scholarly journals A New Absolute Proper Motion Determination of Leo I Using HST/WFPC2 Images and Gaia EDR3

2021 ◽  
Vol 163 (1) ◽  
pp. 1
Author(s):  
Dana I. Casetti-Dinescu ◽  
Caitlin K. Hansen ◽  
Terrence M. Girard ◽  
Vera Kozhurina-Platais ◽  
Imants Platais ◽  
...  
Keyword(s):  
Proper Motion ◽  
Milky Way ◽  
Proper Motions ◽  
Large Area ◽  
Field Of Study ◽  
Data Set ◽  
Polar Structure ◽  
The Galaxy ◽  
The Absolute

Abstract We measure the absolute proper motion of Leo I using a WFPC2/HST data set that spans up to 10 yr to date the longest time baseline utilized for this satellite. The measurement relies on ∼2300 Leo I stars located near the center of light of the galaxy; the correction to absolute proper motion is based on 174 Gaia EDR3 stars and 10 galaxies. Having generated highly precise, relative proper motions for all Gaia EDR3 stars in our WFPC2 field of study, our correction to the absolute EDR3 system does not rely on these Gaia stars being Leo I members. This new determination also benefits from a recently improved astrometric calibration of WFPC2. The resulting proper-motion value, (μ α , μ δ ) = (−0.007 ± 0.035, − 0.119 ± 0.026) mas yr−1 is in agreement with recent, large-area, Gaia EDR3-based determinations. We discuss all the recent measurements of Leo I’s proper motion and adopt a combined, multistudy average of ( μ α 3 meas , μ δ 3 meas ) = ( − 0.036 ± 0.016 , − 0.130 ± 0.010 ) mas yr−1. This value of absolute proper motion for Leo I indicates its orbital pole is well aligned with that of the vast polar structure, defined by the majority of the brightest dwarf spheroidal satellites of the Milky Way.

scholarly journals Maintenance and densification: current proper-motion catalogs

2007 ◽  
Vol 3 (S248) ◽  
pp. 303-309
Author(s):  
T. M. Girard
Keyword(s):  
Proper Motion ◽  
Reference System ◽  
Milky Way ◽  
Raw Material ◽  
Proper Motions ◽  
Schmidt Telescope ◽  
Large Area ◽  
Milky Way Galaxy ◽  
Celestial Reference System

AbstractAn overview of currently available, large-area, proper-motion catalogs is presented. These include the well-known catalogs based on historical Schmidt-telescope surveys as well as other projects that make use of observational material the primary purpose of which, from inception, was the determination of proper motions. The various catalogs are characterized and compared, with an emphasis on their limitations and their appropriateness for various astrophysical uses.In addition to allowing for the maintenance of a practical celestial reference system, absolute proper-motion surveys provide the raw material from which a better understanding of our Galaxy's structure and kinematics can be built. Several examples will be cited in which large proper-motion surveys are used to probe and describe the distinct stellar components that comprise our Milky Way Galaxy.

scholarly journals Determination of Absolute Proper Motions by Use of Automated Measurements of Tautenburg Plates

1990 ◽  
Vol 141 ◽  
pp. 451-452
Author(s):  
R.-D. Scholz
Keyword(s):  
Globular Cluster ◽  
Proper Motion ◽  
Proper Motions ◽  
Automated Measurements ◽  
The Absolute ◽  
Good Agreement

From measurements of Tautenburg Schmidt plates with the APM in Cambridge positional accuracies per plate of 0.″05 for stars and of 0.″10 for galaxies were achieved. With 0.″3/100a accuracy in a single stellar proper motion we obtained the absolute proper motion of the M3 globular cluster in good agreement between the two pairs of plates used.

scholarly journals A revised view of the Canis Major stellar overdensity with DECam and Gaia: new evidence of a stellar warp of blue stars

2020 ◽  
Vol 501 (2) ◽  
pp. 1690-1700
Author(s):  
Julio A Carballo-Bello ◽  
David Martínez-Delgado ◽  
Jesús M Corral-Santana ◽  
Emilio J Alfaro ◽  
Camila Navarrete ◽  
...  
Keyword(s):  
Milky Way ◽  
Dwarf Galaxy ◽  
Line Of Sight ◽  
Proper Motions ◽  
Large Area ◽  
Magnitude Diagram ◽  
The Galaxy ◽  
Pollution Area ◽  
New Evidence ◽  
Astrometric Data

