The JWST-NIRCam View of Sagittarius C. I. Massive Star Formation and Protostellar Outflows

TL;DR

This study uses JWST-NIRCam observations to analyze massive star formation and protostellar outflows in Sagittarius C, revealing new protostars, outflows, and shock features in the Central Molecular Zone.

Contribution

First infrared detection of molecular hydrogen outflows in the CMZ, characterizing massive protostars and discovering new star-forming regions with outflow features.

Findings

Identified 88 molecular hydrogen outflow candidates in Sgr C.

Detected two massive protostars with estimated masses of ~20 M_sun.

Discovered a new star-forming region with bow shocks and protostellar features.

Abstract

We present James Webb Space Telescope (JWST)-NIRCam observations of the massive star-forming molecular cloud Sagittarius C (Sgr C) in the Central Molecular Zone (CMZ). In conjunction with ancillary mid-IR and far-IR data, we characterize the two most massive protostars in Sgr C via spectral energy distribution (SED) fitting, estimating that they each have current masses of $m_* \sim 20\:M_\odot$ and surrounding envelope masses of $\sim 100\:M_\odot$. We report a census of lower-mass protostars in Sgr C via a search for infrared counterparts to mm continuum dust cores found with ALMA. We identify 88 molecular hydrogen outflow knot candidates originating from outflows from protostars in Sgr C, the first such unambiguous detections in the infrared in the CMZ. About a quarter of these are associated with flows from the two massive protostars in Sgr C; these extend for over 1 pc and are associated with outflows detected in ALMA SiO line data. An additional $\sim 40$ features likely trace shocks in outflows powered by lower-mass protostars throughout the cloud. We report the discovery of a new star-forming region hosting two prominent bow shocks and several other line-emitting features driven by at least two protostars. We infer that one of these is forming a high-mass star given an SED-derived mass of $m_* \sim 9\:M_\odot$ and associated massive ($\sim 90\:M_\odot$) mm core and water maser. Finally, we identify a population of miscellaneous Molecular Hydrogen Objects (MHOs) that do not appear to be associated with protostellar outflows.