- ID:
- ivo://CDS.VizieR/J/ApJS/245/32
- Title:
- Newly identified star clusters in Gaia DR2
- Short Name:
- J/ApJS/245/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Star cluster Hunting Pipeline (SHiP) that can identify star clusters in Gaia second data release (DR2) data and establish a star cluster catalog for the Galactic disk. A friend-of-friend-based cluster finder method is used to identify star clusters using five-dimensional stellar parameters, l,b,{omega},{mu}_{alpha}_cos{delta}, and {mu}_{delta}_. Our new catalog contains 2443 star cluster candidates identified from disk stars located within |b|=25{deg} and with G<18mag. An automatic isochrone fitting scheme is applied to all cluster candidates. With a combination of parameters obtained from isochrone fitting, we classify cluster candidates into three classes (Class 1, 2, and 3). Class 1 clusters are the most probable star cluster candidates with the most stringent criteria. Most of these clusters are nearby (within 4kpc). Our catalog is crossmatched with three Galactic star cluster catalogs, Kharchenko+ (2013, J/A+A/558/A53), Cantat-Gaudin+ (2018, J/A+A/618/A93 and 2019, J/A+A/624/A126), and Bica+ (2019, J/AJ/157/12). The proper motion and parallax of matched star clusters are in good agreement with these earlier catalogs. We discover 76 new star cluster candidates that are not listed in these three catalogs. The majority of these are clusters older than log(age/yr)=8.0 and are located in the inner disk with |b|<5{deg}. The recent discovery of new star clusters suggests that current Galactic star cluster catalogs are still incomplete. Among the Class 1 cluster candidates, we find 56 candidates for star cluster groups.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/502/6080
- Title:
- New members of Cygnus OB2 from Gaia DR2
- Short Name:
- J/MNRAS/502/6080
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Due to the high quality of Gaia DR2 stellar parallaxes and proper motions, we can study the Cygnus OB2 region up to G=17.5mag in circular region centred at (l,b)=(79.8{deg},+0.8{deg}) of radius 1{deg}. We detect four over-densities in the Vector Point Diagram. We apply a parametric model of the proper motion distribution and determine their mean proper motions, identify their members and estimate their distances by analyzing the parallaxes of the most probable members. We confirm that one of these regions is Cygnus OB2, whose mean proper motion is (pmRA*cosDE,pmDE)=(-2.71+/-0.02,-4.24+/-0.02)mas/yr. We identify 2767 astrometric members at an estimated distance of 1683 {+/-} 5 pc. A detailed comparison of these members with 333 photometric and spectroscopic Cygnus OB2 members shows that 33 stars of the last group are not members, 16 of them are O-B stars. 300 members in common lead to estimate a distance to the association of 1669+/-6pc. One of the remaining over-densities is the open cluster UCB585 for which we find eight more members, located at ~1460pc. The other two groups count 179 and 188 proper motion members which are distributed throughout the region and situated at a distance of ~1280 pc. The estimated distances of these four groups suggest the existence of different substructures in the Cygnus OB2 region along the line of sight.
- ID:
- ivo://CDS.VizieR/J/A+A/421/643
- Title:
- New nearby stars in the LEHPMS
- Short Name:
- J/A+A/421/643
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a systematic search for new neighbourhood stars among the Liverpool-Edinburgh high proper motion survey which we cross-identified with the DENIS survey. Their high proper motions ensure that they are not giant stars. The distances are estimated using DENIS photometry and we found that 100 stars probably lie within 25 parsecs from the Sun. They are mostly M-dwarfs, and 10 are probably white dwarfs. This is the first distance estimate for 84 stars among them. 10 stars are estimated to be closer than 15 parsecs. In addition, one star, DENIS J2343155-241047, could also lie within 15pc if it belongs to the halo.
- ID:
- ivo://CDS.VizieR/J/MNRAS/355/585
- Title:
- New Northern common proper-motion pairs
- Short Name:
- J/MNRAS/355/585
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A list of 705 new Northern Celestial Hemisphere common proper motion pairs between 18 hours and 6 hours Right Ascension and 0 degrees and roughly 45 degrees Declination as derived from the Second U.S. Naval Observatory CCD Astrograph Catalog is presented, along with details of separation, motion, brightness and colour. This list is supplemented by a further 267 such pairs, derived in exactly the same way as the above 705 within the same Declination range, but for the region between 6 hours and 18 hours Right Ascension that was not included in the printed paper.
