scholarly journals Astrometry and Galactic Structure

1994 ◽  
Vol 161 ◽  
pp. 425-434
Author(s):  
S.R. Majewski
Keyword(s):  
Proper Motion ◽  
Globular Clusters ◽  
Milky Way ◽  
Galactic Structure ◽  
Proper Motions ◽  
Future Prospects ◽  
The Status ◽  
Galactic Globular Clusters ◽  
Remarkable Agreement

The application of astrometric surveys to understanding the structure and kinematics of the Milky Way is discussed, with particular emphasis on some of the issues expected to be addressed in the next decade or so. It is shown that the results of complete proper motion surveys of field stars at the Galactic poles are in remarkable agreement concerning the global kinematics of stars as a function of distance, but that significant differences exist in how these data are decomposed to derive the kinematics of individual Galactic components. The status and future prospects regarding the measurement of proper motions and orbits for Galactic globular clusters and satellites are also discussed.

scholarly journals Kinematics of Galactic Globular Clusters from Schmidt-Plate Astrometry

1995 ◽  
Vol 164 ◽  
pp. 405-405 ◽  
Author(s):  
R.-D. Scholz ◽  
S. Hirte ◽  
M.J. Irwin ◽  
M. Odenkirchen
Keyword(s):  
Radial Velocity ◽  
Proper Motion ◽  
Globular Clusters ◽  
Proper Motions ◽  
Large Numbers ◽  
Solar Motion ◽  
The Galaxy ◽  
Ursa Minor ◽  
Galactic Globular Clusters

From measurements of Tautenburg Schmidt plates with the APM facility in Cambridge we obtained absolute proper motions of the Galactic globular clusters M 3 and M 92 directly with respect to large numbers of background galaxies (Scholz et al. 1993, 1994). We have extended our work to the dSphs in Draco and Ursa Minor (Scholz & Irwin 1994) and to other Galactic globular clusters using Tautenburg, Palomar and UK Schmidt plates. Combining our absolute proper motion of a cluster with its known radial velocity and distance (using common parameters of the solar motion) we derive the cluster orbit in the Galaxy (cf. Odenkirchen & Brosche 1992).

scholarly journals Absolute Proper Motions and Space Velocities of Globular Clusters

1988 ◽  
Vol 126 ◽  
pp. 525-526
Author(s):  
H. -J. Tucholke ◽  
P. Brosche ◽  
M. Geffert
Keyword(s):  
Proper Motion ◽  
Globular Clusters ◽  
Proper Motions ◽  
Angular Momenta ◽  
Galactic Globular Clusters

Proper motions of globular clusters referred to extragalactic background objects provide absolute proper motions leading to space velocities. Some results from the Bonn Observatory proper motion program for galactic globular clusters are shown. Reference stars from the Lick program linked to galaxies are used. Low orbital angular momenta for NGC 4147, NGC 5466 and NGC 6218 were detected. In a further program, proper motions of 47 Tuc and NGC 362 are currently being measured relative to the background of the SMC.

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 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.

scholarly journals Using ground based data as a precursor for Gaia in getting proper motions of satellites

2017 ◽  
Vol 12 (S330) ◽  
pp. 210-213
Author(s):  
Tobias K. Fritz ◽  
Sean T. Linden ◽  
Paul Zivick ◽  
Nitya Kallivayalil ◽  
Jo Bovy
Keyword(s):  
Adaptive Optics ◽  
Globular Cluster ◽  
Proper Motion ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Optical Data ◽  
Line Of Sight ◽  
Wide Field ◽  
Proper Motions ◽  
Tidal Stream

