We present sensitive 1-3 GHz ATCA radio continuum observations of the hitherto unresolved star-forming region known as either IRAS 14482-5857 or PMN 1452-5910. At radio continuum frequencies, this source is characterized by a "filled bubble" structure reminiscent of a classical HII region, dominated by three point sources and surrounded by low surface brightness emission out to the ∼3′ x 4′ source extent observed at other frequencies in the literature. The infrared emission corresponds well to the radio emission, with polycyclic aromatic hydrocarbon emission surrounding regions of hot dust toward the radio bubbles. A bright 4.5 μm point source is seen toward the center of the radio source, suggesting a young stellar object. There is also a linear, outflowlike structure radiating brightly at 8 and 24 μm toward the brightest peak of the radio continuum. In order to estimate the distance to this source, we have used Mopra Southern Galactic Plane CO Survey 12CO (1-0) and 13CO(1-0) molecular line emission data. Integrated intensity, velocity at peak intensity, and line fitting of the spectra all point toward the peak centered at VLSR = -1.1 km s-1 being connected to this cloud. This infers a distance to this cloud of ∼12.7 kpc. Assuming this distance, we estimate a column density and mass toward IRAS 14482-5857 of ∼1.5 × 1021 cm-2 and 2 × 104 M⊙, implying that this source is a site of massive star formation. Reinforcing this conclusion, our broadband spectral fitting infers dust temperatures of 19 and 110 K, emission measures for the subparsec radio point source of EM∼106-7 pc cm-6, electron densities of ne ∼ 103 cm-3, and photon ionization rates of NLy ∼ 1046-48 s-1. The evidence strongly suggests that IRAS 14482-5857 is a distant - hence intense - site of massive star formation.
- HII regions
- ISM: clouds
- ISM: individual objects (IRAS14482-5857, PMN 1452-5910)