Silica-Rich Bright Debris Disk around HD 15407A

TL;DR

This paper reports the discovery of a silica-rich, warm debris disk around HD 15407A, with an unusually large amount of fine dust located near the terrestrial planet zone, indicating recent or ongoing dust production.

Contribution

It provides detailed characterization of a unique debris disk with high fractional luminosity and silica-rich dust, suggesting a different origin or evolution compared to typical debris disks.

Findings

Detected large amount of warm fine dust (~10^(-7) M_Earth)

Dust temperature estimated at 500-600 K, located 0.6-1.0 AU from star

Mid-infrared spectrum shows abundant silica dust

Abstract

We report an intriguing debris disk towards the F3V star HD 15407A, in which an extremely large amount of warm fine dust (~ 10^(-7) M_Earth) is detected. The dust temperature is derived as ~ 500-600 K and the location of the debris dust is estimated as 0.6-1.0 AU from the central star, a terrestrial planet region. The fractional luminosity of the debris disk is ~ 0.005, which is much larger than those predicted by steady-state models of the debris disk produced by planetesimal collisions. The mid-infrared spectrum obtained by Spitzer indicates the presence of abundant micron-sized silica dust, suggesting that the dust comes from the surface layer of differentiated large rocky bodies and might be trapped around the star.