Cannabaceae

thcscience_admin

A CN star has unusually strong cyano radical bands in its spectrum compared to other stars of its stellar class.[1] Cyano radical is a simple molecule of one carbon atom and one nitrogen atom, with absorption bands around wavelengths 388.9 and 421.6 nanometer.[2] This group of stars was first noticed in certain G and K-type giants by J. J. Nassau and W. W. Morgan in 1949,[3] then a further 4,150 were identified by Nancy G. Roman in 1952.[4] They can be distinguished from barium stars by the lack of s-process elements, and from other types of luminous stars by the general weakness of features other than the CN lines.[3]

The excess strength of the CN bands is classified by a positive index with increments of 0.5. A value of zero indicates a normal star and is not listed in the stellar class, while the peak value of 4 is essentially similar to a carbon star. Stars classified in the MK system with a CN suffix are considered "strong" CN stars. Hence, 42 Librae is a strong CN star with a class of K3-III CN2. A value of 0.5 is also termed a marginal CN star, which corresponds to the typical giant stars in the Hyades cluster.[5]

References

[edit]
  1. ^ Keenan, P. C.; Heck, A. (July 1994). "SMR stars, strong-CN stars, and R stars". Revista Mexicana de Astronomía y Astrofísica. 29: 103–110. Bibcode:1994RMxAA..29..103K.
  2. ^ Schmitt, John L. (3 June 1970). "Stars with Strong Cyanogen Absorption". Astrophysical Journal. 163: 75. Bibcode:1971ApJ...163...75S. doi:10.1086/150747.
  3. ^ a b Keenan, Philip C. (August 1987). "Spectral types and their uses". Publications of the Astronomical Society of the Pacific. 99: 713–723. Bibcode:1987PASP...99..713K. doi:10.1086/132036. S2CID 121556654.
  4. ^ Roman, Nancy G. (1 March 1952). "The Spectra of the Bright Stars of Types F5-K5". Astrophysical Journal. 116: 122. Bibcode:1952ApJ...116..122R. doi:10.1086/145598.
  5. ^ Keenan, Philip C.; et al. (July 1987). "Recognition and classification of strong-CN giants". Publications of the Astronomical Society of the Pacific. 99: 629–636. Bibcode:1987PASP...99..629K. doi:10.1086/132025.
source: https://en.wikipedia.org/wiki/CN_star

One thought on “Cannabaceae”

  1. Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
    View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction

Leave a Reply