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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
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Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics Global properties.

Dec 21, 2015

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Page 1: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

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

Page 2: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

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

Page 3: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

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)

Page 4: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

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

Page 5: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

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

Page 6: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

Hot, Fast

10-14 M

Cold, Slow

10-5 M

Warm,Moderate10-8 M

Page 7: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

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

Page 8: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

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

Page 9: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

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

Page 10: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

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

Page 11: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

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

Page 12: Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006 Some Stellar Problems of Interest to Solar Physics  Global properties.

Hot Material Anchored in Warm Wind

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

Anchored features may be similarto coronal loops.