RT Line Simulation Study of YSO Outflow in Early Stage - towards - PowerPoint PPT Presentation

RT Line Simulation Study of YSO Outflow in Early Stage - towards ALMA era - Masako YAMDA(ASIAA) 、 Masahiro MACHIDA, Shu-ichiro INUTSUKA(Kyoto University) 、 Kohji TOMISAKA(NAOJ) 2008 年 12 月 22 日月曜日

Introduction : YSO Outflow Belloche et al.2002 ubiquitous phenomena in star forming region ✦ obs. : wide variations in morphology, velocity... ✦ Studies of YSO outflow : ✦ in star formation processes : angular momentum transfer/ ✦ final mass determination/(possible) triggering mechanism in sequential star formation… physics in outflow : driving mechanism?? ✦ Driving mechanism : several models, but still unclear ✦ B force-driven? ✦ collapse of rotating magnetized molecular core ✦ (Lorentz force ／ centrifugal force) disk wind, X-wind... ✦ entrainment by high-velocity optical jet? ✦ Difficulty in observational study of driving mechanism : spatial extent /evolution / τ ✦ launching region[<100AU, 10 2 yr] ⇔ current obs.[~10 3 -10 4 AU, 10 3 -10 4 yr] ✦ complex velocity field of several components : infall of envelope/disk ~ rotation of disk ~ outflow ✦ launching mechanism ⇔ early stage of evolution ← deeply embedded in progenitor mol. core ✦ 3D non-LTE radiative transfer approach 2008 年 12 月 22 日月曜日

Calculations ✦ Hydrodynamic simulations: 3D nest grid, resistive MHD ✦ initial condition : rotating Bonnor-Ebert sphere ✦ (M=0.6Mo, R=2000AU, T kin =10K) EOS : taken from 1D radiation hydro. simulation ✦ (Masunaga & Inutsuka, 2000) + some modification long evolution, and large spatial extent ✦ stop calculations slightly after the first core ✦ 2000AU formation ✦ Radiative Transfer: [ray tracing with long characteristics method] non-LTE level population up to J=10 for each grid ✦ assume uniform chemical abundance distribution ✦ abs. coeffs. profile : ✦ purely thermal velocity, no micro-turbulence 12 CO CS SiO n crit ~10 2 [1/cc] ~10 5 [1/cc] ~10 5 [1/cc] E 10 5.5K 2.35K 2.08K Hogerheijde&van der Tak(2000) 2008 年 12 月 22 日月曜日

Calculations (cont.) : hydro. evolution 1D Radiative Hydrodynamics Larson (1969) Protostar Tohline (1982) Masunaga & Inutsuka (2000) Log T (K) Adiabatic Phase Second Collapse & Isothermal Phase Protostellar Phases To MS 10 4 Dead region B amplification B amplification B dissipation (10 12 cm -3 <n<10 15 cm -3 ) adopt slightly harder EOS protostar in order to calculate longer (second core) 10 3 period and larger extent H 2 dissociation B B B (endoergic reaction) Molecular Cloud Core 10 2 Adiabatic core (First core) Formation 10 Gas Temperature Log n (cm -3 ) 10 5 10 10 10 15 10 20 Spatial Scale (AU) 10 4 100 1 0.1 2008 年 12 月 22 日月曜日

Calculations (cont.) ✦ simulations: a spatially/temporary snap shot result is cut-out ✦ from Nested Grid simulation L=7 ⇒ emission/absorption in outer part do not enter our results [current limitation of our RT scheme] AMR/nested grid RT scheme (by Prof. Tomisaka , ✦ experimental) ⇒ outer envelope is not completely thin , and introduces un-negligible changes! My analysis/results are taken as qualitatively, not quantitatively! 2008 年 12 月 22 日月曜日

