- ID:
- ivo://CDS.VizieR/J/ApJ/889/56
- Title:
- VVV survey microlensing events; -3.7<b{<}-3.9{deg}
- Short Name:
- J/ApJ/889/56
- Date:
- 17 Jan 2022 11:50:08
- Publisher:
- CDS
- Description:
- We search for microlensing events in fields along the Galactic minor axis, ranging from the Galactic center to -3.7{deg}<b<3.9{deg} using the VISTA Variables in the Via Lactea (VVV) survey near-IR photometry. The new search is made across VVV tiles b291, b305, b319, b347, b361, and b375, covering a total area of about 11.5deg^2^. We find a total of N=238 new microlensing events in this new area, N=74, which are classified as bulge red clump (RC) giant sources. Combining them with N=122 events that we had previously reported in the Galactic center (VVV tile b333), allows us to study the latitude distribution of the microlensing events reaching the Galactic plane at b=00 for the first time. We find a very strong dependence of the number of microlensing events with Galactic latitude, a number that increases rapidly toward the Galactic center by one order of magnitude from |b|=2{deg} to b=0{deg} with a much steeper gradient than with Galactic longitude. The microlensing event population shows a flattened distribution (axial ratio b/a~1.5). The final sample shows a shorter mean timescale distribution than the Galactic plane sample for both the complete population and RC stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/893/65
- Title:
- VVV Survey microlensing events in the Gal. Bulge
- Short Name:
- J/ApJ/893/65
- Date:
- 19 Jan 2022 11:43:07
- Publisher:
- CDS
- Description:
- We search for microlensing events in the zero-latitude area of the Galactic Bulge using the VVV Survey near-IR data. We have discovered a total sample of N=630 events within an area covering 20.68deg^2^ between the years 2010 and 2015. In this paper, we describe the search and present the data for the final sample, including near-IR magnitudes, colors, and proper motions, as well as the standard microlensing parameters. We use the near-IR color-magnitude and color-color diagrams to select NRC=290 events with red-clump sources to analyze the extinction properties of the sample in the central region of the Galactic plane. The timescale distribution and its dependence in the longitude axis is presented. The mean timescale decreases as we approach the Galactic minor axis (b=0{deg}). Finally, we give examples of special microlensing events, such as binaries, short-timescale events, and events with a strong parallax effect.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A169
- Title:
- VVV survey near-infrared colour catalogue
- Short Name:
- J/A+A/647/A169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Vista Variables in the Via Lactea (VVV) near-infrared (IR) variability survey explores some of the most complicated regions of the Milky Way bulge and disk in terms of high extinction and high crowding. We add a new wavelength dimension to the optical information available at the American Association of Variable Star Observers International Variable Star Index (VSX-AAVSO) catalogue to test the VVV survey near-IR photometry to better characterise these objects. We cross-match the VVV and the VSX-AAVSO catalogues along with Gaia Data Release 2 photometry and parallax. We present a catalogue that includes accurate individual coordinates, near-IR magnitudes (ZYJHKs), extinctions AKs, and distances based on Gaia parallaxes. We also show the near-IR CMDs and spatial distributions for the different VSX types of variable stars, including important distance indicators, such as RR Lyrae, Cepheids and Miras. By analysing the photometric flags in our catalogue, we found that around 20% of the stars with measured and verified variability are flagged as "non-stellar source", even when they are outside of the saturation and/or noise regimes. Additionally, we pair-matched our sample with the VIVA catalogue and found that more than half of our sources are missing from the VVV variability list, mostly due to low signal-to-noise observations or photometric problems with a small percentage due to failures in the selection process. Conclusions. Our results suggest that the current knowledge about variability in the Galaxy is biased to the nearby, low extincted stars. The present catalogue also provides the groundwork to characterise the results of future large variability surveys like the Vera C. Rubin Observatory's Legacy Survey of Space and Time in the heavily crowded and reddened regions of the Galactic plane, as wellas follow-up campaigns to characterise specific types of variables. The analysis of the miss-flagged stars can be used to improve the photometric classification of the VVV data allowing to expand the amount of data considered useful for science purposes. Besides, we provide an additional list of stars missed by the VIVA procedures for which the observations are actually good and they were missed due to some failure in the VIVA selection process.
- ID:
- ivo://CDS.VizieR/J/AJ/153/179
- Title:
- VVV Survey RR Lyr stars in Southern Galactic plane
- Short Name:
- J/AJ/153/179
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep near-IR images from the VISTA Variables in the Via Lactea (VVV) Survey were used to search for RR Lyrae stars in the Southern Galactic plane. A sizable sample of 404 RR Lyrae of type ab stars was identified across a thin slice of the fourth Galactic quadrant (295{deg}<l<350{deg}, -2.24{deg}<b<-1.05{deg}). The sample's distance distribution exhibits a maximum density that occurs at the bulge tangent point, which implies that this primarily Oosterhoff type I population of RRab stars does not trace the bar delineated by their red clump counterparts. The bulge RR Lyrae population does not extend beyond l~340{deg}, and the sample's spatial distribution presents evidence of density enhancements and substructure that warrants further investigation. Indeed, the sample may be employed to evaluate Galactic evolution models, and is particularly lucrative since half of the discovered RR Lyrae are within reach of Gaia astrometric observations.
