Two aspects of (Local) Star Formation : SFH & Z-distribution

Transcription

1 Two aspects of (Local) Star Formation : SFH & Z-distribution Francesco Palla INAF-Osservatorio Astrofisico di Arcetri In collaboration with L. Spina (PhD), S. Randich +GES Arcetri Team OA Capodimonte,

2 Two aspects of (Local) Star Formation : SFH & Z-distribution Outline 1.! Star Formation History! YSOs Tracers of Dynamical Evolution of GMCs 2. Heavy elements in SFRs! Z Tracers of Enrichment, Impact on evolution

3 Our Cosmic Garden Our cosmic garden: the Gould Belt!

4 Our cosmic garden: Our the Cosmic Gould Garden Belt! Not exactly an example of a SF complex! seen in large scale views of a spiral disk! We don t know its origin & evolution! Yet, most of the outcome of the SF process! (IMF, SFH, SFR) doesn t seem to differ from elsewhere in the Galaxy!

5 SFH of clusters & associations! SF only occurs above threshold N th (SF>5 mag) >>N(HI!H 2 ~0.5 mag) function of local conditions (G o, A V,x e, )

6

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8 Taurus-Auriga: SF in space & time Distribution of stars 13 CO Distribution of dense gas in filaments C 18 O Onishi et al Palla & Stahler 2002

9 SFH of clusters & associations SF only occurs above threshold N th (SF>5 mag) >>N(HI!H 2 ~0.5 mag) function of local conditions (G o, x e, )!SF starts at low rates & increases in time!sf accelerates with e-folding times t SF ~1-3x10 6 yr, followed by deceleration

10 SFH solar neighborhood Chamaeleon IC Perseus

11 Taurus-Auriga acceleration deceleration

12 SFH solar neighborhood Rho Ophiuchi

13 ! Orionis association Dolan & Mathieu 2002,2004 interior regions interior: SF! 0 external: SF accelerates exterior

14 !"#$%$&'()*+"),-$.')/"0123)421%*"-)) 53!$.6)7898F)7899) 53!$.6)789:)

15 !"#$%$&'()*+"),-$.')/"0123)421%*"-)) SFR SFR GHI<)7899)

16

17 SFH of clusters & associations SF only occurs above threshold N th (SF>5 mag) >>N(HI!H 2 ~0.5 mag) function of local conditions (G o, x e, ) SF starts at low rates & increases in time SF accelerates with e-folding times t~1-3x10 6 yr, followed by decelaration!sf occurs over an extended time period: evidence from MHD/hydro cloud models!

18 SPH Gadget (sink) ApJ 2011 Time evolution of the cloud number density and mass fractions age age Stellar age distributions for isolated cloud (left) & GMC (right)

19 Dynamic Models: Large Spreads! ApJ 2011 Results of Hydro Simulations: young young NB- # dense cores (t) not stars old old Empirical results: # of stars (t)

20 ) ) ))))Mode 1: slow SF Large-scale Gravity! Molecular clouds are in force balance & self-gravitating : quasi-static evolution! t cross ~t ff & t cl ~10 Myr>> t ff! Star birth localized in space & time! threshold (N H, G 0, x e ): SFR is low intially & accelerates in time SFE is low due to rapid deceleration

21 ) ) ))))Mode 2: fast SF Large-scale Turbulence! Molecular clouds are dynamical entities: turbulent fragmentation & dissipation t cl ~ t ff ~2-3 Myr! )SF occurs in shocks from large scale flows! SF is rapid, t SF ~1-2 t cross! SFR is low due to low efficiency in shells

22 Rapid vs Slow SF In both cases, most of star formation takes place in a short (dynamical) time

23 ;"-%A+"2)J)K$23L"'*%)"#"->M+"-"N) G'O-"P)"*)32E)7897)GJGQ)D.2$'3-$)"*)32E)7897N)

