CDROM/APJ/V466/P254     NIR Imaging of R136 in 30 Dor (Brandl+ 1996)
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Adaptive Optics Near-Infrared Imaging of R136 in 30 Doradus: The Stellar
Population of a Nearby Starburst
      B. Brandl, B. J. Sams, F. Bertoldi, A. Eckart, R. Genzel, S. Drapatz,
      R. Hofmann, M. Loewe, and A. Quirrenbach
      <1996, ApJ, 466, 254>
      =1996ApJ...466..254B
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Abstract:
     We report 0.15" resolution near-infrared (NIR) imaging of R136, the
  central region of 30 Doradus in the Large Magellanic Cloud.  Our
  12.8"x12.8" images were recorded with the MPE camera SHARP II at the
  3.6 m ESO telescope, using the adaptive optics system COME ON+.  The
  high spatial resolution and sensitivity (20th magnitude in K) of our
  observations allow our H- and K-band images to be compared and
  combined with recent Hubble Space Telescope (HST) WFPC2 data of R136.
  We fit theoretical models with variable foreground extinction to the
  observed magnitudes of ~1000 stars (roughly half of which were
  detected in HST and NIR bands) and derive the stellar population in
  this starburst region.  We find no red giants or supergiants; however,
  we detect ~110 extremely red sources which are probably young,
  pre-main-sequence low- or intermediate-mass stars.  We obtained
  narrow-band images to identify known and new Wolf-Rayet stars by their
  He II (2.189 um) and BrGamma (2.166 um) emission lines.  The presence
  of W-R stars and absence of red supergiants narrow the cluster age to
  3-5 Myr, while the derived ratio of W-R to O stars of 0.05 in the
  central region favors an age of ~3.5 Myr, with a relatively short
  starburst duration.  For the O stars, the core radius is found to be
  0.1 pc and appears to decrease with increasing stellar mass.  The
  slope of the mass function is Gamma = -1.6 on average, but it steepens
  with increasing distance from the cluster center from Gamma = -1.3
  in the inner 0.4 pc to Gamma = -2.2 outside 0.8 pc for stars more
  massive than 12 Msun.  The radial variation of the mass function
  reveals strong mass segregation that is probably due to the cluster's
  dynamical evolution.

Keywords: H II regions -- infrared: stars -- ISM: individual (30 Doradus) --
  Magellanic Clouds -- stars: early type -- techniques: image processing


File Summary:
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File Name    Lrecl    Records   Explanations
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table3.dat      51        971   The 971 main sequence stars in our field of view
                                (YSO candidates and WR stars were excluded)
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Byte-per-byte Description of file: table3.dat
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   Bytes Format  Units     Label    Explanations
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   1- 4   I4     ---       Star     Star number from Hunter et al. (1995)
   5      1X     ---       ---      Blank
   6-10   I5     pix       X        X position on detector (512x512 grid)
  11-15   I5     pix       Y        Y position on detector (512x512 grid)
  16      1X     ---       ---      Blank
  17-23   F7.2   mag       U       *[]?=-99.99 U magnitude
  24-30   F7.2   mag       V       *[]?=-99.99 V magnitude
  31-37   F7.2   mag       I       *[]?=-99.99 I magnitude
  38-44   F7.2   mag       H       *[]?=-99.99 H magnitude
  45-51   F7.2   mag       K       *[]?=-99.99 K magnitude
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Notes for file: table3.dat
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U, V, I:
  The U, V & I band magnitudes were converted from WFPC2 magnitudes
  according the the relations in Hunter et al. 1995, ApJ, 488, 179.
  Extinction was not taken into account.

H, K:
  The H & K magnitudes were derived from the authors' observations
  with adaptive optics.  Extinction is not taken into account.
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(End)                                               Lee Brotzman [ADS] 22-Oct-96