AbstractWe present our effort to measure the proper motions of satellites in the halo of the Milky Way with mainly ground based telescopes as a precursor on what is possible with Gaia. For our first study, we used wide field optical data from the LBT combined with a first epoch of SDSS observations, on the globular cluster Palomar 5 (Pal 5). Since Pal 5 is associated with a tidal stream it is very useful to constrain the shape of the potential of the Milky Way. The motion and other properties of the Pal 5 system constrain the inner halo of the Milky Way to be rather spherical. Further, we combined adaptive optics and HST to get an absolute proper motion of the globular cluster Pyxis. Using the proper motion and the line-of-sight velocity we find that the orbit of Pyxis is rather eccentric with its apocenter at more than 100 kpc and its pericenter at about 30 kpc. The dynamics excludes an association with the ATLAS stream, the Magellanic clouds, and all satellites of the Milky Way at least down to the mass of Leo II. However, the properties of Pyxis, like metallicity and age, point to an origin from a dwarf of at least the mass of Leo II. We therefore propose that Pyxis originated from an unknown relatively massive dwarf galaxy, which is likely today fully disrupted. Assuming that Pyxis is bound to the Milky Way we derive a 68% lower limit on the mass of the Milky Way of 9.5 × 1011 M⊙.

Internal kinematics of multiple stellar populations in globular clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 324-328
Author(s):  
Mattia Libralato
Keyword(s):  
High Precision ◽  
Globular Clusters ◽  
Hubble Space Telescope ◽  
Stellar Populations ◽  
Stellar Systems ◽  
Proper Motions ◽  
Space Telescope ◽  
Formation And Evolution ◽  
Galactic Globular Clusters ◽  
Shed Light

AbstractSpectroscopy and photometry have revealed existence, complexity and properties of the multiple stellar populations (mPOPs) hosted in Galactic globular clusters. However, the conundrum of the formation and evolution of mPOPs is far from being completely exploited: the available pieces of information seem not enough to shed light on these topics. Astrometry, and in particular high-precision proper motions, can provide us the sought-after answers about how mPOPs formed and have evolved in these ancient stellar systems. In the following, I present a brief overview of the observational results on the internal kinematics of the mPOPs in some GCs thanks to Hubble Space Telescope high-precision proper motions.

scholarly journals Correction to Absolute Proper Motion Using the IAS-Galaxy Model

1990 ◽  
Vol 141 ◽  
pp. 427-429
Author(s):  
Kavan U. Ratnatunga
Keyword(s):  
Reference Frame ◽  
Proper Motion ◽  
Theoretical Models ◽  
Galactic Structure ◽  
Coordinate Frame ◽  
Proper Motions ◽  
Software Interface ◽  
The Galaxy ◽  
Galaxy Model ◽  
Star Catalogs

The IAS-Galaxy model (Ratnatunga, Bahcall and Casertano 1989) is a software interface between theoretical models of the Galaxy and observed kinematic distributions. It has been developed for analysis of many kinematic catalogs to study global galactic structure. In addition, the IASG model can be used to estimate corrections needed to derive absolute parallax and absolute proper motion by evaluating, on a star-by-star basis, the expected mean motion of the reference stars.A theoretical Galaxy model is defined on an inertial coordinate frame. Proper motions are measured in a reference frame defined by a fundamental catalog. The observed distribution of proper motions in star catalogs can be directly compared with the expected distributions evaluated using IASG to check the accuracy of the adopted reference frame in realizing the inertial coordinate frame in the sky.

UBV Photometry for 31 Galactic Globular Clusters

1984 ◽  
Vol 5 (3) ◽  
pp. 360-363
Author(s):  
David A. Hanes
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Homogeneous Body ◽  
Milky Way Galaxy ◽  
Photoelectric Photometry ◽  
Astrophysical Interest ◽  
Ubv Photometry ◽  
Single Aperture ◽  
Galactic Globular Clusters

For many reasons, it is important to have a sound body of reliable photometry for the globular clusters in the Milky Way galaxy. Given the striking appearance of the globular clusters and their historical and astrophysical interest, it is perhaps surprising that the available photoelectric photometry for globular clusters is of mixed quality (see Harris and Racine 1979). Here I present a homogeneous body of photometry through a single aperture and in the UBV system for 31 globular clusters south of declination +12°.

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