Digging into NGC 6334I(N): Multiwavelength Imaging of a Massive Protostellar Cluster

TL;DR

This study provides a detailed multiwavelength analysis of the massive protostellar cluster NGC 6334I(N), revealing complex substructures, hot core temperatures, and multiple outflows, advancing understanding of early massive star formation.

Contribution

It offers the first detection of SMA1b at 3.6 cm, identifies multiple hot cores and outflows, and suggests a binary system within SMA1, enhancing knowledge of protocluster structures.

Findings

Detection of SMA1b at 3.6 cm and a new component at 7 mm.

Hot core temperatures of 165K and 145K for SMA1 and SMA2.

Identification of multiple outflows and water maser groups.

Abstract

We present a high-resolution, multi-wavelength study of the massive protostellar cluster NGC 6334I(N) that combines new spectral line data from the Submillimeter Array (SMA) and VLA with a reanalysis of archival VLA continuum data, 2MASS and Spitzer images. As shown previously, the brightest 1.3 mm source SMA1 contains substructure at subarcsecond resolution, and we report the first detection of SMA1b at 3.6 cm along with a new spatial component at 7 mm (SMA1d). We find SMA1 (aggregate of sources a, b, c, and d) and SMA4 to be comprised of free-free and dust components, while SMA6 shows only dust emission. Our 1.5" resolution 1.3 mm molecular line images reveal substantial hot-core line emission toward SMA1 and to a lesser degree SMA2. We find CH3OH rotation temperatures of 165\pm 9 K and 145\pm 12 K for SMA1 and SMA2, respectively. We estimate a diameter of 1400 AU for the SMA1 hot core emission, encompassing both SMA1b and SMA1d, and speculate that these sources comprise a >800 AU separation binary that may explain the previously-suggested precession of the outflow emanating from the SMA1 region. The LSR velocities of SMA1, SMA2, and SMA4 all differ by 1-2 km/s. Outflow activity from SMA1, SMA2, SMA4, and SMA6 is observed in several molecules including SiO(5--4) and IRAC 4.5 micron emission; 24 micron emission from SMA4 is also detected. Eleven water maser groups are detected, eight of which coincide with SMA1, SMA2, SMA4, and SMA6. We also detect a total of 83 Class I CH3OH 44GHz maser spots which likely result from the combined activity of many outflows. Our observations paint the portrait of multiple young hot cores in a protocluster prior to the stage where its members become visible in the near-infrared.