24 Herschel & Filaments everywhere Andre et al A&A; Molinari et al. 2012

25 <$L123&.'%B)K$23L"'*%)"#"->M+"-"N) NC')*+")(-3#.T*1-012"'*)U-3(L"'*3&.'F)(3%) A.-"%)M$*+)3)M$O")-3'(").U)L3%%"%)3-")U.-L"O) U-.L)L3*"-$32)A.LH-"%%"O)0>)%+.AV%)-"%12&'() U-.L)%1H"-%.'$A)$'*"-%*"223-)*1-012"'A"E)) R2.#"-)J)D3AS.M))))))))))))))))))))))))))?3O.3')))))))))

26 ;"-%A+"2)J)K$23L"'*%)"#"->M+"-"N) ;"-%A+"2)#$"M).U)=31-1%)W799X79::)Y23L"'*)?32L"$-$L)"*)32E)789:)GJG)

27 ;"-%A+"2)J)K$23L"'*%)"#"->M+"-"N)!)4+3-3A*"-$%&A)Y23L"'*)M$O*+)Z8E9)HA)[G-\.1L3'$3')"*)32E)7899])!)Z7^%.'$A)%A32")0"2.M)M+$A+)$'*"-%*"223-)*1-012"'A")0"A.L"%)%10%.'$A)!)K$23L"'*%)L3>)U.-L)0>)*1-012"'*)A.LH-"%%$.').U)$'*"-%*"223-)(3%)

28 <*3-XW5)K.-L3&.'B) Y23L"'*%)!)A.-"%)!)%*3-%XW5%) ; 8) ) # " eq (r) = " c + 1+ % r * + $ M L,crit " 2# % & 0 H 0 & ( ' 2,. -. /2 $ eq (r)r dr $ 2 2c H 0 = s ' & ) %" G # 0 ( [,%*-$V"-)9ab`Q)C'1*%1V3)9aacQ)W3*")7897N]) = 2c 2 s G ' 2 (101 M 0 pc )1 3*)23-(")-)!)- T`) ))1'%*302") "d1$2$0-$1l ) G-")*+").0%"-#3&.'%).U)*+")Y23L"'*%)A.'%$%*"'*).-) ))A.LH3&02")M$*+)*+")%A"'3-$.).U)$%.*+"-L32)Y23L"'*%_) 1/ 2

29 <*3-XW5)K.-L3&.'B) )%+""*%)!)Y23L"'*)!)A.-"%)!)%*3-%XW5%) S3-("%*)) /T0.O>) %$L12P').U) =1-012"'*) 4.-") 98 b )H3-&A2"%) W3*")7897)

30 ;"-%A+"2)J)K$23L"'*%)"#"->M+"-"N)?32L"$-$L)"*)32E)789:)GJG) " eq (r) = " c ) # + 1+ % r +*+* $ H 0 & ( ' 2, p / 2 H Y* e9ebt7e8)#%)h,%* e`f)

31 ;"-%A+"2)J)K$23L"'*%)"#"->M+"-"N) /"3-2>)C%.T=B)97!9`)g)?32L"$-$L)"*)32E)789:)GJG) K$*B)=[-]Zh[-] it9))))) ie8eaj) K$23L"'*%)3-")32L.%*)$%.*+"-L32F)01*)+3#")%+322.M"-) O"'%$*>)H-.Y2"%)*+3')*+".-"&A32)L.O"2%N)

32 K$23L"'*%)k#"->M+"-"B)M+3*)3-")*+">)_) )R.)03AV)*.)=31-1%)lY23L"'*mN) C'*"(-3*"O) $'*"'%$*>) L3H%).U) S9`anXW79:)) $')#3-$.1%) +$(+)O"'%$*>) *-3A"-%)!) g$'"l3&a) $'U.-L3&.') ;3A3-)"*)32E)789:)GJG)

33 K$23L"'*%)k#"->M+"-"B)M+3*)3-")*+">)_) ))R.)03AV)*.)=31-1%)lY23L"'*mN)!)?.%$&.'TH.%$&.'T#"2.A$*>) ))A10").U)2$'")A"'*"-)o 2%-)!)?-"%"'A").U)A.--"23*"O) )))%*-1A*1-"%))!)pXA % q8ej)r)9)t)*+"-l32) )))%10%.'$A)0.*+)$') )))J).1*).U)A.-"%)!) ;3A3-)"*)32E)789:)GJG) s+"-")3-")*+")%+.av%_) )*

