1. Diagnostics of Inhomogeneity in the Outer Atmospheres/Winds of M Supergiants Alexander Brown Center for Astrophysics and Space Astronomy University of Colorado at Boulder

2. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session2 Collaborators Graham Harper (CASA/Colorado) – PI of projects Matt Richter (UC Davis -TEXES) Joanna Brown (Caltech  MPE) Shadrian Strong (UT Austin), Tommy Greathouse (LPI), Andrew Kruger (UC)

3. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session3 Overview How we observe M supergiants determines what we see Temperature Inhomogeneity --- UV spectrum: the Hot View; Radio Continuum : the Cold View Density/Pressure Inhomogeneity --- Spatially resolved CII] electron densities and flow velocities – HST/STIS Kinematic/Turbulence Inhomogeneity --- Mid-Infrared [Fe II] 17.9 & 24.5 μm Diagnostics – TEXES (IRTF/Gemini N)

4. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session4 Betelgeuse – Hot Alfvén Model FOC UV Diameter 2x optical photosphere: Gilliland & Dupree 1996, ApJ, 463, L29 Linear Alfvén wave-driven winds: Hartmann & Avrett 1984, ApJ, 284, 238 UV spectra show many emission lines (Mg II, Fe II, C II) typically formed at chromospheric temperatures.

5. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session5 Very Large Array: 7mm spatially-resolved image First resolved radio results: Lim et al. 1998 Nature, 392, 575 VLA image courtesy of NRAO/AUI and Laure Nelson Neish

6. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session6 Betelgeuse: Cool “radio” models UV: Gilliland & Dupere HST/FOCMulti-frequency VLA+PT imaging Green=new cool model atmosphere

7. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session7 Spatially Sampling the Hot Plasma Stepped STIS E230M 100x25 mas Slit [-75->+75mas] (over VLA K band image) C II] 2325 A Multiplet (+50 mas offset)

8. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session8 Electron Density Diagnostics

9. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session9 Electron density – as function of offset Open symbols --- individual STIS NW-SE scans Filled blue dots --- W–E scan

10. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session10 Observation (right) versus model (left )

11. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session11 Hiding the Hot Stuff κ λ =n e n ion f(T e ) 2.1 Hot plasma 10 2-4 more opaque Radio seeks out hot plasma - but we observe cool plasma - hot plasma has tiny filling-factor What geometry of structures can do this? Shells, radial tubes?

12. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session12 Results from the “Hot” Component Chromospheric electron density 10 7-9 cm -3 1-2 orders of magnitude higher than cool gas changes by an order of magnitude over ΔR=R * C II] emission lines opacity broadened at limb turbulence quite isotropic and uniform Emission at rest with C-o-M of star (i.e. typical). Chromosphere is pervasive on large spatial scales rotationally decouples very rapidly Harper & Brown (2006) ApJ, 646, 1179

13. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session13 Infrared forbidden Fe II

14. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session14 TEXES & IRTF/Gemini-N TEXas Echelon-cross-Echelle Spectrograph: sister of EXES PI John Lacy (hiding below) Matt Richter (UC Davis)

15. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session15 TEXES Characteristics The following is an unpaid advertisement - R=50,000 at 25 μm (evacuated water cell) Wavelength scale: good to better 1 kms -1 Radiometric flux corrections Telluric water features removed to 10% level 3m IRTF 2 arcsec FWHM= jitter-ball+seeing+diffraction Nod 6 arcsec with 2 arcsec dispersion slit 8m Gemini-N improved diffraction+pointing Less efficient than nods, less optimized for mid-IR To be explored Real time IDL data collection/visualization software

16. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session16 Betelgeuse – [Fe II], [Fe I]

17. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session17 M Supergiants Line/continuum contrast: -silicate dust emission -mass-loss rate -wind temperature

18. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session18 M Supergiants II Line width: single stars V turb =11 kms-1 α Sco (M1.5 Iab + B3 V) IRTF & Gemini-N profiles similar - triangular shape

19. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session19 The Full Extent

20. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session20 Summary of [Fe II] Results Excitation temperature of TEXES/ISO lines ISO = Te=1250 K & TEXES > 2000 K Formed close to star Line formation coupled to continuum part chromospheric/part wind Dynamically different from ”hot” component V turb =10-12 kms -1 (cool) vs. 17-19 kms -1 (hot) V cent ~ 0 kms-1 (wind flow still not seen!) All M supergiants observed show [Fe II] Properties not unique to Betelgeuse Harper et al. (2008, in prep).

21. Tuesday, 22 July 2008 Cool Stars XV - Supergiant Splinter Session21 The End Thank You. But ……….. see Poster M5 --- Graham’s CO investigations