G0.253 + 0.016: A Molecular Cloud Progenitor of an Arches-Like Cluster

Abstract

Young massive clusters (YMCs) with stellar masses of 10 4 -10 5 M and core stellar densities of 10 4 -10 5 stars per cubic pc are thought to be the "missing link" between open clusters and extreme extragalactic super star clusters and globular clusters. As such, studying the initial conditions of YMCs offers an opportunity to test cluster formation models across the full cluster mass range. G0.253 + 0.016 is an excellent candidate YMC progenitor. We make use of existing multi-wavelength data including recently available far-IR continuum (Herschel/Herschel Infrared Galactic Plane Survey) and mm spectral line (H 2 O Southern Galactic Plane Survey and Millimetre Astronomy Legacy Team 90 GHz Survey) data and present new, deep, multiple-filter, near-IR (Very Large Telescope/NACO) observations to study G0.253 + 0.016. These data show that G0.253 + 0.016 is a high-mass (1.3 × 10 5 M ), low-temperature (T dust ∼ 20 K), high-volume, and column density (n ∼ 8 × 10 4 cm −3 ; N H 2 ∼ 4 × 10 23 cm −2 ) molecular clump which is close to virial equilibrium (M dust ∼ M virial ) so is likely to be gravitationally bound. It is almost devoid of star formation and, thus, has exactly the properties expected for the initial conditions of a clump that may form an Arches-like massive cluster. We compare the properties of G0.253 + 0.016 to typical Galactic cluster-forming molecular clumps and find it is extreme, and possibly unique in the Galaxy. This uniqueness makes detailed studies of G0.253 + 0.016 extremely important for testing massive cluster formation models.

The Link Between Turbulence, Magnetic Fields, Filaments, and Star Formation in the Central Molecular Zone Cloud G0.253+0.016

“…In all the following measurements and derivations, we only use data within the´-5 10 cm 22 2 column density contour level ( > S N 10). In addition to the combined ALMA+Herschel column density map from Rathborne et al (2014b), we also use the Herschel-only column density map published in Longmore et al (2012). The resolution of the Herschel data is   5 36 -.…”

The Herschel view of the Galactic center

“…the 'Brick') is located just outside the GCB in the dark dust lane that runs from the high longitude side of the GCB to Sgr B2 and beyond. This cloud (Longmore et al 2012) has a mass of over 10 5 M and mean radius of about 2.5 pc. Is is completely opaque at 24 μm and still seen in silhouette against the warm dust background at 70 μm.…”

MALT90: tracing the chemistry and kinematics of molecular clumps within the central molecular zone

“…2. The Brick G000.253+00.016, "The Brick", is an extreme molecular clump located near the Galactic center, which is a potential candidate of an Arches-like massive cluster in an early stage of formation (Longmore et al 2012). G000.253+00.016 appears dark in the mid-to far-IR, implying a low dust temperature and a high density, the presence of widespread emission from hot gas tracers suggests that the gas temperature may be higher (∼70 K) than its dust temperature (∼20K).…”