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We derived the three-dimensional distribution of HI gas in the Milky Way Galaxy using the latest HI survey data cubes and rotation curves. The distance of the HI gas was determined by the kinematic distance using a rotation curve. We solved…

Astrophysics · Physics 2015-06-24 Hiroyuki Nakanishi , Yoshiaki Sofue

Little is known about the portion of the Milky Way lying beyond the Galactic center at distances of more than 9 kilo-parsec from the Sun. These regions are opaque at optical wavelengths due to absorption by interstellar dust, and distances…

Astrophysics of Galaxies · Physics 2017-10-19 Alberto Sanna , Mark J. Reid , Thomas M. Dame , Karl M. Menten , Andreas Brunthaler

Spiral structure can occupy a significant part of the galaxy, but properly accounting for it in photometric decomposition is rarely done. This may lead to significant errors in the parameters determined. To estimate how exactly neglecting…

We report four trigonometric parallaxes for high-mass star-forming regions within 4 kpc of the Galactic center. These measurements were made with the VLBA as part of the BeSSeL Survey. By associating these sources kinematically with…

Astrophysics of Galaxies · Physics 2015-06-18 A. Sanna , M. J. Reid , K. M. Menten , T. M. Dame , B. Zhang , M. Sato , A. Brunthaler , L. Moscadelli , K. Immer

We present new results based on high-resolution observations of Sgr A West at the Galactic center with the VLA at 1.3 cm. We measured proper motions for 71 compact HII components. We also investigated radial velocities in the LSR velocity…

Astrophysics of Galaxies · Physics 2009-06-25 Jun-Hui Zhao , Mark R. Morris , W. M. Goss , Tao An

We discuss a model for the Milky Way obtained by fitting the observed terminal velocities with the radial acceleration relation. The resulting stellar surface density profile departs from a smooth exponential disk, having bumps and wiggles…

Astrophysics of Galaxies · Physics 2019-11-06 Stacy McGaugh

We have obtained deep photometric data in 24 fields along the southeast extension of the major axis of the Sagittarius dwarf spheroidal (Sgr dSph) galaxy, and in four fields along the northwest extension. Using star counts at the expected…

Astrophysics · Physics 2009-10-31 Mario Mateo , Edward W. Olszewski , Heather L. Morrison

Generally, identifying the spiral arms of a spiral galaxy is not a hard task. However, defining the main characteristics, width and length of those structure is not a common task. Previous studies have used different tracers: Star clusters,…

Astrophysics of Galaxies · Physics 2022-06-08 E. Silva-Villa , X Cano-Gómez

Spiral galaxies are observed to exhibit a range of morphologies, in particular in the shape of spiral arms. A key diagnostic parameter is the pitch angle, which describes how tightly wound the spiral arms are. Observationally and…

Astrophysics of Galaxies · Physics 2015-06-11 Robert J. J. Grand , Daisuke Kawata , Mark Cropper

We combine optical and radio observations to trace the spiral structure in the Third Quadrant of the Milky Way. The optical observations consist of a large sample of young open clusters and associations, whereas the radio observations…

The distribution of stars in the Milky Way disc shows a spiral structure--the Snail--in the space of velocity and position normal to the Galactic mid-plane. The Snail appears as straight lines in the vertical frequency--vertical phase plane…

Astrophysics of Galaxies · Physics 2023-04-05 Neige Frankel , Jo Bovy , Scott Tremaine , David W. Hogg

We investigate the impact of spiral structure on global star formation using a sample of 2226 nearby bright disk galaxies. Examining the relationship between spiral arms, star formation rate (SFR), and stellar mass, we find that arm…

Astrophysics of Galaxies · Physics 2021-09-01 Si-Yue Yu , Luis C. Ho , Jing Wang

We assemble 121 spectroscopically-confirmed halo carbon stars, drawn from the literature, exhibiting measurable variability in the Catalina Surveys. We present their periods and amplitudes, which are used to estimate distances from…

Astrophysics of Galaxies · Physics 2015-09-16 Avon Huxor , Eva Grebel

We describe first results of a spectroscopic probe of selected fields from the Grid Giant Star Survey. Multifiber spectroscopy of several hundred stars in a strip of eleven fields along delta approximately -17^{circ}, in the range 12 <~…

We built a family of non-axisymmetric potential models for normal non-barred or weakly-barred spiral galaxies as defined in the simplest classification of galaxies: the Hubble sequence. For this purpose a three-dimensional self-gravitating…

Astrophysics of Galaxies · Physics 2015-06-16 A. Pérez-Villegas , B. Pichardo , E. Moreno

We have imaged a sample of 45 face-on spiral galaxies in the K-band, to determine the morphology of the old stellar population, which dominates the mass in the disk. The K-band images of the spiral galaxies have been used to calculate…

Astrophysics · Physics 2009-10-30 M. S. Seigar , P. A. James

The lack of arm tracers, especially the remote tracers, is one of the most difficult problems preventing us from studying the structure of the Milky Way. Fortunately, with its high-sensitivity CO survey, the Milky Way Imaging Scroll…

Astrophysics of Galaxies · Physics 2016-05-25 Xinyu Du , Ye Xu , Ji Yang , Yan Sun , Facheng Li , Shaobo Zhang , Xin Zhou

What role does Galactic structure play in star formation? We have used the Herschel Hi-GAL compact-clump catalogue to examine trends in evolutionary stage over large spatial scales in the inner Galaxy. We examine the relationship between…

Astrophysics of Galaxies · Physics 2018-07-11 S. E. Ragan , T. J. T. Moore , D. J. Eden , M. G. Hoare , J. S. Urquhart , D. Elia , S. Molinari

The study of dynamical properties of Galactic open clusters is a fundamental prerequisite for the comprehension of their dissolution processes. In this work, we characterized 12 open clusters, namely: Collinder 258, NGC 6756, Czernik 37,…

Solar and Stellar Astrophysics · Physics 2019-07-10 M. S. Angelo , A. E. Piatti , W. S. Dias , F. F. S. Maia

We assemble a catalogue of candidate Sagittarius stream members with 5d and 6d phase-space information, using astrometric data from Gaia DR2, distances estimated from RR Lyrae stars, and line-of-sight velocities from various spectroscopic…

Astrophysics of Galaxies · Physics 2021-02-22 Eugene Vasiliev , Vasily Belokurov , Denis Erkal