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Title: AN ASYMMETRIC STREAMING MOTION IN THE GALACTIC BULGE X-SHAPED STRUCTURE REVEALED BY OGLE-III PROPER MOTIONS

The Galactic bulge shows a double red clump in sightlines at |b| ∼> 5° and –3° ∼< l ∼< 4°. This dump is interpreted as the signature of an X-shaped structure seen almost edge-on. We measure the proper motions of the stars belonging to the closer and the further arms of the X-shaped structure. The intrinsic kinematic properties of the two arms are found by incorporating information taken from the luminosity function. At b = –5°, we find that the proper motion difference between the two arms is a linear function of Galactic longitude for –0.°1 < l < 0.°5, which we interpret as a streaming motion of the stars within the X-shaped structure. A streaming motion was previously reported based on radial velocity data, not the proper motions. The proper motion difference in longitude is constant for –0.°8 < l < –0.°1, which provides an estimate of the bulge rotational speed of 87.9 ± 8.2 km s{sup –1} kpc{sup –1}.
Authors:
;  [1] ; ; ; ; ; ; ;  [2]
  1. Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)
  2. Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland)
Publication Date:
OSTI Identifier:
22270760
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 776; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; ASYMMETRY; LUMINOSITY; MILKY WAY; PROPER MOTION; RADIAL VELOCITY; STARS