The star is also poor in elements heavier than sodium: for example, the iron abundance is only 28% of the solar iron abundance.
Asteroseismic observations of other pulsating Lambda Boötis stars suggest that the peculiar abundance patterns of these stars are confined to the surface only: the bulk composition is likely more normal.
Brown dwarfs would not be stable in such a configuration.
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Because of this special status, stars like HR 8799 have a very complex spectral type.
The luminosity profile of the Balmer lines in the star's spectrum, as well as the star's effective temperature, best match the typical properties of an F0 V star.
This may indicate that the observed element abundances are the result of the accretion of metal-poor gas from the environment around the star.
Astroseismic analysis using spectroscopic data indicates that the rotational inclination of the star is constrained to be greater than or approximately equal to 40°.
In addition, (a) the Phlegraean Fields caldera explosion, which occurred 39,850 years ago, would have stalled the Neandertal/modern human admixture front because of the population sink it generated in Central and Eastern Europe, and (b) the long period of ameliorated climate that came soon after (Greenland Interstadial 8, during which forests underwent a marked expansion in Iberian regions south of 40°N) would have enhanced the “Ebro Frontier” effect.
These findings have two broader paleoanthropological implications: firstly, that, below the Ebro, the archeological record made prior to 37,000 years ago must be attributed, in all its aspects and components, to the Neandertals (or their ancestors); secondly, that modern human emergence is best seen as an uneven, punctuated process during which long-lasting barriers to gene flow and cultural diffusion could have existed across rather short distances, with attendant consequences for ancient genetics and models of human population history.The star is also classified as a Lambda Boötis star, which means its surface layers are depleted in iron peak elements.The star HR 8799 is a member of the Lambda Boötis (λ Boo) class, a group of peculiar stars with an unusual lack of metals—elements heavier than hydrogen and helium—in their upper atmosphere.This chronology represents a lag of minimally 3000 years with the rest of Europe, where that transition and the associated process of Neandertal/modern human admixture took place between 40,000 and 42,000 years ago.The lag implies the presence of an effective barrier to migration and diffusion across the Ebro river depression, which, based on available paleoenvironmental indicators, would at that time have represented a major biogeographical divide.Statistically, for stars hosting a debris disk, the luminosity of this star suggests an age of about 20–150 million years.