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Title: An optical-near-IR study of a triplet of super star clusters in the starburst core of M82

We present HST/STIS optical and Gemini/NIFS near-IR IFU spectroscopy and archival Hubble Space Telescope (HST) imaging of the triplet of super star clusters (A1, A2, and A3) in the core of the M82 starburst. Using model fits to the Space Telescope Imaging Spectrograph (STIS) spectra and the weakness of red supergiant CO absorption features (appearing at ∼6 Myr) in the NIFS H-band spectra, the ages of A2 and A3 are 4.5 ± 1.0 Myr. A1 has strong CO bands, consistent with our previously determined age of 6.4 ± 0.5 Myr. The photometric masses of the three clusters are 4-7 × 10{sup 5} M{sub ☉}, and their sizes are R{sub eff} = 159, 104, 59 mas (∼2.8, 1.8, 1.0 pc) for A1, A2, and A3. The STIS spectra yielded radial velocities of 320 ± 2, 330 ± 6, and 336 ± 5 km s{sup –1} for A1, A2, and A3, placing them at the eastern end of the x{sub 2} orbits of M82's bar. Clusters A2 and A3 are in high-density (800-1000 cm{sup –3}) environments, and like A1, are surrounded by compact H II regions. We suggest the winds from A2 and A3 have stalled, as in A1, due to themore » high ISM ambient pressure. We propose that the three clusters were formed in situ on the outer x{sub 2} orbits in regions of dense molecular gas subsequently ionized by the rapidly evolving starburst. The similar radial velocities of the three clusters and their small projected separation of ∼25 pc suggest that they may merge in the near future unless this is prevented by velocity shearing.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ; ;  [5] ;  [6] ; ; ;  [7] ;  [8]
  1. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany)
  2. Excellence Cluster Universe, Boltzmannstrasse 2, D-85748 Garching bei München (Germany)
  3. Space Telescope Science Institute and European Space Agency, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
  4. University of Utah, Salt Lake City, UT 84112 (United States)
  5. Department of Astronomy, University of Wisconsin-Madison, 5534 Sterling, 475 North Charter Street, Madison, WI 53706 (United States)
  6. Department of Astronomy, University of Virginia, P.O. Box 3818, Charlottesville, VA 22903 (United States)
  7. Instituto Nacional de Astrofísica, Optica y Electronica, Luis Enrique Erro 1, Tonantzintla, C.P. 72840, Puebla (Mexico)
  8. Instituto de Astrofísica de Canarias, C/vía Láctea s/n, E-38200 La Laguna, Tenerife (Spain)
Publication Date:
OSTI Identifier:
22365734
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 789; 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; ABSORPTION; CARBON MONOXIDE; DENSITY; GALAXIES; MASS; ORBITS; RADIAL VELOCITY; SPECTRA; SPECTROSCOPY; STAR CLUSTERS; TELESCOPES