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(abridged) We have measured the absolute proper motions of nine low-latitude, inner Galaxy globular clusters, namely NGC 6273 (M 19), NGC 6284, NGC 6287, NGC 6293, NGC 6333 (M 9), NGC 6342, NGC 6356, NGC 6388 and NGC 6441. These are the…

A moderately deep survey of stellar maser sources toward the Galactic center has been made in the SiO J=1-0 v=1 and v=2 transitions (~ 43 GHz) with the Nobeyama 45-m telescope of a beam size of about 40". At the Galactic center (Sgr A*), 7…

Astrophysics · Physics 2009-10-30 Hideyuki Izumiura , Shuji Deguchi , Takahiro Fujii

We present proper motions for $>$40 stars at projected distances $\leq1.2''$ from Sagittarius A* (Sgr A*). We find evidence on a $\geq2\sigma$ level for radial anisotropy of the cluster of stars within $1''$ of Sgr A*. We find no evidence…

Astrophysics · Physics 2009-11-07 R. Schoedel , R. Genzel , T. Ott , A. Eckart , N. Mouawad , T. Alexander

Kinematic information is crucial for understanding the evolution of complex systems, such as interstellar gas. Obtaining full 3D kinematic information is a crucial final step for modeling and interpretation. Molecular clouds are nurseries…

Astrophysics of Galaxies · Physics 2025-09-24 Ji-Xuan Zhou , Guang-Xing Li , Bing-Qiu Chen

Aims. Red supergiants (RSGs) are among the most luminous of all stars, easily detectable in external galaxies, and may ideally serve as kinematic tracers of Galactic structure. Some RSGs are surrounded by circumstellar envelopes detectable…

Astrophysics of Galaxies · Physics 2015-06-04 L. Verheyen , M. Messineo , K. M. Menten

The Galactic Center hosts a rotating disk of young stars between 0.05 and 0.5 pc of Sgr A*. The ``S-stars'' at a distance $<0.04$ pc, however, are on eccentric orbits with nearly isotropically distributed inclinations. The dynamical origin…

Astrophysics of Galaxies · Physics 2024-11-14 Tatsuya Akiba , Smadar Naoz , Ann-Marie Madigan

We derive the distribution of maser stars in the inner Milky Way (MW) based on an analysis of lV-diagrams (lVd) for two samples of maser stars: 771 OH/IR stars and 363 SiO-maser stars. They are all close to the plane of the MW and have…

During the last $\sim$ 30 Myr the nuclear stellar disk in the Galactic center has been the most prolific star forming region of the Milky Way when averaged by volume. Remarkably, the combined mass of the only three clusters present today in…

Astrophysics of Galaxies · Physics 2023-09-13 Á. Martínez-Arranz , R. Schödel , F. Nogueras-Lara , M. Hosek , F. Najarro

We have discovered a star, SDSS J090745.0+024507, leaving the Galaxy with a heliocentric radial velocity of +853+-12 km/s, the largest velocity ever observed in the Milky Way halo. The star is either a hot blue horizontal branch star or a…

Astrophysics · Physics 2009-11-10 Warren R. Brown , Margaret J. Geller , Scott J. Kenyon , Michael J. Kurtz

A dynamical encounter between a stellar binary and Sgr A* in the Galactic Centre (GC) can tidally separate the binary and eject one member with a velocity beyond the escape speed of the Milky Way. These hypervelocity stars (HVSs) can offer…

Astrophysics of Galaxies · Physics 2022-10-18 Fraser A. Evans , Tommaso Marchetti , Elena Maria Rossi

Nuclear star clusters (NSCs) are located at the photometric and dynamical centers of the majority of galaxies. They are among the densest star clusters in the Universe. The NSC in the Milky Way is the only object of this class that can be…

Astrophysics of Galaxies · Physics 2015-05-13 R. Schoedel , D. Merritt , A. Eckart

The inner ~200 pc region of the Milky Way contains a nuclear stellar disc and a nuclear star cluster that are embedded in the larger Galactic bar. These stellar systems overlap spatially, which makes it challenging to separate stars that…

Astrophysics of Galaxies · Physics 2025-07-16 A. Feldmeier-Krause , T. Veršič , G. van de Ven , E. Gallego-Cano , N. Neumayer

The local stellar kinematics of the Milky Way offer a useful tool for studying the rotation curve of the Galaxy. These kinematics -- usually parameterized by the Oort constants A and B -- depend on the local gradient of the rotation curve…

Astrophysics · Physics 2009-10-30 R. P. Olling , M. R. Merrifield

We reanalyse the measurements of parallax, proper motion, and line-of-sight velocity for 18 masers in high mass star-forming regions presented by Reid et al. (2009). We use a likelihood analysis to investigate the distance of the Sun from…

Astrophysics of Galaxies · Physics 2015-05-13 Paul J. McMillan , James J. Binney

We performed a spectroscopic survey of nearly 700 stars probing the galactic thick disc far from the solar neighbourhood towards the galactic coordinates (l~277, b~47). The derived effective temperatures, surface gravities and overall…

Astrophysics of Galaxies · Physics 2015-05-30 G. Kordopatis , A. Recio-Blanco , P. de Laverny , G. Gilmore , V. Hill , R. F. G. Wyse , A. Helmi , A. Bijaoui , M. Zoccali , O. Bienaymé

We present radio and infrared observations indicating on-going star formation activity inside the $\sim2-5$ pc circumnuclear ring at the Galactic center. Collectively these measurements suggest a continued disk-based mode of on-going star…

Astrophysics of Galaxies · Physics 2015-08-06 F. Yusef-Zadeh , M. Wardle , M. Sewilo , D. A. Roberts , I. Smith , R. Arendt , W. Cotton , J. Lacy , S. Martin , M. W. Pound , M. Rickett , M. Royster

Average stellar orbits of the Galactic disk may have some small intrinsic ellipticity which breaks the exact axisymmetry and there may also be some migration of stars inwards or outwards. Both phenomena can be detected through kinematic…

Astrophysics of Galaxies · Physics 2016-06-08 M. Lopez-Corredoira , C. Gonzalez-Fernandez

We measure the escape speed curve of the Milky Way based on the analysis of the velocity distribution of $\sim 2850$ counter-rotating halo stars from the Gaia DR2. The distances were estimated through the StarHorse code, and only stars with…

In order to study the streaming motions of miras in the Solar neighborhood, we newly surveyed 379 red variables in the SiO maser lines at 42.821 and 43.122 GHz with the Nobeyama 45m radio telescope. Accurate radial velocities were obtained…

Astrophysics of Galaxies · Physics 2015-05-30 S. Deguchi , T. Sakamoto , T. Hasegawa

We have searched for 22 GHz H2O and 43/86/129 GHz SiO masers in bright IRAS point sources in the SMC and LMC, to test whether the kinematics of the mass loss from these stars depends on metallicity. H2O masers were detected in the red…

Astrophysics · Physics 2009-11-06 Jacco Th. van Loon , Albert A. Zijlstra , Valentin Bujarrabal , Lars-Ake Nyman