B
Stellar classification

B
Effective temperature
10,000–25,000 K
Solar radius
1.8–6.6 R
Solar mass
2.1–16 M

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-type 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.

Uses material from the Wikipedia article "B-type main-sequence star", which is released under the Creative Commons BY-SA 3.0.
Astronomical object DistanceWiki
106 AquariiStar, Infra-Red source, UV-emission source, X-ray sourceB379[x]
13 AndromedaeStar, Variable Star of alpha2 CVn type, Infra-Red source, UV-emission source, Variable StarB300[x]
13 VulpeculaeStar, Double or multiple star, Infra-Red source, UV-emission sourceB334[x]
17 VulpeculaeStar, Infra-Red source, UV-emission sourceB504[x]
18 AquilaeStar, Double or multiple star, Eclipsing binary, Ellipsoidal variable Star, Infra-Red source, Spectroscopic binary, UV-emission source, Variable StarB699[x]
18 TauriStar, Star in Cluster, Infra-Red source, UV-emission sourceB410[x]
2 CygniStar, Double or multiple star, Infra-Red source, UV-emission sourceB843[x]
21 Canum VenaticorumStar, Variable Star of alpha2 CVn type, Infra-Red source, UV-emission source, Variable StarB275[x]
26 AndromedaeStar, Double or multiple star, Infra-Red source, UV-emission sourceB662[x]
27 VulpeculaeStar, Infra-Red source, UV-emission sourceB318[x]
28 VulpeculaeStar, Infra-Red source, UV-emission sourceB522[x]
29 PerseiStar, Star in Cluster, Infra-Red source, UV-emission sourceB638[x]
36 AurigaeStar, Variable Star of alpha2 CVn type, Infra-Red source, UV-emission source, Variable StarB1157[x]
4 CygniStar, Variable Star of alpha2 CVn type, Infra-Red source, Spectroscopic binary, UV-emission source, Variable StarB707[x]
42 CamelopardalisStar, Infra-Red source, UV-emission sourceB924[x]
42 CassiopeiaeStar, Eclipsing binary of Algol type , Infra-Red source, UV-emission source, Variable StarB278[x]
43 CamelopardalisStar, Infra-Red source, UV-emission sourceB979[x]
50 BootisStar, Infra-Red source, UV-emission sourceB262[x]
54 AurigaeStar, Double or multiple star, Infra-Red source, UV-emission source, Variable StarB843[x]
57 CygniStar, Eclipsing binary of Algol type , Infra-Red source, Spectroscopic binary, UV-emission source, Variable Star, X-ray sourceB525[x]
58 AquilaeStar, Infra-Red source, UV-emission sourceB372[x]
7 CepheiStar, Infra-Red source, UV-emission sourceB805[x]
8 CygniStar, Infra-Red source, UV-emission sourceB860[x]
a CentauriStar, Infra-Red source, Rotationally variable Star, UV-emission source, Variable StarB457[x]
AcruxStar, Double or multiple star, Spectroscopic binary, UV-emission sourceB321[x]
AdaraStar, Double or multiple star, Infra-Red source, UV-emission source, X-ray sourceB405[x]
AgenaStar, Double or multiple star, Variable Star of beta Cep type, Infra-Red source, UV-emission source, Variable Star, X-ray sourceB392[x]
AlbaliStar, Infra-Red source, High proper-motion Star, UV-emission sourceB208[x]
AlcyoneStar, Double or multiple star, Star in Cluster, Star in Nebula, Be Star, Emission-line Star, Infra-Red source, UV-emission source, X-ray sourceB403[x]
AldhibahStar, Double or multiple star, Infra-Red source, UV-emission sourceB329[x]
AlgenibStar, Double or multiple star, Variable Star of beta Cep type, Blue object, Infra-Red source, UV-emission source, Variable StarB391[x]
AlgolStar, Double or multiple star, Eclipsing binary of Algol type , Infra-Red source, Spectroscopic binary, UV-emission source, Variable Star, X-ray sourceB93[x]
AlkaidStar, Infra-Red source, UV-emission source, Variable StarB104[x]
AlnairStar, Double or multiple star, Infra-Red source, High proper-motion Star, UV-emission source, Variable Star, X-ray sourceB101[x]
