scholarly journals A Proper Motion Study of the Pleiades Cluster

1985 ◽  
Vol 113 ◽  
pp. 477-480
Author(s):  
Floor van Leeuwen
Keyword(s):  
Central Region ◽  
Proper Motion ◽  
Proper Motions ◽  
Motion Study ◽  
First Results ◽  
Image Position

The first results of an extensive proper motion study of the Pleiades cluster are presented. A total of 166 exposures covering a 3 by 3 degrees area are now incorporated. The accuracies of the centennial proper motions range from in the central region to in the outermost region.

scholarly journals First results from a large-scale proper motion study of the Galactic centre

2019 ◽  
Vol 632 ◽  
pp. A116 ◽  
Author(s):  
B. Shahzamanian ◽  
R. Schödel ◽  
F. Nogueras-Lara ◽  
H. Dong ◽  
E. Gallego-Cano ◽  
...  
Keyword(s):  
Proper Motion ◽  
Large Scale ◽  
Interstellar Extinction ◽  
Stellar Disk ◽  
Galactic Centre ◽  
Proper Motions ◽  
Stellar Cluster ◽  
Motion Study ◽  
First Results ◽  
Moving Groups

Proper motion studies of stars in the centre of the Milky Way have typically been limited to the Arches and Quintuplet clusters, and to the central parsec. Here we present the first results of a large-scale proper motion study of stars within several tens of parsecs of Sagittarius A* based on our 0.2″ angular resolution GALACTICNUCLEUS survey (epoch 2015) combined with NICMOS/HST data from the Paschen-α survey (epoch 2008). This comprises the first extensive proper motion study of the central ∼36′×16′ of the Galaxy, which is not covered adequately by any of the existing astronomical surveys, such as Gaia, because of the extreme interstellar extinction (AV ≳ 30 mag). Proper motions can help us to disentangle the different stellar populations along the line-of-sight and interpret their properties in combination with multi-wavelength photometry from GALACTICNUCLEUS and other sources. It also allows us to infer the dynamics and interrelationships between different stellar components (Galactic bulge, nuclear stellar disk, nuclear stellar cluster) of the Galactic centre (GC). In particular, we use proper motions to detect co-moving groups of stars which are able to trace low-mass or partially-dissolved young clusters in the GC that can hardly be discovered by any other means. Our pilot study for this work is based on a field in the nuclear bulge associated with HII regions that show the presence of young stars. We have detected the first group of co-moving stars coincident with an H II region. Using colour–magnitude diagrams, we have inferred that the co-moving stars are consistent with the post-main sequence stars with ages of few Myr. Simulations show that this group of stars is a real group that can indicate the existence of a dissolving or low-to-intermediate-mass young cluster. A census of these undiscovered clusters will ultimately help us to constrain star formation at the GC in the past few ten Myr.

scholarly journals Proper motions in the Galactic bulge: Plaut's window

2007 ◽  
Vol 3 (S245) ◽  
pp. 351-354
Author(s):  
Katherine Vieira ◽  
Dana Cassetti-Dinescu ◽  
René A. Méndez ◽  
R. Michael Rich ◽  
Terrence M. Girard ◽  
...  
Keyword(s):  
Proper Motion ◽  
Galactic Rotation ◽  
Red Giants ◽  
Proper Motions ◽  
Motion Study ◽  
Solar Motion ◽  
Two Samples ◽  
Red Clump ◽  
Good Agreement ◽  
Peak Value

AbstractA proper motion study of a field of 20′ × 20′ inside Plaut's low extinction window (l,b)=(0o, −8o), has been completed. Relative proper motions and photographicBVphotometry have been derived for ~ 21,000 stars reaching toV~ 20.5 mag, based on the astrometric reduction of 43 photographic plates, spanning over 21 years of epoch difference. Proper motion errors are typically 1 mas yr−1. Cross-referencing with the 2MASS catalog yielded a sample of ~ 8700 stars, from which predominantly disk and bulge subsamples were selected photometrically from theJHcolor-magnitude diagram. The two samples exhibited different proper-motion distributions, with the disk displaying the expected reflex solar motion. Galactic rotation was also detected for stars between ~2 and ~3 kpc from us. The bulge sample, represented by red giants, has an intrinsic proper motion dispersion of (σl, σb) = (3.39, 2.91)±(0.11, 0.09) mas yr−1, which is in good agreement with previous results. A mean distance of$6.37^{+0.87}_{-0.77}$kpc has been estimated for the bulge sample, based on the observedKmagnitude of the horizontal branch red clump. The metallicity [M/H] distribution was also obtained for a subsample of 60 bulge giants stars, based on calibrated photometric indices. The observed [M/H] shows a peak value at [M/H] ~ −0.1 with an extended metal poor tail and around 30% of the stars with supersolar metallicity. No change in proper motion dispersion was observed as a function of [M/H]. We are currently in the process of obtaining CCDUBV RIphotometry for the entire proper-motion sample of ~ 21,000 stars.

