dwarf star

dwarf star

(dwarf) Any star lying on the main sequence of the Hertzsprung–Russell diagram. The term arises from the early dual classification of stars into giants (g) and dwarfs (d ): the Sun was classified as d G2. This system has been superseded by that of luminosity classes (see spectral types), and these ‘dwarf’ stars are of luminosity class V. The term main-sequence star is now more common, especially to prevent confusion with white dwarfs; late-type main-sequence stars, however, are still referred to as red dwarfs.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

dwarf star

[¦dwȯrf ′stär]

(astronomy)

A star that typically has surface temperature of 5730 K, radius of 428,000 miles (690,000 kilometers), mass of 2 × 10³³ grams, and luminosity of 4 × 10³³ ergs per second. Also known as main sequence star.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Dwarf Star

 

a star of relatively small size and low luminosity. Most dwarf stars form the lower part of the main sequence of the Hertzsprung-Russell diagram. Their average density ranges from 1 to 60 g/cm³. Evidently, all stars of average and small mass are dwarf stars at a certain stage in their evolution, which is characterized by the start of nuclear reactions and the burning of hydrogen in the star’s nucleus. In addition, dwarfs include stars existing in a state of gravitational contraction for a long time because of their very small mass. Dwarf stars have well-developed convection zones and extended chromospheres; therefore, emission lines are encountered in their spectra. A typical dwarf star is our sun. Among dwarfs there are a considerable number of stars with variable characteristics. A large part of the spherical subsystem of the Milky Way Galaxy and of the planar subsystem excluding the spiral arms consists of dwarf stars. The white dwarfs considerably differ in their structure from ordinary (or red) dwarfs.

V. S. AVEDISOVA

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.