Project Introduction

From 10861 ATLASGAL clump, we identified 463 high-mass starless clump (HMSC) candidates with −60 < l < 60 degree and −1 < b < 1 degree. All of these sources have been queried in SIMBAD to make sure they are not associated with any known star-forming indicator. Young stellar objects were identified from the GLIMPSE catalog using color-based criteria and the associated clumps were excluded. We also make sure that the HMSC candidates have neither point sources at 24 and 70 µm nor strong extended emission at 24 µm. Most of the identified HMSCs are infrared dark and some are even dark at 70 µm. Their distribution shows crowding in Galactic spiral arms and toward the Galactic center and some well known star-forming complexes, and some HMSCs are associated with large-scale filaments. Some basic parameters were attained from column density and dust temperature maps which were constructed via fitting far-infrared and submillimeter continuum data to modified blackbodies. The HMSC candidates have sizes, masses, and densities similar to clumps associated with Class II methanol masers and H ii regions, suggesting that these starless clumps will evolve into star-forming clumps. More than 90% of the HMSC candidates have densities above some proposed thresholds for forming high-mass stars. The HMSC candidates have dust temperatures and luminosity-to-mass ratios significantly lower than star-forming sources, suggesting they are genuinely at very early stages of high-mass star formation. Twenty sources with equivalent radii < 0.15 pc and mass surface densities > 0.08 g cm^2\ could be possible high-mass starless cores. Further investigations toward these HMSCs would undoubtedly shed light on comprehensively understanding the birth of high-mass stars.

Related Publications

1. High-mass Starless Clumps in the Inner Galactic Plane: The Sample and Dust Properties, Yuan et al., 2017, ApJS, 231, 11