1. Stellar Winds of Massive Stars Lamers & Cassinelli (1999)
P Cygni Lines
Emission Lines
IR and Radio Excess Emission
Theory of Radiation Driven Winds

2. [Steven Cranmer, CfA]

3. Stellar Wind Outflows
Winds found in all luminous stars: Kudritzski
Mass loss by radiative winds: momentum of radiation field captured by opaque lines in UV
loss rates: 10-6 solar masses/yr (⅓ Earth/yr)
terminal velocities: 103 km/sec
velocity law (β≈0.8):

5. P Cygni Lines formed by scattering in resonance lines
examples in IUE Atlas of O-type Spectra
terminal velocity, β determined but hard to get mass loss rate: need ionization model and unsaturated lines
need detailed structure of filling factor
FUSE: P V 1118, 1128 Angstroms Fullerton et al. 2006, ApJ, 637, 1025

8. Emission Lines Hα; Paschen, Brackett lines in near IR He II 1640, 4686
numerous N, C lines in WR stars
formed by recombination (density2) in the base level of wind
strength depends on temperature and:

9. IR and Radio Excess Emission
f-f (Bremsstrahlung) emission from outer parts of wind; excess flux at long wavelengths
kν ~ ν -2 higher opacity at longer wavelength
if know T(r), v(r) then can determine mass loss rate from excess
effective size larger at longer wavelength (τ=1)

11. CHARA image of wind of P Cyg in H-band
Richardson et al.
2013, ApJ, 769, 118

12. Theory of Radiation-Driven Winds
see handout from Kuditzki, Pauldrach & Puls 1988, O Stars and WR Stars, NASA SP-497

18. 2

19. To really know a star ... get a spectrum
“If a picture is worth a thousand words, then a spectrum is worth a thousand pictures.” (Prof. Ed Jenkins, Princeton University)