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

The BN/KL outflowAn enigmatic flow associated with a star forming regionReported for the first time by Allen and Burton (1993) and Taylor (1994)

Subaru Infrared Telescope

Orion BN/KL

Trapezium

Orion `South

Lbol~105 Lsun (Orion BN/KL)M ~ 10 Msun

E ~ 1047 ErgHigh vel. >100 km s-1

Very poor collimatedBright in optical and infrared bands

BN

nI

Gaussian fittingA common center

SMA CO(2-1) & H2Red: 35 to 130 km s-1

Blue: -35 to -120 km s-1

Zapata et al. (2009)

No a common outflow: Explosive disintegration of a massive young stellar system

Rodriguez et al. (2005)Gomez et al. (2006)

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

3D MovieAge = 500 yrs

Subaru Infrared TelescopeJ, K’, H2

Southeastern parts also fainter

Chernin & Wright (1996)CO(1-0) & HCNOutflow model Orion KL

?

Hot core

The famous Orion-KL Hot CoreA peculiar hot core “Heart-shaped” First discovered “hot core” (Ho et al. 1979)

Wilson et al. (2000)NH3 (4,4)

Zapata et al. (2004)CH3CN & 1.3 mm

Orion South Compact Hot CoresN(H2) > 1023 cm2

Tdust ~ 200 K

Guélin et al. (2007)IRAM 30

Friedel and Snyder (2007)CARMA

Chemical and velocity diversity

Hot core

IRc 6

What is putting the hot in the Orion KL Hot Core?

Radio sourcesNH3

Mid-infrared

SHUPING et al (2004)Menten & Reid (1995)

See for a more complete debate: Blake et al. (1996), Liu et al. (2002), and de Vicente et al .(2002)

The Submillimeter ArrayMillimeter and submillimeter molecular and continuum observationsModerate angular resolution ~ 3-4”

Hot molecular tracers: mainly vibrational excited emission.

CH3CN k=3 -- SMA880 μm – SCUBA-JCMTCO(2-1) & H2

A close relation between the Hot Core and the explosive flow

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

Cold molecular gas

Hot molecular gas

Obscured Protostar:CentimeterSubmillimiterInfrared

Orion KL Hot Core

Internally

Externally (outflow, stars)

Simple model of the Hot Core

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

Where is the hot molecular gas within the core?

The Orion’s heart: CH3CN lines

Midinfrared, molecular, centimeter and submillimeter emission

Kinematics of the molecular gas in hot core:Filaments !

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(123-113) 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.