n
Alternative spelling of accretion disk [(astronomy) A structure formed by matter falling into a gravitational source such as a galaxy, black hole, or protostar.]
n
Initialism of active galactic nucleus. [(astronomy) A compact region at the center of a galaxy that has a much higher than normal luminosity over at least some portion, and possibly all, of the electromagnetic spectrum.]
n
Alternative form of Alderson disk [A hypothetical megastructure in the form of a disk with a star located in a hole running through its axis, and massive enough to have its own atmosphere]
n
A hypothetical megastructure in the form of a disk with a star located in a hole running through its axis, and massive enough to have its own atmosphere
n
(astronomy) Initialism of brightest cluster galaxy.
n
(astronomy) a type of active galaxy with an active galactic nucleus (AGN), named after its prototype, BL Lacertae
n
(astronomy) An object which is either an optically violent variable quasar (OVV quasar) or a BL Lac object or which has properties of both.
n
(astronomy) broad emission-line radio-galaxy
n
(astronomy) broad emission-line Seyfert type-1 galaxy
n
(astronomy, obsolete) Blue stellar object: a radio-quiet quasar.
n
(astronomy) Abbreviation of galaxy cluster. [(astronomy, galaxies) A cluster of hundreds of galaxies.]
n
(astronomy) dwarf elliptical galaxy
n
(astronomy) dwarf irregular galaxy
n
(astronomy) dwarf irregular galaxy
n
(astronomy, with definite article, often capitalized) The constellation Draco.
n
(astronomy) A dwarf spheroidal galaxy
n
(astronomy) a star of spectral type O, B, A, or F0 to F5.
n
(astronomy) Acronym of enormous Lyman-alpha nebula. [(astronomy) A large gas cloud (nebula) larger than galaxies, found in intergalactic space, which radiates with an emission spectrum containing 2.47 THz lines (Lyman-alpha lines).]
n
(astronomy) emission-line galaxy
n
(astronomy) A nebula composed of ionized gases which produce visible light (as distinct from a reflection nebula, which reflects the light produced by neighboring stars).
n
All the accumulated radiation in the universe due to star formation processes, plus a contribution from active galactic nuclei (AGNs).
n
(astronomy) A type of weak supernova whose luminous shell cools quickly and within days goes dark
v
(archaic) To gather together into a luminous whole.
n
(astronomy) giant elliptical galaxy
n
(astronomy) a quasar embedded in a double-lobed radio source, similar to a radio galaxy, whereby the quasar replaces a non-quasar galaxy, where the radio source extends over 1Mpc.
n
(astronomy) a very large radio galaxy; a double radio source having an overall projected linear length exceeding 2 megaparsecs (or more specifically, 2×h₅₀⁻¹ Mpc)
n
(astronomy) by extension, prefix for any catalogued in the Gliese star catalog
n
(astronomy) by extension, prefix for any catalogued in the Gliese star catalog and expansions
n
(astronomy) A globular cluster
n
(countable, astronomy) Abbreviation of green pea galaxy. [(astronomy) A type of galaxy, found in the local universe, that are active, undergoing high rates of star formation, which provides a green tinge, and are compact, visually appearing akin to peas. These active galaxies have strong oxygen emission lines and no active galactic nucleus (“AGN”), similar to small galaxies in the distant early universe, but unlike those in the nearby contemporary universe.]
n
(astronomy) Ellipsis of green pea galaxy. [(astronomy) A type of galaxy, found in the local universe, that are active, undergoing high rates of star formation, which provides a green tinge, and are compact, visually appearing akin to peas. These active galaxies have strong oxygen emission lines and no active galactic nucleus (“AGN”), similar to small galaxies in the distant early universe, but unlike those in the nearby contemporary universe.]
n
(astronomy) A large nebula of gas and plasma of glowing low density in which star formation has recently taken place.
n
(astronomy) Abbreviation of Hertzsprung-Russell diagram. [(astronomy) A graphic representation of the absolute magnitude of stars against their color (or surface temperature), which shows the main sequence of stars plus the white dwarfs and red giants.]
n
(astronomy) Initialism of high-mass X-ray binary: a binary star system that is strong in X-rays, and in which the normal stellar component is a massive star, and the compact X-ray-emitting component is a neutron star, black hole, or white dwarf.
n
(astronomy) irregular galaxy
n
(supernovae astronomy) A cloud of gas that obscures the poles of a star undergoing hypernova (HN), which gets heated by the polar jet escaping the hypernova progenitor star (hnp), and may absorb the energy of a weak gamma-ray burst (GRB), leaving an observable HN lacking the associated GRB, or be penetrated by a stronger GRB, giving a HN with an associated GRB.
n
(astrophysics) Abbreviation of fourth Lagrange point, located 60 degrees ahead on the orbit of the smaller object in orbit around a larger one
n
(astronomy) Initialism of low-mass X-ray binary: a binary star system that is strong in X-rays, and in which the normal stellar component is a main sequence star, degenerate dwarf, or evolved star from the main sequence, and the compact X-ray emitting component is a neutron star, black hole, or white dwarf
n
(astronomy, cosmology) the volume of space around the Milky Way Galaxy out to a distance of approximately 10 megaparsecs or 35 million lightyears away or out to a cosmological redshift recessional radial velocity of 550km/s or z<0.002
n
(astronomy) A fully-convective red dwarf or M dwarf star
n
(astronomy) Initialism of luminous red nova: an astronomical event, believed to be a type of stellar explosion, intermediate in power between a nova and a supernova, and such that as the explosive debris expands it reddens and cools, unlike a nova or supernova, in which thinning explosive debris exposes hotter interior layers.
