1. with Mark Westmoquette (UCL) Jay Gallagher (Wisconsin-Madison) Bob O’Connell (Virginia) Richard de Grijs (Sheffield) Linda J. Smith University College London MODEST-6 Workshop 29-31 August 2005 HST/STIS SPECTROSCOPY OF A YOUNG SSC IN THE STARBURST CORE OF M82

2. WFPC2 BVI+H  STScI-PRC2001-08b R. de Grijs STIS slit = 52” REGION A: 86 clusters!! In projection: Density of 1450 /kpc 2 Mean separation = 11 +/- 5 pc Mean radius = 5 +/- 2 pc (Melo et al. 2005) A

3. 180 pc STIS slit position 52” x 0.1” 0”.1 = 1.8 pc M82-A1 WFPC2 V-band image

4. STIS G430L + G750M spectra of M82-A1 Age = 6.4 +/- 0.4 Myr E(B-V) = 1.35 +/- 0.15 mag V = 17.23 +/- 0.1 mag M V = -14.8 +/- 0.4 mag Mass = 7-13 x 10 5 M sun Half-light radius = 3.0 +/- 0.5 pc Mass density = 6-11 x 10 3 M sun pc -3

5. [NII]+H  [SII] Distance along slit -> Small HII region around M82-A1 Half-light radius = 4.5 +/- 0.5 pc Electron density = 1800 cm -3 Pressure P/k = 2 x 10 7 cm -3 K