Debris disks around stars in the NIKA2 era

J F Lestrade ,M Calvo ,R Adam ,Mark Booth ,P Thébault ,S Shu ,J Goupy ,G Lagache ,G Pisano ,N Ponthieu ,K Schuster ,F Ruppin ,H Aussel ,Peter A R Ade ,A Monfardini ,J.-C Augereau ,F.‐X Désert ,C Krämer ,H Roussel ,F Kéruzoré ,A Bideaud ,Philip Daniel Mauskopf ,A Gómez ,A Sievers ,B Ladjelate ,C Romero ,Charlene Lefèvre ,J F Macías-Pérez ,A Catalano ,S Leclercq ,P André ,M De Petris ,A Ritacco ,A Benoı̂t ,E F C Driessen ,F Mayet ,W S Holland ,Anita Beelen ,A Andrianasolo ,B Comis ,O Bourrion ,C Tucker ,L Perotto ,V Revéret ,S Doyle ,R Zylka

doi:10.1051/epjconf/202022800015

Abstract

The new NIKA2 camera at the IRAM 30m radiotelescope was used to observe three known debris disks in order to constrain the SED of their dust emission in the millimeter wavelength domain. We have found that the spectral index between the two NIKA2 bands (1mm and 2mm) is consistent with the Rayleigh-Jeans regime (λ-2), unlike the steeper spectra (λ-3) measured in the submillimeter-wavelength domain for two of the three disks - around the stars Vega and HD107146. We provide a succesful proof of concept to model this spectral inversion in using two populations of dust grains, those smaller and those larger than a grain radius a0 of 0.5mm. This is obtained in breaking the slope of the size distribution and the functional form of the absorption coefficient of the standard model. The third disk - around the star HR8799 - does not exhibit this spectral inversion but is also the youngest.

Highlights

We have found that the spectral index between the two NIKA2 bands (1mm and 2mm) is consistent with the
A debris disk orbiting a main sequence star is made of residual planetesimals left over from the agglomeration processes during the early phase of planet formation
The largest planetesimals − sub-km to hundreds of km in diameters − around other stars than the Sun have a total cross sectional area that is insufficient to be detected by our telescopes

Summary

Introduction

A debris disk orbiting a main sequence star is made of residual planetesimals left over from the agglomeration processes during the early phase of planet formation. When giant planets are present in these distant systems, planetesimals are gravitationally stirred and collide at a significant rate to produce a multitude of fragments including a myriad of small dust particles which has a total cross sectional area large enough to be observable for stars up to ∼ 100 pc. This dust can be detected both in scattered light and in thermal emission as an excess above the stellar photospheric level from mid-wave infrared to millimeter wavelengths or longer. We have started NIKA2 observations during winter 2017 to complement these studies with photometry at 1.2mm and 2mm

NIKA2 observations of three stars with known debris disks

Proof of concept to model the spectral inversion

Concluding remarks