The VVV Survey of the Milky Way: first year results (original) (raw)
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VISTA Variables in the Via Lactea (VVV): The public ESO near-IR variability survey of the Milky Way
New Astronomy, 2010
We describe the public ESO near-IR variability survey (VVV) scanning the Milky Way bulge and an adjacent section of the mid-plane where star formation activity is high. The survey will take 1929 h of observations with the 4-m VISTA telescope during 5 years (2010-2014), covering 109pointsourcesacrossanareaof520deg2,including33knownglobularclustersand10 9 point sources across an area of 520 deg 2 , including 33 known globular clusters and 109pointsourcesacrossanareaof520deg2,including33knownglobularclustersand350 open clusters. The final product will be a deep near-IR atlas in five passbands (0.9-2.5 lm) and a catalogue of more than 10 6 variable point sources.
Context. The ESO public survey VISTA variables in the Vía Láctea (VVV) started in 2010. VVV targets 562 sq. deg in the Galactic bulge and an adjacent plane region and is expected to run for about five years. Aims: We describe the progress of the survey observations in the first observing season, the observing strategy, and quality of the data obtained. Methods: The observations are carried out on the 4-m VISTA telescope in the ZYJHKs filters. In addition to the multi-band imaging the variability monitoring campaign in the Ks filter has started. Data reduction is carried out using the pipeline at the Cambridge Astronomical Survey Unit. The photometric and astrometric calibration is performed via the numerous 2MASS sources observed in each pointing. Results: The first data release contains the aperture photometry and astrometric catalogues for 348 individual pointings in the ZYJHKs filters taken in the 2010 observing season. The typical image quality is 0.9 arcsec {-1.0 arcsec}. The stringent photometric and image quality requirements of the survey are satisfied in 100% of the JHKs images in the disk area and 90% of the JHKs images in the bulge area. The completeness in the Z and Y images is 84% in the disk, and 40% in the bulge. The first season catalogues contain 1.28 × 108 stellar sources in the bulge and 1.68 × 108 in the disk area detected in at least one of the photometric bands. The combined, multi-band catalogues contain more than 1.63 × 108 stellar sources. About 10% of these are double detections because of overlapping adjacent pointings. These overlapping multiple detections are used to characterise the quality of the data. The images in the JHKs bands extend typically 4 mag deeper than 2MASS. The magnitude limit and photometric quality depend strongly on crowding in the inner Galactic regions. The astrometry for Ks = 15-18 mag has rms 35-175 mas. Conclusions: The VVV Survey data products offer a unique dataset to map the stellar populations in the Galactic bulge and the adjacent plane and provide an exciting new tool for the study of the structure, content, and star-formation history of our Galaxy, as well as for investigations of the newly discovered star clusters, star-forming regions in the disk, high proper motion stars, asteroids, planetary nebulae, and other interesting objects. Based on observations taken within the ESO VISTA Public Survey VVV, Programme ID 179.B-2002.
2012
Context. The ESO public survey VISTA variables in the Vía Láctea (VVV) started in 2010. VVV targets 562 sq. deg in the Galactic bulge and an adjacent plane region and is expected to run for about five years. Aims. We describe the progress of the survey observations in the first observing season, the observing strategy, and quality of the data obtained. Methods. The observations are carried out on the 4-m VISTA telescope in the ZY JHK s filters. In addition to the multi-band imaging the variability monitoring campaign in the K s filter has started. Data reduction is carried out using the pipeline at the Cambridge Astronomical Survey Unit. The photometric and astrometric calibration is performed via the numerous 2MASS sources observed in each pointing. Results. The first data release contains the aperture photometry and astrometric catalogues for 348 individual pointings in the ZY JHK s filters taken in the 2010 observing season. The typical image quality is ∼0. 9−1. 0. The stringent photometric and image quality requirements of the survey are satisfied in 100% of the JHK s images in the disk area and 90% of the JHK s images in the bulge area. The completeness in the Z and Y images is 84% in the disk, and 40% in the bulge. The first season catalogues contain 1.28 × 10 8 stellar sources in the bulge and 1.68 × 10 8 in the disk area detected in at least one of the photometric bands. The combined, multi-band catalogues contain more than 1.63 × 10 8 stellar sources. About 10% of these are double detections because of overlapping adjacent pointings. These overlapping multiple detections are used to characterise the quality of the data. The images in the JHK s bands extend typically ∼4 mag deeper than 2MASS. The magnitude limit and photometric quality depend strongly on crowding in the inner Galactic regions. The astrometry for K s = 15−18 mag has rms ∼ 35−175 mas. Conclusions. The VVV Survey data products offer a unique dataset to map the stellar populations in the Galactic bulge and the adjacent plane and provide an exciting new tool for the study of the structure, content, and star-formation history of our Galaxy, as well as for investigations of the newly discovered star clusters, star-forming regions in the disk, high proper motion stars, asteroids, planetary nebulae, and other interesting objects.
