Cannabaceae

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Carbon-enhanced metal-poor stars, usually referred to as CEMP stars, are a class of chemically peculiar star. CEMP stars have [C/Fe] > +1, which means compared to the Sun these stars have carbon enhanced at least ten times more than iron, and [Fe/H] < -1, meaning that iron is less than a tenth that in the Sun.

These are further categorized by whether r-process or s-process elements are enhanced. CEMP-no stars have no enhancement. Some of these are the earliest formed in the Milky Way. The others are termed CEMP-r, CEMP-s, or CEMP-r/s.[1][2] Metal-poor stars are more likely to be CEMP stars, and once [Fe/H] < -5.0, then all the stars are CEMP stars.[1]

Subdivisions

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CEMP-r stars have [Eu/Fe] > +1 and [Ba/Eu] < 0.[1]

CEMP-s stars have [Ba/Fe] > +1 and [Ba/Eu] > +0.5[1] 80% of CEMP stars fall into this category.[1]

CEMP-r/s stars have [Ba/Eu] between 0 and +0.5 so they are under the level for CEMP-s stars.[1]

CEMP-no stars have [Ba/Fe] < 0.[1] About 20% of CEMP stars fall into this category.[1]

References

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  1. ^ a b c d e f g h Catherine r. Kennedy (29 May 2014). "Carbon-Enhanced Metal-Poor Stars in the Milky Way" (PDF). Canberra. Archived from the original (PDF) on October 19, 2015. Retrieved 18 December 2016.
  2. ^ Carollo, Daniela; Freeman, Ken; Beers, Timothy; Placco, Vinicius; Tumlinson, Jason; Martell, Sarah (20 June 2014). "Carbon-Enhanced Metal-Poor Stars: CEMP-s and CEMP-no Sub-Classes in the Halo System of the Milky Way". The Astrophysical Journal. 788 (2): 180. arXiv:1401.0574. Bibcode:2014ApJ...788..180C. doi:10.1088/0004-637X/788/2/180. S2CID 59932382.


source: https://en.wikipedia.org/wiki/CEMP_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

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