- ID:
- ivo://CDS.VizieR/J/other/RAA/21.93
- Title:
- 74 new open clusters found in Gaia DR2
- Short Name:
- J/other/RAA/21.9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on astrometric data from Gaia Data-Release 2 (DR2), we employ an un- supervised machine learning method to blindly search for open star clusters in the Milky Way within the Galactic latitude range of |b|<20degree. In addition to 2080known clusters, 74 new open cluster candidates are found. In this work, we present the positions, apparent radii, parallaxes, proper motions and member stars of these candidates. Meanwhile, to obtain the physical parameters of each candidate cluster, stellar isochrones are fit to the photometric data. The results show that the apparent radii and the observed proper motion dispersions of these new candidates are consistent with those of open clusters previously identified in Gaia DR2.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A45
- Title:
- 570 new open clusters in the Galactic disc
- Short Name:
- J/A+A/635/A45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters are key targets for studies of Galaxy structure and evolution, and stellar physics. Since the Gaia data release 2 (DR2), the discovery of undetected clusters has shown that previous surveys were incomplete. Our aim is to exploit the Big Data capabilities of machine learning to detect new open clusters in Gaia DR2, and to complete the open cluster sample to enable further studies of the Galactic disc. We use a machine-learning based methodology to systematically search the Galactic disc for overdensities in the astrometric space and identify the open clusters using photometric information. First, we used an unsupervised clustering algorithm, DBSCAN, to blindly search for these overdensities in Gaia DR2 (l, b, varpi, mu_alpha_*, mu_delta_), then we used a deep learning artificial neural network trained on colour-magnitude diagrams to identify isochrone patterns in these overdensities, and to confirm them as open clusters. We find 570 new open clusters distributed along the Galactic disc in the region |b|<20{deg}. We detect substructure in complex regions, and identify the tidal tails of a disrupting cluster UBC 274 of ~3Gyr located at ~2kpc. Adapting the mentioned methodology to a Big Data environment allows us to target the search using the physical properties of open clusters instead of being driven by computational limitations. This blind search for open clusters in the Galactic disc increases the number of known open clusters by 45%.
- ID:
- ivo://CDS.VizieR/J/A+AS/83/317
- Title:
- New proper-motion LTT stars Dec<-40, 0<RA<4h30
- Short Name:
- J/A+AS/83/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Data are given for 104 LTT stars found on 11 areas, covering 25 squares degrees each, south of declination -40deg and right ascension between 00h and 04h30m. Three stars present differences in proper motion >0.10", six present differences in position angle >=20deg and one presents those differences in both values.
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/2327
- Title:
- New proper motion objects from UKIDSS GPS
- Short Name:
- J/MNRAS/443/2327
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UKIDSS Galactic Plane Survey (GPS) began in 2005 as a seven year effort to survey ~1800deg^2^ of the northern Galactic plane in the J, H, and K passbands. The survey included a second epoch of K-band data, with a baseline of two to eight years, for the purpose of investigating variability and measuring proper motions. We have calculated proper motions for 167 million sources in a 900deg^2^ area located at l>60{deg} in order to search for new high proper motion objects. Visual inspection has verified 617 high proper motion sources (>200mas/yr) down to K=17, of which 153 are new discoveries. Among these, we have a new spectroscopically confirmed T5 dwarf, an additional T dwarf with estimated type T6, 13 new L dwarf candidates, and two new common proper motion systems containing ultracool dwarf candidates. We provide improved proper motions for an additional 12 high proper motion stars that were independently discovered in the WISE data set during the course of this investigation.
- ID:
- ivo://CDS.VizieR/J/A+A/353/958
- Title:
- New proper motions in 0<RA<7h, -63<DE<-32{deg}
- Short Name:
- J/A+A/353/958
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of about 100 new high-proper motion stars in the region between 0^h^ and 7^h^ in right ascension and -63{deg} and -32{deg} in declination, with proper motions between 0.3 and 1.0arcsec/yr. In addition we have obtained improved coordinates and photographic photometry for another about 100 already known high-proper motion stars in the same region. In this study we have made use of APM measurements of UKST survey plates in 40 survey fields. Using all available information (position, proper motion, photographic R magnitude and B_J_-R colour index), we draw some preliminary conclusions on the nature of the new high-proper motion stars, particularly of extreme cases.
- ID:
- ivo://CDS.VizieR/J/AJ/133/2898
- Title:
- New proper-motion stars (-90<DE< -47)
- Short Name:
- J/AJ/133/2898
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 1606 new proper-motion systems in the southern sky (declinations -90{deg} to -47{deg}) with 0.40"/yr>{mu}>=0.18"/yr. This effort is a continuation of the SuperCOSMOS-RECONS (SCR) proper-motion search to lower proper motions than reported in Papers VIII, X, XII, and XV in this series. Distance estimates are presented for the new systems, assuming that all stars are on the main sequence. We find that 31 systems are within 25pc, including two systems (SCR 0838-5855 and SCR 1826-6542) that we anticipate to be within 10pc. These new discoveries constitute a more than 10-fold increase in new systems found in the same region of sky searched for systems with mu>=0.40"/yr, suggesting a happy hunting ground for new nearby slower proper-motion systems in the region just north (declinations -47{deg} to 0{deg}), much of which has not been rigorously searched during previous efforts.
