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| Lynds Dark Nebulae (LDN) | |
|---|---|
| Name | Lynds Dark Nebulae |
| Type | Dark nebula catalogue |
| Discoverer | Beverly T. Lynds |
| Year | 1962 |
| Entries | 1802 |
Lynds Dark Nebulae (LDN) are a catalogued set of dark nebulae compiled in the mid-20th century that mark regions of high extinction against star fields and emission nebulae. They serve as reference points in studies of interstellar medium structure, star formation, and molecular cloud complexes. The catalogue entries are widely used in observational programs at observatories and in surveys by institutions and missions studying the Milky Way.
The catalogue was assembled to provide a systematic list of dark nebulae visible on photographic plates and has since been cross-referenced by observatories such as Palomar Observatory, Kitt Peak National Observatory, and missions like IRAS and WISE. It complements other surveys undertaken by organizations including Royal Astronomical Society-affiliated programs and facilities such as Mount Wilson Observatory and European Southern Observatory. The compilation has informed research by teams at Harvard College Observatory, Caltech, and Max Planck Institute for Astronomy.
The compilation was prepared by Beverly T. Lynds and published in 1962 after inspection of plates from photographic sky surveys including those from Palomar Observatory Sky Survey. The work was contemporaneous with catalogues such as the Messier catalog re-evaluations and the continuing mapping efforts of researchers at Yerkes Observatory and Mount Stromlo Observatory. Lynds assigned opacity classes to nebulae and provided positions that were later cross-matched by projects at Smithsonian Astrophysical Observatory, Jet Propulsion Laboratory, and university groups at University of Chicago and University of Cambridge.
Entries in the catalogue correspond to dense concentrations of dust and molecular gas whose properties were later quantified using spectroscopy at facilities like Atacama Large Millimeter/submillimeter Array and James Clerk Maxwell Telescope. Chemical inventories derived from observations by National Radio Astronomy Observatory teams detect molecules such as CO traced in surveys by Institute for Radio Astronomy in the Millimeter Range collaborators and isotopologues studied by groups at Max Planck Institute for Radio Astronomy. Dust grain models informed by data from Herschel Space Observatory and Spitzer Space Telescope link extinction features to silicate and carbonaceous compositions investigated by researchers at California Institute of Technology and University of California, Berkeley.
Initial detection relied on optical photographic contrast techniques employed at Palomar Observatory Sky Survey and analytical methods refined at Harvard College Observatory. Later infrared mapping by IRAS and mid-infrared imaging by Spitzer Space Telescope revealed embedded sources, while submillimeter continuum surveys by Atacama Pathfinder Experiment and spectral line mapping by NRAO enabled mass and kinematic estimates. Radio observatories such as Green Bank Observatory and Arecibo Observatory contributed molecular line detections, and space missions like Gaia provided parallax constraints through associated stellar reddening analyses used by teams at European Space Agency.
The catalogue spans the northern and southern skies with concentrations along the Galactic Plane and prominent associations near complexes mapped by surveys at Cerro Tololo Inter-American Observatory and Anglo-Australian Observatory. Well-studied entries coincide with regions such as those adjacent to Taurus Molecular Cloud, Ophiuchus cloud complex, and Perseus Molecular Cloud where follow-up work by Harvard-Smithsonian Center for Astrophysics and University of Leiden has focused. Specific LDN entries are often referenced in studies of dark lanes near objects catalogued in the New General Catalogue and in investigations by researchers at University of Colorado Boulder and University of Tokyo.
LDN regions are frequently sites of low- and intermediate-mass star formation and are integral to theories developed at institutions like Princeton University and Cambridge University concerning core collapse and protostellar evolution. Observational programs using Submillimeter Array and instruments at European Southern Observatory have resolved dense cores within LDN objects, confirming links to pre-stellar cores catalogued by teams at Max Planck Institute for Astronomy and Sofia (airborne observatory). The interplay of turbulence, magnetic fields measured by groups at Harvard University, and feedback processes studied at University of California, Santa Cruz inform models such as those advanced by theorists at Institute for Advanced Study.
Cross-identifications connect LDN entries to objects in catalogues including the Barnard Catalogue, the Sharpless catalog, and the Catalogue of Dark Nebulae by Hartley cited in archival work at Royal Observatory Edinburgh. Subsequent surveys by 2MASS and Sloan Digital Sky Survey produced databases used by research teams at University of Pennsylvania and Johns Hopkins University to reconcile positional and nomenclature discrepancies. Institutional archives at Vatican Observatory and museum collections linked to Smithsonian Institution preserve original plates that underpin modern catalog cross-matching efforts.
Category:Catalogues of astronomical objects