ALMA Imaging of Millimeter/Submillimeter Continuum Emission in Orion KL

Abstract

We have carried out high resolution observations with Atacama Large Millimeter/Submillimeter Array (ALMA) of continuum emission from Orion KL region. We identify 11 compact sources at ALMA band 6 (245 GHz) and band 7 (339 GHz), including Hot Core, Compact Ridge, SMA1, IRc4, IRc7, and a radio source I (Source I). Spectral energy distribution (SED) of each source is determined by using previous 3 mm continuum emission data. Physical properties such as size, mass, hydrogen number density and column density are discussed based on the dust graybody SED. Among 11 identified sources, Source I, a massive protostar candidate, is a dominant energy source in Orion KL. We extensively investigate its SED from centimeter to submillimeter wavelengths. The SED of Source I can be fitted with a single power-law index of 1.97 suggesting an optically thick emission. We employ the H${}^{-}$ free-free emission as an opacity source of this optically thick emission. The temperature, density, and mass of the circumstellar disk associated with Source I are constrained by the SED of H${}^{-}$ free-free emission. Still the fitting result shows a significant deviation from the observed flux densities. Combined with the thermal dust graybody SED to explain excess emission at higher frequency, a smaller power-law index of 1.60 for the H${}^{-}$ free-free emission is obtained in the SED fitting. The power-law index smaller than 2 would suggest a compact source size or a clumpy structure unresolved with the present study. Future higher resolution observations with ALMA are essential to reveal more detailed spatial structure and physical properties of Source I.

34 pages, 9 figures, Accepted by ApJ

References in corpus (9)

• The distance to the Orion Nebula
• Monitoring the Large Proper Motions of Radio Sources in the Orion BN/KL Region
• Proplyds and Massive Disks in the Orion Nebula Cluster Imaged with CARMA and SMA
• Imaging the Ionized Disk of the High-Mass Protostar Orion-I
• Subarcsecond Imaging of the NGC 6334 I(N) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate
• Identifying the outflow driving sources in Orion-KL
• A 1.3 cm wavelength radio flare from a deeply embedded source in the Orion BN/KL region
• Hubble Space Telescope NICMOS Polarization Measurements of OMC-1
• VERA and ALMA Observations of the H2O Supermaser Burst in Orion KL

Cited by in corpus (7)

• ALMA Observations of Orion Source I at 350 and 660 GHz
• ALMA Images of the Orion Hot Core at 349 GHz
• ALMA observations of the archetypal "hot core" that isn't: Orion KL
• Evidence for dense gas heated by the explosion in Orion KL
• Outflow-Confined HII regions. II. The Early Break-Out Phase
• ALMA band 8 continuum emission from Orion Source I
• Extremely high excitation SiO lines in disk-outflow system in Orion Source I