High-resolution Observations of the Massive Protostar in IRAS 18566+0408
- Physics Department, New Mexico Tech, 801 Leroy Place, Socorro, NM 87801 (United States)
- INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)
- Instituto de Radioastronomía y Astrofísica, P.O. Box 3-72 Universidad Nacional Autónoma de México, Morelia 58090 (Mexico)
- Institute of Liberal Arts and Sciences, Tokushima University, 1-1 Minami Jousanjima-machi, Tokushima 770-8502 (Japan)
- Physics Department, Western Illinois University, 1 University Circle, Macomb, IL 61455 (United States)
We report 3 mm continuum, CH{sub 3}CN(5–4) and {sup 13}CS(2–1) line observations with CARMA (Combined Array for Research in Millimeter-wave Astronomy), in conjunction with 6 and 1.3 cm continuum VLA data, and 12 and 25 μm broadband data from the Subaru Telescope toward the massive proto-star IRAS 18566+0408. The VLA data resolve the ionized jet into four components aligned in the E–W direction. Radio components A, C, and D have flat centimeter SEDs indicative of optically thin emission from ionized gas, and component B has a spectral index α = 1.0, and a decreasing size with frequency ∝ν{sup −0.5}. Emission from the CARMA 3 mm continuum and from the {sup 13}CS(2–1) and CH{sub 3}CN(5–4) spectral lines is compact (i.e., <6700 au) and peaks near the position of the VLA centimeter source, component B. Analysis of these lines indicates hot and dense molecular gas, which is typical for HMCs. Our Subaru telescope observations detect a single compact source, coincident with radio component B, demonstrating that most of the energy in IRAS 18566+0408 originates from a region of size <2400 au. We also present UKIRT near-infrared archival data for IRAS 18566+0408, which show extended K-band emission along the jet direction. We detect an E–W velocity shift of about 10 km s{sup −1} over the HMC in the CH{sub 3}CN lines possibly tracing the interface of the ionized jet with the surrounding core gas. Our data demonstrate the presence of an ionized jet at the base of the molecular outflow and support the hypothesis that massive protostars with O-type luminosity form with a mechanism similar to lower mass stars.
- OSTI ID:
- 22876043
- Journal Information:
- Astrophysical Journal, Vol. 843, 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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