The VVV near-IR galaxy catalogue beyond the Galactic disc
Monthly Notices of the Royal Astronomical Society, 2021
Knowledge about the large-scale distribution of galaxies is far from complete in the Zone of Avoidance (ZoA), which is mostly due to high interstellar extinction and to source confusion at lower Galactic latitudes. Past near-infrared (NIR) surveys, such as the Two Micron All Sky Survey (2MASS), have shown the power of probing large-scale structure at these latitudes. Our aim is to map the galaxy distribution across the Southern Galactic plane using the VISTA Variables in the Vía Láctea Survey (VVV), which reach 2–4 mag deeper than 2MASS. We used SExtractor+PSFEx to identify extended objects and to measure their sizes, the light concentration index, magnitudes, and colours. Morphological and colour constraints and visual inspection were used to confirm galaxies. We present the resulting VVV NIR Galaxy Catalogue (VVV NIRGC) of 5563 visually confirmed galaxies, of which only 45 were previously known. This is the largest catalogue of galaxies towards the Galactic plane, with 99 per cent...
New VVV Survey Globular Cluster Candidates in the Milky Way Bulge
The Astrophysical Journal
It is likely that a number of Galactic globular clusters remain to be discovered, especially toward the Galactic bulge. High stellar density combined with high and differential interstellar reddening are the two major problems for finding globular clusters located toward the bulge. We use the deep near-IR photometry of the VISTA Variables in the Vía Láctea (VVV) Survey to search for globular clusters projected toward the Galactic bulge, and hereby report the discovery of 22 new candidate globular clusters. These objects, detected as high density regions in our maps of bulge red giants, are confirmed as globular cluster candidates by their color-magnitude diagrams. We provide their coordinates as well as their near-IR color-magnitude diagrams, from which some basic parameters are derived, such as reddenings and heliocentric distances. The color-magnitude diagrams reveal well defined red giant branches in all cases, often including a prominent red clump. The new globular cluster candidates exhibit a variety of extinctions (0.06 < A Ks < 2.77) and distances (5.3 < D < 9.5 kpc). We also classify the globular cluster candidates into 10 metal-poor and 12 metal-rich clusters, based on the comparison of their colormagnitude diagrams with those of known globular clusters also observed by the VVV Survey. Finally, we argue that the census for Galactic globular clusters still remains incomplete, and that many more candidate globular clusters (particularly the low luminosity ones) await to be found and studied in detail in the central regions of the Milky Way.
The First Galaxy Cluster Discovered by the VISTA Variables in the Vía Láctea Survey
The Astrophysical Journal, 2019
We report the first confirmed detection of the galaxy cluster VVV-J144321-611754 at very low latitudes (l = 315.836 • , b =-1.650 •) located in the tile d015 of the VISTA Variables in the Vía Láctea (VVV) survey. We defined the region of 30× 30 arcmin 2 centered in the brightest galaxy finding 25 galaxies. For these objects, extinction-corrected median colors of (H-K s) = 0.34 ± 0.05 mag, (J-H) = 0.57 ± 0.08 mag and (J-K s) = 0.87 ± 0.06 mag, and R 1/2 = 1.59 ± 0.16 arcsec; C = 3.01 ± 0.08; and Sersic index, n = 4.63 ± 0.39 were estimated. They were visually confirmed showing characteristics of early-type galaxies in the near-IR images. An automatic clustering analysis performed in the whole tile found that the concentration of galaxies VVV-J144321-611754 is a real, compact concentration of early-type galaxies. Assuming a typical galaxy cluster with low X-ray luminosity, the photometric redshift of the brightest galaxy is z = 0.196 ± 0.025. Follow-up near-IR spectroscopy with FLAMINGOS-2 at the Gemini-South telescope revealed that the two brighter cluster galaxies have typical spectra of early-type galaxies and the estimated redshift for the brightest galaxy VVV-J144321.06-611753.9 is z = 0.234±0.022 and for VVV-J144319.02-611746.1 is z = 0.232±0.019. Finally, these galaxies clearly follow the cluster Red Sequence in the rest-frame near-IR color-magnitude diagram with the slope similar to galaxy cluster at redshift of 0.2. These results are consistent with the presence of a bona fide galaxy cluster beyond the Milky Way disk.
