A Highly Collimated Flow from the High-mass Protostar ISOSS J23053+5953 SMM2

Abstract

We present Very Large Array C, X, and Q-band continuum observations, as well as 1.3 mm continuum and CO(2-1) observations with the Submillimeter Array toward the high-mass protostellar candidate ISOSS J23053+5953 SMM2. Compact cm continuum emission was detected near the center of the SMM2 core with a spectral index of 0.24 (±0.15) between 6 and 3.6 cm, and a radio luminosity of 1.3 (±0.4) mJy kpc 2 . The 1.3 mm thermal dust emission indicates a mass of the SMM2 core of 45.8 (±13.4) M , and a density of 7.1 (±1.2) × 10 6 cm −3 . The CO(2-1) observations reveal a large, massive molecular outflow centered on the SMM2 core. This fast outflow (> 50 km s −1 from the cloud systemic velocity) is highly collimated, with a broader, lower-velocity component. The large values for outflow mass (45.2 ± 12.6 M ), and momentum rate (6 ± 2 × 10 −3 M km s −1 yr −1 ) derived from the CO emission are consistent with those of flows driven by high-mass YSOs. The dynamical timescale of the flow is between 1.5 − 7.2 × 10 4 yr. We also found from the C 18 O to thermal dust emission ratio that CO is depleted by a factor of about 20, possibly due to freeze out of CO molecules on dust grains. Our data are consistent with previous findings that ISOSS J23053+5953 SMM2 is an emerging high-mass protostar in an early phase of evolution, with an ionized jet, and a fast, highly collimated, and massive outflow.

Broadband VLA Spectral-line Survey of a Sample of Ionized Jet Candidates

“…High-mass stars (M  8 M e ) have widespread effects in the medium where they form and are likely a key factor that regulates further star formation in their natal clouds by feedback mechanisms, from the development of H II regions to supernovae (e.g., Zinnecker & Yorke 2007). During the earliest phases of formation, high-mass protostars can drive large (1 pc) and massive (10 M e ) molecular outflows that inject mechanical energy into the natal environment (e.g., Arce et al 2007;Bally 2016;Torii et al 2017;Rodríguez et al 2021). At smaller scales (∼10 4 au), high-sensitivity radio continuum observations find evidence that young high-mass protostars also drive ionized jets (e.g., Purser et al 2016;Rosero et al 2019;Purser et al 2021).…”