x -ray d iagnostics of g rain d epletion in m atter a ccreting onto t t auri s tars
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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