The VISTA Variables in the Vía Láctea infrared variability catalogue (VIVA-I)
Monthly Notices of the Royal Astronomical Society
High extinction and crowding create a natural limitation for optical surveys towards the central regions of the Milky Way, where the gas and dust are mainly confined. Large-scale near-infrared (IR) surveys of the Galactic plane and bulge are a good opportunity to explore open scientific questions as well as to test our capability to explore future data sets efficiently. Thanks to the VISTA Variables in the Vía Láctea (VVV) ESO public survey, it is now possible to explore a large number of objects in those regions. This paper addresses the variability analysis of all VVV point sources having more than 10 observations in VVVDR4 using a novel approach. In total, the near-IR light curves of 288 378 769 sources were analysed using methods developed in the New Insight Into Time Series Analysis project. As a result, we present a complete sample having 44 998 752 variable star candidates (VVV-CVSC), which include accurate individual coordinates, near-IR magnitudes (Z,Y,J, and Hs), extinctio...
The VVV near-IR galaxy catalogue in a Northern part of the Galactic disc
Monthly Notices of the Royal Astronomical Society
The automated identification of extragalactic objects in large surveys provides reliable and reproducible samples of galaxies in less time than procedures involving human interaction. However, regions near the Galactic disc are more challenging due to the dust extinction. We present the methodology for the automatic classification of galaxies and non-galaxies at low Galactic latitude regions using both images and photometric and morphological near-IR data from the VISTA Variables in the Vía Láctea eXtended (VVVX) survey. Using the VVV NIR Galaxy Catalogue (VVV NIRGC), we analyse by statistical methods the most relevant features for galaxy identification. This catalogue was used to train a convolutional neural network with image data and an XGBoost model with both photometric and morphological data and then to generate a data set of extragalactic candidates. This allows us to derive probability catalogues used to analyse the completeness and purity as a function of the configuration ...
Monthly Notices of the Royal Astronomical Society
In order to characterize 22 new globular cluster (GC) candidates in the Galactic bulge, we present their colour-magnitude diagrams (CMDs) and K s-band luminosity functions (LFs) using the near-infrared VVV database as well as Gaia-DR2 proper motion dataset. CMDs were obtained, on one hand, after properly decontaminating the observed diagrams from background/foreground disc stars and other sources. On the other hand, CMDs were also obtained based upon star selection in proper motion diagrams. Taking into account our deep CMDs and LFs analyses, we find that 17 out of 22 new GC candidates may be real and should therefore be followed-up, while 5 candidates were discarded from the original sample. We also search for RR Lyrae and Mira variable stars in the fields of these new GC candidates. In particular, we confirm that Minni 40 may be a real cluster. If confirmed by further follow-up analysis, it would be the closest GC to the Galactic centre in projected angular distance, located only 0.5 deg away from it. We consider that it is very difficult to confirm the physical reality of these small, poorly-populated bulge GCs so in many cases alternative techniques are needed to corroborate our findings.
We report the development of a suitable set of transforming equations to convert the JHK VISTA photometric system (used in the VVV survey) to the widely used 2MASS photometric system. Our transformation equations have been calculated for each of 145 VVV Galactic disk fields; covering a large portion of Fourth Galactic Quadrant (295 • ≤ l ≤ 350 • and −2 • ≤ b ≤ 2 • ). Several constraints were used to extract the best sources in both systems to improve the photometric quality of the transformations. Resumen. En este trabajo se muestra el desarrollo de un conjunto de ecuaciones de transformación para convertir el sistema fotométrico JHK de VISTA (usado en el sondeo VVV) al sistema de 2MASS, el cual es ampliamente usado. Nuestras ecuaciones de transformación han sido calculadas para cada uno de los 145 campos del disco galáctico cubierto por VVV, los cuales abarcan la región del cuarto cuadrante comprendida entre 295 • ≤ l ≤ 350 • and −2 • ≤ b ≤ 2 • . En cada campo, fueron usadas múltiples restricciones para mejorar la calidad fotométrica en la selección de las estrellas usadas durante este procedimiento.