ALMA IMAGING OF MILLIMETER/SUBMILLIMETER CONTINUUM EMISSION IN ORION KL
- National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181–8588 (Japan)
- Korea Astronomy and Space Science Institute, Hwaam-dong 61-1, Yuseong-gu, Daejeon, 305-348 (Korea, Republic of)
- Chile Observatory, National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan)
We have carried out high-resolution observations with the Atacama Large Millimeter/Submillimeter Array (ALMA) of continuum emission from the Orion Kleinmann–Low (KL) region. We identify 11 compact sources at ALMA band 6 (245 GHz) and band 7 (339 GHz), including the Hot Core, Compact Ridge, SMA1, IRc4, IRc7, and a radio source I (Source I). A 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{sup −} 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{sup −} 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{sup −} free–free emission is obtained in the SED fitting. The power-law index smaller than two 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.
- OSTI ID:
- 22522082
- Journal Information:
- Astrophysical Journal, Vol. 801, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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