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Start Over Subject proper motions Validation Level 2
281. Kinematics of halo red giants
ID:
ivo://CDS.VizieR/J/ApJ/769/87
Title:
Kinematics of halo red giants
Short Name:
J/ApJ/769/87
Date:
21 Oct 2021
Publisher:
CDS
Description:
We explore the kinematics and orbital properties of a sample of red giants in the halo system of the Milky Way that are thought to have formed in globular clusters based on their anomalously strong UV/blue CN bands. The orbital parameters of the CN-strong halo stars are compared to those of the inner- and outer-halo populations as described by Carollo et al. (2007Natur.450.1020C, 2010ApJ...712..692C), and to the orbital parameters of globular clusters with well-studied Galactic orbits. The CN-strong field stars and the globular clusters both exhibit kinematics and orbital properties similar to the inner-halo population, indicating that stripped or destroyed globular clusters could be a significant source of inner-halo field stars, and suggesting that both the CN-strong stars and the majority of globular clusters are primarily associated with this population.
282. Kinematics of red giant and RR Lyrae stars
ID:
ivo://CDS.VizieR/J/AJ/115/168
Title:
Kinematics of red giant and RR Lyrae stars
Short Name:
J/AJ/115/168
Date:
21 Oct 2021
Publisher:
CDS
Description:
The kinematics of 122 red giant and 124 RR Lyrae stars in the solar neighborhood are studied using accurate measurements of their proper motions obtained by the Hipparcos astrometry satellite, combined with their published photometric distances, metal abundances, and radial velocities. A majority of these sample stars have metal abundances of [Fe/H]<=-1 and thus represent the old stellar populations in the Galaxy. The halo component, with [Fe/H]<=-1.6, is characterized by a lack of systemic rotation [(<U>, <V>, <W>)=(16+/-18, -217+/-21, -10+/-12)km/s] and a radially elongated velocity ellipsoid [(<U>, <V>, <W>)=(161+/-10, 115+/-7, 108+/-7)km/s]. About 16% of such metal-poor stars have low orbital eccentricities (e<0.4), and we see no evidence of a correlation between [Fe/H] and e. Based on the model for the e-distribution of orbits, we show that this fraction of low-e stars for [Fe/H]<=-1.6 is explained by the halo component alone, without introducing the extra disk component claimed by recent workers. This is also supported by the absence of a significant change in the e-distribution with height from the Galactic plane. In the intermediate-metallicity range (-1.6<[Fe/H]<=-1), we find that stars with disklike kinematics have only modest effects on the distributions of rotational velocities and e for the sample at |z|<1kpc. This disk component appears to constitute only 10% for -1.6<[Fe/H]<=-1 and 20% for -1.4<[Fe/H]<=-1. It is also verified that this metal-weak disk has a mean rotation of ~195km/s and a vertical extent of 1 kpc, which is consistent with the thick disk's dominating at [Fe/H]=-0.6 to -1. We find no metallicity gradient in the halo, whereas there is an indication of a metallicity gradient in the metal-weak tail of the thick disk. The implications of these results for the early evolution of the Galaxy are also presented.
283. Kinematics of RR Lyr and HB stars in NGP
ID:
ivo://CDS.VizieR/J/MNRAS/375/1381
Title:
Kinematics of RR Lyr and HB stars in NGP
Short Name:
J/MNRAS/375/1381
Date:
21 Oct 2021
Publisher:
CDS
Description:
Radial velocities and proper motions (derived from the GSC-II data base) are given for 38 RR Lyrae (RRL) stars and 79 blue horizontal branch (BHB) stars in a ~200deg^2^ area around the North Galactic Pole (NGP). Both heliocentric (UVW) and galactocentric (VR, Vphi, Vz) space motions are derived for these stars using a homogeneous distance scale consistent with (m-M)0=18.52 for the Large Magellanic Cloud (LMC).
