- ID:
- ivo://CDS.VizieR/J/AJ/142/3
- Title:
- 1.4GHz observations of Stripe 82
- Short Name:
- J/AJ/142/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high-resolution radio survey of the Sloan Digital Sky Survey (SDSS) Southern Equatorial Stripe, a.k.a. Stripe 82. This 1.4GHz survey was conducted with the Very Large Array primarily in the A-configuration, with supplemental B-configuration data to increase sensitivity to extended structure. The survey has an angular resolution of 1.8" and achieves a median rms noise of 52{mu}Jy/beam over 92deg^2^. This is the deepest 1.4GHz survey to achieve this large of an area, filling a gap in the phase space between small, deep and large, shallow surveys. It also serves as a pilot project for a larger high-resolution survey with the Expanded Very Large Array. We discuss the technical design of the survey and details of the observations, and we outline our method for data reduction. We present a catalog of 17969 isolated radio components, for an overall source density of ~195sources/deg^2^. The astrometric accuracy of the data is excellent, with an internal check utilizing multiply observed sources yielding an rms scatter of 0.19" in both right ascension and declination. A comparison to the SDSS-DR7 Quasar Catalog further confirms that the astrometry is well tied to the optical reference frame, with mean offsets of 0.02+/-0.01" in right ascension, and 0.01+/-0.02" in declination. A check of our photometry reveals a small, negative CLEAN-like bias on the level of 35{mu}Jy. We report on the catalog completeness, finding that 97% of FIRST-detected quasars are recovered in the new Stripe 82 radio catalog, while faint, extended sources are more likely to be resolved out by the resolution bias. We conclude with a discussion of the optical counterparts to the catalog sources, including 76 newly detected radio quasars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/482/483
- Title:
- GHz-peaked spectrum (GPS) sources
- Short Name:
- J/A+A/482/483
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gigahertz-peaked spectrum (GPS) sources and high frequency peakers (HFPs) are among the smallest of active galactic nuclei currently believed to represent the earliest phases in the evolution of extragalactic radio sources. Recently there has been evidence of contamination by other types of radio sources among the GPS and HFP samples, but the confirmed GPS sources or HFPs also seem to form a very heterogeneous population. We study the statistical clustering of the GPS sources and the HFPs by taking as many source parameters as possible to find homogeneous groups among the sources. We expect the clustering to give us insight into the physical parameters that play a role in different source populations. We have collected a sample of 206 GPS sources and HFPs from the literature and gathered a massive database of various source properties, such as the redshift, the size, the polarization, the magnitudes, and the properties of the radio continuum. To visualize and to cluster these multidimensional data we used self-organising maps (SOM), which are neural networks trained by an unsupervised algorithm. We have classified the sources with an auxiliary classification to trace the locations of different types of radio continuum spectra on the map.
- ID:
- ivo://CDS.VizieR/J/A+A/418/103
- Title:
- 86GHz SiO maser survey in the Inner Galaxy
- Short Name:
- J/A+A/418/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a compilation and study of DENIS, 2MASS, ISOGAL, MSX and IRAS 1-25 microns photometry for a sample of 441 late-type stars in the inner Galaxy, which we previously searched for 86GHz SiO maser emission (Messineo et al., 2002, Cat. <J/A+A/393/115>). The comparison of the DENIS and 2MASS J and Ks magnitudes shows that most of the SiO targets are indeed variable stars. The MSX colours and the IRAS [12]-[25] colour of our SiO targets are consistent with those of Mira type stars with dust silicate feature at 9.7 microns feature in emission, indicating only a moderate mass-loss rate.
- ID:
- ivo://CDS.VizieR/J/PAZh/22/269
- Title:
- Giant branch and variable stars in NGC 3201
- Short Name:
- J/PAZh/22/269
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate equatorial coordinates have been determined for variable stars in the globular cluster NGC 3201. Results of photographic BV photometry are presented.
