Debris disks from the Herschel/DUNES survey

DUst Around NEarby Stars. The survey observational results

Concerning planet hosts -

Quote :

8.5. Debris discs/planets

The number of known stars hosting exoplanets in the DUNES sample is 21. This figure includes HIP 107350 with a companion of mass MP = 16 MJ , i.e., in the brown dwarf mass regime although it is listed in the Extrasolar Planets Encyclopaedia (http://exoplanet.eu). Six of these stars - HIP 7978, HIP 14954, HIP 27887, HIP 65721, HIP 107350, and HIP 109378 - have debris disc detected with Herschel. A further star, HIP 40693 has a warm disc (Beichman et al. 2005) but no excess in our images. HIP 27887 and HIP 109378 are new debris disc detections by Herschel. If we consider the 20 pc DUNES sample, the number of stars hosting planets is 16, out of which 4 have debris discs (HIP 107350 is not included). Thus, the incidence rate of debris discs among exoplanet hosts is 25% ± 5%, i.e., only marginally larger than the fraction of discs around stars irrespective of whether they host a planet. HIP 7978, HIP 107350 and HIP 109378 have been studied by Liseau et al. (2010), Ertel et al. (2012a) and Eiroa et al. (2011), respectively. All DUNES and DEBRIS stars hosting exoplanets, including the disc nondetections, currently are the subject of a detailed treatment in two papers in preparation (Marshall et al., and Moro-Martín et al.).

Those stars are:

HIP #	Common name(s)
HIP 7978	HD 10647, q1 Eridani
HIP 14954	94 Ceti, HD 19994 (binary or triple, crossing disk?)
HIP 27887	HD 40307
HIP 65721	70 Virginis
HIP 107350	HN Pegasi
HIP 109378	HD 210277
HIP 40693	HD 69830

Concerning those two new detections:

• I shouldn't have to tell you why HD 40307 is significant. The presence of a fairly wide (46 AU) and faint (2.9*10^-5 Lstar) disk is similar to that of the Edgeworth-Kuiper belt and is one of the faintest debris disks yet known. HD 40307 joins Tau Ceti in possession of a large, low-mass planetary system and residual material from their formation.
  
  
• HD 210277 is an interesting one, and not because of the previously-proposed-but-then-disproved disk; more rather, its Jovian planetary companion has a high eccentricity (0.48) that is likely best caused by planet-planet scattering. The disk probably escaped damage during planetary formation because it is very wide (160 AU), but it is still quite faint (5.4*10^-5 Lstar).
  

Notable new detections from non-planet hosts are a cold disk for the nearby, solar type ~30 AU binary Alpha Mensae (HIP 29271), a disk for the young, very nearby late-K Groombridge 1618 (HIP 49908) and the also young RS CvN binary DE Boötis (HIP 72848), and finally an extremely faint disk for the early-type 110 Herculis (HIP 92043).

The Alpha Mensae and HD 210277 discs were mentioned in this thread.

Hadn't heard that HD 40307 has a debris disc before though.

well you could count Fomalhaut, too. It may be a late asteroid belt, but it could condense to form planets. It already has one in the process of formation Fomalhaut b.

Count it where? If the disc wasn't imaged by Herschel/DUNES survey you cant count it.