John Bally Center for Astrophysics and Space Astronomy
Department of Astrophysical and Planetary Sciences
University of Colorado, Boulder
Recent Developments Recent Developments in Stellar and Planetary Systemin Stellar and Planetary System Formation Formation
Introduction Introduction • Star Formation: The fundamental cosmic (baryonic) process Determines cosmic fate of normal matter
Star Formation
Galaxy formation, evolution, IMF
Elements(He => U)
Clusters
black holes(AGN, stellar)
Light, K.E. of ISM
Planet formation
Conditions for life
Where planets also form
• Giant Molecular Cloud Core
• Gravitational Collapse & Fragmentation
• Rotation & Magnetic Fields
Raw material for star birth
Proto-stars, proto-binaries, proto-clusters
Accretion disks, jets, & outflows
Shrink size by 107; increase density by x 1021 !
Star FormationStar Formation
• PlanetsC. LadaMost may form in clusters!
Star-Formation:Star-Formation:• SF occurs in Giant Molecular Clouds (GMCs): Decay of turbulence +• Gravity + B Collapse => disks, jets => stars, planets• Fragmentation: Non-hierachical multiples: disintegration Dense (mostly unbound) clusters: < n*> ~ 103 - 105 pc -3 • 90% of stars born in OB associations: Multiple SN Superbubbles => inject short-lived isotopes
GMCs
OB *ssuperbubbles
Supershells / ringsgravity
20 - 50 Myr
Galactic 'ecology'
NGC 1333
IC 348
IRAS 03235+3004
M.Bate
SO
Spitzer IRAC
HH 46/47
HST 1997 - 1994
HH 46/47
HST 1997 - 1994
Irradiated jets in Car (Tr 14)
The Orion Star Forming Complex
Wei-Hao Wang
Infrared view of winter sky (10 - 120 m)
The Orion/Eridanus Bubble (H): d=180 to 500pc; l > 300 pc Orion OB1 Association: ~40 > 8 M stars: ~20 SN in 10 Myr
1a (8 - 12 Myr; d ~ 350 pc))
1b (3 -6 Myr; d ~ 420 pc)
1c (2 - 6 Myr; d ~ 420 pc)
1d (<2 Myr; d ~ 460 pc)
Ori (< 3 Myr)
Barnards's Loop Eridanus Loop
Orion B
Orion A
Orion Nebula
Orion MolecularClouds
13CO 2.6 mm
20
Orion belowthe Belt:
Horsehead Nebula
Orion Nebula
NGC 2024 (OB1 d)
Orionis (c)
NGC 1977
OriNGC1980: Source of Col + AE Aur ; V ~ 150 km/s runaways, 2.6 Myr ago
NGC 1981
Ori OB1c
Ori OB1d
NKLTrapezium
OMC1-S
(L = 105 Lo
t << 105 yr)
(L = 104 Lo ,
t < 105 yr)
(L = 105 Lo
t < 105 yr )
OMC 1 Outflow
t = 3,000 yr)
Orion NebulaOrion Nebula
Trapezium clusterTrapezium cluster
Proper motions:Van Altena et al. 88
Vesc ~ 6 km s-1
2.6
1.8
5 2.5
OrionBN/KLH2
NICFPSAPO 3.5 mFirst light21 Nov 04
0.5 – 2.2 m
104 AU
11.7 m
Gemini STReCS
104 AU
OMC1OMC1H2 fingers
High-velocity stars: I , BN , n (Gomez et al. 2005)
BN: V~ 30 km s-1
I: ~ 13 km s-1
n: ~ 20 km s-1
d253-535 in M43
UV photo-ablation of disks & planet formation:UV photo-ablation of disks & planet formation:
Orion Nebula: Disks seen in silhouette
HST 16
HST 10
HST 17
Irradiated proto-planetary disks:
Anatomy of a planetary systemforming in an OB association
Disk mass-loss:Disk mass-loss:UV Radiation => heatimg = > Mass – loss ~ 1 Myr
r > GM / c2
~ 40 AU for Soft UV (91 < < 200 nm)
~ 5 AU for ionizing UV ( < 91 nm) (for Solar mass) Self-irradiation by central star vs. External irradiation by nearby massive star:
Lself(UV) / 4 d*2 = Lexternal(UV) / 4 dOB
2
Lexternal(UV) ~ 1049 photons / sec Lself(UV) ~ 1040 - 1043 photons / sec
Impacts of the environment: Impacts of the environment: Life of a massive star ~ 3 to 40 Myr ~ planet formation time-scale• Clustering, multiplicity: - Close-encounters - Truncate, shock-heat disks• UV radiation: - External + Self => Mass-lost in ~ few Myr
UV dose: 1042 – 1045 t ( sec-1)
Main-sequence star (3 – 30 Myr) Blue-supergiant (< 106 years) Supernova (1 year)• Massive star winds, Supernovae: - Inject short-lived isotopes: 26Al, 60Fe
UV => Fast Growth of Planetesimals:UV => Fast Growth of Planetesimals:
Grain growth => Solids settle to mid-planeUV => Remove dust depleted gas => High metallicity in mid-planeGravity => Instability => 1 - 100 km planetesimals
- Fast Formation of 1 to 100 km planetesimals
Growing grains: Orion 114-426 (Throop et al. 2001)
Oldest meteorites: (CAIs: 4,567.6 Myr old = 0 )Chondrules: +2 to 4 Myr
26Al => 26 Mg (t1/2 ~ 0.7 Myr) 60Fe => stable elements (t1/2 ~ 1.5 Myr) => Solar System formed in Orion-like OB association SN within few pc, few Myr of forming Solar System
Supernovae:Supernovae:
ConclusionsConclusions• Most stars form in Orion-like regions - Sibling star interactions - Jets => halt star formation• Proto-planetary disks processed by UV - Gas lost in few x 106 years - Grain growth + sedimantation + UV => Prompt planetesimal formation• Massive Stars: - Mutual interactions => high velocity stars (BN) => explosive outflows - HII regions => halt star formation - Supernavae: => Inject 60Fe, 26Al, …
The End