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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?

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Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006

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  1. 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 Andrea Dupree SAO/CfA New England Space Science Consortium (NESSC) March 1, 2006

  2. 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

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

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

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

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

  7. 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

  8. 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

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

  10. Alpha Ori: Extended (very) Inhomogeneous cool atmosphere 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 Dust 600K 24R Mg II 40 R 1 R = 700 R Gilliland & Dupree 1996, Lobel et al. 2004 Uitenbroeck et al. 1998, Lim et al. 1998

  11. 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

  12. 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.

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