284. Kinematics of Sco-Cen OB Association
ID:
ivo://CDS.VizieR/J/PAZh/33/643
Title:
Kinematics of Sco-Cen OB Association
Short Name:
J/PAZh/33/643
Date:
21 Oct 2021
Publisher:
CDS
Description:
A fine structure related to the kinematic peculiarities of three components of the Scorpius-Centaurus association (LCC = Lower Centaurus-Crux, UCL = Upper Centaurus-Lupus, and US = Upper Scorpius) has been revealed in the UV-velocity distribution of Gould Belt stars. We have been able to identify the most likely members of these groups by applying the method of analyzing the two-dimensional probability density function of stellar UV velocities that we developed. A kinematic analysis of the identified structural components has shown that, in general, the center-of-mass motion of the LCC, UCL, and US groups follows the motion characteristic of the Gould Belt, notably its expansion. The entire Scorpius-Centaurus complex is shown to possess a proper expansion with an angular velocity parameter of 46+/-8km/s/kpc for the kinematic center with l_0_=-40{deg} and R_0_=110pc found. Based on this velocity, we have estimated the characteristic expansion time of the complex to be 21+/-4Myr. The proper rotation velocity of the Scorpius-Centaurus complex is lower in magnitude, is determined less reliably, and depends markedly on the data quality.
285. Kinematics of W UMa-type binaries
ID:
ivo://CDS.VizieR/J/MNRAS/357/497
Title:
Kinematics of W UMa-type binaries
Short Name:
J/MNRAS/357/497
Date:
21 Oct 2021
Publisher:
CDS
Description:
The kinematics of 129 W Ursae Majoris type binaries (W UMas) were studied. The sample is heterogeneous with different orbits and physically different components from F to K spectral-type main-sequence stars. The computed U, V, W space velocities indicate that the sample is also heterogeneous in velocity space.
286. Kinematic study of open clusters
ID:
ivo://CDS.VizieR/J/MNRAS/407/2109
Title:
Kinematic study of open clusters
Short Name:
J/MNRAS/407/2109
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Galactic population of open clusters provides an insight into star formation in the Galaxy. The open cluster catalogue by Dias et al. (Cat. B/ocl) is a rich source of data, including kinematic information. This large sample made it possible to carry out a systematic analysis of 481 open cluster orbits, using parameters based on orbit eccentricity and separation from the Galactic plane. These two parameters may be indicative of origin, and we find them to be correlated. We also find them to be correlated with metallicity, another parameter suggested elsewhere to be a marker for origin in that high values of any of these two parameters generally indicate a low metallicity ([Fe/H]solar<-0.2dex). The resulting analysis points to four open clusters in the catalogue being of extragalactic origin by impact of high-velocity cloud on the disc: Berkeley 21, 32, 99 and Melotte 66, with a possible further four due to this origin (NGC 2158, 2420, 7789 and IC 1311). A further three may be due to Galactic globular cluster impact on the disc, i.e. of internal Galactic origin (NGC 6791, 1817 and 7044).
287. K-M stars of class I candidate RSGs in Gaia DR2
ID:
ivo://CDS.VizieR/J/AJ/158/20
Title:
K-M stars of class I candidate RSGs in Gaia DR2
Short Name:
J/AJ/158/20
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate individual distances and luminosities of a sample of 889 nearby candidate red supergiants (RSGs) with reliable parallaxes ({omega}/{sigma}_{omega}_>4 and RUWE<2.7) from Gaia Data Release 2 (DR2, Cat. I/345). The sample was extracted from the historical compilation of spectroscopically derived spectral types by Skiff (Cat. B/mk), and consists of K-M stars that are listed with class I at least once. The sample includes well-known RSGs from Humphreys (1978ApJS...38..309H), Elias et al. (1985ApJS...57...91E), Jura & Kleinmann (1990ApJS...73..769J), and Levesque et al. (2005ApJ...628..973L). Infrared and optical measurements from the Two Micron All Sky Survey, Catalog of Infrared Observations (CIO), Midcourse Space Experiment, Wide-field Infrared Survey Explorer, MIPSGAL, Galactic Legacy Infrared Midplane Extraordinaire (GLIMPSE), and The Naval Observatory Merged Astrometric Dataset catalogs allow us to estimate the stellar bolometric magnitudes. We analyze the stars in the luminosity versus effective temperature plane and confirm that 43 sources are highly probably RSGs with M_bol_< -7.1 mag. Of the stars in the sample, 43% have masses >7 M_{sun}_. Another ~30% of the sample consists of giant stars.
