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3861. 2MASS/SDSS data for 806 ultracool dwarfs
ID:
ivo://CDS.VizieR/J/MNRAS/404/1817
Title:
2MASS/SDSS data for 806 ultracool dwarfs
Short Name:
J/MNRAS/404/1817
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identify 806 ultracool dwarfs (of which 34 are newly discovered L dwarfs) from their Sloan Digital Sky Survey (SDSS) riz photometry and obtain proper motions through cross-matching with the United Kingdom Infrared Telescope Infrared Deep Sky Survey (UKIDSS) and Two-Micron All-Sky Survey (2MASS). Proper-motion and distance constraints show that nine of our ultracool dwarfs are members of widely separated binary systems.
3862. Mass segregation in open clusters
ID:
ivo://CDS.VizieR/J/A+A/333/897
Title:
Mass segregation in open clusters
Short Name:
J/A+A/333/897
Date:
21 Oct 2021
Publisher:
CDS
Description:
On the basis of the best available member list and duplicity information, we have studied the radial structure of Praesepe and of the very young open cluster NGC 6231. We have found mass segregation among the cluster members and between binaries and single stars, which is explained by the greater average mass of the multiple systems. However, the degree of mass segregation for stars between 1.5 and 2.3M_{sun}_ is less pronounced in Praesepe than in the Pleiades. Furthermore, mass segregation is already present in the very young open cluster NGC 6231 although this cluster is likely still not dynamically relaxed. We discuss the implications of these results and propose a qualitative scenario for the evolution of mass segregation in open clusters. In Praesepe the mass function of single stars and primaries appears to be significantly different, like in the Pleiades. We observe an absence of ellipticity of the outer part of Praesepe.
3863. 2MASS-selected Flat Galaxy Catalog (2MFGC)
ID:
ivo://CDS.VizieR/J/other/BSAO/57.5
Title:
2MASS-selected Flat Galaxy Catalog (2MFGC)
Short Name:
J/other/BSAO/57.
Date:
21 Oct 2021
Publisher:
CDS
Description:
An all-sky catalog of 18020 disc-like galaxies is presented. The galaxies are selected from the Extended Source Catalog of the Two Micron All-Sky Survey (XSC 2MASS) basing on their 2MASS axial ratio a/b>=3. The Catalog contains data on magnitudes of a galaxy in the J, H, Ks bands, its axial ratio, positional angle, index of luminosity concentration, as well as identification of the galaxy with the LEDA and the NED databases. Unlike the available optical catalogs, the new 2MFGC catalog seems to be more suitable to study cosmic streaming on a scale of z~0.1. The dipole moment of distribution of the bright (K<11mag) 2MFGC objects (l=227{deg}, b=41{deg} or SGL=90{deg}, SGB=-43{deg}) lies within statistical errors (+/-15{deg}) in the direction of the IRAS dipole and the optical RFGC dipole.
3864. 2MASS-selected Isolated Galaxies (2MIG)
ID:
ivo://CDS.VizieR/VII/257
Title:
2MASS-selected Isolated Galaxies (2MIG)
Short Name:
VII/257
Date:
21 Oct 2021
Publisher:
CDS
Description:
We undertook searches for isolated galaxies based on automatic selection of infrared sources from the Two Micron All-Sky Survey (2MASS, Cat. II/246) followed by a visual inspection of their surrounding. Using a modified criterion by Karachentseva (1973SoSAO...8....3K), we compiled a catalog of 3227 isolated galaxies (2MIG) containing 6% of 2MASS Extended Sources (2MASX, Cat. VII/233) brighter than K_s_=12mag with angular diameters a_K_<=30". The most isolated 2493 galaxies among them enter in the 2MASS Very Isolated Galaxy Catalog, 2MVIG. Being situated in the regions of extremely low mass density, the 2MVIG galaxies can serve as a reference sample for investigation the influence of environment on structure and evolution of galaxies.
3865. 2MASS-Selected sample of ultracool dwarfs
ID:
ivo://CDS.VizieR/J/AJ/126/2421
Title:
2MASS-Selected sample of ultracool dwarfs
Short Name:
J/AJ/126/2421
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the initial results of our effort to create a statistically robust, volume-limited sample of ultracool dwarfs from the Two Micron All Sky Survey Second Incremental Data Release (<II/241>). We are engaged in a multifaceted search for nearby late-type objects, and this is the first installment of our search using purely photometric selection. The goal of this work is a determination of the low-mass star and brown dwarf luminosity function in the infrared. Here we outline the construction of the sample, dubbed 2MU2, and present our first results, including the discovery of 186 M7-L6 dwarfs, 47 of which are likely to be within 20pc of the Sun. These results represent 66% of the ultracool candidates in our sample yet constitute a 127% increase in the number of ultracool dwarfs known within the volume searched (covering 40% of the sky out to 20pc). In addition, we have identified 10 M4-M6.5 objects that are likely to be within 20pc (or within 1{sigma}). Finally, based on these initial data, we present a preliminary luminosity function and discuss several interesting features of the partial sample presented here. Once our sample is complete, we will use our measured luminosity function to constrain the mass function of low-mass stars and brown dwarfs.
