On the Star Formation Rates in GMCs with
- Slides: 22
On the Star Formation Rates in GMCs with Marco Lombardi, Joao Alves, Jan Forbrich, Gus Munch Kevin Covey & Carlos Roman
z = 1 - 10
Bouwens et al. 2010
z = 0. 000
S. Guisard ESO Pipe Nebula Rho Ophiuchi Cloud
Star Formation Activity in the Pipe: Spitzer MIPS/IRAC survey of entire cloud (Frobrich et al. 2009) Result: 18 YSOs!! YSOs C 2 D: Brooke et al. 2006
Overall star formation activity is insignificant, confined to 0. 2 % of the total gaseous mass. YSOs 1 -3 Myr Covey et al. 2010 C 2 D: Brooke et al. 2006
8300 M 7600 M Yield = SFR x Δt 18 YSOs N(YSOs)Oph = 10 x N(YSOs)Pipe SFROph = 10 x SFRPipe 200 YSOs
But what about GMCs?
The California Molecular Cloud Lombardi, Lada & Alves 2009 A&A, in press
The California Molecular Cloud A Bona Fide GMC! t~ c p 5 8 n te x E Mass = 105 Mo Lada, Lombardi & Alves 2009
Comparing the California and Orion Molecular Clouds The two clouds are nearly identical in mass & size YSOs(Orion) > 10 x YSOs(Califoria) SFR(Orion) > 10 x SFR(California) IRAS California Molecular Cloud Orion Molecular Cloud
More on Variations in Star Formation Rates in GMCs IRAS Mooney & Solomon 1988 Ap. JL 334, 51 California Molecular Cloud Orion Molecular Cloud SFR(Orion) > 10 x SFR(California)
664 M 8300 M 65 M 7600 Yield M Lombardi et al. 2008 = SFR x Δt 200 YSOs 18 YSOs N(YSOs)Oph = 10 x N(YSOs)Pipe Mass(Oph) = 10 x Mass(Pipe) for Ak > 1. 0
Comparing the California and Orion Molecular Clouds The two clouds are nearly identical in mass & size YSOs(Orion) > 10 x YSOs(Califoria) SFR(Orion) > 10 x SFR(California) OMC has 10 x as much material at Ak >1 mag as the CMC
SFR is directly proportional to total gas mass at Ak>1. 0 SFR ~ N(YSOs) / tsf For these clouds tsf ≈ 2 ± 1 Myr So N(YSOs) ~ SFR Ak > 1. 0 corresponds to Σgas > 150 M pc-2
Star Formation Efficiency is constant within x 4 for the dense gas For 0. 5 solar mass stars this translates to <SFE> = 23% ± 13% in the dense gas
Proposed Relation Between Density and the SFR = { 0 εobs M(Ak > 1) / tsf for Ak < 1. 0 for Ak ≥ 1. 0 Σgas ≥ 150 M pc-2 Where: eobs = SFEobs ≈ 0. 23
Proposed Relation Between Density and the SFR = { 0 for ρ < ρ crit εobs M(ρ >ρcrit) / tsf for ρ ≥ ρcrit ρ crit ≈ 10 4 mm. H cm-3 Where: eobs = SFEobs ≈ 0. 23 tsf = g tff (rcrit) and g ≈ 5 – 10
Proposed Relation Between Density and the SFR = { 0 for ρ < ρ crit εobs M(ρ >ρcrit) / tsf for ρ ≥ ρcrit Gao & Solomon 2004 Galaxies LIR SFR ~ MDG Milky Way GMCs Wu et al. 2005 In external galaxies global star formation rate correlates directly with amount of dense gas
The End 1. - Star Formation Rates in Molecular Clouds of similar mass vary considerably 2. . - Level of Star Formation correlates directly with total gaseous mass above a threshold column density of Av ≈ 10 mag 3. - The SFR is proportional to the total cloud mass above a critical volume density of n ≈104 cm-3
- Myrrh is mine its bitter perfume
- Ratios and proportions guided notes
- Ratios rates and unit rates
- Ratios rates and unit rates
- What is a unit ratio
- Difference between a* and ao* algorithm in ai
- What does star events stand for?
- Cassandra lovejoy
- Star formation
- Star formation
- Expcism
- Formation initiale vs formation continue
- Sơ đồ cơ thể người
- Tư thế ngồi viết
- Hình ảnh bộ gõ cơ thể búng tay
- đặc điểm cơ thể của người tối cổ
- Mật thư tọa độ 5x5
- Chụp tư thế worms-breton
- ưu thế lai là gì
- Thẻ vin
- Cái miệng nó xinh thế chỉ nói điều hay thôi
- Thơ thất ngôn tứ tuyệt đường luật
- Các châu lục và đại dương trên thế giới