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Title: A WARP IN PROGRESS: H I AND RADIO CONTINUUM OBSERVATIONS OF THE SPIRAL NGC 3145

VLA H i observations and λ6 cm radio continuum observations are presented of the barred-spiral galaxy NGC 3145. In optical images NGC 3145 has stellar arms that appear to cross, forming “X”-features. Our radio continuum observations rule out shock fronts at three of the four “X”-features, and our H i data provide evidence of gas motions perpendicular to the disk of NGC 3145. In large portions of NGC 3145, particularly in the middle-to-outer disk, the H i line profiles are skewed. Relative to the disk, the gas in the skewed wing of the line profiles has z-motions away from us on the approaching side of the galaxy and z-motions of about the same magnitude (∼40 km s{sup −1}) toward us on the receding side. These warping motions imply that there has been a perturbation with a sizeable component perpendicular to the disk over large spatial scales. Two features in NGC 3145 have velocities indicating that they are out-of-plane tidal arms. One is an apparent branch of a main spiral arm on the northeastern side of NGC 3145; the velocity of the branch is ∼150 km s{sup −1} greater than the spiral arm where they appear to intersect in projection. Themore » other is the arm on the southwestern side that forms three of the “X”-features. It differs in velocity by ∼56 km s{sup −1} from that of the disk at the same projected location. H i observations are presented also of the two small companions NGC 3143 and PGC 029578. Based on its properties (enhanced SFR, H i emission 50% more extended on its northeastern side, etc.), NGC 3143 is the more likely of the two companions to have interacted with NGC 3145 recently. A simple analytic model demonstrates that an encounter between NGC 3143 and NGC 3145 is a plausible explanation for the observed warping motions in NGC 3145.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. 110 Westchester Rd, Newton, MA 02458 (United States)
  2. University of Hertfordshire, Centre for Astrophysics Research, College Lane, Hatfield AL10 9AB (United Kingdom)
  3. Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)
  4. IBM Research Division, T.J. Watson Research Center, 1101 Kitchawan Rd., Yorktown Heights, NY 10598 (United States)
  5. Department of Physics and Astronomy, Vassar College, 124 Raymond Av., Poughkeepsie, NY 12604 (United States)
Publication Date:
OSTI Identifier:
22520161
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 150; Journal Issue: 3; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC RADIO SOURCES; DISTURBANCES; EMISSION; GALAXIES; HYDROGEN; RADIOWAVE RADIATION; STAR CLUSTERS; VELOCITY