{"id":566,"date":"2022-03-02T16:50:32","date_gmt":"2022-03-02T16:50:32","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/astronomy\/?post_type=chapter&p=566"},"modified":"2022-03-02T16:50:35","modified_gmt":"2022-03-02T16:50:35","slug":"key-terms-15","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/astronomy\/chapter\/key-terms-15\/","title":{"raw":"Key Terms","rendered":"Key Terms"},"content":{"raw":"
\r\n
\r\n \t
apparent brightness<\/dt>\r\n \t
a measure of the amount of light received by Earth from a star or other object\u2014that is, how bright an object appears in the sky, as contrasted with its luminosity<\/dd>\r\n<\/dl>\r\n
\r\n \t
brown dwarf<\/dt>\r\n \t
an object intermediate in size between a planet and a star; the approximate mass range is from about 1\/100 of the mass of the Sun up to the lower mass limit for self-sustaining nuclear reactions, which is about 0.075 the mass of the Sun; brown dwarfs are capable of deuterium fusion, but not hydrogen fusion<\/dd>\r\n<\/dl>\r\n
\r\n \t
color index<\/dt>\r\n \t
difference between the magnitudes of a star or other object measured in light of two different spectral regions\u2014for example, blue minus visual (B\u2013V) magnitudes<\/dd>\r\n<\/dl>\r\n
\r\n \t
giant<\/dt>\r\n \t
a star of exaggerated size with a large, extended photosphere<\/dd>\r\n<\/dl>\r\n
\r\n \t
luminosity<\/dt>\r\n \t
the rate at which a star or other object emits electromagnetic energy into space; the total power output of an object<\/dd>\r\n<\/dl>\r\n
\r\n \t
magnitude<\/dt>\r\n \t
an older system of measuring the amount of light we receive from a star or other luminous object; the larger the magnitude, the less radiation we receive from the object<\/dd>\r\n<\/dl>\r\n
\r\n \t
proper motion<\/dt>\r\n \t
the angular change per year in the direction of a star as seen from the Sun<\/dd>\r\n<\/dl>\r\n
\r\n \t
radial velocity<\/dt>\r\n \t
motion toward or away from the observer; the component of relative velocity that lies in the line of sight<\/dd>\r\n<\/dl>\r\n
\r\n \t
space velocity<\/dt>\r\n \t
the total (three-dimensional) speed and direction with which an object is moving through space relative to the Sun<\/dd>\r\n<\/dl>\r\n
\r\n \t
spectral class<\/dt>\r\n \t
(or spectral type) the classification of stars according to their temperatures using the characteristics of their spectra; the types are O, B, A, F, G, K, and M with L, T, and Y added recently for cooler star-like objects that recent survey have revealed<\/dd>\r\n<\/dl>\r\n<\/div>\r\n
This book was adapted from the following: Fraknoi, A., Morrison, D., & Wolff, S. C. (2016). Key Terms In Astronomy<\/i>. OpenStax. https:\/\/openstax.org\/books\/astronomy\/pages\/17-key-terms under a Creative Commons Attribution License 4.0<\/a><\/div>\r\n
Access the entire book for free at\u00a0https:\/\/openstax.org\/books\/astronomy\/pages\/1-introduction<\/a><\/div>","rendered":"
\n
\n
apparent brightness<\/dt>\n
a measure of the amount of light received by Earth from a star or other object\u2014that is, how bright an object appears in the sky, as contrasted with its luminosity<\/dd>\n<\/dl>\n
\n
brown dwarf<\/dt>\n
an object intermediate in size between a planet and a star; the approximate mass range is from about 1\/100 of the mass of the Sun up to the lower mass limit for self-sustaining nuclear reactions, which is about 0.075 the mass of the Sun; brown dwarfs are capable of deuterium fusion, but not hydrogen fusion<\/dd>\n<\/dl>\n
\n
color index<\/dt>\n
difference between the magnitudes of a star or other object measured in light of two different spectral regions\u2014for example, blue minus visual (B\u2013V) magnitudes<\/dd>\n<\/dl>\n
\n
giant<\/dt>\n
a star of exaggerated size with a large, extended photosphere<\/dd>\n<\/dl>\n
\n
luminosity<\/dt>\n
the rate at which a star or other object emits electromagnetic energy into space; the total power output of an object<\/dd>\n<\/dl>\n
\n
magnitude<\/dt>\n
an older system of measuring the amount of light we receive from a star or other luminous object; the larger the magnitude, the less radiation we receive from the object<\/dd>\n<\/dl>\n
\n
proper motion<\/dt>\n
the angular change per year in the direction of a star as seen from the Sun<\/dd>\n<\/dl>\n
\n
radial velocity<\/dt>\n
motion toward or away from the observer; the component of relative velocity that lies in the line of sight<\/dd>\n<\/dl>\n
\n
space velocity<\/dt>\n
the total (three-dimensional) speed and direction with which an object is moving through space relative to the Sun<\/dd>\n<\/dl>\n
\n
spectral class<\/dt>\n
(or spectral type) the classification of stars according to their temperatures using the characteristics of their spectra; the types are O, B, A, F, G, K, and M with L, T, and Y added recently for cooler star-like objects that recent survey have revealed<\/dd>\n<\/dl>\n<\/div>\n
This book was adapted from the following: Fraknoi, A., Morrison, D., & Wolff, S. C. (2016). Key Terms In Astronomy<\/i>. OpenStax. https:\/\/openstax.org\/books\/astronomy\/pages\/17-key-terms under a Creative Commons Attribution License 4.0<\/a><\/div>\n
Access the entire book for free at\u00a0https:\/\/openstax.org\/books\/astronomy\/pages\/1-introduction<\/a><\/div>\n","protected":false},"author":33,"menu_order":11,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[48],"contributor":[],"license":[],"class_list":["post-566","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":556,"_links":{"self":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/566","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/users\/33"}],"version-history":[{"count":1,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/566\/revisions"}],"predecessor-version":[{"id":567,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/566\/revisions\/567"}],"part":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/parts\/556"}],"metadata":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/566\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/media?parent=566"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapter-type?post=566"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/contributor?post=566"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/license?post=566"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}