ABSTRACT We present the Dark Energy Camera (DECam) imaging combined with Gaia Data Release 2 (DR2) data to study the Canis Major overdensity. The presence of the so-called Blue Plume stars in a low-pollution area of the colour–magnitude diagram allows us to derive the distance and proper motions of this stellar feature along the line of sight of its hypothetical core. The stellar overdensity extends on a large area of the sky at low Galactic latitudes, below the plane, and in the range 230° < ℓ < 255°. According to the orbit derived for Canis Major, it presents an on-plane rotation around the Milky Way. Moreover, additional overdensities of Blue Plume stars are found around the plane and across the Galaxy, proving that these objects are not only associated with that structure. The spatial distribution of these stars, derived using Gaia astrometric data, confirms that the detection of the Canis Major overdensity results more from the warped structure of the Milky Way disc than from the accretion of a dwarf galaxy.

scholarly journals The Tautenburg Part Of The Programme Studying The Main Meridional Section Of The Galaxy

1988 ◽  
Vol 133 ◽  
pp. 451-454
Author(s):  
E. Schilbach
Keyword(s):  
Proper Motion ◽  
Proper Motions ◽  
Schmidt Telescope ◽  
Meridional Section ◽  
Mean Error ◽  
The Galaxy ◽  
The Mean

The programme for the determination of proper motions with reference to galaxies for 6000 stars on 17 fields near the main meridional section of the Galaxy is presented. For each field there are 2 or 3 first-epoch plates taken with the Tautenburg Schmidt-telescope before 1970. In preliminary investigations the mean error of an individual proper motion was found to be per century both for bright (8m–12m) and for faint (16m–18m) stars.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

scholarly journals Galactic Kinematics on the Basis of Modern Proper Motion Data

1995 ◽  
Vol 166 ◽  
pp. 217-226
Author(s):  
M. Miyamoto
Keyword(s):  
High Precision ◽  
Proper Motion ◽  
Galactic Kinematics ◽  
Dark Halo ◽  
Motion Data ◽  
Structure And Dynamics ◽  
The Galaxy ◽  
Galactic Astronomy ◽  
Astrometric Data

An accumulation of high precision astrometric data in conjunction with high-precision monitoring of the Earth's orientation, motivates “Galactic Astronomy”. As regards local kinematics, all of the three components of both the vorticity and the shear of stars can be completely determined, in addition to the velocity ellipsoid. We can now be released from the constraint of the “axisymmetric” galaxy. The determination of the proper motion of the LMC will be crucial to understanding the global structure and dynamics of the Galaxy with the dark halo and MACHO's motions.

scholarly journals Orbits of Galactic Globular Clusters from Schmidt Plate Astrometry

1994 ◽  
Vol 161 ◽  
pp. 453-459 ◽  
Author(s):  
M. Odenkirchen ◽  
R.-D. Scholz ◽  
M.J. Irwin
Keyword(s):  
Globular Clusters ◽  
Proper Motions ◽  
Mass Model ◽  
Orbital Parameters ◽  
The Galaxy ◽  
Galactic Globular Clusters

We present results from orbit integrations for the globular clusters M 3 and M 92. Absolute proper motions recently measured from Tautenburg Schmidt plates and a three-component mass model for the Galaxy have been used to derive the galactic orbits of these clusters. Orbital parameters and the influence of observational uncertainties on the determination of the orbits are discussed.

scholarly journals Astrometry With Schmidt Telescopes

1984 ◽  
Vol 78 ◽  
pp. 217-224
Author(s):  
C A Murray
Keyword(s):  
Reference Frame ◽  
Proper Motions ◽  
Large Area ◽  
Full Field ◽  
Potential Value ◽  
Focal Surface ◽  
Single Plate ◽  
Trigonometric Parallaxes ◽  
The Absolute

Photographic astrometry, including work with Schmidt telescopes, can be divided into two main fields, (i) the measurement of positions of objects relative to a reference frame of stars with known celestial coordinates, and (ii) the measurement of relative proper motions and trigonometric parallaxes from a series of plates taken on the same field. The former demands a knowledge of the absolute transformation between angles on the sky and measurements on a plate, whereas in the latter we are only interested in differential transformations from plate to plate. The potential value of Schmidt telescopes for both these fields of astrometry lies in the large area of sky and range of magnitude which can be imaged on a single plate. The former advantage is however, to some extent offset by the curvature of the focal surface which means that, in order to utilize the full field the plates must be constrained to the form of the focal surface during exposure.

scholarly journals Proper Motions With Respect to the Extragalactic Reference Frame

1990 ◽  
Vol 141 ◽  
pp. 407-417
Author(s):  
A. R. Klemola
Keyword(s):  
Reference Frame ◽  
Proper Motion ◽  
Milky Way ◽  
Proper Motions ◽  
Stellar Proper Motions

The Lick proper motion program, one of several using galaxies as a reference frame, is summarized with a statement of work accomplished for the non-Milky Way sky. The problem of identifying relatively transparent regions at low galactic latitudes is discussed, with tabular results presented for 41 windows from the literature having observable galaxies. These fields may be helpful for attaching stellar proper motions directly to the extragalactic frame.

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