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Yellow supergiants generally have spectral types of F and G, although sometimes late A or early K stars are included. [1] [2] [3] These spectral types are characterised by hydrogen lines that are very strong in class A, weakening through F and G until they are very weak or absent in class K. Calcium H and K lines are present in late A spectra, but stronger in class F, and strongest in class G ...
Type I Cepheid variables, more luminous still and mostly supergiants, with even longer periods; Delta Scuti variables, includes subgiant and main-sequence stars. Yellow giants may be moderate-mass stars evolving for the first time towards the red-giant branch, or they may be more evolved stars on the horizontal branch.
Supergiant stars are rarely yellow supergiants because F and G class supergiants are physically unstable; they are most often a transitional phase between blue supergiants and red supergiants. Some yellow supergiants, the Cepheid variables, pulsate with a period proportional to their absolute magnitude; hence, if their apparent magnitude is ...
Intrinsic variable types in the Hertzsprung–Russell diagram showing the Yellow Hypergiants above (i.e. more luminous than) the Cepheid instability strip. A yellow hypergiant (YHG) is a massive star with an extended atmosphere, a spectral class from A to K, and, starting with an initial mass of about 20–60 solar masses, has lost as much as half that mass.
Artist's illustration of Wezen, a yellow supergiant 1,600 light-years away in the Canis Major constellation. Delta Canis Majoris is a supergiant of class F8. Its surface temperature is around 5,818 K, [12] and it is 14 to 15 times more massive than the Sun. Its absolute magnitude is −6.77, [8] and it lies around 1,600 light-years away. It is ...
RW Cephei has been classified as a semi-regular variable star of type SRd, meaning that it is a slowly varying yellow giant or supergiant. The General Catalogue of Variable Stars cites a 1952 study giving a period of approximately 346 days, [ 35 ] [ 5 ] while other studies suggest different periods and certainly no strong periodicity.
Rigel, the brightest star in the constellation Orion is a typical blue-white supergiant; the three stars of Orion's Belt are all blue supergiants; Deneb is the brightest star in Cygnus, another blue supergiant; and Delta Cephei (itself the prototype) and Polaris are Cepheid variables and yellow supergiants.
The most luminous member is the ~2nd magnitude yellow supergiant Mirfak, also known as Alpha Persei. Bright members also include Delta, Sigma, Psi, 29, 30, 34, and 48 Persei. The Hipparcos satellite and infrared color-magnitude diagram fitting have been used to establish a distance to the cluster of ~560 light-years (172 pc).