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| Nebulae | |
|---|---|
| Type | Nebula |
| Epoch | J2000 |
Nebulae Nebulae are diffuse astronomical objects composed of gas and dust found within galaxies such as Milky Way and Andromeda Galaxy. They appear across electromagnetic bands observed by instruments on missions like Hubble Space Telescope, Chandra X-ray Observatory, Spitzer Space Telescope and ground facilities such as Very Large Telescope, Atacama Large Millimeter/submillimeter Array and Keck Observatory. Studies by institutions including European Space Agency, NASA and Max Planck Society connect nebular research to projects at Harvard–Smithsonian Center for Astrophysics and Jet Propulsion Laboratory.
Nebulae encompass structures first cataloged in catalogs like the Messier catalog and the New General Catalogue and include objects identified by astronomers such as Charles Messier, William Herschel and Edmond Halley. Observational programs at observatories including Mount Wilson Observatory, Palomar Observatory and Royal Greenwich Observatory refined understanding through spectroscopy developed by figures including William Huggins, Joseph von Fraunhofer and Gustav Kirchhoff. Modern surveys from projects like the Sloan Digital Sky Survey and missions such as Gaia (spacecraft) map nebular distributions in the Local Group and beyond.
Common categories comprise emission nebulae exemplified by Orion Nebula; reflection nebulae such as Pleiades nebulosity; planetary nebulae including Ring Nebula and Helix Nebula; dark nebulae typified by the Horsehead Nebula; and supernova remnants like Crab Nebula and Cassiopeia A. H II regions, photodissociation regions (PDRs), Bok globules and protoplanetary disks (proplyds) appear in star-forming complexes like Tarantula Nebula and Eagle Nebula. Regions influenced by massive stars in clusters such as Trumpler 14 and NGC 604 illustrate environmental diversity.
Nebular gas primarily contains hydrogen and helium with heavier elements (metals) enriched by processes traced to sources such as Type Ia supernovae, Type II supernovae and asymptotic giant branch stars studied in the context of Stellar nucleosynthesis. Emission lines from ions like [O III], H-alpha and [N II] measured with spectrographs used at Keck Observatory and Very Large Telescope inform electron temperature and density diagnostics developed by researchers at institutions like Max Planck Institute for Astronomy and California Institute of Technology. Dust grain populations with silicates and carbonaceous compounds relate to work by teams at Jet Propulsion Laboratory and laboratories at Massachusetts Institute of Technology comparing infrared spectra from Spitzer Space Telescope and Infrared Space Observatory.
Nebular formation ties to processes in molecular clouds cataloged by surveys such as the Five College Radio Astronomy Observatory maps and observations by ALMA. Collapse triggered by mechanisms including supernova shocks from remnants like Vela Supernova Remnant, cloud–cloud collisions, and spiral-arm compression in galaxies such as Milky Way and M83 leads to star formation episodes studied in clusters like Orion Nebula Cluster and NGC 2244. Evolutionary pathways connect protostellar outflows observed with Subaru Telescope and feedback from massive stars in associations like Cygnus OB2 to dispersal of natal material and transition to planetary nebula stages traced in surveys by European Southern Observatory.
Classification schemes developed through work by catalogers of Messier catalog, New General Catalogue, and spectral classification refined by Annie Jump Cannon employ imaging from Hubble Space Telescope and radio maps from Very Large Array. Techniques include narrowband imaging in filters centered on H-alpha and [O III], integral field spectroscopy used at Gemini Observatory and radio interferometry at ALMA and Very Large Array. Citizen science projects such as Galaxy Zoo and professional collaborations like International Astronomical Union working groups standardize nomenclature and metadata for surveys including Pan-STARRS.
Nebular environments host protostars in cores studied by Submillimeter Array and host late evolutionary stages when intermediate-mass stars produce planetary nebulae investigated by researchers at University of Cambridge and University of California, Berkeley. Massive-star feedback responsible for triggering and quenching star formation links nebulae to stellar clusters such as Trapezium Cluster and supernova progenitors associated with remnants like SN 1987A. Chemical enrichment documented through nebular spectroscopy informs galactic chemical evolution models developed at institutes like Institute of Astronomy, Cambridge and Observatoire de Paris.
Historical observations by Galileo Galilei and cataloging by Charles Messier shaped early perceptions; debates involving William Herschel and later spectroscopic work by William Huggins transformed nebulae from nebulous patches into astrophysical entities. Nebulae appear widely in art and literature from works inspired by J. M. W. Turner and poets such as Percy Bysshe Shelley, and in popular media tied to franchises like Star Trek and Star Wars where visualizations draw on images from Hubble Space Telescope and planetarium programs at institutions such as Royal Observatory Greenwich.
Category:Astronomical objects