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  2. Stellar classification - Wikipedia

    en.wikipedia.org/wiki/Stellar_classification

    [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 ...

  3. List of nearest stars by spectral type - Wikipedia

    en.wikipedia.org/wiki/List_of_nearest_stars_by...

    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.

  4. Beta Cassiopeiae - Wikipedia

    en.wikipedia.org/wiki/Beta_Cassiopeiae

    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.

  5. Capella - Wikipedia

    en.wikipedia.org/wiki/Capella

    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 ...

  6. Main sequence - Wikipedia

    en.wikipedia.org/wiki/Main_sequence

    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 ...

  7. Theta Eridani - Wikipedia

    en.wikipedia.org/wiki/Theta_Eridani

    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 ...

  8. HD 219134 - Wikipedia

    en.wikipedia.org/wiki/HD_219134

    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 ...

  9. Thuban - Wikipedia

    en.wikipedia.org/wiki/Thuban

    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.