VLT/SPHERE Multiwavelength High-contrast Imaging of the HD 115600 Debris Disk: New Constraints on the Dust Geometry and the Presence of Young Giant Planets

Abstract

Young and dynamically active planetary systems can form disks of debris that are easier to image than the planets themselves. The morphology and evolution of these disks can help to infer the properties of the putative planets responsible for generating and shaping the debris structures. We present integral field spectroscopy and dual-band imaging from VLT/SPHERE (1.0 − 1.7µm) of the debris disk around the young F2V/F3V star HD 115600. We aim to 1) characterize the geometry and composition of the debris ring, 2) search for thermal emission of young giant planets, and 3) in the absence of detected planets, to refine the inferred properties of plausible planets around HD 115600 to prepare future attempts to detect them. Using a different dust scattering model (ZODIPIC) than in the discovery paper (Henyey-Greenstein) to model the disk geometry, we find a 0 = 46 ± 2 au for the disk's central radius and offsets ∆α, ∆δ = −1.0 ± 0.5, 0.5 ± 0.5 au. This offset is smaller than previously found, suggesting that unseen planets of lower masses could be sculpting the disk. Spectroscopy of the disk in Y-J bands with SPHERE shows reddish color, which becomes neutral or slightly blue in H band seen with GPI, broadly consistent with a mixed bulk disk composition of processed organics and water ice. While our observed field contains numerous background objects at wide separations, no exoplanet has been directly observed to a mass sensitivity limit of 2 − 3(5 − 7)M J between a projected separation of 40 and 200 au for hot (cold)-start models.

Debris Disk Results from the Gemini Planet Imager Exoplanet Survey's Polarimetric Imaging Campaign

“…5. HD 115600 is also detected for the first time in polarized intensity, with previous total intensity detections produced by GPI (Currie et al 2015b) and SPHERE (Gibbs et al 2019). Under the assumption of forward-scattering dust, our polarized intensity data identify the front side (i.e., near side) of the disk to be the NW side.…”

Multiband Imaging of the HD 36546 Debris Disk: A Refined View from SCExAO/CHARIS*

“…In this study, we present the first multiwavelength scattered-light imaging of the debris disk around HD 36546 (Currie et al 2017), using the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system and the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) integral field spectrograph in broadband (spanning NIR J, H, and K bands, 1.13-2.39 μm) mode (Groff et al 2016). HD 36546ʼs disk is highly inclined, bright in scattered light, and has an extremely high fractional luminosity (L IR /L å ∼ 4 × 10 −3 ) comparable to long-studied debris disks around β Pictoris and HR 4796A as well as new benchmarks such as HD 115600 (Smith & Terrile 1984;Schneider et al 2014;Currie et al 2015b;Millar-Blanchaer et al 2015;Gibbs et al 2019).…”

PACO ASDI: an algorithm for exoplanet detection and characterization in direct imaging with integral field spectrographs

“…The results are compared to two standard algorithms: TLOCI and KLIP. These two algorithms are currently used for the exploitation of the SPHERE science data (Lagrange et al 2019a;Mesa et al 2019b;Gratton et al 2019;Gibbs et al 2019;Maire et al 2019). In the following, they are applied both in ADI and ASDI mode.…”

“…This could be explained by the stronger source selfsubtraction that occurs when several spectral channels are processed jointly. This observation could illustrate why experts tend to apply also ADI detection and/or characterization algorithms on ASDI datasets by processing each spectral channel independently (Nielsen et al 2017;Perrot et al 2019;Gibbs et al 2019;Maire et al 2020, see also Maire et al 2014Rameau et al 2015 for the challenge of ASDI processing). The empirical confidence intervals are also smaller with PACO ASDI.…”