SEARCHING FOR DUST AROUND HYPER METAL POOR STARS

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 die possibility that their low metallicities are related to the depletion of elements onto dust grains in the formation of a debris disk. Six o...

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Bibliographic Details
Published in:The Astrophysical journal 2014-08, Vol.791 (2), p.1-9
Main Authors: Venn, Kim A, PUZIA, THOMAS H, DIVELL, MIKE, Cote, Stephanie, Lambert, David L, Starkenburg, Else
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ASYMPTOTIC SOLUTIONS
Debris
DETECTION
Disks
Dust
DUSTS
ELEMENT ABUNDANCE
ENERGY SPECTRA
EXCEPTIONS
Fluxes
Grains
HEAT EXCHANGERS
IRON
MASS
METALLICITY
Spectral energy distribution
STARS
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Summary: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 die 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 [< or =, slant] 290 K), or debris disks with inner radii [< or =, slant]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 mu m is detected at the 2[sigma] 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.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1088/0004-637X/791/2/98