34 K$23L"'*%)k#"->M+"-"B)M+3*)3-")*+">)_) )R.)03AV)*.)=31-1%)lY23L"'*mN) ;3A3-)"*)32E)789:)GJG) /,=)Y23L"'*)01*)Wt/5Sk<B) D3$')A2.1O)L3O").U):n)lY23L"'*%m)Z8En)HA)2.'()

35 K$23L"'*%)k#"->M+"-"B)M+3*)3-")*+">)_) R.)03AV)*.)=31-1%)lY23L"'*mN) 4S,t5)Z98)HA) Wt/5Sk<)o 2%- Z`Tj)VLX%) 2% KCSGDk/=)Z8En)HA)oTA.+"-"'*) ;3A3-)"*)32E)789:)GJG) 4,!k<)M$*+XM$*+.1*)%*3-%)

36 W1*)+.M)O.)O"'%")A.-"%)3A*1322>)U.-L_) GHIS)7898) o"->)%+3-h)*-3'%$&.') U-.L)*1-012"'A")*.) A.+"-"'A")$')O"'%") A.-"%E) s+3*)a31%"%)$*_) s3#")o3lh$'() *..)2.'(N) <&22)1'V'.M'f)

37 K$23L"'*%)k#"->M+"-")N)_) 4+3'(").U)?3-3O$(L)U.-) =1-012"'A")R"'"-3&.') =1-012"'A")$')Y23L"'*%)-"%12&' '()) U-.L)$'*"-3A&'()%+.AV%) =1-012"'A")O-$#"') 0>)(-3#$*>N) <2.M)O>'3L$A32)"#.21&.')

38 Two aspects of (Local) Star Formation : SFH & Z-distribution Outline 1. Star Formation History! YSOs Tracers of Dynamical Evolution of GMCs 2. Metallicity in SFRs! Z Tracer of Enrichment, Impact on SF

39 s+>)l"*322$a$*>_)! <"2UT"'-$A+L"'*)3'O)lA+"L$A32)*3(($'(mB) 301'O3'A"%)1%"O)3%)%$('3*1-"%).U)*+") "'#$-.'L"'*)M+"-")*+")%*3-%)M"-")0.-')! </T$'O1A"O)%*3-)U.-L3&.'B))H-.(-"%%$#") ))))thh"-)<a.-h$1%)6)l.-")o$%*3'*)<k!%n])!)g01'o3'a"%).u)u.1'()<*3-%b)5$%a)o$%%$h3&.')j) )))?23'"*)U.-L3&.')

40 RGCGTk<,)<1-#">B)C'$&32)!"%12*%) <H"A*-.%A.H$A)<1-#">)T)4.T?C%B))IE)R$2L.-")")<E)!3'O$A+) :88)'$(+*%B)n)>-Q)0"($''$'(B)I3'13->)7897) *3-("*B98vn)%*3-%)[012("F)*+$AV)")*+$')O$%V)J)+32.]) Z988).H"')A21%*"-%)r))Z78)>.1'()[wZ988)D>-]) ))))D"L0"-%+$H)J)D"*322$A$*>) O"*"-L$'3&.').U)<K!%)Ju,4%)) "!Arcetri: Lorenzo Spina, G. Sacco, SR, FP,! E. Franciosini, L. Morbidelli, L.Magrini!

41 RGCGTk<,)<1-#">B)C'$&32)!"%12*%)

42 [Fe/H] in Star Forming Regions & Young Open Clusters OCs have higher [Fe/H] than SFRs - SFRs do not show higher than solar abundances - So far, no evidence of enrichment but

43 ,1-)A.%L$A)(3-O"'B)R.12OP%)W"2*) zwzz 8 ) p),-$b)zzz 8 ) R.12OP%)) W"2*) zez 8 ) zwzz 8 ) zwzz 8 ) zwzz 8 ) zwzz 8 )

44 Two aspects of (Local) Star Formation : Conclusions! Existence of thresholds for SF: A V,K, x e, G 0! Star formation occurs at an accelerating pace! large-scale contraction of parent clouds! SF in filaments: origin? dense cores?! SFRs/Young Clusters: ~solar metallicity! No/Weak evidence for direct Z-enrichment