GG Tauri A: dark shadows on the ringworld

R Brauer,A Dutrey,E Pantin,E Habart,S Guilloteau,E Di Folco

doi:10.1051/0004-6361/201935966

R Brauer, A Dutrey + Show 4 more

Open Access

https://doi.org/10.1051/0004-6361/201935966

Copy DOI

Abstract

Context. With its high complexity, large size, and close distance, the ringworld around GG Tau A is an appealing case to study the formation and evolution of protoplanetary disks around multiple star systems. However, investigations with radiative transfer models usually neglect the influence of the circumstellar dust around the individual stars. Aims. We investigate how circumstellar disks around the stars of GG Tau A influence the emission that is scattered at the circumbinary disk and if constraints on these circumstellar disks can be derived. Methods. We performed radiative transfer simulations with the POLArized RadIation Simulator (POLARIS) to obtain spectral energy distributions and emission maps in the H-Band (near-infrared). Subsequently, we compared them with observations to achieve our aims. Results. We studied the ratio of polarized intensity at different locations in the circumbinary disk. We conclude that the observed scattered-light near-infrared emission is best reproduced if the circumbinary disk lies in the shadow of at least two coplanar circumstellar disks surrounding the central stars. This implies that the inner wall of the circumbinary disk is strongly obscured around the midplane, while the observed emission is actually dominated by the upper-most disk layers. In addition, the inclined dark lane (“gap”) on the western side of the circumbinary disk, which has been a stable, nonrotating, feature for approximately 20 yr, can only be explained by the self-shadowing of a misaligned circumstellar disk surrounding one of the two components of the secondary close-binary star GG Tau Ab.

Highlights

The formation of stars and their surrounding disks due to a collapse of a molecular cloud is still an ongoing topic of research (e.g., Petr-Gotzens et al 2015; Dutrey et al 2016)
We investigate how circumstellar disks around the stars of GG Tau A influence the emission that is scattered at the circumbinary disk and if constraints on these circumstellar disks can be derived
We studied the ratio of polarized intensity at different locations in the circumbinary disk

Summary

Introduction

The formation of stars and their surrounding disks due to a collapse of a molecular cloud is still an ongoing topic of research (e.g., Petr-Gotzens et al 2015; Dutrey et al 2016). We performed radiative transfer (RT) simulations to derive constraints on the structure and orientation of the circumstellar disks by comparing simulated emission maps and spectral energy distributions with observations. In contrast to previous studies, we considered the circumstellar disks as spatially resolved in our model of GG Tau A. We included the CS disks around the stars in our radiative transfer model and investigated their influence on the emission of GG Tau A. Circumbinary disk Observations of the CB disk around the stars of GG Tau A show an almost smooth and continuous ring-like dust distribution with brightness variations that are usually caused by the subtraction of the point spread function (PSF), the scattering phase function of the dust grains, and the inclination of the disk (e.g., Fig. 5 top left; Duchêne et al 2004; Yang et al 2017). The inner CS disks and the orbit of the stars are in the same plane as the CB disk, unless otherwise noted

Dust grains

Disks around Ab1 and Ab2

Conclusions