288. Knots in the deep [FeII]+[SiI] image of the SNR Cas A
ID:
ivo://CDS.VizieR/J/ApJ/866/139
Title:
Knots in the deep [FeII]+[SiI] image of the SNR Cas A
Short Name:
J/ApJ/866/139
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a long-exposure (~10hr), narrowband image of the supernova (SN) remnant Cassiopeia A (Cas A) centered at 1.644{mu}m emission. The passband contains [FeII] 1.644{mu}m and [SiI] 1.645{mu}m lines, and our "deep [FeII]+[SiI] image" provides an unprecedented panoramic view of Cas A, showing both shocked and unshocked SN ejecta, together with shocked circumstellar medium at subarcsecond (~0.7" or 0.012pc) resolution. The diffuse emission from the unshocked SN ejecta has a form of clumps, filaments, and arcs, and their spatial distribution correlates well with that of the Spitzer [SiII] infrared emission, suggesting that the emission is likely due to [SiI] not [FeII] as in shocked material. The structure of the optically invisible western area of Cas A is clearly seen for the first time. The area is filled with many quasi-stationary flocculi (QSFs) and fragments of the disrupted ejecta shell. We identified 309 knots in the deep [FeII]+[SiI] image and classified them into QSFs and fast-moving knots (FMKs). The comparison with previous optical plates indicates that the lifetime of most QSFs is >~60yr. The total H+He mass of QSFs is ~0.23M_{sun}_, implying that the mass fraction of dense clumps in the progenitor's mass ejection immediately prior to the SN explosion is about 4%-6%. FMKs in the deep [FeII]+[SiI] image mostly correspond to S-rich ejecta knots in optical studies, while those outside the southeastern disrupted ejecta shell appear Fe-rich. The mass of the [FeII] line emitting, shocked dense Fe ejecta is ~3x10^-5^M_{sun}_.
289. Known LT dwarfs in the Gaia DR1
ID:
ivo://CDS.VizieR/J/MNRAS/469/401
Title:
Known LT dwarfs in the Gaia DR1
Short Name:
J/MNRAS/469/401
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identify and investigate known ultracool stars and brown dwarfs that are being observed or indirectly constrained by the Gaia mission. These objects will be the core of the Gaia ultracool dwarf sample composed of all dwarfs later than M7 that Gaia will provide direct or indirect information on. We match known L and T dwarfs to the Gaia first data release, the Two Micron All Sky Survey and the Wide-field Infrared Survey Explorer AllWISE survey and examine the Gaia and infrared colours, along with proper motions, to improve spectral typing, identify outliers and find mismatches. There are 321 L and T dwarfs observed directly in the Gaia first data release, of which 10 are later than L7. This represents 45 per cent of all the known LT dwarfs with estimated GaiaG magnitudes brighter than 20.3mag. We determine proper motions for the 321 objects from Gaia and the Two Micron All Sky Survey positions. Combining the Gaia and infrared magnitudes provides useful diagnostic diagrams for the determination of L and T dwarf physical parameters. We then search the Tycho-Gaia astrometric solution, Gaia first data release subset, to find any objects with common proper motions to known L and T dwarfs and a high probability of being related. We find 15 new candidate common proper motion systems.
290. Known members of Orion A with Gaia DR2 data
ID:
ivo://CDS.VizieR/J/ApJ/884/6
Title:
Known members of Orion A with Gaia DR2 data
Short Name:
J/ApJ/884/6
Date:
04 Dec 2021
Publisher:
CDS
Description:
The star-forming region of the Orion Nebula (ONC) is ideal to study the stellar dynamics of young stars in a clustered environment. Using Gaia DR2 we search for pre-main sequence stars with unusually high proper motions that may be representative of a dynamical ejection from unstable young triple systems or other close three-body encounters. We identify 26 candidate stars that are likely to have had such an encounter in the last 1Myr. Nine of these stars could be traced back to the densest central-most region of the ONC, the Trapezium, while five others have likely interactions with other OB-type stars in the cluster. Seven stars originate from other nearby populations within the Orion Complex that coincidentally scattered toward the ONC. A definitive point of origin cannot be identified for the remaining sources. These observations shed light on the frequency of the ejection events in young clusters.