galaxy Comparison Table

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galaxy comparison table

Subject has classification criteria is part of is a kind of has classification criterion has wavelength has number of Cepheid has acronym has mass has emission line has luminosity has definition has distance

active galaxy galaxy 10⁴³ to 10⁴⁶ ergs s^-1 Active galactic nuclei are very luminous. Their energy output is in two forms: nonthermal continuum and thermal emission line.

blue compact galaxy galaxy BCG

compact galaxy galaxy A galaxy similar to an N galaxy but with no disk or nebulous background. It is an object of high surface brightness which appears slightly nonstellar on photographs and which has a larger redshift than normal stars in our Galaxy. Nearest "compact" galaxy is M32.

dwarf galaxy galaxy A small, faint galaxy, exemplified by those that orbit the Milky Way: Ursa Minor, Draco, Sculptor, Sextans, Carina, Fornax, Leo II, and Leo I.

elliptical galaxy E0 (spherical) to E7 (greatest eccentricity) galaxy A galaxy with an ellipsoidal shape, without spiral arms. Ellipticals have little interstellar matter and no blue giants - the only giants are red, and they give ellipticals a slightly redder color than spirals. Ellipticals apparently produce only Type I supernovae.

emission line galaxy galaxy

field galaxy galaxy An isolated galaxy which does not belong to any cluster of galaxies. The ratio of galaxies in clusters to field galaxies is about 23:1.

galaxy containing Cepheids galaxy determined from Cepheid period-luminosity relation

gravitational lens galaxy A galaxy that intervenes between us and a distant astronomical object and that gravitationally deflects the light from that distant object. (Light, like matter, is attracted by gravity.) Gravitational lenses can focus, distort, and split light beams in the same way that ordinary glass lenses do.

infrared galaxy galaxy

irregular galaxy galaxy A galaxy with amorphous structure and with relatively low mass (10⁸-10¹⁰ M_sun). Fewer than 10% of all galaxies are classified as irregular.

low surface brightness galaxy galaxy LSBG A galaxy which is very faint because it contains a very limited number of stars.

lyman break galaxy galaxy LBG

N galaxy galaxy A galaxy with a small, bright, blue nucleus superposed on a considerably fainter red background. (In the Yerkes 1974 system, a galaxy with a small nucleus containing a considerable fraction of the luminosity; N^-, less pronounced N galaxies; N⁺, extreme examples of N galaxies.) Also, a type of radio galaxy having a brilliant, starlike nucleus containing most of the luminosity of the system. N galaxies are compact galaxies, and as a class are intermediate between Seyfert galaxies and quasars in properties of form, color, spectra, redshift, and optical and radio variability.

protogalaxy galaxy A galaxy during the early phase, before it has developed its present shape and mix of stars.

radio galaxy celestial sphere radio source radio A galaxy that is extremely luminous at radio wavelengths. A radio galaxy is usually a giant elliptical - the largest galaxy in a cluster - and is a strong emitter of synchrotron radiation. M87 and M82 are examples.

ring galaxy galaxy A galaxy with a ring-like appearance. The ring contains luminous blue stars, but relatively little luminous matter is present in the central regions. It is believed that such a system was an ordinary galaxy that recently suffered a head-on collision with another galaxy.

S0 galaxy galaxy Galaxy with nuclei surrounded by disklike structure without arms.

spiral galaxy galaxy Subdivided according to the openness of the spiral arms as Sa spiral, Sb spiral or Sc spiral. 10¹⁰ to 10¹² M_sun A galaxy with a prominent nuclear bulge and luminous spiral arms of gas, dust, and young stars that wind out from the nucleus.

starburst galaxy galaxy Any galaxy in which an anomalously large rate of star formation is taking place.

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Subject	has classification criteria	is part of	is a kind of	has classification criterion	has wavelength	has number of Cepheid	has acronym	has mass	has emission line	has luminosity	has definition	has distance
active galaxy			galaxy							10⁴³ to 10⁴⁶ ergs s^-1	Active galactic nuclei are very luminous. Their energy output is in two forms: nonthermal continuum and thermal emission line.
blue compact galaxy			galaxy				BCG
compact galaxy			galaxy								A galaxy similar to an N galaxy but with no disk or nebulous background. It is an object of high surface brightness which appears slightly nonstellar on photographs and which has a larger redshift than normal stars in our Galaxy. Nearest "compact" galaxy is M32.
dwarf galaxy			galaxy								A small, faint galaxy, exemplified by those that orbit the Milky Way: Ursa Minor, Draco, Sculptor, Sextans, Carina, Fornax, Leo II, and Leo I.
elliptical galaxy	E0 (spherical) to E7 (greatest eccentricity)		galaxy								A galaxy with an ellipsoidal shape, without spiral arms. Ellipticals have little interstellar matter and no blue giants - the only giants are red, and they give ellipticals a slightly redder color than spirals. Ellipticals apparently produce only Type I supernovae.
emission line galaxy			galaxy
field galaxy			galaxy								An isolated galaxy which does not belong to any cluster of galaxies. The ratio of galaxies in clusters to field galaxies is about 23:1.
galaxy containing Cepheids			galaxy									determined from Cepheid period-luminosity relation
gravitational lens			galaxy								A galaxy that intervenes between us and a distant astronomical object and that gravitationally deflects the light from that distant object. (Light, like matter, is attracted by gravity.) Gravitational lenses can focus, distort, and split light beams in the same way that ordinary glass lenses do.
infrared galaxy			galaxy
irregular galaxy			galaxy								A galaxy with amorphous structure and with relatively low mass (10⁸-10¹⁰ M_sun). Fewer than 10% of all galaxies are classified as irregular.
low surface brightness galaxy			galaxy				LSBG				A galaxy which is very faint because it contains a very limited number of stars.
lyman break galaxy			galaxy				LBG
N galaxy			galaxy								A galaxy with a small, bright, blue nucleus superposed on a considerably fainter red background. (In the Yerkes 1974 system, a galaxy with a small nucleus containing a considerable fraction of the luminosity; N^-, less pronounced N galaxies; N⁺, extreme examples of N galaxies.) Also, a type of radio galaxy having a brilliant, starlike nucleus containing most of the luminosity of the system. N galaxies are compact galaxies, and as a class are intermediate between Seyfert galaxies and quasars in properties of form, color, spectra, redshift, and optical and radio variability.
protogalaxy			galaxy								A galaxy during the early phase, before it has developed its present shape and mix of stars.
radio galaxy		celestial sphere	radio source		radio						A galaxy that is extremely luminous at radio wavelengths. A radio galaxy is usually a giant elliptical - the largest galaxy in a cluster - and is a strong emitter of synchrotron radiation. M87 and M82 are examples.
ring galaxy			galaxy								A galaxy with a ring-like appearance. The ring contains luminous blue stars, but relatively little luminous matter is present in the central regions. It is believed that such a system was an ordinary galaxy that recently suffered a head-on collision with another galaxy.
S0 galaxy			galaxy								Galaxy with nuclei surrounded by disklike structure without arms.
spiral galaxy			galaxy	Subdivided according to the openness of the spiral arms as Sa spiral, Sb spiral or Sc spiral.				10¹⁰ to 10¹² M_sun			A galaxy with a prominent nuclear bulge and luminous spiral arms of gas, dust, and young stars that wind out from the nucleus.
starburst galaxy			galaxy								Any galaxy in which an anomalously large rate of star formation is taking place.