scholarly journals The Y dwarf population with HST: unlocking the secrets of our coolest neighbours – I. Overview and first astrometric results

2020 ◽  
Vol 501 (1) ◽  
pp. 911-915
Author(s):  
C Fontanive ◽  
L R Bedin ◽  
D C Bardalez Gagliuffi
Keyword(s):  
Proper Motion ◽  
Hubble Space Telescope ◽  
Proper Motions ◽  
Brown Dwarf ◽  
Space Telescope ◽  
First Results

ABSTRACT In this paper, we present our project that aims at determining accurate distances and proper motions for the Y brown dwarf population using the Hubble Space Telescope. We validate the program with our first results, using a single new epoch of observations of the Y0pec dwarf WISE J163940.83−684738.6. These new data allowed us to refine its proper motion and improve the accuracy of its parallax by a factor of three compared to previous determinations, now constrained to ϖ = 211.11 ± 0.56 mas. This newly derived absolute parallax corresponds to a distance of 4.737 ± 0.013 pc, an exquisite and unprecedented precision for faint ultracool Y dwarfs.

scholarly journals Determining Motions and Birthplaces of Pulsars through VLBI Astrometry

1998 ◽  
Vol 164 ◽  
pp. 391-392
Author(s):  
T. J. Galama ◽  
J. Van Paradijs ◽  
E. P. J. van den Heuvel ◽  
A. G. de Bruyn ◽  
R. M. Campbell ◽  
...  
Keyword(s):  
Flux Density ◽  
Proper Motion ◽  
Mass Range ◽  
Solar Neighborhood ◽  
Proper Motions ◽  
First Results ◽  
Motion Measurements

AbstractWe present first results of global VLBI astrometric pulsar parallax and proper motion measurements (phase-reference). The aim is to obtain information on pulsar motions and pulsar birthplaces. Proper motions could provide answers to questions like: How large are pulsar velocities at birth? How are these velocities produced and what is the final galactic pulsar distribution? Identification of birthplaces (with, e.g., an OB-association) provides information on the pulsar progenitor population (the fraction of pulsars born in binaries; the mass range of the progenitors etc.). We have a first epoch on three pulsars, selected on the basis of age (young < 3 Myr), flux density (relatively strong) and presence in the solar neighborhood (d < 3 kpc). Gating increases the SNR by typically a factor of 5.

scholarly journals Solar Motion And Galactic Rotation: Results From The Lick Northern Proper Motion Program

1988 ◽  
Vol 133 ◽  
pp. 427-432
Author(s):  
Robert B. Hanson
Keyword(s):  
Proper Motion ◽  
Rotation Curve ◽  
Zero Point ◽  
Galactic Rotation ◽  
Proper Motions ◽  
Circular Velocity ◽  
Solar Motion ◽  
First Results ◽  
Galactic Rotation Curve ◽  
Detailed Presentation

This paper reports the first results of solar motion and galactic rotation studies which are being done at Lick Observatory, using the new data from the Lick Northern Proper Motion (NPM) Program. This study finds: (1) A = +11.31 ± 1.06 and B = −13.91 ± 0.92 km/s/kpc, consistent with a nearly flat galactic rotation curve with a local circular velocity near 200 km/s; (2) solar apex locations lying near the standard apex for low galactic latitudes, but trending strongly toward the direction of galactic rotation for high galactic latitudes; (3) RMS external error estimates for the Lick proper motions: for the absolute zero-point in a typical NPM field, and for the overall systematic zero-point error. A more detailed presentation of these results has been given by Hanson (1987). The NPM program is reviewed in another paper in this Symposium, and has been described in detail by Klemola, Jones, and Hanson (1987).

scholarly journals A jet proper motion study in the early Universe

2018 ◽  
Vol 14 (S342) ◽  
pp. 252-253
Author(s):  
Krisztina Perger ◽  
Sándor Frey ◽  
Krisztina É. Gabányi
Keyword(s):  
Early Universe ◽  
Proper Motion ◽  
Very Long Baseline Interferometry ◽  
Cosmological Models ◽  
Proper Motions ◽  
Distant Source ◽  
Long Baseline ◽  
Motion Study

AbstractWe constrained the jet proper motion of PMN J2134–0419 at z = 4.33 to μ = 0.035±0.023mas yr−1 using very long baseline interferometry (VLBI). This is the second most distant source where such a measurement could be made. Another distant blazar SDSS J1026+2542 (z = 5.27) shows jet component proper motions up to μ = 0.112 ± 0.031 mas yr−1. In both cases, the measured values are consistent with the expectations of current ΛCDM cosmological models.

