- ID:
- ivo://CDS.VizieR/J/A+AS/126/81
- Title:
- IC 2602 VRI photometry
- Short Name:
- J/A+AS/126/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of VRI photometry of the young open cluster IC 2602. Two 15x15arcmin^2^ fields were observed in February and May 1991 using the 1-m Swope telescope at Las Campanas. Using theoretical isochrones obtained from D'Antona & Mazzitelli (1994ApJS...90..467D), and allowing for observational and other uncertainties, we identify 78 primary candidate members with 12<V<18.5 from their positions on colour-magnitude diagrams. We compare the cluster field with an offset field of similar galactic latitude and estimate the contamination due to background stars to be large, >=50%, as might be expected given its low galactic latitude. We also compare our photometry with that given for the X-ray detected stars of Randich et al. (1995A&A...300..134R) present complimentary narrow band H{alpha} photometry for a subset of the stars.
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- ID:
- ivo://CDS.VizieR/J/ApJ/862/33
- Title:
- Improved & expanded membership catalog for NGC752
- Short Name:
- J/ApJ/862/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nearby open cluster NGC 752 presents a rare opportunity to study stellar properties at ages >1Gyr. However, constructing a membership catalog for it is challenging; most surveys have been limited to identifying its giants and dwarf members earlier than mid-K. We supplement past membership catalogs with candidates selected with updated photometric and proper-motion criteria, generating a list of 258 members, a >50% increase over previous catalogs. Using a Bayesian framework to fit MESA Isochrones & Stellar Tracks evolutionary models to literature photometry and the Tycho-Gaia Astrometric Solution data available for 59 cluster members, we infer the age of and distance to NGC 752: 1.34+/-0.06Gyr and 438_-6_^+8^pc. We also report the results of our optical monitoring of the cluster using the Palomar Transient Factory. We obtain rotation periods for 12 K and M cluster members, the first periods measured for such low-mass stars with a well-constrained age >1Gyr. We compare these new periods to data from the younger clusters Praesepe and NGC 6811, and to a theoretical model for angular momentum loss, to examine stellar spin-down for low-mass stars over their first 1.3Gyr. While on average NGC 752 stars are rotating more slowly than their younger counterparts, the difference is not significant. Finally, we use our spectroscopic observations to measure H{alpha} for cluster stars, finding that members earlier than ~M2 are magnetically inactive, as expected at this age. Forthcoming Gaia data should solidify and extend the membership of NGC 752 to lower masses, thereby increasing its importance for studies of low-mass stars.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A104
- Title:
- Improving the open cluster census. I.
- Short Name:
- J/A+A/646/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The census of open clusters in the Milky Way is in a never-before seen state of flux. Recent works have reported hundreds of new open clusters thanks to the incredible astrometric quality of the Gaia satellite, but other works have also reported that many open clusters discovered in the pre Gaia era may be associations. We aim to conduct a comparison of clustering algorithms used to detect open clusters, attempting to statistically quantify their strengths and weaknesses by deriving the sensitivity, specificity, and precision of each as well as their true positive rate against a larger sample. We selected DBSCAN, HDBSCAN, and Gaussian mixture models for further study, owing to their speed and appropriateness for use with Gaia data. We developed a preprocessing pipeline for Gaia data and developed the algorithms further for the specific application to open clusters. We derived detection rates for all 1385 open clusters in the fields in our study as well as more detailed performance statistics for 100 of these open clusters. DBSCAN was sensitive to 50%-62% of the true positive open clusters in our sample, with generally very good specificity and precision. HDBSCAN traded precision for a higher sensitivity of up to 82%, especially across different distances and scales of open clusters. Gaussian mixture models were slow and only sensitive to 33% of open clusters in our sample, which tended to be larger objects. Additionally, we report on 41 new open cluster candidates detected by HDBSCAN, three of which are closer than 500pc. When used with additional post-processing to mitigate its false positives, we have found that HDBSCAN is the most sensitive and effective algorithm for recovering open clusters in Gaia data. Our results suggest that many more new and already reported open clusters have yet to be detected in Gaia data.
- ID:
- ivo://CDS.VizieR/J/BaltA/17/1
- Title:
- Infrared photometry in GL490 star-forming region
- Short Name:
- J/BaltA/17/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the infrared photometry data extracted from the 2MASS, IRAS and MSX databases, 50 suspected young stellar objects (YSOs) are selected from about 37500 infrared objects in the 3x3deg^2^ area with the center at (l,b=142.5,+1.0), in the vicinity of the young stellar object GL 490 in the dark cloud T 942 (Dobashi et al., 2005PASJ...57S...1D, Cat. <VII/244>). The spectral energy distributions between 700nm and 100um suggest that most of the selected objects may be YSOs of classes I and II. In the color-magnitude diagram Ks vs. H-Ks the suspected YSOs occupy an area right of the main sequence what can be interpreted as being caused by the effects of luminosity, interstellar and circumstellar reddening and infrared thermal emission in circumstellar envelopes and disks.