- ID:
- ivo://CDS.VizieR/J/AJ/89/636
- Title:
- Giant M stars in Baade's Window
- Short Name:
- J/AJ/89/636
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-infrared small-dispersion spectra obtained with a grism at the prime focus of CTIO's 4-m telescope have been used to survey and classify late-type red giants found in a circular area with a diameter of 24.4 arcmin which is contained within Baade's Window. The survey is complete to a distance that extends past the galactic nuclear bulge. The presented stars therefore constitute a unique complete sample of the red giant population of the nuclear bulge. A total of 306 red giants, including all giants of type M6 or later, are presented with a list of their coordinates, spectral classes, and apparent I magnitudes. A finding chart is also given. No C or S stars were found even though they should have been detected if they exist. Evidence is presented of uneven foreground interstellar obscuration in Baade's Window.
2236. Giants DDO photometry
- ID:
- ivo://CDS.VizieR/J/AJ/100/1191
- Title:
- Giants DDO photometry
- Short Name:
- J/AJ/100/1191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of G and K giants approximately 4kpc from the Sun, covering the abundance range from solar to extreme halo has been selected without kinematic bias in a field aligned to measure galactic rotation. Accurate abundances, distances, and radial velocities have been measured. This sample has been combined with nonkinematically selected solar neighborhood objects taken from the literature, in order to examine the kinematics of the transition from disk to "thick disk" to halo. The metal-rich objects in the sample, with 0>[Fe/H]>-0.8, rotate rapidly around the galactic center and have low azimuthal velocity dispersion, {sigma}_{phi}_=40+/-10km/s. For objects in the range -0.5>[Fe/H]>-0.8, we find a small value for the asymmetric drift of 35+/-10km/s. We associate these objects with the thick disk, confirming the kinematical results of Ratnatunga and Freeman (1989, Cat.<V/65>) and others. In the abundance range -1.0>[Fe/H]>=-1.6 we find, in addition to objects with normal halo kinematics, objects in a disk configuration, confirming the results of Norris, Bessell, and Pickles (1985ApJS...58..463N). This disk is rotating rapidly, V_rot_=170+/-15km/s, and has a scale height of 1.4+/-0.7kpc, these kinematical and spatial properties are similar to those of the thick disk. We show that these objects have different kinematics from that of the globular clusters and a sample of local RR Lyraes in the same abundance range. This suggests to us that these objects are better associated with the thick disk than the halo, and we refer to them as "metal-weak thick-disk stars". Hence we suggest that the conventional chemical description of the thick disk (Gilmore and Wyse, 1985AJ.....90.2015G) be widened to include stars with abundances as low as [Fe/H]=-1.6. At the galactic plane, the density of these metal-weak thick-disk stars is similar to that of halo stars, so they significantly affect the measurement, from samples selected on abundance, of the components of the velocity ellipsoid for the halo in the solar neighborhood. For the halo giants in our sample we measure {sigma}_{phi}_=102+/-24 and V_rot_=17+/-24km/s. The rotation velocity and velocity ellipsoid for the metal-weak halo in the solar neighborhood have been rederived for objects with [Fe/H]<=-1.6 from the large sample of Norris (1986ApJS...61..667N), thus removing the possibility of contamination by metal-weak thick-disk stars. We derive V_rot_=25+/-15km/s and ({sigma}_r_, {sigma}_{phi}_, {sigma}_{theta}_)=(133+/-8, 98+/-13, 94+/-6)km/s. These values are more consistent with other information about the shape of the halo. For a description of the DDO photometric system, see e.g. <GCPD/12>
- ID:
- ivo://CDS.VizieR/J/A+A/577/A59
- Title:
- g'i' photometry in 5 isolated elliptical galaxies
- Short Name:
- J/A+A/577/A59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As tracers of star formation, galaxy assembly and mass distribution, globular clusters have provided important clues to our understanding of early-type galaxies. But their study has been mostly constrained to galaxy groups and clusters where early-type galaxies dominate, leaving the properties of the globular cluster systems (GCSs) of isolated ellipticals as a mostly uncharted territory. We present Gemini-South/GMOS g'i' observations of five isolated elliptical galaxies: NGC 3962, NGC 2865, IC 4889, NGC 2271 and NGC 4240. Photometry of their GCSs reveals clear color bimodality in three of them, remaining inconclusive for the other two. All the studied GCSs are rather poor with a mean specific frequency S_N_~1.5, independently of the parent galaxy luminosity. Considering also previous work, it is clear that bimodality and especially the presence of a significant, even dominant, population of blue clusters occurs at even the most isolated systems, casting doubts on a possible accreted origin of metal-poor clusters as suggested by some models. Additionally, we discuss the possible existence of ultra-compact dwarfs around the isolated elliptical NGC 3962.
