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| G0.253+0.016 | |
|---|---|
| Name | G0.253+0.016 |
| Type | Molecular cloud |
| Constellation | Sagittarius |
| Epoch | J2000 |
| Distance | ~26,000 ly |
| Mass | ~1–3×10^5 M☉ |
| Radius | ~3 pc |
| Other names | "The Brick", M0.25+0.01 |
G0.253+0.016 G0.253+0.016 is a dense, massive molecular cloud in the central region of the Milky Way often nicknamed "The Brick". It is notable for extreme physical conditions similar to those in starburst and galactic nucleus environments such as Arp 220, M82, NGC 253 and for an apparent paucity of current high-mass star formation compared with clouds like those in the Orion Nebula, W51 and Sgr B2. Studies connect it to research programs involving facilities named after Atacama Large Millimeter/submillimeter Array, Very Large Array, Herschel Space Observatory and Spitzer Space Telescope.
G0.253+0.016 is a compact, high-column-density molecular cloud situated near the Galactic Center that has been targeted by observational campaigns similar to those of Sgr A*, Sgr B2, Central Molecular Zone surveys and comparative studies of extragalactic starbursts such as NGC 4945 and Centaurus A. The object attracted attention in the context of proposals connecting initial conditions for massive cluster formation like those inferred for Arches Cluster, Quintuplet Cluster, and theoretical models developed around Jean's instability analogs and simulations run on platforms used by groups such as those at Max Planck Institute for Astronomy, Harvard–Smithsonian Center for Astrophysics, and European Southern Observatory.
The cloud lies within the Central Molecular Zone at projected coordinates near the position of Sagittarius A* and within the nuclear region probed alongside objects like Sgr C and Sgr D. Distance estimates place it at ~8.3 kpc from the Sun, consistent with measurements tied to the Galactic Center distance used in studies by teams from University of Cambridge, University of California, Berkeley, and Ohio State University. It has a mass of order 10^5 solar masses, a radius of a few parsecs, and peak column densities comparable to those measured in IRDCs studied by surveys from Planck Collaboration, Bolocam Galactic Plane Survey, and ATLASGAL. Observations report high kinetic temperatures and large velocity dispersions analogous to conditions seen near Sgr B2 and in the nucleus of NGC 1068. The cloud’s chemistry reveals species detected in surveys by JCMT, IRAM 30m Telescope, and Nobeyama Radio Observatory teams, including tracers used in works by researchers at Max Planck Institute for Radio Astronomy and NRAO.
Despite extreme densities and masses comparable to precursors posited for clusters like the Arches Cluster and Westerlund 1, G0.253+0.016 shows little sign of embedded massive star formation signatures such as ultracompact H II region analogs observed in W49 or bright maser emission typical of regions like Orion KL and Cepheus A. Surveys with ALMA, SMA, and VLA have constrained embedded sources and compared fragmentation scales to those derived from models by groups at Princeton University, University of Tokyo, and University of Chicago. The absence of widespread star formation prompts comparisons with the star-forming thresholds discussed by proponents of the Krumholz and McKee frameworks, and with conditions inferred for proto-cluster clouds in M51 and M83. Proposals invoking tidal shear, strong magnetic support studied by teams at Harvard College Observatory, and turbulent pressure such as in simulations from Max Planck Institute for Astrophysics have been advanced to explain the cloud’s suppressed star formation.
G0.253+0.016 was highlighted in millimeter and submillimeter continuum and spectral-line maps from projects using JCMT Gould Belt Survey-style instruments, follow-up imaging from ALMA and SMA, and infrared constraints from Spitzer and Herschel programs led by groups at University of Leeds, University of California, Los Angeles, and Leiden Observatory. Radio recombination line and molecular line analyses have been performed by researchers affiliated with Leiden University, University of Bonn, and University of Oxford to characterize kinematics and chemistry; comparisons have been drawn to molecular inventories in Orion Molecular Cloud and Sgr B2 catalogues compiled by teams at Columbia University and University of Arizona. High-resolution analyses using techniques developed at Max Planck Institute for Extraterrestrial Physics and National Radio Astronomy Observatory provided maps of dense-gas tracers like HCN, HCO+, and N2H+, and infrared extinction mapping tied to methods from 2MASS and GLIMPSE surveys.
The cloud serves as a testbed for theories of massive cluster formation, turbulence-regulated star formation advanced by authors from University of California, Santa Cruz, Imperial College London, and Carnegie Institution for Science, and for models addressing the influence of environmental factors emphasized by researchers at Kavli Institute for Theoretical Physics and Institute for Advanced Study. Numerical simulations using codes developed at Princeton and Institute for Computational Astrophysics incorporate tidal forces from Sagittarius A* analogues, magnetic field geometries akin to those observed by SOFIA teams, and cosmic-ray ionization rates discussed in works by Los Alamos National Laboratory and Columbia University. The disparity between mass and star formation efficiency in G0.253+0.016 informs debates about cluster survivability seen in studies of Young Massive Clusters and about initial mass function universality addressed by groups at Caltech, Yale University, and University of Bonn.