Lambda BoÃ¶tis star
A lambda Bootis Star is a special type of Pekuliären stars ( "peculiar " - engl particularly, intrinsically related to the chemical composition. ) With a low proportion of "iron - peak" elements ( a measure of the low proportion the most stable elements in the vicinity of iron) in its surface layers. In this class of stars with spectral types late B to early F, the elements of the iron group by up to a factor of 100 are common, while the lighter elements such as C, N, O and S have a solar incidence. Less than 2 % of all main sequence stars in these spectral classes belong to the lambda Bootis stars.
The possible explanations for the differing chemical composition of the photosphere of these stars are in:
- Atmospheric diffusion
- Accretion from the interstellar matter by means of an accretion disk
Since the abundances in the photosphere of the lambda Bootis Star of the interstellar medium are similarly likely to play the dominant role of the accretion. The depletion of the iron group elements in the interstellar medium is a result of dust formation in the last phase of life of stars with intermediate mass, the AGB stars. The duration of the frequency of the iron -peak elements in lambda Bootis stars, should be only a few million years, as it comes through the rotation of the stars in a slow mixing of the layers of the atmosphere after the star has left a cloud of interstellar matter.
The prototype of this star is Lambda Bootis.