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/3702
- Title:
- gi photometry of Bootes I
- Short Name:
- J/MNRAS/461/3702
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep stellar photometry of the Bootes I dwarf spheroidal galaxy in g- and i-band filters, taken with the Dark Energy Camera at Cerro Tololo in Chile. Our analysis reveals a large, extended region of stellar substructure surrounding the dwarf, as well as a distinct overdensity encroaching on its tidal radius. A radial profile of the Bootes I stellar distribution shows a break radius indicating the presence of extra-tidal stars. These observations strongly suggest that Bootes I is experiencing tidal disruption, although not as extreme as that exhibited by the Hercules dwarf spheroidal. Combined with revised velocity dispersion measurements from the literature, we see evidence suggesting the need to review previous theoretical models of the Bootes I dwarf spheroidal galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/1425
- Title:
- gi photometry of 14 LMC star clusters
- Short Name:
- J/MNRAS/444/1425
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Gemini South GMOS g, i photometry of 14 intermediate-age Large Magellanic Cloud (LMC) star clusters, namely: NGC 2155, 2161, 2162, 2173, 2203, 2209, 2213, 2231, 2249, Hodge 6, SL 244, 505, 674, and 769, as part of a continuing project to investigate the extended main-sequence turn-off (EMSTO) phenomenon. Extensive artificial star tests were made over the observed field of view. These tests reveal the observed behaviour of photometric errors with magnitude and crowding. The cluster stellar density radial profiles were traced from star counts over the extent of the observed field. We adopt cluster radii and build colour-magnitude diagrams (CMDs) with cluster features clearly identified. We used the cluster (g, g-i) CMDs to estimate ages from the matching of theoretical isochrones. The studied LMC clusters are confirmed to be intermediate-age clusters, which range in age 9.10<log(t)<9.60. NGC 2162 and NGC 2249 look like new EMSTO candidates, in addition to NGC 2209, on the basis of having dual red clumps.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/30
- Title:
- gi photometry of Sextans dSph galaxy stars
- Short Name:
- J/MNRAS/460/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present wide-field g- and i-band stellar photometry of the Sextans dwarf spheroidal galaxy and its surrounding area out to four times its half-light radius (r_h_=695pc), based on images obtained with the Dark Energy Camera at the 4-m Blanco telescope at CTIO. We find clear evidence of stellar substructure associated with the galaxy, extending to a distance of 82-arcmin (2kpc) from its centre. We perform a statistical analysis of the overdensities and find three distinct features, as well as an extended halo-like structure, to be significant at the 99.7 per cent confidence level or higher. Unlike the extremely elongated and extended substructures surrounding the Hercules dwarf spheroidal galaxy, the overdensities seen around Sextans are distributed evenly about its centre, and do not appear to form noticeable tidal tails. Fitting a King model to the radial distribution of Sextans stars yields a tidal radius r_t_=83.2-arcmin+/-7.1 arcmin (2.08+/-0.18kpc), which implies the majority of detected substructure is gravitationally bound to the galaxy. This finding suggests that Sextans is not undergoing significant tidal disruption from the Milky Way, supporting the scenario in which the orbit of Sextans has a low eccentricity.
