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HD 106617


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The primordial abundance of Li-6 and Be-9
Light element (Li-6, Li-7 and Be-9) depletion isochrones for halo starshave been calculated with standard stellar evolution models. Thesemodels include the latest available opacities and are computed throughthe subgiant branch. If Li-6 is not produced in appreciable amounts bystellar flares, then the detection of Li-6 in HD 84937 by Smith,Lambert, and Nissen is compatible with standard stellar evolution andstandard big bang nucleosynthesis only if HD 84937 is a subgiant. Thepresent parallax is consistent with HD 84937 being a subgiant star atthe 2.5 sigma level. The most metal poor star with a measured Be-9abundance is HD 140283, which is a relatively cool subgiant. Standardstellar evolution predicts that Be-9 will have been depleted in thisstar by approx. 0.3 dex (for Teff = 5640 K). Revising theabundance upward changes the oxygen-beryllium relation, suggestingincompatibility with standard cosmic-ray production models, and hence,standard big bang nucleosynthesis. However, an increase in the derivedtemperature of HD 1402283 to 5740 K would result in little depletion ofBe-9 and agreement with standard big bang nucleosynthesis.

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Gözlemler ve gökölçümü verileri

Takýmyýldýz:Buyuk Ayi
Sað Açýklýk:12h15m38.15s
Yükselim:+57°36'26.2"
Görünürdeki Parlaklýk:8.212
Uzaklýk:141.443 parsek
özdevim Sað Açýklýk:-80.9
özdevim Yükselim:11.7
B-T magnitude:8.687
V-T magnitude:8.252

Kataloglar ve belirtme:
Özgün isimleri   (Edit)
HD 1989HD 106617
TYCHO-2 2000TYC 3840-699-1
USNO-A2.0USNO-A2 1425-07787996
HIPHIP 59794

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