Connecting low- and high-mass star formation: the intermediate-mass protostar IRAS 05373+2349 VLA 2

TL;DR

This study investigates an intermediate-mass protostar, IRAS 05373+2349 VLA 2, revealing its properties are intermediate between low- and high-mass star formation, bridging a gap in understanding stellar evolution.

Contribution

It provides detailed observational analysis of an IM protostar, demonstrating its intermediate characteristics and contributing to the understanding of protostellar evolution across mass regimes.

Findings

VLA 2 exhibits an ionised stellar wind or jet.

The large-scale outflow has properties between low- and high-mass stars.

The IM protostar's characteristics bridge the gap in star formation regimes.

Abstract

Until recently, there have been few studies of the protostellar evolution of intermediate-mass (IM) stars, which may bridge the low- and high-mass regimes. This paper aims to investigate whether the properties of an IM protostar within the IRAS 05373+2349 embedded cluster are similar to that of low- and/or high-mass protostars. We carried out Very Large Array as well as Combined Array for Research in Millimeter Astronomy continuum and 12CO(J=1-0) observations, which uncover seven radio continuum sources (VLA 1-7). The spectral index of VLA 2, associated with the IM protostar is consistent with an ionised stellar wind or jet. The source VLA 3 is coincident with previously observed H2 emission line objects aligned in the north-south direction (P.A. -20 to -12 deg), which may be either an ionised jet emanating from VLA 2 or (shock-)ionised cavity walls in the large-scale outflow from VLA 2. The position angle between VLA 2 and 3 is slightly misaligned with the large-scale outflow we map at ~5-arcsec resolution in 12CO (P.A. ~30 deg), which in the case of a jet suggests precession. The emission from the mm core associated with VLA 2 is also detected; we estimate its mass to be 12-23 Msun, depending on the contribution from ionised gas. Furthermore, the large-scale outflow has properties intermediate between outflows from low- and high-mass young stars. Therefore, we conclude that the IM protostar within IRAS 05373+2349 is phenomenologically as well as quantitatively intermediate between the low- and high-mass domains.