First Results of the Lick Proper Motion Program

1970 ◽  
Vol 7 ◽  
pp. 167-183 ◽  
Author(s):  
S. Vasilevskis ◽  
A. R. Klemola
Keyword(s):  
Proper Motion ◽  
Pilot Program ◽  
Proper Motions ◽  
Yellow Light ◽  
Full Coverage ◽  
Original Plan ◽  
First Results ◽  
Crude Analysis

Photography of the second epoch of the Lick Proper Motion Program (Wright 1950) was started in 1968. The original plan (Vasilevskis 1954) was modified in several respects. It was decided to carry out a pilot program first, before the start of a full coverage of the sky accessible from Lick. It was also decided to make use of the new lens corrected for yellow light (Vasilevskis 1964), in addition to the blue lens used for the first epoch. The aims of the pilot program were formulated: (1) carry out the necessary error investigations, (2) develop methods and procedures to a stage of routine, (3) derive proper motions of stars measured, and (4) attempt to arrive at some astronomical conclusions based on these motions. The program was limited to 97 fields nearly uniformly distributed over the sky north of -23° all these fields were photographed, measured and reduced, 78 of them contain a sufficient number of galaxies for proper motion reference. This report will be limited to presenting a few results obtained from the first crude analysis of proper motions that became available only a week ago. These results, therefore may change significantly in the process of further analysis.

scholarly journals On the Use of Statistical Parallaxes for the Proper Motion Reductions

1990 ◽  
Vol 141 ◽  
pp. 65-66
Author(s):  
N.M. Bronnikova ◽  
N.A. Shakht
Keyword(s):  
Proper Motion ◽  
Galactic Rotation ◽  
Proper Motions ◽  
Image Position

The Pulkovo program of determination of proper motions with respect to galaxies approaches completion. It consists of 157 fields from +90° to −4° of declination. The proper motions and reductions with use of galaxies were derived for all areas. The errors of reductions are equal to ± 0.″006. In addition the statistical reductions Rx, Ry were computed for the control and for the zones of avoidance. The following formulae were used: where is the secular parallax according to Binnendijk [1]; P and P′ are parallactic factors; Q and Q′ are members dependent on the galactic rotation.

scholarly journals Absolute Proper and Space Motion of the Globular Cluster M2

1994 ◽  
Vol 161 ◽  
pp. 464-466
Author(s):  
M. Geffert ◽  
C. Forner ◽  
M. Hiesgen ◽  
A.R. Klemola
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Reference Frames ◽  
Proper Motions ◽  
The Past ◽  
Motion Study ◽  
Space Motion ◽  
First Results

Space motions of globular clusters are important for the understanding of the kinematics and chemical evolution of the Milky Way. The greatest problem for the determination of the space motions of the globular clusters arises from the difficulties of getting absolute proper motions. In the past these were determined using classical stellar reference frames, modelling of the non-cluster stars in the field and extragalactic objects in the region of the cluster (see e.g. Cudworth &amp; Hanson 1993; Geffert et al. 1993 for references). However, as shown for M 15 and M 3 (Geffert et al. 1993; Tucholke et al. 1993), the results based on different methods for deriving the absolute proper motions differ by up to yrs. In order to get a more complete view of the differences between the various methods it is therefore very interesting to get absolute proper motions based on all three methods for further objects. We present here the first results of a new proper motion study of the globular cluster M 2.

scholarly journals Membership and Internal Motions of Faint Stars in the Globular Cluster M 3

1994 ◽  
Vol 161 ◽  
pp. 461-463
Author(s):  
R.-D. Scholz ◽  
N.V. Kharchenko
Keyword(s):  
Globular Cluster ◽  
Proper Motion ◽  
Stepwise Regression ◽  
Regression Method ◽  
Proper Motions ◽  
Internal Motions ◽  
Motion Study

A proper motion study from Tautenburg Schmidt plates is presented for the globular cluster M 3 and its vicinity. The plates were scanned with the Automated Photographic Measuring (APM) system in Cambridge (UK). With a limiting magnitude of B = 21, proper motions of 2 to 3 mas/yr accuracy have been obtained for stars with B &lt; 19. The proper motions were determined applying a stepwise regression method with 3rd order polynomials in the plate-to-plate solutions with about 2000 reference galaxies. We used the results for the determination of membership probabilities and looked for internal motions of M 3.

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