Alpha AraeStar, Double or multiple star, Be Star, Emission-line Star, Eruptive variable Star, Infra-Red source, UV-emission source, Variable Star, X-ray sourceB267[x]
Alpha DoradusStar, Double or multiple star, Variable Star of alpha2 CVn type, Infra-Red source, UV-emission source, Variable StarB169[x]
Alpha LupiStar, Double or multiple star, Variable Star of beta Cep type, Infra-Red source, UV-emission source, Variable Star, X-ray sourceB465[x]
Alpha MuscaeStar, Double or multiple star, Variable Star of beta Cep type, Infra-Red source, UV-emission source, Variable StarB316[x]
Alpha TelescopiiStar, Infra-Red source, UV-emission sourceB278[x]
AlpheratzStar, Double or multiple star, Variable Star of alpha2 CVn type, Infra-Red source, High proper-motion Star, Spectroscopic binary, UV-emission source, Variable StarB96[x]
AlshatStar, Double or multiple star, Infra-Red source, UV-emission sourceB253[x]
AludraStar, Double or multiple star, Star in Cluster, Infra-Red source, Pulsating variable Star, Blue supergiant, UV-emission source, Variable StarB1989[x]
AR CassiopeiaeStar, Double or multiple star, Eclipsing binary of Algol type , Infra-Red source, Spectroscopic binary, UV-emission source, Variable StarB621[x]
Arkab PriorStar, Double or multiple star, Infra-Red sourceB378[x]
AsteropeStar, Double or multiple star, Star in Cluster, Infra-Red source, UV-emission source, Variable StarB372[x]
AtikStar, Double or multiple star, Ellipsoidal variable Star, Infra-Red source, Spectroscopic binary, UV-emission source, Variable Star, X-ray sourceB751[x]
AtlasStar, Double or multiple star, Star in Cluster, Infra-Red source, Spectroscopic binary, UV-emission source, Variable StarB382[x]
BellatrixStar, Double or multiple star, Infra-Red source, UV-emission source, Variable Star, X-ray sourceB253[x]
Beta LupiStar, Infra-Red source, UV-emission source, Variable StarB382[x]
Beta MuscaeStar, Double or multiple star, Infra-Red source, Spectroscopic binary, UV-emission sourceB342[x]
Beta SculptorisStar, Infra-Red source, UV-emission source, X-ray sourceB175[x]
BW VulpeculaeStar, Variable Star of beta Cep type, Infra-Red source, UV-emission source, Variable StarB1045[x]
C CarinaeStar, Double or multiple star, Infra-Red source, UV-emission sourceB253[x]
CelaenoStar, Double or multiple star, Star in Cluster, Infra-Red source, UV-emission source, Variable StarB377[x]
CG AndromedaeStar, Variable Star of alpha2 CVn type, Infra-Red source, UV-emission source, Variable StarB613[x]
Chi CarinaeStar, Variable Star of beta Cep type, Infra-Red source, UV-emission source, Variable Star, X-ray sourceB455[x]
d LupiStar, Double or multiple star, Be Star, Infra-Red source, UV-emission source, Variable StarB428[x]
Delta CentauriStar, Double or multiple star, Be Star, Emission-line Star, Infra-Red source, UV-emission source, Variable StarB415[x]
Delta CrucisStar, Variable Star of beta Cep type, Infra-Red source, UV-emission source, Variable StarB345[x]
Delta FornacisStar, Infra-Red source, UV-emission sourceB847[x]
Delta TucanaeStar, Double or multiple star, UV-emission source, Variable StarB251[x]
E CarinaeStar, Be Star, Emission-line Star, Infra-Red source, UV-emission source, Variable StarB968[x]
e LupiStar, Infra-Red source, Spectroscopic binary, UV-emission source, X-ray sourceB504[x]
ElectraStar, Double or multiple star, Star in Cluster, Star in Nebula, Be Star, Emission-line Star, Infra-Red source, Spectroscopic binary, UV-emission source, Variable StarB405[x]
EO AurigaeStar, Eclipsing binary of Algol type , Infra-Red source, Spectroscopic binary, UV-emission source, Variable StarB1539[x]
Epsilon CentauriStar, Double or multiple star, Variable Star of beta Cep type, UV-emission source, Variable StarB427[x]
