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Star and Planet Formation Sommer term 2007 Henrik Beuther & Sebastian Wolf 16.4 Introduction (H.B. & S.W.) 23.4 Physical processes, heating and cooling, radiation transfer (H.B.) 30.4 Gravitational collapse & early protostellar evolution I (H.B.) 07.5 Gravitational collapse & early protostellar evolution II (H.B.) 14.5 Protostellar and pre-main sequence evolution (H.B.) 21.5 Outflows and jets (H.B.) 28.5 Pfingsten (no lecture) 04.6 Clusters, the initial mass function (IMF), massive star formation (H.B.) 11.6 Protoplanetary disks: Observations + models I (S.W.) 18.6 Gas in disks, molecules, chemistry, keplerian motions (H.B.) 25.6 Protoplanetary disks: Observations + models II (S.W.) 02.7 Accretion, transport processes, local structure and stability (S.W.) 09.7 Planet formation scenarios (S.W.) 16.7 Extrasolar planets: Searching for other worlds (S.W.) 23.7 Summary and open questions (H.B. & S.W.) More Information and the current lecture files: http://www.mpia.de/homes/beuther/lecture_ss07.html and http://www.mpia.de/homes/swolf/vorlesung/sommer2007.html Emails: [email protected], [email protected] Accretion disks 1.3mm IRAS NIR 1.3mm IRAS NIR Full line: no inner whole Dashed line: Inner whole Beckwith et al. 1990 Early single-dish observations toward T-Tauri stars revealed cold dust emission. In spherical symmetry this would not be possible since the corresponding gas and dust would extinct any emission from the central protostar. --> Disk symmetry necessary! Simple case: flat, black disk T ~ r-3/4, Ldisk ~ 1/4 L* Model SEDs Beckwith et al. 1996, 1999 Effects of gaps on disk SED Full line: no gap Long-dashed: gap 0.75 to 1.25 AU Short-dashed: gap 0.5 to 2.5 AU Dotted: gap 0.3 to 3 AU To become detectable gap has to cut out at least a decade of disk size. Additional FIR excess - Larger inner or smaller outer disk radii even increase the discrepancy. - Data indicate that outer disk region is hotter than expected from flat, black disk model --> Disk flaring Disk flaring The scale height h of a disk increases with radius r because the thermal energy decreases more slowly with increasing radius r than the vertical component of the gravitational energy: Evert, grav ~ h/r * GM*/r ~ Etherm ~ kT(r) with T(r) ~ r-3/4 --> h ~ k/GM* r5/4 Hydrostatic equilibrium, radiative transfer models for flared disks I Chiang & Goldreich 1997 Hydrostatic equilibrium , radiative transfer models for flared disks II h nvert ~ exp(z2/2h2) Chiang & Goldreich 1997 Hydrostatic equlibrium, radiative transfer models for flared disks III Chiang & Goldreich 1997 Flat spectrum disks Class I protostar disk Infalling envelope Outflow cavity Class II T Tauri star - Flat-spectrum sources have too much flux to be explained by heating of protostar only. - In very young sources, they are still embedded in infalling envelope --> this can scatter light and cause additional heating of outer disk. Flat spectrum sources younger than typical class II T Tauri stars. Calvet et al. 1994, Natta et al. 1993 Molecules in Space 2 3 4 5 6 7 8 9 10 11 12 13 atoms -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------H2 C3 c-C3H C5 C5H C6H CH3C3N CH3C4H CH3C5N? HC9N CH3OC2H5 HC11N AlF C2H l-C3H C4H l-H2C4 CH2CHCN HCOOCH3 CH3CH2CN (CH3)2CO AlCl C2O C3N C4Si C2H4 CH3C2H CH3COOH? (CH3)2O NH2CH2COOH? C2 C2S C3O l-C3H2 CH3CN HC5N C7H CH3CH2OH CH3CH2CHO CH CH2 C3S c-C3H2 CH3NC HCOCH3 H2C6 HC7N CH+ HCN C2H2 CH2CN CH3OH NH2CH3 CH2OHCHO C8H CN HCO CH2D+? CH4 CH3SH c-C2H4O CH2CHCHO CO HCO+ HCCN HC3N HC3NH+ CH2CHOH CO+ HCS+ HCNH+ HC2NC HC2CHO CP HOC+ HNCO HCOOH NH2CHO CSi H2O HNCS H2CHN C5N HCl H2S HOCO+ H2C2O HC4N KCl HNC H2CO H2NCN NH HNO H2CN HNC3 NO MgCN H2CS SiH4 NS MgNC H3O+ H2COH+ NaCl N2H+ NH3 OH N2O SiC3 PN NaCN C4 SO OCS SO+ SO2 SiN c-SiC2 SiO CO2 SiS NH2 CS H3+ HF SiCN SH AlNC FeO(?) SiNC Currently 129 detected interstellar molecules (from November 2005) Molecules in disks 2 3 4 5 6 7 8 9 10 11 12 13 atoms -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------H2 C3 c-C3H C5 C5H C6H CH3C3N CH3C4H CH3C5N? HC9N CH3OC2H5 