1. The hot core that is not a “Hot Core”: Orion KL
Luis Zapata (MPIfR)
Johannes Schmid-Burgk (MPIfR)
Karl Menten (MPIfR)
Max Planck Institut für Radioastronomie

2. The BN/KL outflow
An enigmatic flow associated with a star forming region
Reported for the first time by Allen and Burton (1993) and Taylor (1994)
Orion BN/KL
Trapezium
Orion `South
Lbol~105 Lsun (Orion BN/KL)
M ~ 10 Msun
E ~ 1047 Erg
High vel. >100 km s-1
Very poor collimated
Bright in optical and infrared bands
Subaru Infrared Telescope

3. No a common outflow: Explosive disintegration of a massive young stellar systemBN n I
Gaussian fitting
A common center
SMA CO(2-1) & H2
Red: 35 to 130 km s-1
Blue: -35 to -120 km s-1
Zapata et al. (2009)
Rodriguez et al. (2005)
Gomez et al. (2006)

4. An isotropic explosive flow?
CO(2-1) – high velocity gas
~ 40 filaments

5. 3D Movie
Age = 500 yrs

6. Southeastern parts also fainter
Subaru Infrared Telescope
J, K’, H2

7. ? Chernin & Wright (1996) CO(1-0) & HCN Outflow model Orion KL
Hot core

8. The famous Orion-KL Hot Core
A peculiar hot core “Heart-shaped”
First discovered “hot core” (Ho et al. 1979)
Orion South Compact Hot Cores
Wilson et al. (2000)
NH3 (4,4)
N(H2) > 1023 cm2
Tdust ~ 200 K
Zapata et al. (2004)
CH3CN & 1.3 mm

9. Chemical and velocity diversity
IRc 6
Hot core
Friedel and Snyder (2007)
CARMA
Guélin et al. (2007)
IRAM 30

10. What is putting the hot in the Orion KL Hot Core?
See for a more complete debate: Blake et al. (1996), Liu et al. (2002),
and de Vicente et al .(2002)
Radio sources
NH3
Mid-infrared
SHUPING et al (2004)
Menten & Reid (1995)

11. The Submillimeter Array
Millimeter and submillimeter molecular and continuum observations
Moderate angular resolution ~ 3-4”
Hot molecular tracers: mainly vibrational excited emission.

12. CH3CN k=3 -- SMA 880 μm – SCUBA-JCMT CO(2-1) & H2
A close relation between the Hot Core and the explosive flow
CH3CN k=3 -- SMA
880 μm – SCUBA-JCMT
CO(2-1) & H2

13. SMA CO(3-2) filaments vs. Position Angle

14. Simple model of the Hot Core
Orion KL Hot Core
Simple model of the Hot Core
Internally
Cold molecular gas
Hot molecular gas
Obscured Protostar:
Centimeter
Submillimiter
Infrared
Externally (outflow, stars)

15. Where is the hot molecular gas within the Orion’s core?
Torsionally and vibrationally excited lines

16. Where is the hot molecular gas within the core?

17. The Orion’s heart: CH3CN lines

18. Midinfrared, molecular, centimeter and submillimeter emission

19. Kinematics of the molecular gas in hot core:
Filaments !

20. Summary
A good correlation exists between the absence of CO filamentary flow structures or “fingers” and the area behind the position of the Orion KL Hot Core.
The torsionally/vibrationally excited lines and CH3CN(12-11), all of which are supposed to trace hot and dense molecular gas, are located toward the northeast lobe of the “heart” structure.
The HC3N(37-36)(v7=1) and CH3OH(74,3-63,3) A− (vt=1) lines appear to form a shell around the strongest submillimeter compact source.
The CH3CN( ) and HC3N(37-36)(7=1) maps of the kinematics of the molecular gas within the Hot Core surprisingly reveal filament-like structures pointing toward the dynamical origin.
The hottest molecular emission coincides well with a chain of mid-infrared (IRS2a-d) and OH maser emission, suggesting that part of the infrared emission of the Orion KL region maybe is generated by strong shocks.
All of these observations suggest the southeast and southwest sectors of the explosive flow to have impinged on a pre-existing very dense part of the Extended Ridge, thus creating the bright Orion KL Hot Core.