RR Lyrae star

RR Lyrae star
Astron. one of a group of pulsating variable stars found in the halo of the Milky Way, with periods between 1.2 and 30 hours; all have approximately the same luminosity and are therefore used for measuring distances. Also called cluster variable.
[ < NL: RR (variable star designation) of LYRA]

* * *

      any of a group of old giant stars of the class called pulsating variables (see variable star) that pulsate with periods of about 0.2–1 day. They belong to the broad Population II class of stars (see Populations I and II) and are found mainly in the thick disk and halo of the Milky Way Galaxy and often in globular clusters. There are several subclasses—designated RRa, RRb, RRc, and RRd—based on the manner in which the light varies with time. The intrinsic luminosities of RR Lyrae stars are relatively well-determined, which makes them useful as distance indicators.

John Donald Fernie
 

* * *


Universalium. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • RR Lyrae star — Astron. one of a group of pulsating variable stars found in the halo of the Milky Way, with periods between 1.2 and 30 hours; all have approximately the same luminosity and are therefore used for measuring distances. Also called cluster variable …   Useful english dictionary

  • star — starless, adj. /stahr/, n., adj., v., starred, starring. n. 1. any of the heavenly bodies, except the moon, appearing as fixed luminous points in the sky at night. 2. Astron. any of the large, self luminous, heavenly bodies, as the sun, Polaris,… …   Universalium

  • star cluster — Astron. a number of stars of common origin held together as a group by gravitational attraction. Cf. globular cluster, open cluster, stellar association. * * * ▪ astronomy Introduction  either of two general types of stellar assemblages held… …   Universalium

  • Lyrae — Dieser Artikel oder Abschnitt ist nicht hinreichend mit Belegen (Literatur, Webseiten oder Einzelnachweisen) versehen. Die fraglichen Angaben werden daher möglicherweise demnächst gelöscht. Hilf Wikipedia, indem du die Angaben recherchierst und… …   Deutsch Wikipedia

  • Lyrae — n. Lyre, constellation in the Northern Hemisphere which contains the star Vega (Astronomy); female first name …   English contemporary dictionary

  • variable star — Astron. a star that varies markedly in brightness from time to time. Also called variable. [1780 90] * * * Star whose observed brightness varies noticeably in intensity. Pulsating variables expand and contract in cycles, pulsating rhythmically in …   Universalium

  • Beta Lyrae — ▪ star       eclipsing binary star, the two component stars of which are so close together that they are greatly distorted by their mutual attraction; they exchange material and share a common atmosphere. Beta Lyrae is a member of a class of… …   Universalium

  • RR Lyrae variable — RR Lyrae variables are periodic variable stars, commonly found in globular clusters, and often used as standard candles to measure galactic distances. This type of variable is named after the prototype, the variable star RR Lyrae in the… …   Wikipedia

  • Alpha Lyrae — Pour les articles homonymes, voir Véga (homonymie). α Lyrae Vue infrarouge du disque de débris …   Wikipédia en Français

  • Α Lyrae — Alpha Lyrae Pour les articles homonymes, voir Véga (homonymie). α Lyrae Vue infrarouge du disque de débris …   Wikipédia en Français

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”