HC11N AlF C2H l-C3H C4H l-H2C4 CH2CHCN HCOOCH3 CH3CH2CN (CH3)2CO AlCl C2O C3N C4Si C2H4 CH3C2H CH3COOH? (CH3)2O NH2CH2COOH? C2 C2S C3O l-C3H2 CH3CN HC5N C7H CH3CH2OH CH3CH2CHO CH CH2 C3S c-C3H2 CH3NC HCOCH3 H2C6 HC7N CH+ HCN C2H2 CH2CN CH3OH NH2CH3 CH2OHCHO C8H CN HCO CH2D+? CH4 CH3SH c-C2H4O CH2CHCHO CO HCO+ HCCN HC3N HC3NH+ CH2CHOH CO+ HCS+ HCNH+ HC2NC HC2CHO CP HOC+ HNCO HCOOH NH2CHO CSi H2O HNCS H2CHN C5N HCl H2S HOCO+ H2C2O HC4N KCl HNC H2CO H2NCN NH HNO H2CN HNC3 NO MgCN H2CS SiH4 NS MgNC H3O+ H2COH+ NaCl N2H+ NH3 OH N2O SiC3 PN NaCN C4 SO OCS SO+ SO2 SiN c-SiC2 SiO CO2 SiS NH2 CS H3+ HF SiCN SH AlNC FeO(?) SiNC DCO+ Currently 129 detected interstellar molecules (from November 2005) Disk dynamics: Keplerian motion Simon et al.2000 DM Tau Guilloteau et al. 1998 For a Keplerian supported disk, centrifugal force should equal grav. force. Fcen = mv2/r = Fgrav = Gm*m/r2 --> v = (Gm*/r)1/2 Ohashi et al. 1997 Velocity Non-Keplerian motion: AB Aur - Central depression in cold dust and gas emission. - Non-Keplerian velocity profile vr -0.4+-0.01 PdBI, Pietu et al. 2005 SMA, Lin et al. 2006 SMA, Lin et al. 2006 CO(3-2) 345GHz continuum - Possible explanations Formation of lowmass companion or planet in inner disk. Early evolutionary phase where Keplerian motion is not established yet (large envelope). Disk-jet co-rotation in DG Tau red blue Testi et al. 2002 Corotation of disk and jet Bacciotti et al. 2002 Disk structure Different lines trace different optical depth. Pietu et al. 2007 Relatively robust results - Disk sizes between 200 and 2000AU. - Most disks are in Keplerian rotation. - Temperature structure consistent with flared disk models and T at CO disk surface (t=1) goes like T(r) ~ r-0.6. - Vertical temperature gradients with cooler disk mid-plane. - Disk temperature increase with increasing central stellar mass. - Beyond 150AU, disks around low-mass stars have T<17K, therefore, CO can freeze out on dusk grains. Inner disk regions Squares: gaseous inner disk radii (CO fundamental) Circles: dust inner disk radii (interferometry and SEDs) Najita et al. 2007 - Mid-infrared emission lines of vibrationally excited CO traces gas > 1000K. - The gas rotates at Keplerian velocity --> line-widths converts to inner disk radii. - Inner gas disk extends beyond disk sublimation radius and is close to co-rotation radius (coupling of stellar magnetic field to disk). Disks in massive star formation IRAS18089-1732 Beuther & Walsh Hot rotating structure not in Keplerian motion. IRAS20126+4104, Cesaroni et al. 1997, 1997, 2005 Keplerians disk around central protostar of ~7Msun - Still deeply embedded, large distances, clustered environment --> confusion Current obs. status largely “Velocity gradient perpendicular to outflow”. (Sub)mm interferometry important to disentangle the spatial confusion. The right spectral line tracer still missing which can distinguish the disk emission from the surrounding envelope emission. Summary Bergin et al. 2006 Star and Planet Formation Sommer term 2007 Henrik Beuther & Sebastian Wolf 16.4 Introduction (H.B. & S.W.) 23.4 Physical processes, heating and cooling, radiation transfer (H.B.) 30.4 Gravitational collapse & early protostellar evolution I (H.B.) 07.5 Gravitational collapse & early protostellar evolution II (H.B.) 14.5 Protostellar and pre-main sequence evolution (H.B.) 21.5 Outflows and jets (H.B.) 28.5 Pfingsten (no lecture) 04.6 Clusters, the initial mass function (IMF), massive star formation (H.B.) 11.6 Protoplanetary disks: Observations + models I (S.W.) 18.6 Gas in disks, molecules, chemistry, keplerian motions (H.B.) 25.6 Protoplanetary disks: Observations + models II (S.W.) 02.7 Accretion, transport processes, local structure and stability (S.W.) 09.7 Planet formation scenarios (S.W.) 16.7 Extrasolar planets: Searching for other worlds (S.W.) 23.7 Summary and open questions (H.B. & S.W.) More Information and the current lecture files: http://www.mpia.de/homes/beuther/lecture_ss07.html and http://www.mpia.de/homes/swolf/vorlesung/sommer2007.html Emails: [email protected], [email protected]
