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The Birth of Stars and Planets in the Orion Nebula
K. Smith
(STScI)
Orion (the hunter)
Why Orion?
• Closest massive star forming region (450pc)
(there are closer low mass star forming regions)
• Relatively young (1Myr)
• Now believed that our Sun started life in such an environment
Giant molecular clouds
Found throughout galactic plane
Are the sites of star formation
Dame et al
Star formation…
Stars form in clusters and groups
NGC 346, SMC
Pleiades
NGC 1850, LMC
Orion + CO
Barnard loop
Rosette Nebula
Orion and surroundings in the visibleNGC 1741
NGC 2022
Witch Head Nebula
IRAS 100 micron image
…and in the far-infrared
Stellar density in Taurus vs. Orion
14.6´ × 15.1´ @140pc = 0.59pc ×0.61pc
7´ × 7´ @450pc = 0.91pc ×0.91pc
Massive stars• Disperse the cloud• Ionise the gas• May disrupt low mass
star disks• Burn out quickly
Hot stars, ionized gas
and dusty nebulae trace
star formation
NGC2024
Horsehead
NGC1976M42
NGC1977
Massive stars• Disperse the cloud• Ionise the gas• May disrupt low mass
star disks• Burn out quickly
Low mass stars• Have disks and accrete
material for several million years
• Launch jets• Form planetary
systems
The current paradigm (Low Mass Objects)
Cloud collapse
104 yr
Disk/wind
105 yr
Planetary system
109 yr107 yr
Low-mass binary
HH 30
Sargent & Beckwith 1987, Ap. J., 323, 294.
13CO 2-1 4.4-5.8 km s-1
1000
AU
HL TauXZ Tau
HH 305000 AU
Mundt et al. 1990, A&A, 232, 37.
SII 6717 Å 3.5m Calar Alto
Disk / jet “standard” model
e.g. Lin et al, 1994, Ap. J., 435, 821.
Ray et al. 1996, Ap. J., 468, L103.
HST images of disks provided "proof"
Disks in the IR (NICMOS/HST)
HK Tau B
C. Koresko, Ap.J.Lett. 1998
Adaptive optics on Keck
Jets
Jets from binaries
Treasury program
104 HST orbits, parallel ACS +WFPC2 +NIC3• ACS: B (420s), V (385s), I (385s), z (385s), Ha (340s)• WFPC-2: U (2400s), B (80s), I (10s), Ha (400s)• NIC-3: J (5256s), H (4192s)
2 Orientations• 100° (35 orbits, Fall 2004) • 280° (69 orbits, Spring 2005)
Precise tiling pattern allows for full coverage with ACS and WFPC2
PI : M. Robberto
Mapping strategy
Mapping strategy
Fall campaign on 2-Mass
On ESO Optical Image On 2MASS JHK Color
Mapping strategy
MotivationApart from pretty picture, what do we learn?
IMF - the distribution of masses
HR diagram - test models of stellar evolution
Reaction of disks to different environments
Binary properties
For every massive star (>10Msol)…
there are many hundreds of lower mass stars
Hillenbrand & Carpenter, 2000
The HR diagram
Hillenbrand 1997
PSF subtraction reveals close binary companions
Companion is 0.45" from the primary, flux ratio ~6 mag I band
Original images, visits 49, 4a, 4c final drizzled
Disks in the Orion environment
114-426: giant dark silhouette disk
IR emission from Disks
Chiang & Goldreich 1997, Ap. J., 490, 368.
Superheated surfacelayer with small grainsproduces infrared.
“Black” interior producesmillimeter-wave emission.
The cluster core
The core region
Proplyds
400 AU2000 AU
Section of the Orion Nebula
114-426183-405
206-446 182-413
O’Dell & Wen 1992, Ap.J., 387, 229; McCaughrean & O’Dell 1996, AJ, 108, 1382.
Disk evaporationDisk evaporation
6 – 13.6 eV UV photons
Disk evaporationDisk evaporation
6 – 13.6 eV UV photons
Disk evaporationDisk evaporation
6 – 13.6 eV UV photons
Disk evaporationDisk evaporation
6 – 13.6 eV UV photons
Disk evaporationDisk evaporation
6 – 13.6 eV UV photons> 13.6 eV photons
Disk evaporationDisk evaporation
6 – 13.6 eV UV photons> 13.6 eV photons
Disk evaporationDisk evaporation
6 – 13.6 eV UV photons> 13.6 eV photons
Stellar wind
Disk evaporationDisk evaporation
6 – 13.6 eV UV photons> 13.6 eV photons6 – 13.6 eV UV photons> 13.6 eV photons
Stellar wind
Disk evaporationDisk evaporation
Disks are evaporated by FUV photons
Animation showing HH502 motion between Aug 2002
and Nov 2004 (2.25 yr)
To sum up…
The treasury programme is the widest and deepest survey yet made of the Orion nebula cluster
The main goals;
Determine the IMF for low mass stars in Orion
Obtain a precise HR diagram to test models
Observe disks in a ‘hostile’ environment - believed to be similar to the birth environment of the Sun