n
(astronomy) Lyman-alpha blob
n
(astronomy) collectively, the pair of galaxies, the Large Magellanic Cloud and Small Magellanic Cloud; also sometimes includes the Magellanic Bridge and Magellanic Stream.
n
A region within a solid astronomical body that is of higher density than the surrounding material.
n
(astronomy) A small galactic halo
n
(astronomy, stars) A high-energy binary star system that includes black hole or neutron star and which resembles a quasar.
n
(astronomy) Any of a class of pulsating variable stars characterized by very red colours, pulsation periods longer than 100 days, and amplitudes greater than one magnitude in infrared and 2.5 magnitude at visual wavelengths.
n
(astronomy) Abbreviation of Markarian galaxy. [(astronomy) Any of a class of galaxies that have nuclei with excessive amounts of ultraviolet emissions.]
n
(astronomy, now historical) The hypothetical source of a galactic radio emission at 1665 megahertz (later identified as due to hydroxyl radicals in interstellar space).
n
(astronomy) narrow emission-line radio-galaxy
n
(astronomy) narrow emission-line Seyfert type-1 galaxy
n
(astronomy) Abbreviation of planetary nebula nucleus. [(astronomy) The remnant hot luminous core of the stellar progenitor of the planetary nebula, which ionizes the surrounding planetary nebula.]
n
(astronomy) The assemblage of material that coalesces to form a galactic halo
n
(astronomy, obsolete) Quasi-Stellar Galaxy, a quasar
n
(dated) a radio-quiet quasar
n
Alternative form of quasi-stellar radio-source [(astronomy) a quasar]
n
(dated) a radio-loud quasar
n
(astronomy) Type of galaxy that is very luminous at radio wavelengths.
n
(astronomy) Any nebula that emits radio waves
n
(obsolete, astronomy) A discrete astronomical radio source
n
Alternative spelling of radio galaxy [(astronomy) Type of galaxy that is very luminous at radio wavelengths.]
n
(astronomy) A galaxy which has stopped star formation due to the energetic winds spewing forth from the active galactic nucleus, heating and disrupting gas accumulation and collapse to form new stars, resulting in a population of aging reddening stars.
n
(galaxies) A type of passive, massive and compact elliptical galaxy, that has been little changed over many billions of years, having little internal activity, little to no interaction with other galaxies, little to no new star formation in billions of years. The galaxies typically are many times more massive, and many times smaller, than our Milky Way Galaxy. The redness grows as stars age, which as a population, become redder with time.
n
(astronomy) A very large, red star, such as Betelgeuse and Antares.
n
(astronomy) Radio-loud quasar.
n
(astronomy) Abbreviation of supernova. [(astronomy) The explosion of a star, which increases its absolute magnitude to typically a billion times that of our sun. Some leave only debris, while others fade to invisibility as neutron stars or black holes.]
n
(astronomy) a spiral galaxy which contains a DRAGN
n
(astronomy) A hypothetical quark star made of strange matter.
n
(astronomy) A supernova whose spectrum lacks, or is highly deficient in, hydrogen lines, and where the star has already blown away its outer hydrogen envelope, having exposed the lower enveloping helium layer, prior to the explosion.
n
(astronomy) A type of starburst galaxy that primarily emits radiation in the sub-mm/T-hertz range. Due to the extreme dustiness of the galaxy, they are visible mostly in infrared emissions at their redshift, which are subsequently redshifted into the submm/THz range by Hubble expansion.
n
(astronomy) A very large cloud of stellar material
n
(astronomy) A very large nebula
n
(astronomy) An extremely energetic stellar flare event that is bright enough to be mistaken for a supernova, but through later spectral analysis is revealed to not be one.
n
(astronomy) Abbreviation of Seyfert galaxy., a type of AGN class of active galaxy.
n
(astronomy) The Triangulum Galaxy, a relatively nearby spiral galaxy to the Milky Way; M33.
n
(astronomy) Abbreviation of Thorne-Zytkow object. [(astronomy) A star that contains a core made from another star. It is formed when a neutron star collides with a star, typically a red giant or supergiant, and the neutron star is swallowed by the red giant star.]
n
(astronomy) Ellipsis of ultraluminous X-ray source (“ULX source”).
n
(astronomy) Initialism of warm-hot intergalactic medium. [(astronomy) A sparse, warm-to-hot (105 to 107 K) plasma that cosmologists believe to exist in the spaces between galaxies and to contain 40–50% of the baryons in the universe at the current epoch.]
n
(astronomy, stars) Abbreviation of yellow supergiant. [(astronomy) A supergiant star, of spectral type F or G, that is smaller than a red supergiant]
adj
(astronomy) Abbreviation of zero-age main sequence.
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