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X -RAY D IAGNOSTICS of G RAIN D EPLETION in M ATTER A CCRETING onto T T AURI S TARS

X -RAY D IAGNOSTICS of G RAIN D EPLETION in M ATTER A CCRETING onto T T AURI S TARS. Paola Testa (MIT) Jeremy Drake (SAO) Lee Hartmann (SAO). http://chandra.harvard.edu/photo/2003/twhy/index.html. Chandra Workshop – July 13 2005. O UTLINE.

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X -RAY D IAGNOSTICS of G RAIN D EPLETION in M ATTER A CCRETING onto T T AURI S TARS

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  1. X-RAY DIAGNOSTICSof GRAIN DEPLETIONin MATTER ACCRETINGonto T TAURI STARS Paola Testa(MIT) Jeremy Drake(SAO) Lee Hartmann(SAO) http://chandra.harvard.edu/photo/2003/twhy/index.html Chandra Workshop – July 13 2005

  2. OUTLINE • X-ray SPECTROSCOPY of CLASSICAL T TAURISTARS: • signatures of accretion – TW Hya et al. • SURVEY of CORONAL ABUNDANCES in ACTIVE STARS: • Ne/O • Ne/O as DIAGNOSTICS for the ACCRETING MATERIAL

  3. X-ray EMISSION from YOUNG STARS

  4. MEG HEG X-ray HIGH RESOLUTION SPECTROSCOPY of CLASSICAL T TAURI STARS • TW Hydrae

  5. X-ray HIGH RESOLUTION SPECTROSCOPY of CLASSICAL T TAURI STARS • TW Hydrae • cool He-like triplets (Ne, O) indicate unusually high plasma density • thermal distribution extremely peaked • anomalous abundances: extremely abundant (~ factor 10) Ne, underabundant Fe

  6. X-ray HIGH RESOLUTION SPECTROSCOPY of CLASSICAL T TAURI STARS is TW Hya the only young object with these peculiar characteristics? • OTHER TTS in TWA do not show signature of accretion: HD 98800 (Kastner et al. 2004), TWA 5 (Argiroffi et al. 2005) • BP TAU: XMM-RGS spectra show high density for OVII • HD 163296(HERBIG AeSTAR): remarkably isothermal plasma (BUT only low energy resolution spectra, ACIS-I, Swartz et al. 2005)

  7. CORONAL ABUNDANCES from CHANDRAHETGSPECTRA large sample of HETG spectra: 22 active stars, within ~140 pc from the Sun, at different activity levels • ABUNDANCES DIAGNOSTICS: Ne, the Sun, Star Formation and Planets

  8. CHANDRAHETG SPECTRA: Single Stars

  9. CHANDRAHETG SPECTRA: Binary Stars

  10. e.g. for Ne/O diagnostics, line ratio of NeIX, NeX, OVII ELEMENT ABUNDANCES Chandra HETG spectral resolution allows line-based abundances analysis (based on strong X-ray emission lines of H-like and He-like abundant ions)

  11. (Drake & Testa, 2005) ELEMENT ABUNDANCES • Ne/O

  12. ELEMENT ABUNDANCES • Ne/O • Ne/O extremely constant on a wide range of activity levels • Ne/O in coronae of nearby stars ~2.7 times higher than the assumed solar photospheric value (Drake & Testa, Nature, 2005)

  13. Ne and the SOLAR MODEL PROBLEM • Models calculated with latest solar abundances (Asplund et al 2004) fail to predict sound speed, He abundance and depth of convection zone inferred from helioseismology (Bahcall et al 2005; Antia & Basu 2005) • Ne higher by a factor > 2.6 can solve the solar model problem (Bahcall et al 2005 ; Antia & Basu 2005; Antia & Basu 2004) Bahcall et al (2005)

  14. Constancy of Ne/O in coronae use for exploring O depletion in accreting systems Measure of disk/planetary evolution cool He-like triplets of OVII and NeIX indicate unusually high ne http://chandra.harvard.edu/photo/2003/twhy/index.html STAR FORMATION and PLANETS • Two known T Tauri stars with X-ray accretion shock signatures: BP Tau (~1Myr, Schmitt et al 2005); TW Hya (~10Myr, Kastner et al. 2002, Stelzer & Schmitt 2004)

  15. Constancy of Ne/O in coronae use for exploring O depletion in accreting systems Measure of disk/planetary evolution Two known T Tauri stars with X-ray accretion shock signatures: BP Tau (~1Myr, Schmitt et al 2005); TW Hya (~10Myr, Kastner et al. 2002,Stelzer & Schmitt 2004) STAR FORMATION and PLANETS • TW Hya shows O depletion by a factor ~2 indicative of evolved disk with large grains Drake, Testa & Hartmann (2005)

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