- ID:
- ivo://CDS.VizieR/J/ApJ/581/258
- Title:
- Infrared photometry in the Arches Cluster
- Short Name:
- J/ApJ/581/258
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and use new spectra and narrowband images, along with previously published broadband images, of stars in the Arches cluster to extract photometry, astrometry, equivalent width, and velocity information. The data are interpreted with a wind/atmosphere code to determine stellar temperatures, luminosities, mass-loss rates, and abundances. We have doubled the number of known emission-line stars, and we have also made the first spectroscopic identification of the main sequence for any population in the Galactic center.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1574
- Title:
- Infrared photometry of IC348 members
- Short Name:
- J/AJ/131/1574
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near- and mid-infrared photometry obtained with the Spitzer Space Telescope of 300 known members of the IC 348 cluster. We merge this photometry with existing ground-based optical and near-infrared photometry in order to construct optical-infrared spectral energy distributions (SEDs) for all the cluster members and present a complete atlas of these SEDs.
- ID:
- ivo://CDS.VizieR/J/AJ/129/656
- Title:
- Infrared photometry of NGC 6791
- Short Name:
- J/AJ/129/656
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep JHK photometry of the old and metal-rich open cluster NGC 6791. The photometry reaches below the main-sequence turnoff to K~16.5mag. We combine our photometry with that from Stetson et al. (2003, Cat. <J/PASP/115/413>) to provide color-magnitude diagrams showing K versus J-K, K versus V-K, and V versus V-K.
- ID:
- ivo://CDS.VizieR/J/ApJ/573/366
- Title:
- Infrared photometry of Trapezium cluster
- Short Name:
- J/ApJ/573/366
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the results of a new multiepoch, multiwavelength, near-infrared census of the Trapezium cluster in Orion to construct and analyze the structure of its infrared (K-band) luminosity function. Specifically, we employ an improved set of model luminosity functions to derive this cluster's underlying initial mass function (IMF) across the entire range of mass from OB stars to substellar objects down to near the deuterium-burning limit. The observations were performed at FLWO (Fred Lawrence Whipple Observatory, Smithsonian Astrophysical Observatory), and ESO-NTT (European Southern Observatory, New Technology Telescope), between Dec. 1997 and Marche 2000 (see the "Table 5" section below)
- ID:
- ivo://CDS.VizieR/J/MNRAS/374/399
- Title:
- Infrared star clusters with |b|<20{deg}
- Short Name:
- J/MNRAS/374/399
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used star density maps obtained from the Two-Micron All-Sky Survey (2MASS) to obtain a sample of star clusters in the entire Galactic Plane with |b|<20{deg}. A total of 1788 star cluster candidates are identified in this survey. Among those are 681 previously known open clusters and 86 globular clusters. A statistical analysis indicates that our sample of 1021 new cluster candidates has a contamination of about 50 per cent. Star cluster parameters are obtained by fitting a King profile to the star density. These parameters are used to statistically identify probable new globular cluster candidates in our sample. A detailed investigation of the projected distribution of star clusters in the Galaxy demonstrates that they show a clear tendency to cluster on spatial scales in the order of 12-25pc, a typical size for molecular clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/488/211
- Title:
- Infrated photometry of NGC 1893
- Short Name:
- J/A+A/488/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The independence of the star formation processes with respect to the environmental conditions is controversial. In particular it is not clear whether star formation in the outer Galaxy, where the environmental conditions are, theoretically, less conducive, occurs in the same way as in the inner Galaxy. We investigate the population of NGC 1893, a young cluster (~3-4Myr) in the outer part of the Galaxy (galactic radius >11kpc) in order to explore the effects of environmental conditions on star forming regions. We present the infrared observations obtained with the IRAC camera on board of the Spitzer Space Telescope and analyze the color-color diagrams to establish the membership of stars with excesses. We also merge this information with that obtained from Chandra ACIS-I observations, in order to identify the Class III population. We find that the cluster is very rich, with 242 PMS Classical T-Tauri stars and 7 Class 0/I stars. Moreover we identify 110 Class III candidate cluster members in the ACIS-I field of view. We estimate a disk fraction for NGC 1893 of about 67%, similar to fraction calculated for nearby star forming regions of the same age. Although the environmental conditions are not favorable, star formation can clearly be very successful in the outer Galaxy, allowing creation of a very rich cluster like NGC 1893.