Non-LTE results : integrated intensity integrated intensity : full & blue/red almost symmetric ✦ distribution of red/blue components θ =0, 30, 60, 90 deg. [SiO(J=7-6) E 7 =58K], barotropic 1000 1000 θ =0 θ =30 in outflow & disk : red and ✦ blue contours show separate 500 500 peaks outflow not in perfect symmetry ✦ 0 0 z z in red/blue contours due to optical thickness & -500 -500 velocity structure effects 2,000AU envelope -1000 -1000 θ =30, 60deg. : almost circular ✦ -1000 -500 0 500 1000 -1000 -500 0 500 1000 envelope at the outer part x x ⇔ infalling motion of envelope toward the center θ =60 θ =90 1000 1000 Δθ (10AU)=0.07” if D=140pc ✦ 500 500 0 0 z z ALMA can resolve these structures -500 -500 (..and SMA as well?) -1000 -1000 -1000 -500 0 500 1000 -1000 -500 0 500 1000 x x 2008 年 12 月 22 日月曜日

Column density : dust continuum dust continuum : expect for higher angular resolution obs. compared with lines ✦ � β � 0 . 25[mm] κ ν = 0 . 1 × T b = B ν (1 − exp( − τ ν )) λ 1000 1000 1000 θ =0(pole-on) θ =30 (a) 150GHz (b) 220GHz (c) 350GHz 500 500 500 y[AU] y[AU] y[AU] 0 0 0 -500 -500 -500 -1000 -1000 -1000 -1000 -500 0 500 1000 -1000 -500 0 500 1000 -1000 -500 0 500 1000 θ =60 x[AU] x[AU] x[AU] θ =60 θ =90(edge-on) 6.00e-02 1000 1000 T d =10K~T gas (d) 650GHz (e) 850GHz 5.00e-02 500 500 4.00e-02 ✴ high column density at T b [K] y[AU] y[AU] 0 0 3.00e-02 disk - difficult to look 2.00e-02 further inside -500 -500 1.00e-02 ✴ emission from outflow -1000 -1000 0.00e+00 component is quite weak -1000 -500 0 500 1000 -1000 -500 0 500 1000 x[AU] x[AU] 2008 年 12 月 22 日月曜日

Column density : dust continuum dust continuum : opt. thin in mm. bands - how about submm. band? ✦ � β � 0 . 25[mm] κ ν = 0 . 1 × T b = B ν (1 − exp( − τ ν )) λ max( τ )=0.40 max( τ )=0.80 max( τ )=2.01 1000 1000 1000 θ =0(pole-on) θ =30 (a) 150GHz (b) 220GHz (c) 350GHz 500 500 500 y[AU] y[AU] y[AU] 0 0 0 -500 -500 -500 -1000 -1000 -1000 -1000 -500 0 500 1000 -1000 -500 0 500 1000 -1000 -500 0 500 1000 x[AU] x[AU] x[AU] max( τ )=6.94 max( τ )=11.9 θ =60 θ =90(edge-on) 3.00e-02 1000 1000 (d) 650GHz (e) 850GHz 2.50e-02 500 500 2.00e-02 y[AU] y[AU] 0 0 τ 0 1.50e-02 T d =10K~T gas 1.00e-02 -500 -500 5.00e-03 -1000 -1000 0.00e+00 -1000 -500 0 500 1000 -1000 -500 0 500 1000 x[AU] x[AU] 2008 年 12 月 22 日月曜日

Excitation Temperature : CO adopt “standard” mol. ✦ 12 abundance y=3x10 -4 10 8 n crit (1-0)~10 2 cm -3 , n crit ∝ J 3 ✦ 6 4 J=1-0 J=2-1 J=3-2 J=1-0 J=2-1 J=3-2 huge optical thickness ( τ 0 up ✦ 1-0 2-1 3-2 2 to 4,000) and high density 0 12 (10 6 cm -3 < n < 10 11 cm -3 ) in the T ex [K] T ex [K] 10 simulation box, pop. energy 8 distribution becomes LTE 6 even at high J (J=10-9) J=4-3 J=5-4 J=6-5 4 (T ex = T kin ~10K) J=4-3 J=5-4 J=6-5 4-3 5-4 6-5 2 0 12 10 8 J=7-6 J=8-7 J=9-8 6 4 J=7-6 J=8-7 J=9-8 7-6 8-7 9-8 n[cm -3 ] 2 0 10 6 10 7 10 8 10 9 10 10 10 6 10 7 10 8 10 9 10 10 10 6 10 7 10 8 10 9 10 10 10 11 10 11 10 11 n[cm -3 ] 2008 年 12 月 22 日月曜日

