S t a r F o r m a t i o n i n T u r b u l e n - PowerPoint PPT Presentation

S t a r F o r m a t i o n i n T u r b u l e n t , M a g n e t i z e d C l o u d s F u m i t a k a N a k a m u r a ( N i i g a t a U n i v e r s i t y ) Z h i - Y u nL i ( U n i v e r s i t y o f V i r g i n i a )

P r o p e r t i e s o f M o l e c u l a r C l o u d s � S u p e r s o n i c t u r b u l e n c e m o l e c u l a r c l o u d i s h i g h l y t u r b u l e n t . l i n e w i d t h δV i s l a r g e r t h a n C s . � S t r o n g m a g n e t i c f i e l d o b s e r v e d B f i e l d i s c l o s e t o a c r i t i c a l v a l u e . c r i t i c a l m a s s Supercritical Φ = Φ = M cr 0 . 13 , magnetic flux 1 / 2 G s u p e r c r i t i c a l v s . s u b c r i t i c a l ↓ M > M < M M cr cr Subcritical q u a s i - s t a t i c c o n t r a c t i o n d u e t o a m b i p o l a r d i f f u s i o n H e i l e s& C r u t c h e r 2 0 0 2

１．G a l a c t i c S t a r F o r m a t i o n D i s p e r s e d m o d e ： l o w - m a s s s t a r s T a u r u s l o w S F E ( a f e w % ) M a g n e t i c a l l y - r e g u l a t e d m o d e l ( a m b i p o l a r d i f f u s i o n , i n s i d e - o u t ) ( ) S h u , A d a m s , L i z a n o1 9 8 7 T u r b u l e n c e - a c c e l e r a t e d , m a g n e t i c a l l y r e g u l a t e d s t a r f o r m a t i o n ( ） L i & N a k a m u r a 2 0 0 4 ; N a k a m u r a & L i 2 0 0 5 C l u s t e r m o d e ： m a s s i v e a n d l o w - m a s s s t a r s O r i o n h i g h S F E ( 1 0 - 2 0 % ) S t r o n g s u p e r s o n i c t u r b u l e n c e S t r o n g m a g n e t i c f i e l d （C r u t c h e r 2 0 0 5 ） F e e d b a c k f r o m y o u n g s t a r s （B a l l y e t a l . 1 9 9 9 ）

２．T u r b u l e n c e s i m u l a t i o n s � O b s e r v a t i o n s o f c l u s t e r f o r m i n g r e g i o n s I m p o r t a n c e o f p r o t o s t e l l a r o u t f l o w s E f f e c t o f o u t f l o w s （C i r c i n u sc o m p l e x B a l l y e t a l . 1 9 9 9 ; （N G C 1 3 3 3 ） N G C 1 3 3 3 Q u i l l e ne t a l . 2 0 0 5 ; s e e a l s o N o r m a n & S i l k 1 9 8 0 ) � H D T u r b u l e n t s i m u l a t i o n s ( K l e s s e ne t a l . 1 9 9 8 ; B a t e e t a l . 2 0 0 3 ) S i n k p a r t i c l e , b u t n o p r o t o s t e l l a r o u t f l o w s � M H D T u r b u l e n t s i m u l a t i o n s T i l l e y & P u d r i t z 2 0 0 5 , S u g i m o t o & H a n a w a 2 0 0 4 ) Q u i l l e ne t a l . ( 2 0 0 5 ) p r i o r t o s t a r f o r m a t i o n

3 . O u r s i m u l a t i o n s � P r e v i o u s n u m e r i c a l s i m u l a t i o n s h a v e n ’ t t a k e n i n t o a c c o u n t t h e e f f e c t o f s t e l l a r f e e d b a c k . � W e i n c l u d e s e l f - g r a v i t y , s u p e r s o n i c t u r b u l e n c e , m a g n e t i c f i e l d , a n d p r o t o s t e l l a r o u t f l o w . 3 D M H D t u r b u l e n t s i m u l a t i o n s

Q u e s t i o n s � W h a t d e t e r m i n e s t h e e f f i c i e n c y o f s t a r f o r m a t i o n ? m a g n e t i c f i e l d , p r o t o s t e l l a r o u t f l o w � H o w i s t u r b u l e n c e m a i n t a i n e d i n c l u s t e r f o r m i n g c l u m p s ? p r o t o s t e l l a r o u t f l o w

