Limits on unresolved planetary companions to white dwarf remnants of 14 intermediate-mass stars

Abstract

We present Spitzer IRAC photometry of white dwarf remnants of 14 stars with M = 3-5 M ⊙. We do not detect mid-infrared excess around any of our targets. By demanding a 3σ photometric excess at 4.5 μm for unresolved companions, we rule out planetary mass companions down to 5, 7, or 10 M J for 13 of our targets based on the Burrows et al. substellar cooling models. Combined with previous IRAC observations of white dwarf remnants of intermediate-mass stars, we rule out ≥10M J companions around 40 white dwarfs and ≥5M J companions around 10 white dwarfs. © 2009. The American Astronomical Society. All rights reserved.