High-Mass Stars on the Main Sequence

• high effective temperature:
  • ionizing photons
  • HII regions: N108 B, Tarantula Nebula, in the M33 galaxy
• high luminosity:
  • short lifetimes
  • found near birthsites--OB associations
  • Cave Nebula wide field, zoom; Sco-Cen
• strong mass loss, especially highest masses: Wolf-Rayet stars
  • WR 124, Thor's Helmet, S308: optical, X-ray
  • eta Carinae: optical (HST), X-ray (Chandra)

High-Mass Stars Beyond the Main Sequence

• supergiants on the HR diagram: low to high mass, Sun vs massive star
• MESA simulations: massive star plots here (Paxton+ 2011), here (Paxton+ 2013), here (Paxton+ 2015)
• supergiants resolved! Betelgeuse HST, VLT, interferometry
• advanced burning
• silicon burning to the iron core
• core collapse