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| NGC 6334 | |
|---|---|
| Name | NGC 6334 |
| Other names | Cat's Paw Nebula, Bear Claw Nebula, Caldwell 117 |
| Type | Emission nebula, star-forming region |
| Constellation | Scorpius |
| Epoch | J2000 |
| Distance | ~1.3–1.7 kpc |
| Size | ~45′ × 30′ |
NGC 6334 is a bright emission nebula and massive star-forming complex located in the constellation Scorpius. The region contains multiple compact H II regions, dense molecular clouds, and young stellar objects that make it a key laboratory for researching massive star formation and feedback in the nearby Milky Way. NGC 6334 has been observed from the optical to the radio by numerous facilities and surveys, and it is commonly referred to in the literature by the informal names Cat's Paw Nebula and Bear Claw Nebula.
NGC 6334 is an extended emission nebula associated with a giant molecular cloud in the Sagittarius Arm of the Milky Way Galaxy. The complex hosts clusters of young massive stars, ultracompact H II regions, and dense cores identified in millimeter and submillimeter surveys by instruments like the Atacama Large Millimeter/submillimeter Array and the James Clerk Maxwell Telescope. The nebula's morphology and embedded sources have been cataloged in surveys such as the Two Micron All Sky Survey and the Spitzer Space Telescope Galactic Plane surveys, which complement historical optical descriptions from observatories including the Royal Observatory, Edinburgh and the Palomar Observatory.
The nebula was cataloged in the 19th century by observers working with instruments at institutions like the Royal Observatory, Greenwich and later incorporated into catalogs maintained by the New General Catalogue compilers. Systematic radio observations began in the mid-20th century with arrays such as the Parkes Observatory and the Effelsberg 100-m Radio Telescope, while infrared and submillimeter studies accelerated with missions including the Infrared Astronomical Satellite, the Infrared Space Observatory, and the Herschel Space Observatory. High-resolution interferometric imaging of embedded protostars has been performed by facilities including the Very Large Array, the Submillimeter Array, and the Atacama Pathfinder Experiment. Ground-based optical imaging and spectroscopy have been contributed by telescopes at Cerro Tololo Inter-American Observatory and the European Southern Observatory.
The complex structure comprises filamentary molecular gas, dense clumps, and ionized bubbles driven by massive stars cataloged from surveys like the Census of High- and Medium-mass Protostars and the RMS survey. Molecular line maps in transitions of carbon monoxide and ammonia reveal velocity components and turbulence similar to those in regions such as Orion Nebula and W51. Dust continuum measurements from Planck and Herschel constrain column densities and temperatures, showing cold dense cores adjacent to warm photodissociation regions. Magnetic field orientations inferred from polarimetric studies with instruments like the James Clerk Maxwell Telescope POL-2 show ordered fields that may influence collapse and filamentary accretion as in studies of Taurus Molecular Cloud and Perseus Molecular Cloud.
NGC 6334 hosts active high-mass star formation with identified protostellar objects at various evolutionary stages, including hot molecular cores, hypercompact H II regions, and massive young stellar objects cataloged in databases maintained by the Centre de Données astronomiques de Strasbourg and the Max Planck Institute for Astronomy. Outflows traced by CO and SiO line emission and shock-excited masers such as water maser and methanol maser are associated with massive protostars similar to sources in DR21 and NGC 2024. Feedback from O-type and B-type stars produces ionization fronts, photoevaporative flows, and triggered secondary star formation reminiscent of processes studied in RCW 49 and Carina Nebula.
Embedded within or adjacent to the complex are multiple infrared clusters and compact radio sources designated in catalogs like the IRAS point source catalog and the MSX survey. Neighboring star-forming regions and molecular clouds in the same spiral arm, such as complexes cataloged by the Galactic Ring Survey and the ATLASGAL survey, provide environmental context. The nebula's young stellar clusters are often cross-listed with entries in the 2MASS and GLIMPSE catalogs and compared with stellar populations found in regions studied by the Gaia mission and the VISTA Variables in the Via Lactea survey.
Optical emission-line imaging (Hα, [S II]) from observatories like the Anglo-Australian Observatory reveals ionized nebular features, while near-infrared imaging from the Very Large Telescope and the United Kingdom Infrared Telescope penetrates dust to reveal embedded clusters. Mid-infrared photometry and spectroscopy by the Spitzer Space Telescope and the Wide-field Infrared Survey Explorer detect warm dust and polycyclic aromatic hydrocarbon features. Far-infrared and submillimeter continuum and line observations by Herschel, Planck, ALMA, and APEX probe cold dust and dense gas, and radio interferometry with the Very Large Array and single-dish mapping with Nobeyama Radio Observatory and Mopra Observatory trace molecular chemistry and ionized regions. Maser studies using the European VLBI Network and the Very Long Baseline Array provide precise kinematic and distance constraints via proper motions.
Kinematic distances derived from molecular line velocities place the complex at roughly 1.3–1.7 kiloparsecs, consistent with parallax and proper-motion constraints from maser VLBI campaigns associated with networks like the Bar and Spiral Structure Legacy (BeSSeL) Survey. The region resides in a spiral-arm environment influenced by large-scale structures cataloged by the CO Galactic Plane Survey and subject to galactic shear and spiral-arm streaming motions studied in the context of the Milky Way's structure. Environmental comparisons are frequently made with other massive star-forming sites such as W49 and W43, informing theories of cluster formation and massive star feedback.
Category:Emission nebulae Category:Star-forming regions Category:Scorpius (constellation)