Infrared surveys of Galactic star clusters

Ivanov, V. D.; Messineo, M.; Zhu, Qingfeng; Figer, D. F.; Borissova, J.; Kurtev, R.; Ivanov, G. R.

doi:10.1017/s1743921309991062

Cited by 3 publications

(3 citation statements)

References 35 publications

(39 reference statements)

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“…Most of the new cluster candidates are faint and compact (with small angular sizes) having radii between 20 and 30 arcsec. An automated search for lessconcentrated candidates over the whole VVV area (bulge and disk) based on the color cuts algorithm (Ivanov et al 2010) is in progress. Due to our search being directed towards star formation regions along the Southern Galactic plane we found (based on the preliminary photometric analysis) that approximately 85% of the star cluster candidates are younger than 5 Myr.…”

Section: Discussionmentioning

confidence: 99%

“…to compare the Galactic open cluster systems with those of the LMC, SMC, and other extragalactic cluster populations; as well as addressing many other questions. The results presented in this paper are part of a larger program aimed at characterizing the hidden star cluster population in the Galaxy (Borissova et al 2003(Borissova et al , 2006Ivanov et al 2002Ivanov et al , 2005Ivanov et al , 2010Ivanov et al , 2011Kurtev et al 2007Kurtev et al , 2008Kurtev et al , 2009Hanson et al 2008Hanson et al , 2010Bica et al 2003;Dutra et al 2003;Longmore et al 2011). Initially, the project was based on cluster candidates identified from 2MASS (Skrutskie et al 2006) and the Spitzer Space Telescope Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE, Benjamin et al 2003) survey.…”

Section: Introductionmentioning

confidence: 99%

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New Galactic star clusters discovered in the VVV survey

Borissova

Bonatto

Kurtev

et al. 2011

A&A

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108

170

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Context. VISTA Variables in the Vía Láctea (VVV) is one of the six ESO Public Surveys operating on the new 4-m Visible and Infrared Survey Telescope for Astronomy (VISTA). VVV is scanning the Milky Way bulge and an adjacent section of the disk, where star formation activity is high. One of the principal goals of the VVV Survey is to find new star clusters of different ages. Aims. In order to trace the early epochs of star cluster formation we concentrated our search in the directions to those of known star formation regions, masers, radio, and infrared sources. Methods. The disk area covered by VVV was visually inspected using the pipeline processed and calibrated K S -band tile images for stellar overdensities. Subsequently, we examined the composite JHK S and Z JK S color images of each candidate. PSF photometry of 15 × 15 arcmin fields centered on the candidates was then performed on the Cambridge Astronomy Survey Unit reduced images. After statistical field-star decontamination, color-magnitude and color-color diagrams were constructed and analyzed. Results. We report the discovery of 96 new infrared open clusters and stellar groups. Most of the new cluster candidates are faint and compact (with small angular sizes), highly reddened, and younger than 5 Myr. For relatively well populated cluster candidates we derived their fundamental parameters such as reddening, distance, and age by fitting the solar-metallicity Padova isochrones to the color-magnitude diagrams.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New Galactic star clusters discovered in the VVV survey

Borissova

Bonatto

Kurtev

et al. 2011

A&A

Self Cite

108

170

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“…Near-and mid-infrared observations come to aid in such cases because of the reduced dust extinction, as compared to the optical regime (Schlafly et al 2016). This has resulted in larger number of clusters being detected in infrared as compared to the optical (Ivanov et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Star cluster detection and characterization using generalized Parzen density estimation

Nambiar

Das

Vig

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Star cluster studies hold the key to understanding star formation, stellar evolution, and origin of galaxies. The detection and characterization of clusters depend on the underlying background density and the cluster richness. We examine the ability of the Parzen Density Estimation (a.k.a. Parzen Windows) method, which is a generalization of the well-known Star Count method, to detect clusters and measure their properties. We apply it on a range of simulated and real star fields, considering square and circular windows, with and without Gaussian kernel smoothing. Our method successfully identifies clusters and we suggest an optimal standard deviation of the Gaussian Parzen window for obtaining the best estimates of these parameters. Finally, we demonstrate that the Parzen Windows with Gaussian kernels are able to detect small clusters in regions of relatively high background density where the Star Count method fails.

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Near-infrared spectroscopy of candidate red supergiant stars in clusters

Messineo

Zhu

Ivanov

et al. 2014

A&A

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Context. Clear identifications of Galactic young stellar clusters farther than a few kpc from the Sun are rare, despite the large number of candidate clusters. Aims. We aim to improve the selection of candidate clusters rich in massive stars with a multiwavelength analysis of photometric Galactic data that range from optical to mid-infrared wavelengths.Methods. We present a photometric and spectroscopic analysis of five candidate stellar clusters, which were selected as overdensities with bright stars (K s < 7 mag) in GLIMPSE and 2MASS images. Results. A total of 48 infrared spectra were obtained. The combination of photometry and spectroscopy yielded six new red supergiant stars with masses from 10 M to 15 M . Two red supergiants are located at Galactic coordinates (l, b) = (16.• 7, −0.• 63) and at a distance of about ∼3.9 kpc; four other red supergiants are members of a cluster at Galactic coordinates (l, b) = (49.• 3, +0.• 72) and at a distance of ∼7.0 kpc. Conclusions. Spectroscopic analysis of the brightest stars of detected overdensities and studies of interstellar extinction along their line of sights are fundamental to distinguish regions of low extinction from actual stellar clusters. The census of young star clusters containing red supergiants is incomplete; in the existing all-sky near-infrared surveys, they can be identified as overdensities of bright stars with infrared color-magnitude diagrams characterized by gaps.

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Infrared surveys of Galactic star clusters

Cited by 3 publications

References 35 publications

New Galactic star clusters discovered in the VVV survey

New Galactic star clusters discovered in the VVV survey

Star cluster detection and characterization using generalized Parzen density estimation

Near-infrared spectroscopy of candidate red supergiant stars in clusters

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