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In this paper we present a novel method to identify and characterize stellar clusters deeply embedded in a dark molecular cloud. The method is based on measuring stellar surface density in wide-field infrared images using star counting…

Instrumentation and Methods for Astrophysics · Physics 2017-11-29 Marco Lombardi , Charles J. Lada , Joao Alves

We describe an objective and automated method for detecting clusters of galaxies from optical imaging data. This method is a variant of the so-called `matched-filter' technique pioneered by Postman et al. (1996). With simultaneous use of…

Astrophysics · Physics 2009-10-30 Wataru Kawasaki , Kazuhiro Shimasaku , Mamoru Doi , Sadanori Okamura

We develop a galaxy cluster finding algorithm based on spectral clustering technique to identify optical counterparts and estimate optical redshifts for X-ray selected cluster candidates. As an application, we run our algorithm on a sample…

Astrophysics of Galaxies · Physics 2016-07-15 Eman Mahmoud , Ali Takey , Amin Shoukry

OB associations, as an intermediate stage between Galactic clusters and field stars, play an important role in understanding the star formation process, early stellar evolution, and Galactic evolution. In this work, we construct a large…

Astrophysics of Galaxies · Physics 2025-08-12 Zhicun Liu , Xiao-Long Wang , Wenyuan Cui , Jianrong Shi , Chao Liu , Xiang-Xiang Xue , Min Fang , Yang Huang , Guozhen Hu , Gang Zhao

We developed and applied a computer analysis method to detect ring galaxy candidates in the first data release of PanSTARRS. The method works by applying a low-pass filter, followed by dynamic global thresholding to search for closed…

Astrophysics of Galaxies · Physics 2017-06-14 Ian Timmis , Lior Shamir

A direct approach to studying the galaxy-halo connection is to analyze groups and clusters of galaxies that trace the underlying dark matter halos, emphasizing the importance of identifying galaxy clusters and their associated brightest…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-22 Hai-Xia Ma , Tsutomu T. Takeuchi , Suchetha Cooray , Yongda Zhu

OB associations are primordial tracers of star formation and Galactic structure. Originally defined about 80 years ago, their historical membership lists have been superseded thanks to the precise astrometry from ESA's \textit{Gaia}'s…

Aims: According to some estimations, there are as many as 100000 open clusters in the Galaxy, but less than 2000 of them have been discovered, measured, and cataloged. We plan to undertake data mining of multiwavelength surveys to find new…

Astrophysics · Physics 2009-11-13 S. E. Koposov , E. V. Glushkova , I. Yu. Zolotukhin

In this work we explore the possibility of applying machine learning methods designed for one-dimensional problems to the task of galaxy image classification. The algorithms used for image classification typically rely on multiple costly…

Astrophysics of Galaxies · Physics 2022-02-23 F. Tarsitano , C. Bruderer , K. Schawinski , W. G. Hartley

We present a 900 sec, wide-field U image of the inner region of the Andromeda galaxy obtained during the commissioning of the blue channel of the Large Binocular Camera mounted on the prime focus of the Large Binocular Telescope. Relative…

In this work, we update the catalog of OB stars based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) data release 7 and modified the OB stars selection criterion the spectral line indices space. The new catalog…

Solar and Stellar Astrophysics · Physics 2024-10-22 Zhicun Liu , Wenyuan Cui , Jiajia Gu , Jianrong Shi , Guozhen Hu , Xiao-Long Wang , Zhenyan Huo

Rare extragalactic objects can carry substantial information about the past, present, and future universe. Given the size of astronomical databases in the information era it can be assumed that very many outlier galaxies are included in…

Astrophysics of Galaxies · Physics 2021-01-13 Lior Shamir

We have applied the MCS image deconvolution algorithm (Magain, Courbin & Sohy 1998) to HST/WFPC2 V, I data of three M31 bulge globular clusters (G170, G177, and G198) and control fields near each cluster. All three clusters are clearly…

Astrophysics · Physics 2007-05-23 P. Jablonka , F. Courbin , G. Meylan , A. Sarajedini , T. J. Bridges , P. Magain

Open clusters (OCs) in our Galaxy can be found in pairs, possibly forming physical binaries, or in groups. These objects offer unique insights into the process of star formation and testify to the dynamical interactions at local and…

Astrophysics of Galaxies · Physics 2026-04-22 Qingshun Hu , Yufei Cai , Caroline Soubiran , Yu Dai , Yuting Li , Yangping Luo , Mingfeng Qin

We have used a star-count algorithm based the Panoramic Survey Telescope And Rapid Response System 3$\pi$ survey data aim to identify and characterize uncharted open clusters (OCs). With limiting magnitudes of about 22 mag in \gps, \rps,…

Astrophysics of Galaxies · Physics 2013-09-04 C. C. Lin , W. P. Chen

Context.Identification of new star cluster candidates in M31 is fundamental for the study of the M31 stellar cluster system. The machine-learning method convolutional neural network (CNN) is an efficient algorithm for searching for new M31…

Astrophysics of Galaxies · Physics 2022-04-15 Shoucheng Wang , Bingqiu Chen , Jun Ma , Qian Long , Haibo Yuan , Dezi Liu , Zhimin Zhou , Wei Liu , Jiamin Chen , Zizhao He

The orientations of the red galaxies in a filament are aligned with the orientation of the filament. We thus develop a location-alignment-method (LAM) of detecting filaments around clusters of galaxies, which uses both the alignments of red…

Astrophysics of Galaxies · Physics 2015-10-29 Yu Rong , Yuan Liu , Shuang-Nan Zhang

The massive stellar content, the OB associations and the star clusters in an HST field in M101 = NGC 5457 are investigated. A clustering algorithm yields 79 putative associations. Their size distribution is similar to that found in the…

Astrophysics · Physics 2009-10-28 F. Bresolin , R. Kennicutt , P. Stetson

Galaxy groups provide the means for a great diversity of studies that contribute to a better understanding of the structure of the universe on a large scale and allow the properties of galaxies to be linked to those of the host halos.…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-22 Facundo Rodriguez , Manuel Merchán

Aims - We present the first results of a large spectroscopic survey of globular clusters and candidate globular clusters in the nearby M~31 galaxy. The survey is aimed at the classification of known candidate M~31 clusters and at the study…

Astrophysics · Physics 2009-11-11 S. Galleti , L. Federici , M. Bellazzini , A. Buzzoni , F. Fusi Pecci