Debris disks as seen by Herschel/DUNES

Abstract

The far-infrared excesses produced by debris disks are common features of stellar systems. These disks are thought to contain solids ranging from micron-sized dust to planetesimals. Naturally, their formation and evolution are linked to those of potential planets. With this motivation, the Herschel open time key programme DUNES (DUst around NEarby Stars) aims at further characterising known debris disks and discovering new ones in the regime explored by the Herschel space observatory. On the one hand, in their survey of 133 nearby FGK stars, DUNES discovered a class of extremely cold and faint debris disks, different from well-known disks such as the one around Vega in that their inferred typical grain sizes are rather large, indicating low dynamical excitation and low collision rates. On the other hand, for the more massive disk around the sun-like star HD 207129, well-resolved PACS images confirmed the ring-liked structure seen in HST images and provided valuable information for an in-depth study and benchmark for models. Employing both models for power-law fitting and collisional evolution we found the disk around HD 207129 to feature low collision rates and large grains, as well. Transport by means of Poynting-Robertson drag likely plays a role in replenishing the dust seen closer to the star, inside of the ring. The inner edge is therefore rather smooth and the contribution from the extended halo of barely bound grains is small. Both slowly self-stirring and planetary perturbations could potentially have formed and shaped this disk.

PROBING FOR EXOPLANETS HIDING IN DUSTY DEBRIS DISKS: DISK IMAGING, CHARACTERIZATION, AND EXPLORATION WITHHST/STIS MULTI-ROLL CORONAGRAPHY

“…They none-the-less offer symbiotic capabilities for imaging moderate contrast features in the bright regions of angularly small disks, enhanced when limited to polarized flux, in particular in the nIR where Strehl ratios and imaging performance is improved (and with spatial resolution, e.g., in K-band, comparable to STIS in the optical and thus providing, in combination, significant color diagnostics).In addition to the remainder of the approximately dozen HST-discovery images of debris disks not followed up in this study, including a few recently found in NICMOS LAPLACE reprocessed data withKLIP (Elodie et al 2014), there are now known debris disks at < 50 pc that are resolved at long wavelength by the Herschel Space Observatory. E.g., HD 139664 (reported in this paper with STIS), HD 127821 and HD 13337 all L IR /L star ~ 10 -4(Su et al 2013), HD 207129(Löhne et al 2012) and Eta Crv(Duchêne et al 2014). These Herschelresolved debris disks are typically too large in angular extent to image with extreme AO systems (and in some cases too large for complete imaging by the James Web Space Telescope (JWST)), but can be fully imaged with HST/STIS.…”

“…reprocessed data withKLIP (Elodie et al 2014), there are now known debris disks at < 50 pc that are resolved at long wavelength by the Herschel Space Observatory. E.g., HD 139664 (reported in this paper with STIS), HD 127821 and HD 13337 all L IR /L star ~ 10 -4(Su et al 2013), HD 207129(Löhne et al 2012) and Eta Crv(Duchêne et al 2014). These Herschelresolved debris disks are typically too large in angular extent to image with extreme AO systems (and in some cases too large for complete imaging by the James Web Space Telescope (JWST)), but can be fully imaged with HST/STIS.…”

Temperature condensation trend in the debris-disk binary systemζ2Reticuli

“…The satellite Herschel overcome some of these difficulties, thanks to their greater sensivity and spatial resolution. Different Herschel surveys such as SUNS, DEBRIS (Matthews et al 2010;Phillips et al 2010), and DUNES (Eiroa et al 2010;Löhne et al 2012;Eiroa et al 2013) do include multiple systems in their samples. However, the circumstellar nature of the dust have been determined in few multiple systems (see e.g.…”

ExoVista: A Suite of Planetary System Models for Exoplanet Studies

“…For the massive, collisional disks we currently observe, only a small fraction of the dust spirals inward, such that the disk density interior to the ring is a much smaller fraction of the ring itself. However, theoretical studies suggest a much larger fraction of dust will spiral inward in less massive disks where collisions are rare, so much so that the disk can appear to be continuous all the way from the ring in to the sublimation distance when viewed at visible wavelengths (e.g., Wyatt 1999;Kuchner & Stark 2010;Löhne et al 2012;Kennedy & Piette 2015).…”