motions.
- ID:
- ivo://CDS.VizieR/J/ApJ/845/146
- Title:
- The Carnegie-Chicago Hubble Program. II. IC 1613
- Short Name:
- J/ApJ/845/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IC 1613 is an isolated dwarf galaxy within the Local Group. Low foreground and internal extinction, low metallicity, and low crowding make it an invaluable testbed for the calibration of the local distance ladder. We present new, high-fidelity distance estimates to IC 1613 via its Tip of the Red Giant Branch (TRGB) and its RR Lyrae (RRL) variables as part of the Carnegie-Chicago Hubble Program, which seeks an alternate local route to H_0_ using Population II stars. We have measured a TRGB magnitude I_ACS_^TRGB^=20.35+/-0.01_stat_+/-0.01_sys_mag using wide-field observations obtained from the IMACS camera on the Magellan-Baade telescope. We have further constructed optical and near-infrared RRL light curves using archival BI- and new H-band observations from the ACS/WFC and WFC3/IR instruments on board the Hubble Space Telescope (HST). In advance of future Gaia data releases, we set provisional values for the TRGB luminosity via the Large Magellanic Cloud and Galactic RRL zero-points via HST parallaxes. We find corresponding true distance moduli {mu}_0_^TRGB^=24.30+/-0.03_stat_+/-0.05_sys_mag and <{mu}_0_^RRL^>=24.28+/-0.04_stat+sys_mag. We compare our results to a body of recent publications on IC 1613 and find no statistically significant difference between the distances derived from Population I and II stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/197/21
- Title:
- The Carnegie-Irvine Galaxy Survey (CGS). I.
- Short Name:
- J/ApJS/197/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Carnegie-Irvine Galaxy Survey (CGS) is a long-term program to investigate the photometric and spectroscopic properties of a statistically complete sample of 605 bright (B_T_<12.9mag), southern ({delta}<0{deg}) galaxies using the facilities at Las Campanas Observatory. This paper, the first in a series, outlines the scientific motivation of CGS, defines the sample, and describes the technical aspects of the optical broadband (BVRI) imaging component of the survey, including details of the observing program, data reduction procedures, and calibration strategy. The overall quality of the images is quite high, in terms of resolution (median seeing ~1"), field of view (8.9'x8.9'), and depth (median limiting surface brightness ~27.5, 26.9, 26.4, and 25.3mag/arcsec^2^ in the B, V, R, and I bands, respectively). We prepare a digital image atlas showing several different renditions of the data, including three-color composites, star-cleaned images, stacked images to enhance faint features, structure maps to highlight small-scale features, and color index maps suitable for studying the spatial variation of stellar content and dust. In anticipation of upcoming science analyses, we tabulate an extensive set of global properties for the galaxy sample. These include optical isophotal and photometric parameters derived from CGS itself, as well as published information on multiwavelength (ultraviolet, U-band, near-infrared, far-infrared) photometry, internal kinematics (central stellar velocity dispersions, disk rotational velocities), environment (distance to nearest neighbor, tidal parameter, group, or cluster membership), and HI content.