Andrea Dupree SAO/CfANew 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

Global properties of Sunneeded for comparison tostars …

M-dot as function of solar activity.

Coronal hole area (divergence)as function of solar cycle.

Acceleration of individual ionsRadiative losses

The Sun as an Examplein Search for Winds

Dupree, Penn, & Jones 1996

Extended blue wingof He I (10830A)signifying outflowfound in coronal holes, particularly in centers of supergranulation cells.

(Dupree et al. 1996)

He I Wind Diagnostic in Evolved Cool Stars

Dupree et al. 2003

Extension of He Iabsorption to shorterwavelengths indicates fast chromospheric expansion (> 90 km/s)

P Cygni emission signals an extended atmosphere

Far UV Lines Show Wind OpacityCool luminous stars show substantial line asymmetriesIn lines from 80000K – 300,000 K indicating massive winds.

Hot, Fast

10-14 M

Cold, Slow

10-5 M

Warm,Moderate10-8 M

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, includingdiscrete absorption features.

Modeling with PANDORAindicates M~4x10-10 Myr-1

AB Doradus… a young cool rapidly rotating dwarf star

H-alpha spectra give photospheric spot distribution

Plus Zeeman measuresgive surface B whichcan be modeled for coronal equilibrium distribution

Closed fields Open fields

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

windWhen open field linespresent:Low fluxAbsorption in profile

Mean profile

Flare profile showsflare traversing stellardisk

Alpha Ori: Extended (very)Inhomogeneous cool atmosphere

Gilliland & Dupree 1996, Lobel et al. 2004Uitenbroeck 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?

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

FUSE spectra show Fe XVIIIat photospheric velocitiesin stars with warm winds.

Anchored features may be similarto coronal loops.