Mid‐Infrared Spectra of Dust Debris around Main‐Sequence Stars

Abstract

We report spectra obtained with the Spitzer Space Telescope in theλ=14-35μm range of 19 nearby main-sequence stars with infrared excesses.The six stars with strong dust emission show no recognizable spectralfeatures, suggesting that the bulk of the emitting particles havediameters larger than 10 μm. If the observed dust results from collisionalgrinding of larger solids, we infer minimum masses of the parentbody population between 0.004 and 0.06 M⊕. We estimate grain productionrates of ~1010 g s-1 around λ Boo and HR 1570; selective accretionof this matter may help explain their peculiar surface abundances.There appear to be inner truncations in the dust clouds at 48, 11,52, and 54 AU around HR 333, HR 506, HR 1082, and HR 3927, respectively.Based on observations with the NASA Spitzer Space Telescope, whichis operated by the California Institute of Technology for NASA.