x -ray d iagnostics of g rain d epletion in m atter a ccreting onto t t auri s tars

XX-RAY-RAY D DIAGNOSTICSIAGNOSTICS ofof G GRAIN RAIN

DDEPLETIONEPLETION in in MMATTERATTER A ACCRETINGCCRETING ontoonto T T T TAURIAURI S STARSTARS

http://chandra.harvard.edu/photo/2003/twhy/index.html

Chandra Workshop – July 13 2005

Paola Testa (MIT)

Jeremy Drake (SAO)

Lee Hartmann (SAO)

OOUTLINEUTLINE

• X-ray SX-ray SPECTROSCOPY of PECTROSCOPY of CCLASSICAL LASSICAL T TT TAURIAURI

SSTARS:TARS:signatures of accretion – TW Hya et al. signatures of accretion – TW Hya et al.

• SSURVEY of URVEY of CCORONAL ORONAL AABUNDANCES in BUNDANCES in AACTIVE CTIVE

SSTARS: TARS:

Ne/ONe/O• Ne/O Ne/O as as DDIAGNOSTICS for the IAGNOSTICS for the AACCRETING CCRETING

MMATERIALATERIAL

X-ray EX-ray EMISSION from MISSION from YYOUNG OUNG

SSTARSTARS

X-ray HX-ray HIGH IGH RRESOLUTION ESOLUTION

SSPECTROSCOPY of PECTROSCOPY of CCLASSICAL LASSICAL T T TTAURI AURI SSTARSTARS TW HydraeTW Hydrae

MEGHEG

X-ray HX-ray HIGH IGH RRESOLUTION ESOLUTION

SSPECTROSCOPY of PECTROSCOPY of CCLASSICAL LASSICAL T T TTAURI AURI SSTARSTARS TW HydraeTW Hydrae

• cool He-like triplets (Ne, O) cool He-like triplets (Ne, O) indicate unusually high plasma indicate unusually high plasma densitydensity• thermal distribution extremely thermal distribution extremely peaked peaked • anomalous abundances: extremely anomalous abundances: extremely abundant (~ factor 10) Ne, abundant (~ factor 10) Ne, underabundant Feunderabundant Fe

X-ray HX-ray HIGH IGH RRESOLUTION ESOLUTION

SSPECTROSCOPY of PECTROSCOPY of CCLASSICAL LASSICAL T T TTAURI AURI SSTARSTARS

is TW Hya the only young object with these peculiar is TW Hya the only young object with these peculiar characteristics?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 Ae STAR): remarkably isothermal plasma (BUT only low energy resolution spectra, ACIS-I, Swartz et al. 2005)

ABUNDANCES DIAGNOSTICS: Ne, the Sun, Star Formation and Planets

large sample of HETG spectra: 22 active stars, within large sample of HETG spectra: 22 active stars, within ~140 pc from the ~140 pc from the Sun, at different activity levelsSun, at different activity levels

CCORONAL ORONAL AABUNDANCES from BUNDANCES from

CCHANDRAHANDRA HETGHETG SSPECTRAPECTRA

Single Stars

CCHANDRAHANDRA HETG HETG SSPECTRAPECTRA::

Binary Stars

CCHANDRAHANDRA HETG HETG SSPECTRAPECTRA::

EELEMENT LEMENT AABUNDANCESBUNDANCES

ChandraChandra HETG spectral resolution allows line-based HETG spectral resolution allows line-based abundances analysis abundances analysis (based on strong X-ray emission lines of H-like and He-(based on strong X-ray emission lines of H-like and He-like abundant ions)like abundant ions)

e.g. for Ne/O diagnostics, line ratio of NeIX, NeX, OVII

EELEMENT LEMENT AABUNDANCESBUNDANCES

(Drake & Testa, 2005)

Ne/ONe/O

EELEMENT LEMENT AABUNDANCESBUNDANCES

(Drake & Testa, Nature, 2005)

Ne/ONe/O

• Ne/O extremely constant on a Ne/O extremely constant on a wide wide range of activity levelsrange of activity levels

• Ne/O in coronae of nearby Ne/O in coronae of nearby stars ~2.7 stars ~2.7 times higher than times higher than the assumed the assumed solar solar photospheric valuephotospheric value

Bahcall et al (2005)

Ne Ne and the and the SSOLAR OLAR MMODEL ODEL

PPROBLEMROBLEM

• Models calculated with Models calculated with latest solar latest solar abundances abundances ((Asplund et al 2004) ) fail to fail to predict sound speed, He predict sound speed, He abundance and depth of abundance and depth of convection zone inferred from convection zone inferred from

helioseismology helioseismology ((Bahcall et al 2005; Antia & Basu 2005))

• Ne higher by a factor > 2.6 Ne higher by a factor > 2.6 can solve can solve the solar model the solar model problem problem ((Bahcall et al 2005 ; Antia & Basu 2005; Antia & Basu 2004) )

• Constancy of Ne/O in coronae use for Constancy of Ne/O in coronae use for exploring O depletion in accreting systemsexploring O depletion in accreting systems– Measure of disk/planetary evolutionMeasure of disk/planetary evolution

SSTAR TAR FFORMATION and ORMATION and PPLANETSLANETS

http://chandra.harvard.edu/photo/2003/twhy/index.html

cool He-like cool He-like triplets of Otriplets of OVIIVII and and NeNeIXIX indicate indicate unusually high nunusually high nee

• Two known T Tauri stars with X-ray Two known T Tauri stars with X-ray accretion shock signatures: BP Tau accretion shock signatures: BP Tau (~1Myr, (~1Myr, Schmitt et al 2005); TW Hya ); TW Hya (~10Myr, (~10Myr, Kastner et al. 2002, Stelzer & Schmitt 2004))

• Constancy of Ne/O in coronae use for Constancy of Ne/O in coronae use for exploring O depletion in accreting systemsexploring O depletion in accreting systems– Measure of disk/planetary evolutionMeasure of disk/planetary evolution

• Two known T Tauri stars with X-ray Two known T Tauri stars with X-ray accretion shock signatures: BP Tau (~1Myr, accretion shock signatures: BP Tau (~1Myr, Schmitt et al 2005); TW Hya (~10Myr, Schmitt et al 2005); TW Hya (~10Myr, Kastner et al. 2002,Stelzer & Schmitt 2004)Kastner et al. 2002,Stelzer & Schmitt 2004)

Drake, Testa & Hartmann (2005)

SSTAR TAR FFORMATION and ORMATION and PPLANETSLANETS

• TW Hya shows O depletion by a TW Hya shows O depletion by a factor ~2 factor ~2 indicative of evolved disk indicative of evolved disk with large grainswith large grains