The luminosity class II in the Yerkes spectral classification is given to bright giants. These are stars which straddle the boundary between giants and supergiants, and the classification is in general given to giant stars with exceptionally high luminosity, but which are not sufficiently bright or massive to be classified as supergiants. In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ... The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... According to the Hertzsprung-Russell diagram, a red giant is a large non-main sequence star of stellar classification K or M; so-named because of the reddish appearance of the cooler giants. Examples include Aldebaran and Arcturus. ... Supergiants are the most massive stars. ... Luminosity has different meanings in several different fields of science. ...
Well known stars which are classified as bright giants include:
Adhara (ε Canis Majoris): a blue-white (B-type) bright giant
Pherkad (γ Ursae Minoris): a white (A-type) bright giant
Sargas (θ Scorpii): a yellow-white (F-type) bright giant
Dabih (β¹ Capricornis): a yellow (G-type) bright giant
Alphard (α Hydrae): an orange (K-type) bright giant
Rasalgethi (α¹ Herculis): a red (M-type) bright giant
Adhara (ε CMa / ε Canis Majoris / Epsilon Canis Majoris), is the second brightest star in the constellation Canis Major, and one of the brightest stars in the nighttime sky. ... Pherkad (also Pherkab) is the designation of the star gamma Ursae Minoris. ... Sargas (Bayer designation θ Scorpii, Theta Scorpii) is a star in the constellation Scorpius. ... Beta Capricorni (β Cap / β Capricorni) is a star in the constellation Capricornus. ... Alphard is the α star in the constellation of Hydra Alphard (Bayer designation α Hydrae) is the brightest star in the constellation Hydra. ... Ras Algethi (Arabic Rasalgethi from Ra`s al-Jathi a Head of the kneeling one) (α 1 Herculis | 64 Herculis) is a double star system with a primary massive red giant star and a closer companion. ...
Even though Thuban is the alpha star in Draco, at apparent magnitude 3.65 it is over a magnitude fainter than the brightest star in the constellation, Etamin (γ Dra), whose apparent magnitude is 2.23.
Thuban is not a main sequence star; it has now ceased hydrogen fusion in its core and is fusing helium.
This indicates that Thuban has not been a giantstar for very long and is likely still in the process of expanding, probably to eventually become a K class red/orange giant of the Aldebaran sort.
Polaris, Alpha Ursae Minoris, is the brightstar closest to the north celestial pole.
The main star is a Population II cepheid variable, the pulsations of which cause it steadily cycle between 8% brighter than its average luminosity and 8% dimmer (0.15 magnitudes in total) with a 3.97 day period.
The star, visible to the naked eye, that is closest to the south celestial pole is the dim Sigma Octantis.
Feeds |
Contact