Astrophys. J., 791, 98 (2014/August-3)
Searching for dust around hyper metal poor stars.
VENN K.A., PUZIA T.H., DIVELL M., COTE S., LAMBERT D.L. and STARKENBURG E.
Abstract (from CDS):
We examine the mid-infrared fluxes and spectral energy distributions for stars with iron abundances [Fe/H] ←5, and other metal-poor stars, to eliminate the possibility that their low metallicities are related to the depletion of elements onto dust grains in the formation of a debris disk. Six out of seven stars examined here show no mid-IR excesses. These non-detections rule out many types of circumstellar disks, e.g., a warm debris disk (T ≤ 290 K), or debris disks with inner radii ≤ 1 AU, such as those associated with the chemically peculiar post-asymptotic giant branch spectroscopic binaries and RV Tau variables. However, we cannot rule out cooler debris disks, nor those with lower flux ratios to their host stars due to, e.g., a smaller disk mass, a larger inner disk radius, an absence of small grains, or even a multicomponent structure, as often found with the chemically peculiar Lambda Bootis stars. The only exception is HE0107-5240, for which a small mid-IR excess near 10 µm is detected at the 2σ level; if the excess is real and associated with this star, it may indicate the presence of (recent) dust-gas winnowing or a binary system.
dust, extinction - stars: abundances - stars: chemically peculiar - stars: individual: HE0107-5240
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