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- B-type_main-sequence_star abstract "A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars are extremely luminous and blue. Their spectra have neutral helium, which are most prominent at the B2 subclass, and moderate hydrogen lines. Examples include Regulus and Algol A.This class of stars was introduced with the Harvard sequence of stellar spectra and published in the Revised Harvard photometry catalogue. The definition of type B stars was the presence of non-ionized helium lines with the absence of singly ionized helium in the blue-violet portion of the spectrum. All of the spectral classes, including the B type, were subdivided with a numerical suffix that indicated the degree to which they approached the next classification. Thus B2 is two tenths of the way from type B (or B0) to type A.Later, however, more refined spectra showed lines of ionized helium for stars of type B0. Likewise, A0 stars also show weak lines of non-ionized helium. Subsequent catalogues of stellar spectra classified the stars based on the strengths of absorption lines at specific frequencies, or by comparing the strengths of different lines. Thus, in the MK Classification system, the spectral class B0 has the line at wavelength 438.7 nm being stronger than the line at 420.0 nm. The Balmer series of hydrogen lines grows stronger through the B class, then peak at type A2. The lines of ionized silicon are used to determine the sub-class of the B-type stars, while magnesium lines are used to distinguish between the temperature classes.Type-B stars do not have a corona and lack a convection zone in their outer atmosphere. They have a higher mass loss rate than smaller stars such as the Sun, and their stellar wind has velocities of about 3,000 km/s. The energy generation in main-sequence B-type stars comes from the CNO cycle of thermonuclear fusion. Because the CNO cycle is very temperature sensitive, the energy generation is heavily concentrated at the center of the star, which results in a convection zone about the core. This results in a steady mixing of the hydrogen fuel with the helium byproduct of the nuclear fusion. Many B-type stars have a rapid rate of rotation, with an equatorial rotation velocity of about 200 km/s.".
- B-type_main-sequence_star wikiPageID "1575837".
- B-type_main-sequence_star wikiPageRevisionID "594971809".
- B-type_main-sequence_star subject Category:B-type_main-sequence_stars.
- B-type_main-sequence_star subject Category:Star_types.
- B-type_main-sequence_star comment "A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars are extremely luminous and blue. Their spectra have neutral helium, which are most prominent at the B2 subclass, and moderate hydrogen lines.".
- B-type_main-sequence_star label "B-type main-sequence star".
- B-type_main-sequence_star label "B型主序星".
- B-type_main-sequence_star label "B型主系列星".
- B-type_main-sequence_star label "Gwiazdy typu widmowego B".
- B-type_main-sequence_star label "Stella di classe B V".
- B-type_main-sequence_star label "Type-B hoofdreeksster".
- B-type_main-sequence_star sameAs Αστέρας_τύπου_Β.
- B-type_main-sequence_star sameAs Stella_di_classe_B_V.
- B-type_main-sequence_star sameAs B型主系列星.
- B-type_main-sequence_star sameAs B형_주계열성.
- B-type_main-sequence_star sameAs Type-B_hoofdreeksster.
- B-type_main-sequence_star sameAs Gwiazdy_typu_widmowego_B.
- B-type_main-sequence_star sameAs m.05cqp5.
- B-type_main-sequence_star sameAs Q767432.
- B-type_main-sequence_star sameAs Q767432.
- B-type_main-sequence_star wasDerivedFrom B-type_main-sequence_star?oldid=594971809.
- B-type_main-sequence_star isPrimaryTopicOf B-type_main-sequence_star.