摘要:Context. Debris discs are a consequence of the planet formation process
and constitute the fingerprints of planetesimal systems. Their counterparts in the solar
system are the asteroid and Edgeworth-Kuiper belts.
Aims. The aim of this paper is to provide robust numbers for the
incidence of debris discs around FGK stars in the solar neighbourhood.
Methods. The full sample of 177 FGK stars with d ≤ 20 pc proposed for the
DUst around NEarby Stars (DUNES) survey is presented. Herschel/PACS
observations at 100 and 160 μm were obtained, and were complemented in some cases
with data at 70 μm and at 250, 350, and 500 μm SPIRE photometry. The
123 objects observed by the DUNES collaboration were presented in a previous paper. The
remaining 54 stars, shared with the Disc Emission via a Bias-free Reconnaissance in IR and
Sub-mm (DEBRIS) consortium and observed by them, and the combined full sample are studied
in this paper. The incidence of debris discs per spectral type is analysed and put into
context together with other parameters of the sample, like metallicity, rotation and
activity, and age.
Results. The subsample of 105 stars with d ≤ 15 pc containing 23 F,
33 G, and 49 K stars is complete for F stars, almost complete for G stars, and contains a
substantial number of K stars from which we draw solid conclusions on objects of this
spectral type. The incidence rates of debris discs per spectral type are 0.26+0.21-0.14 (6 objects with excesses out of 23 F stars), 0.21+0.17-0.11 (7 out of 33 G stars), and 0.200.14-0.09 (10 out of 49 K stars); the fraction for all three
spectral types together is 0.22+0.08-0.07 (23 out of 105 stars). The uncertainties correspond to
a 95% confidence level. The medians of the upper limits of Ldust/L∗
for each spectral type are 7.8 ×
10-7 (F), 1.4 ×
10-6 (G), and 2.2 × 10-6 (K); the lowest values are around
4.0 × 10-7. The
incidence of debris discs is similar for active (young) and inactive (old) stars. The
fractional luminosity tends to drop with increasing age, as expected from collisional
erosion of the debris belts.