ALMA observations of the archetypal "hot core" that isn't: Orion KL

Abstract

We present sensitive high angular resolution ($\sim$ 0.1${}^{\prime \prime }$ -- 0.3${}^{\prime \prime }$) continuum ALMA (The Atacama Large Millimeter/Submillimeter Array) observations of the archetypal hot core located in Orion-KL. The observations were made in five different spectral bands (bands 3, 6, 7, 8, and 9) covering a very broad range of frequencies (149 -- 658 GHz). Apart of the well-know millimeter emitting objects located in this region (Orion Source I and BN), we report the first submillimeter detection of three compact continuum sources (ALMA 1-3) in the vicinities of the Orion-KL hot molecular core. These three continuum objects have spectral indices between 1.47 to 1.56, and brightness temperatures between 100 to 200 K at 658 GHz suggesting that we are seeing moderate optically thick dust emission with possible grain growth. However, as these objects are not associated with warm molecular gas, and some of them are farther out from the molecular core, we thus conclude that they cannot heat the molecular core. This result favours the hypothesis that the hot molecular core in Orion-KL core is heated externally.

Accepted to ApJ

References in corpus (7)

• The ALMA View of the OMC1 Explosion in Orion
• ALMA Observations of Orion Source I at 350 and 660 GHz
• ALMA Imaging of Millimeter/Submillimeter Continuum Emission in Orion KL
• VERA and ALMA Observations of the H2O Supermaser Burst in Orion KL
• ALMA Images of the Orion Hot Core at 349 GHz
• Circumbinary Molecular Rings Around Young Stars in Orion
• ALMA band 8 continuum emission from Orion Source I

Cited by in corpus (6)

• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- VIII. A search for hot cores by using C${}_2$H${}_5$CN, CH${}_3$OCHO and CH${}_3$OH lines
• Sulfur-bearing molecules in Orion KL
• The complexity of Orion: an ALMA view III. The explosion impact
• Evidence for dense gas heated by the explosion in Orion KL
• Extremely high excitation SiO lines in disk-outflow system in Orion Source I
• Illuminating a tadpole's metamorphosis II: observing the on-going transformation with ALMA