Search

Start Over Subject photometry
6651. The B[e] phenomenon. VII. AS 386 follow-up
ID:
ivo://CDS.VizieR/J/ApJ/856/158
Title:
The B[e] phenomenon. VII. AS 386 follow-up
Short Name:
J/ApJ/856/158
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of spectroscopic and photometric observations of the emission-line object AS 386. For the first time we found that it exhibits the B[e] phenomenon and fits the definition of an FS CMa type object. The optical spectrum shows the presence of a B-type star with the following properties: Teff=11000+/-500K, log L/L_{sun}_=3.7+/-0.3, a mass of 7+/-1M_{sun}_, and a distance D=2.4+/-0.3kpc from the Sun. We detected regular radial velocity variations of both absorption and emission lines with the following orbital parameters: Porb=131.27+/-0.09 days, semiamplitude K1=51.7+/-3.0km/s, systemic radial velocity {gamma}=-31.8+/-2.6km/s, and a mass function of f(m)=1.9+/-0.3M_{sun}_. AS 386 exhibits irregular variations of the optical brightness (V=10.92+/-0.05mag), while the near-IR brightness varies up to ~0.3mag following the spectroscopic period. We explain this behavior by a variable illumination of the dusty disk inner rim by the B-type component. Doppler tomography based on the orbital variations of emission-line profiles shows that the material is distributed near the B-type component and in a circumbinary disk. We conclude that the system has undergone a strong mass transfer that created the circumstellar material and increased the B-type component mass. The absence of any traces of a secondary component, whose mass should be >=7M_{sun}_, suggests that it is most likely a black hole.
6652. The Blanco Cosmology Survey (BCS)
ID:
ivo://CDS.VizieR/J/ApJ/757/83
Title:
The Blanco Cosmology Survey (BCS)
Short Name:
J/ApJ/757/83
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Blanco Cosmology Survey (BCS) is a 60 night imaging survey of ~80deg^2^ of the southern sky located in two fields: (5hr,-55{deg}) and (23hr,-55{deg}). The survey was carried out between 2005 and 2008 in griz bands with the Mosaic2 imager on the Blanco 4m telescope. The primary aim of the BCS survey is to provide the data required to optically confirm and measure photometric redshifts for Sunyaev-Zel'dovich effect selected galaxy clusters from the South Pole Telescope and the Atacama Cosmology Telescope. We process and calibrate the BCS data, carrying out point-spread function-corrected model-fitting photometry for all detected objects. The median 10{sigma} galaxy (point-source) depths over the survey in griz are approximately 23.3 (23.9), 23.4 (24.0), 23.0 (23.6), and 21.3 (22.1), respectively. The astrometric accuracy relative to the USNO-B survey is ~45mas. We calibrate our absolute photometry using the stellar locus in grizJ bands, and thus our absolute photometric scale derives from the Two Micron All Sky Survey, which has ~2% accuracy. The scatter of stars about the stellar locus indicates a systematic floor in the relative stellar photometric scatter in griz that is ~1.9%, ~2.2%, ~2.7%, and ~2.7%, respectively. A simple cut in the AstrOmatic star-galaxy classifier spread_ model produces a star sample with good spatial uniformity. We use the resulting photometric catalogs to calibrate photometric redshifts for the survey and demonstrate scatter {delta}z/(1+z)=0.054 with an outlier fraction {eta}<5% to z~1. We highlight some selected science results to date and provide a full description of the released data products.
6653. The 4 brightest red giants in the UFD galaxy Ret 2
ID:
ivo://CDS.VizieR/J/AJ/151/82
Title:
The 4 brightest red giants in the UFD galaxy Ret 2
Short Name:
J/AJ/151/82
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ultra-faint dwarf (UFD) galaxy Reticulum 2 (Ret 2) was recently discovered in images obtained by the Dark Energy Survey (Diehl et al. 2014SPIE.9149E..0VD). We have observed the four brightest red giants in Ret 2 at high spectral resolution using the Michigan/Magellan Fiber System. We present detailed abundances for as many as 20 elements per star, including 12 elements heavier than the Fe group. We confirm previous detection of high levels of r-process material in Ret 2 (mean [Eu/Fe]=+1.69+/-0.05) found in three of these stars (mean [Fe/H]=-2.88+/-0.10). The abundances closely match the r-process pattern found in the well-studied metal-poor halo star CS 22892-052. Such r-process-enhanced stars have not been found in any other UFD galaxy, though their existence has been predicted by at least one model. The fourth star in Ret 2 ([Fe/H]=-3.42+/-0.20) contains only trace amounts of Sr ([Sr/Fe]=-1.73+/-0.43) and no detectable heavier elements. One r-process enhanced star is also enhanced in C (natal [C/Fe]~+1.1). This is only the third such star known, which suggests that the nucleosynthesis sites leading to C and r-process enhancements are decoupled. The r-process-deficient star is enhanced in Mg ([Mg/Fe]=+0.81+/-0.14), and the other three stars show normal levels of {alpha}-enhancement (mean [Mg/Fe]=+0.34+/-0.03). The abundances of other {alpha} and Fe-group elements closely resemble those in UFD galaxies and metal-poor halo stars, suggesting that the nucleosynthesis that led to the large r-process enhancements either produced no light elements or produced light-element abundance signatures indistinguishable from normal supernovae.
6654. The Canada-France Redshift Survey (CFRS)
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.
6655. 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.
6656. The Carina projects. I. Bright variables stars
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.
6657. The Carina project. X. Radial velocities
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.
6658. The Carnegie-Chicago Hubble Program. II. IC 1613
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.
6659. The Carnegie-Irvine Galaxy Survey (CGS). I.
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.
6660. The Carnegie-Irvine Galaxy Survey (GGS). II.
ID:
ivo://CDS.VizieR/J/ApJS/197/22
Title:
The Carnegie-Irvine Galaxy Survey (GGS). II.
Short Name:
J/ApJS/197/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Carnegie-Irvine Galaxy Survey (CGS) is a comprehensive investigation of the physical properties of a complete, representative sample of 605 bright (B_T_<=12.9mag) galaxies in the southern hemisphere. This contribution describes the isophotal analysis of the broadband (BVRI) optical imaging component of the project. We pay close attention to sky subtraction, which is particularly challenging for some of the large galaxies in our sample. Extensive crosschecks with internal and external data confirm that our calibration and sky subtraction techniques are robust with respect to the quoted measurement uncertainties. We present a uniform catalog of one-dimensional radial profiles of surface brightness and geometric parameters, as well as integrated colors and color gradients. We use the geometric parameters, in conjunction with the amplitude and phase of the m=2 Fourier mode, to identify bars and quantify their size and strength. Finally, we utilize the information encoded in the m=1 Fourier profiles to measure disk lopsidedness.