Excitation Temperature : SiO adopt “standard” mol. ✦ 12 abundance y=2x10 -8 10 8 n crit (1-0)~10 5 cm -3 ✦ 6 ⇔ 10 6 cm -3 < n < 10 11 cm -3 4 J=1-0 J=2-1 J=3-2 1-0 2-1 3-2 2 low-J and in dense regime (n ✦ 0 12 > 10 8 cm -3 ), pop. is LTE T ex [K] 10 high-J and in tenuous regime ✦ 8 (n < 10 8 cm -3 ), T ex decreases to 6 ~ 5K 4 J=4-3 J=5-4 J=6-5 4-3 5-4 6-5 ⇒ non-LTE effects can be 2 0 observed ( ⇔ 12 CO) 12 10 8 6 4 J=7-6 J=8-7 J=9-8 7-6 8-7 9-8 n[cm -3 ] 2 0 10 6 10 7 10 8 10 9 10 10 10 6 10 7 10 8 10 9 10 10 10 6 10 7 10 8 10 9 10 10 10 11 10 11 10 11 n[cm -3 ] 2008 年 12 月 22 日月曜日

Average Line Profile : CO θ =30deg, solid line: intensity, dashed line: τ 0 J=1-0 J=2-1 J=3-2 huge optical thickness ⇒ strongly saturated line profile ✦ very weak wing-like components around Vr=+/-2km/sec ✦ ... but even in these wing components, τ 0 ~100-400 ✦ qualitative characteristics are quite independent on viewing angle θ ✦ 2008 年 12 月 22 日月曜日

Average Line Profile : SiO θ =30deg, solid line: intensity, dashed line: τ 0 J=1-0 J=4-3 J=7-6 optical thickness is still large, but smaller than 12 CO : line profiles do not show ✦ saturation < τ > SiO ~0.01x< τ > CO : SiO will present inner structures that 12 CO cannot ✦ non-LTE pop. & smaller τ ✦ ⇒ double peak profile appears with respect to Vr=0 km sec -1 qualitative characteristics are quite independent on viewing angle θ ✦ double-peak structure even in pole-on [ θ =0] view ✦ 2008 年 12 月 22 日月曜日

Non-LTE results : PV diagram (CO) Huge τ and then almost feature-less PV diagram ✦ CO(2-1), 30deg, vel. 1st-moment 4.0 500 500 1000 (a) (b) 5.0 2.0 (a) (b) 400 400 0.5 Vr[km sec -1 ] Vr[km sec -1 ] 500 300 300 0.0 0.0 K K Vr[km sec -1 ] 200 200 y[AU] -2.0 0 0.0 (c) -5.0 100 100 -4.0 0 0 -500 Angular Offset Angular Offset -0.5 4.0 500 -1000 (c) -1000 0 1000 -500 500 2.0 x[AU] 400 (a) : spiky structure up to +/- 5 km sec-1, wobble ones by ✦ Vr[km sec -1 ] 300 several velocity components [outflow, rot. of outflow & disk, 0.0 K accretion of envelope, ...] 200 -2.0 (b) : small gradient from blue to red [mainly from disk] ✦ 100 -4.0 0 (c) : small gradient from red to blue in inner part [mainly from ✦ Angular Offset bipolar vel. of outflows] 2008 年 12 月 22 日月曜日

Non-LTE results : PV diagram (CO) structures in (c) line ✦ CO(2-1), 30deg, 1st-moment (a) 500 1000 (a) (b) 5.0 400 0.5 500 Vr[km sec -1 ] 300 Vr[km sec -1 ] 0.0 K y[AU] 0 0.0 (c) 200 vel. gradient -500 -5.0 ( Δ v~1km/sec) -0.5 100 -1000 -1000 0 1000 -500 500 0 Angular Offset x[AU] spikes : appear all the PV diagrams of cuts through the very small near-center ✦ regions in FOV NOT appear in some of the cuts passing the very center ✦ velocity (+/- 5km sec -1 ) > bulk velocity of fluids (|v| up to 3 km sec -1 )! ✦ 2008 年 12 月 22 日月曜日