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[c] [11] Some of the most massive stars lie within this spectral class. O-type stars frequently have complicated surroundings that make measurement of their spectra difficult. O-type spectra formerly were defined by the ratio of the strength of the He II λ4541 relative to that of He I λ4471, where λ is the radiation wavelength. Spectral type ...
Below there are lists the nearest stars separated by spectral type. The scope of the list is still restricted to the main sequence spectral types: M, K, F, G, A, B and O. It may be later expanded to other types, such as S, D or C. The Alpha Centauri star system is the closest star system to the Sun.
Beta Cassiopeiae (β Cassiopeiae, abbreviated Beta Cas or β Cas), officially named Caph / ˈ k æ f /, [12] [13] is a Delta Scuti variable star in the constellation of Cassiopeia. It is a giant star belonging to the spectral class F2. The white star of second magnitude (+2.28 mag, variable) has an absolute magnitude of +1.3 mag.
The MK spectral types of the two stars have been measured a number of times, and they are both consistently assigned a luminosity class of III indicating a giant star. [69] The composite spectrum appears to be dominated by the primary star due to its sharper absorption lines ; the lines from the secondary are broadened and blurred by its rapid ...
Comparison of main sequence stars of each spectral class. By treating the star as an idealized energy radiator known as a black body, the luminosity L and radius R can be related to the effective temperature T eff by the Stefan–Boltzmann law: = where σ is the Stefan–Boltzmann constant. As the position of a star on the HR diagram shows its ...
Theta Eridani is a binary system with some evidence suggesting it is part of a multiple star system. [7] [22] The main star, θ 1 Eridani, is of spectral class A4 with a +3.2 apparent magnitude. Its companion star, θ 2 Eridani, is of spectral class A1 with an apparent magnitude of +4.1. The angular separation of the two stars is equal to 8.3 ...
As of March 2017, the star is known to have at least 5 planets, with two of them (HD 219134 b and c) known to be transiting, rocky super-Earths. [17] [18] While a 2016 study suggested that the radial velocity signal corresponding to planet f might be caused by stellar activity, [16] it has been confirmed by subsequent studies in 2017 [17] and ...
The radial velocity variations of the stars can be measured and the pair have a somewhat eccentric orbit of 51.4 days. [3] The secondary is a main-sequence star slightly cooler than the primary, with an A1 spectral class. [3] The secondary star was detected in high spatial resolution observations using the Navy Precision Optical Interferometer.