Accounting for the foreground contribution to the dust emission towards Kepler's supernova remnant
Whether or not supernovae contribute significantly to the overall dust budget is a controversial subject. Submillimetre (sub-mm) observations, sensitive to cold dust, have shown an excess at 450 and 850 μm in young remnants Cassiopeia A (Cas A) and Kepler. Some of the sub-mm emission from Cas A has been shown to be contaminated by unrelated material along the line of sight. In this paper, we explore the emission from material towards Kepler using sub-mm continuum imaging and spectroscopic observations of atomic and molecular gas, via H i, 12CO(J= 2–1) and 13CO(J= 2–1). We detect weak CO emission (peak T*A = 0.2–1 K, 1–2 km s−1 full width at half-maximum) from diffuse, optically thin gas at the locations of some of the sub-mm clumps. The contribution to the sub-mm emission from foreground molecular and atomic clouds is negligible. The revised dust mass for Kepler's remnant is 0.1–1.2 M⊙ , about half of the quoted values in the original study by Morgan et al., but still sufficient to explain the origin of dust at high redshifts.
Published inMonthly Notices of the Royal Astronomical Society