Epsilon HydriStar, Infra-Red source, High proper-motion Star, UV-emission source, Variable StarB152[x]
Epsilon LupiStar, Double or multiple star, Variable Star of beta Cep type, Infra-Red source, Spectroscopic binary, UV-emission sourceB504[x]
Epsilon OrionisStar, Double or multiple star, Emission-line Star, Infra-Red source, Interstellar matter, Pulsating variable Star, Blue supergiant, UV-emission source, Variable Star, X-ray sourceB1976[x]
Eta AquariiStar, Blue object, Infra-Red source, UV-emission sourceB168[x]
Eta LupiStar, Double or multiple star, Infra-Red source, UV-emission sourceB442[x]
G CentauriStar, Double or multiple star, Infra-Red source, UV-emission sourceB448[x]
Gamma LupiStar, Double or multiple star, Ellipsoidal variable Star, Infra-Red source, Spectroscopic binary, UV-emission source, Variable StarB421[x]
Gamma MuscaeStar, Infra-Red source, Pulsating variable Star, UV-emission source, Variable StarB325[x]
GienahStar, Infra-Red source, UV-emission source, Variable StarB153[x]
GomeisaStar, Double or multiple star, Be Star, Emission-line Star, Infra-Red source, UV-emission source, Variable StarB162[x]
H CentauriStar, Infra-Red source, Pulsating variable Star, UV-emission source, Variable StarB369[x]
H VelorumStar, Double or multiple star, Infra-Red source, Spectroscopic binary, UV-emission sourceB1264[x]
HD 37017Star, Double or multiple star, Star in Cluster, Star in Nebula, Infra-Red source, Radio-source, Spectroscopic binary, UV-emission source, Variable Star, X-ray sourceB1240[x]
HIP 22588Star, Infra-Red source, UV-emission sourceB784[x]
HIP 56379Star, Herbig Ae/Be star, Be Star, Emission-line Star, Infra-Red source, UV-emission source, Variable StarB316[x]
HR 6875Star, Double or multiple star, Infra-Red source, UV-emission source, Variable StarB487[x]
HR 7029Star, Double or multiple star, Infra-Red source, UV-emission sourceB466[x]
HR 7739Star, Double or multiple star, Be Star, Emission-line Star, Infra-Red source, UV-emission source, Variable StarB992[x]
Iota AquariiStar, Infra-Red source, Spectroscopic binary, UV-emission sourceB175[x]
Iota AquilaeStar, Double or multiple star, Infra-Red source, UV-emission sourceB391[x]
Iota AraeStar, Double or multiple star, Be Star, Emission-line Star, Infra-Red source, UV-emission source, Variable StarB935[x]
j CentauriStar, Be Star, Emission-line Star, Infra-Red source, UV-emission source, Variable StarB595[x]
JabbahStar, Double or multiple star, Star in Nebula, Infra-Red source, Spectroscopic binary, UV-emission sourceB474[x]
Kaus AustralisStar, Double or multiple star, Infra-Red source, UV-emission source, X-ray sourceB143[x]
l CentauriStar, Double or multiple star, Infra-Red source, UV-emission sourceB364[x]
L VelorumStar, Infra-Red source, UV-emission sourceB903[x]
Lambda LupiStar, Double or multiple star, Infra-Red source, Spectroscopic binary, UV-emission sourceB777[x]
M CarinaeStar, Infra-Red source, UV-emission source, Variable StarB308[x]
MaiaStar, Double or multiple star, Star in Cluster, Star in Nebula, Infra-Red source, UV-emission source, Variable Star, X-ray sourceB383[x]
MarkabStar, Infra-Red source, UV-emission source, Variable StarB133[x]
MeropeStar, Double or multiple star, Star in Cluster, Star in Nebula, Variable Star of beta Cep type, Be Star, Emission-line Star, Infra-Red source, UV-emission source, Variable Star, X-ray sourceB381[x]
MintakaStar, Double or multiple star, Eclipsing binary of Algol type , Eclipsing binary, Infra-Red source, Spectroscopic binary, UV-emission source, Variable Star, X-ray sourceB693[x]
MZ AurigaeStar, Be Star, Emission-line Star, Infra-Red source, Rotationally variable Star, UV-emission source, Variable StarB1575[x]
NunkiStar, Double or multiple star, Infra-Red source, UV-emission sourceB228[x]