3866. 2MASS survey of wide multiplicity in 3 associations
ID:
ivo://CDS.VizieR/J/ApJ/662/413
Title:
2MASS survey of wide multiplicity in 3 associations
Short Name:
J/ApJ/662/413
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a search for wide binary systems among 783 members of three nearby young associations: Taurus-Auriga, Chamaeleon I, and two subgroups of Upper Scorpius. Near-infrared (JHK) imagery from 2MASS was analyzed to search for wide (1"-30"; ~150-4500AU) companions to known association members, using color-magnitude cuts to reject likely background stars. We identify a total of 131 candidate binary companions with colors consistent with physical association, of which 39 have not been identified previously in the literature.
3867. 2MASS view of Sgr dSph. VII. Kinematics
ID:
ivo://CDS.VizieR/J/ApJ/756/74
Title:
2MASS view of Sgr dSph. VII. Kinematics
Short Name:
J/ApJ/756/74
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have assembled a large-area spectroscopic survey of giant stars in the Sagittarius (Sgr) dwarf galaxy core. Using medium resolution (R~15000), multifiber spectroscopy we have measured velocities of these stars, which extend up to 12{deg} from the galaxy's center (3.7 core radii or 0.4 times the King limiting radius). From these high-quality spectra we identify 1310 Sgr members out of 2296 stars surveyed, distributed across 24 different fields across the Sgr core. Additional slit spectra were obtained of stars bridging from the Sgr core to its trailing tail. Our systematic, large-area sample shows no evidence for significant rotation, a result at odds with the ~20km/s rotation required as an explanation for the bifurcation seen in the Sgr tidal stream; the observed small (<=4km/s) velocity trend primarily along the major axis is consistent with models of the projected motion of an extended body on the sky with no need for intrinsic rotation. The Sgr core is found to have a flat velocity dispersion (except for a kinematically colder center point) across its surveyed extent and into its tidal tails, a property that matches the velocity dispersion profiles measured for other Milky Way dwarf spheroidal (dSph) galaxies. We comment on the possible significance of this observed kinematical similarity for the dynamical state of the other classical Milky Way dSphs in light of the fact that Sgr is clearly a strongly tidally disrupted system.
3868. 2MASS 6X Point Source Working Database / Catalog
ID:
ivo://CDS.VizieR/II/281
Title:
2MASS 6X Point Source Working Database / Catalog
Short Name:
II/281
Date:
21 Oct 2021
Publisher:
CDS
Description:
A special set of observations that utilized exposure times six times longer than the main 2MASS survey measurements were conducted in the final year of 2MASS observatory operations. The 2MASS "6x" observations achieved sensitivities ~1 mag deeper than the main 2MASS survey, and covered approximately 590 deg2 of sky in 30 discrete regions. The 2MASS 6x Point Source Working Databases (6x-PSWDB and 6x-XSWDB) contain all detections extracted from the raw 6x imaging data during pipeline data reduction. The 6x WDB entries include reliable detections of astrophysical sources, as well as spurious detections of noise excursions, image artifacts and transient events such as meteor trails, cosmic rays and hot pixels. In addition, the WDBs may contain multiple, independent detections of objects scanned more than once during the 6x observations. The 2MASS 6x Point Source Catalogs (6x-PSC and 6x-XSC) is a subset of extractions in the 6x-PSWDB that have been identified to be high reliability source detections, with only one measurement of sources detected multiple times for uniformity.
3869. 2MASS6x survey of the Lockman Hole
ID:
ivo://CDS.VizieR/J/AJ/125/2521
Title:
2MASS6x survey of the Lockman Hole
Short Name:
J/AJ/125/2521
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have carried out a survey of the Lockman Hole covering over 24deg^2^ using the Two Micron All Sky Survey (2MASS) observing system in a special mode that reaches roughly 1mag deeper than the nominal 2MASS survey. The resultant point-source catalog reaches to approximately (J, H, Ks)<(17.8, 16.5, 16.0)mag with completeness and reliability in excess of 90%-95% at the faintest levels. These data will be useful in identifying sources in SIRTF surveys of this area. We have cataloged 69,115 objects, almost twice as many as in the nominal 2MASS survey of this region. The sample includes a large number of potential new active galaxies, as well as a T dwarf candidate.
3870. Master Catalogue towards the Magellanic Clouds (MC2)
ID:
ivo://CDS.VizieR/IV/33
Title:
Master Catalogue towards the Magellanic Clouds (MC2)
Short Name:
IV/33
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Master Catalogue of stars towards the Magellanic Clouds (MC2) is a multi-wavelength reference catalogue. The current paper presents the first results of the MC2 project. We started with a massive cross-identification of the two recently released near-infrared surveys: the DENIS Catalogue towards the Magellanic Clouds (DCMC) with more than 1.3 million sources identified in at least two of the three DENIS filters (I J Ks) and the 2nd Incremental Release of the 2MASS point source catalogue (J H Ks) covering the same region of the sky. Both point source catalogues provide an unprecedented wealth of data on the stellar populations of the Magellanic Clouds (MCs). The cross-matching procedure has been extended to optical wavelength ranges, including the UCAC1 (USNO) and GSC2.2 catalogues. New cross-matching procedures for very large catalogues have been developed and important results on the astrometric and photometric accuracy of the cross-identified catalogues were derived. The cross-matching of large surveys is an essential tool to improve our understanding of their specific contents. This study has been partly supported by the ASTROVIRTEL project that aims at improving access to astronomical archives as virtual telescopes. This work has been supported by ASTROVIRTEL, a project funded by the European Commission under FP5 Contract No. HPRI-CT-1999-00081.