ANDREA nessc

Slide1: 

Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics Global properties of the solar wind Stellar winds: more massive, different acceleration profiles Young stars: sector structure, discrete absorbing components? Inhomogeneities: cool material in warm winds; hotter material in warm wind

Spatial Resolution only for Sun and Betelgeuse : 

Spatial Resolution only for Sun and Betelgeuse Global properties of Sun needed for comparison to stars … M-dot as function of solar activity. Coronal hole area (divergence) as function of solar cycle. Acceleration of individual ions Radiative losses

Slide3: 

The Sun as an Example in Search for Winds Dupree, Penn, & Jones 1996 Extended blue wing of He I (10830A) signifying outflow found in coronal holes, particularly in centers of supergranulation cells. (Dupree et al. 1996)

Slide4: 

He I Wind Diagnostic in Evolved Cool Stars Dupree et al. 2003 Extension of He I absorption to shorter wavelengths indicates fast chromospheric expansion (> 90 km/s) P Cygni emission signals an extended atmosphere

Far UV Lines Show Wind Opacity: 

Far UV Lines Show Wind Opacity Cool luminous stars show substantial line asymmetries In lines from 80000K – 300,000 K indicating massive winds.

Slide6: 

Hot, Fast 10-14 M Cold, Slow 10-5 M Warm,Moderate 10-8 M

Winds from Young Stars: 

Winds from Young Stars The closest accreting T Tauri star faces us almost pole-on. Strong signatures of winds extend smoothly to T~300,000K and appear in absorption to ~-300 km/s. The H-alpha line signals both accretion and outflow, including discrete absorption features. Modeling with PANDORA indicates M~4x10-10 Myr-1

AB Doradus… a young cool rapidly rotating dwarf star: 

AB Doradus… a young cool rapidly rotating dwarf star H-alpha spectra give photospheric spot distribution Plus Zeeman measures give surface B which can be modeled for coronal equilibrium distribution Closed fields Open fields

AB Dor (cont.): FUSE spectra of O VI reveal structured atmosphere and wind: 

AB Dor (cont.): FUSE spectra of O VI reveal structured atmosphere and wind When open field lines present: Low flux Absorption in profile Mean profile Flare profile shows flare traversing stellar disk

Slide10: 

Alpha Ori: Extended (very) Inhomogeneous cool atmosphere Gilliland & Dupree 1996, Lobel et al. 2004 Uitenbroeck et al. 1998, Lim et al. 1998 The first direct imaging of the surface of a star (other than the Sun) revealed variable hot spots on the chromospheric surface. H2O 0.5R Radio 3800K 2R Mg II 40 R 1 R = 700 R Dust 600K 24R

Cool Structures in Active Starsand Sun too?: 

Cool Structures in Active Stars and Sun too? Lines from T < 5.5 dex K are suspiciously weak both in Capella and the Sun. Is absorption by neutral H the culprit? Brickhouse et al 1996

Hot Material Anchored in Warm Wind: 

Hot Material Anchored in Warm Wind FUSE spectra show Fe XVIII at photospheric velocities in stars with warm winds. Anchored features may be similar to coronal loops.