- ID:
- ivo://CDS.VizieR/J/A+A/216/44
- Title:
- Walraven photometry in Sco-Cen association
- Short Name:
- J/A+A/216/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Walraven photometry is presented of established and probable members of the Scorpio-Centaurus OB association. For each star, effective temperature and surface gravity are derived using Kurucz atmosphere models (1979ApJS...40....1K). From the Straizys and Kuriliene (1981Ap&SS..80..353S) tables, absolute magnitudes are calculated. Distance moduli and visual extinctions are determined for all stars. From a comparison of the HR-diagrams of the stars in each subgroup with theoretical isochrones, the ages of the three subgroups are derived. The distances to the three subgroups are shown to be different; there is a general trend (also within each subgroup) for the distances to be larger at higher galactic longitudes. The visual extinction in the youngest subgroup Upper-Scorpius, is well correlated with the IRAS 100-micron map. The distance toward the Ophiuchus dark clouds is found to be 125 pc, based on the photometric distances to the stars. Most of the early-type stars in Upper-Scorpius are located at the far side of the dark clouds.
- ID:
- ivo://CDS.VizieR/J/A+AS/98/505
- Title:
- Walraven photometry near AG Car
- Short Name:
- J/A+AS/98/505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Walraven-photometric data of 114 stars of 5.9<V<14.7 within 17 arcmin of the Luminous Blue Variable AG Car (HD 94910). The results are expressed in terms of V-magnitude in the Johnson system and in observed and extinction-free colours in the Walraven system. For a description of the Walraven photometric system, see e.g. <GCPD/11>
- ID:
- ivo://CDS.VizieR/J/ApJ/697/1741
- Title:
- Warped disks of YSOs in Galactic center
- Short Name:
- J/ApJ/697/1741
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The central parsec around the supermassive black hole in the Galactic center (GC) hosts more than 100 young and massive stars. Outside the central cusp (R~1") the majority of these O and Wolf-Rayet (W-R) stars reside in a main clockwise system, plus a second, less prominent disk or streamer system at large angles with respect to the main system. Here we present the results from new observations of the GC with the AO-assisted near-infrared imager NACO and the integral field spectrograph SINFONI on the ESO/VLT. These include the detection of 27 new reliably measured W-R/O stars in the central 12" and improved measurements of 63 previously detected stars, with proper motion uncertainties reduced by a factor of 4 compared to our earlier work. Based on the sample of 90 well measured W-R/O stars, we develop a detailed statistical analysis of their orbital properties and orientations. We show that half of the W-R/O stars are compatible with being members of a clockwise rotating system.
- ID:
- ivo://CDS.VizieR/J/AJ/128/712
- Title:
- Washington Photometry in NGC 5128
- Short Name:
- J/AJ/128/712
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the global properties of the globular cluster system (GCS) around NGC 5128, the central giant elliptical galaxy in the nearby Centaurus group, we have obtained deep CCD imaging for an area of almost 2{deg}^2^ centered on the galaxy. Our data, in the CMT_1_ Washington photometric system, reach an approximate limiting magnitude of T_1_~R~22 and contain magnitudes, colors, and coordinates for more than 100,000 objects. Of these, the vast majority (about 99%) are either foreground stars or faint background galaxies; the old-halo globular clusters make up the remaining tiny fraction of the sample. Our database, however, provides the material for understanding the large-scale features of the GCS, including its metallicity distribution (MDF), luminosity distribution, and spatial structure.
- ID:
- ivo://CDS.VizieR/J/AJ/128/723
- Title:
- Washington Photometry in NGC 5128. II
- Short Name:
- J/AJ/128/723
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Building on the CMT_1_ photometric database presented in Paper I (Cat. <J/AJ/128/712>), in this paper we derive the large-scale properties of the globular cluster system (GCS) in NGC 5128, the nearest giant elliptical and the dominant galaxy in the Centaurus group. Using the metallicity-sensitive C-T_1_ color index, we discuss the metallicity distribution function (MDF) for a subsample of 211 previously identified clusters, all on a homogeneous photometric system. We find the MDF to be strongly bimodal, with metallicity peaks at [Fe/H]=-1.55 and -0.55 and with nearly equal numbers of clusters in each of the metal-poor and metal-rich modes. Finally, we present a list of 327 new cluster candidates not identified in any previous surveys; most of these are in the less well studied bulge region of the galaxy and along the minor axis.
- ID:
- ivo://CDS.VizieR/J/AJ/136/2321
- Title:
- Washington photometry of Bootes I stars
- Short Name:
- J/AJ/136/2321
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Washington CT_1_T_2_ photometry of a field central to the Bootes I dwarf spheroidal galaxy, which was discovered as a stellar overdensity in the Sloan Digital Sky Survey (DR5). We show that the Washington filters are much more effective than the Sloan filters in separating the metal-poor turn-off stars in the dwarf galaxy from the foreground stars. We detect 165 objects in the field, and statistically determine that just over 40% of the objects are nonmembers. Our statistical analysis mostly agrees with radial velocity measurements of the brighter stars. We find that there is a distinct main-sequence turn-off and subgiant branch, where there is some evidence of a spread in chemical abundance.