４. M o d e l � I s o t h e r m a l s p h e r i c a l c l o u d � U n i f o r m m a g n e t i c f i e l d ( s u p e r c r i t i c a l ) ） ( � S u p e r s o n i c v e l o c i t y f i e l d （L a r s o n ’ s l a w ) ∝ − n E k k ⎛ ⎞ ⎛ ⎞ pc T 0 . 11 ⎜ ⎟ − = × ⎜ ⎟ 4 3 6 . 1 10 cm n ⎜ ⎟ H 2 ⎝ ⎠ ⎝ ⎠ 20 K L J 0.17 pc ⎛ ⎞ ⎛ ⎞ ⎛ ⎞ L pc T 0 . 11 = ≈ ⎜ ⎟ ⎜ ⎟ = α µ ⎜ ⎟ J pc 1 / 2 L 9 L 1 ⎜ ⎟ 71 G B ⎜ ⎟ J x ⎝ ⎠ ⎝ ⎠ 0 . 11 pc ⎝ ⎠ 20 K L J ⎛ ⎞ ⎛ ⎞ = µ α = T L for = ⎜ ⎟ B x 112 G 2 . 5 ⎜ ⎟ J M 626 M ⎜ ⎟ � ⎝ ⎠ ⎝ ⎠ pc 20 K 0 . 11 1 pc = 9L J Effective radius = 1.5L J L J = thermal Jeans length � S t a r f o r m a t i o n a n d p r o t o s t e l a l r o u t f l o w s ρ = ρ 3 100 @ 128 cr 0

５. E f f e c t o f M a g n e t i c F i e l d : N o o u t f l o w � α = 2.5, M = 10 c o l u m n d e n s i t y １ ２ ３ D i r e c t i o n o f i n i t i a l B f i e l d D i r e c t i o n o f i n i t i a l B f i e l d ３ − = × = 4 3 cm pc n H 6 . 1 10 , L 0 . 99 2 , 0 ２ = µ = = １ B 111 G , M 626 M , T 20 K � 0

S t a r F o r m a t i o n E f f i c i e n c y � I n t h e a b s e n c e o f m a g n e t i c f i e l d , t h e S F E b e c o m e s t o o h i g h . � M a g n e t i c f i e l d c a n N o T N o B T N o B r e d u c e t h e S F E . T B ρ ≥ ρ M ( ) = cr SFE M S t r o n g e r B tot ρ = ρ 100 cr 0

S u m m a r y 1 � T h e i n i t i a l t u r b u l e n c e d e c a y s q u i c k l y . I t i s d i f f i c u l t t o m a i n t a i n s u p e r s o n i c t u r b u l e n t m o t i o n s . � M a g n e t i c f i e l d i s n e e d e d t o r e d u c e t h e S F E t h a t i s c o n s i s t e n t w i t h o b s e r v a t i o n s ( 1 0 – 2 0 % ) . � T h e c l o u d t e n d s t o c o l l a p s e i n t o a s i n g l e d e n s e c o r e n e a r t h e c e n t e r .

6 ．E f f e c t o f S t e l l a r O u t f l o w � C r e a t i o n o f “ s t a r s ” ρ > ρ = ρ = ε ε ≈ For 100 M M 0 . 2 cr 0 star core � P r o t o s t e l l a r o u t f l o w ( M a t z n e r & M c K e e 2 0 0 0 ; N a k a m u r a & L i 2 0 0 5 ) M V f : o u t f l o w s t r e n g t h = = − 1 W W km s P 100 f outflow M star ★ C i r c i n u sc o m p l e x f ～ 0 . 3 ( B a l l y e t a l . 1 9 9 9 ) ★ L 1 5 5 1 I R S 5 f = 0 . 2 3 ～ 0 . 3 9 − f ~ 0 . 3 0 . 4 ★ L 1 1 5 7 f ～ 0 . 3 ★ M a t z n e r & M c K e e m o d e l f ～ 0 . 4 ★ X - w i n d m o d e l f ～ 1 / 3 ( S h ue t a l . 2 0 0 0 )

E f f e c t o f O u t f l o w C o l u m n d e n s i t y � α = 2.5, M = 10, f = 0.5 １ ２ ３ D i r e c t i o n o f i n i t i a l B f i e l d D i r e c t i o n o f i n i t i a l B f i e l d ３ = × − = M V 4 3 cm pc n H 6 . 1 10 , L 0 . 99 = = − 1 W W km s P 100 f 2 , 0 ２ outflow M = µ = = star １ B 111 G , M 626 M , T 20 K � 0

S t a r F o r m a t i o n E f f i c i e n c y � O u t f l o w r e g u l a t e s S F E s . M V = = − 1 W W km s P 100 f outflow M star

7 . T u r b u l e n c e G e n e r a t i o n � I n i t i a l t u r b u l e n c e d e c a y s q u i c k l y . � O u t f l o w s c a n g e n e r a t e a n d m a i n t a i n t u r b u l e n c e a t a l e v e l o f M a c h 5 ( 1 – 1 . 5 k m s ) . - 1