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Gap, Shadows, Spirals, and Streamers: SPHERE Observations of Binary-Disk Interactions in GG Tauri A

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Gap, Shadows, Spirals, and Streamers: SPHERE Observations of Binary-Disk Interactions in GG Tauri A UvA-DARE (Digital Academic Repository) Gap, shadows, spirals, and streamers SPHERE observations of binary-disk interactions in GG Tauri A Keppler, M.; Penzlin, A.; Benisty, M.; van Boekel, R.; Henning, T.; van Holstein, R.G.; Kley, W.; Garufi, A.; Ginski, C.; Brandner, W.; Bertrang, G.H.-M.; Boccaletti, A.; de Boer, J.; Bonavita, M.; Brown Sevilla, S.; Chauvin, G.; Dominik, C.; Janson, M.; Langlois, M.; Lodato, G.; Maire, A.-L.; Ménard, F.; Pantin, E.; Pinte, C.; Stolker, T.; Szulágyi, J.; Thebault, P.; Villenave, M.; Zurlo, A.; Rabou, P.; Feautrier, P.; Feldt, M.; Madec, F.; Wildi, F. DOI 10.1051/0004-6361/202038032 Publication date 2020 Document Version Final published version Published in Astronomy & Astrophysics License CC BY Link to publication Citation for published version (APA): Keppler, M., Penzlin, A., Benisty, M., van Boekel, R., Henning, T., van Holstein, R. G., Kley, W., Garufi, A., Ginski, C., Brandner, W., Bertrang, GH-M., Boccaletti, A., de Boer, J., Bonavita, M., Brown Sevilla, S., Chauvin, G., Dominik, C., Janson, M., Langlois, M., ... Wildi, F. (2020). Gap, shadows, spirals, and streamers: SPHERE observations of binary-disk interactions in GG Tauri A. Astronomy & Astrophysics, 639, [A62]. https://doi.org/10.1051/0004-6361/202038032 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material UvA-DAREinaccessible is a serviceand/or provided remove by it the from library the of website. the University Please of Amsterdam Ask the (http Library:s://dare.uva.nl) https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. A&A 639, A62 (2020) Astronomy https://doi.org/10.1051/0004-6361/202038032 & © M. Keppler et al. 2020 Astrophysics Gap, shadows, spirals, and streamers: SPHERE observations of binary-disk interactions in GG Tauri A? M. Keppler1, A. Penzlin2, M. Benisty3,4, R. van Boekel1, T. Henning1, R. G. van Holstein5,6, W. Kley2, A. Garufi7, C. Ginski8,5, W. Brandner1, G. H.-M. Bertrang1, A. Boccaletti9, J. de Boer5, M. Bonavita10,11, S. Brown Sevilla1, G. Chauvin3,4, C. Dominik8, M. Janson12, M. Langlois13,14, G. Lodato15, A.-L. Maire16,1, F. Ménard3, E. Pantin17, C. Pinte18,3, T. Stolker19, J. Szulágyi20, P. Thebault21, M. Villenave3, A. Zurlo22,23,14, P. Rabou3, P. Feautrier3, M. Feldt1, F. Madec14, and F. Wildi24 (Affiliations can be found after the references) Received 26 March 2020 / Accepted 15 May 2020 ABSTRACT Context. A large portion of stars is found to be part of binary or higher-order multiple systems. The ubiquity of planets found around single stars raises the question of whether and how planets in binary systems form. Protoplanetary disks are the birthplaces of planets, and characterizing them is crucial in order to understand the planet formation process. Aims. Our goal is to characterize the morphology of the GG Tau A disk, one of the largest and most massive circumbinary disks. We also aim to trace evidence for binary-disk interactions. Methods. We obtained observations in polarized scattered light of GG Tau A using the SPHERE/IRDIS instrument in the H-band filter. We analyzed the observed disk morphology and substructures. We ran 2D hydrodynamical models to simulate the evolution of the circumbinary ring over the lifetime of the disk. Results. The disk and also the cavity and the inner region are highly structured, with several shadowed regions, spiral structures, and streamer-like filaments. Some of these are detected here for the first time. The streamer-like filaments appear to connect the outer ring with the northern arc. Their azimuthal spacing suggests that they may be generated through periodic perturbations by the binary, which tear off material from the inner edge of the outer disk once during each orbit. By comparing observations to hydrodynamical simulations, we find that the main features, in particular, the gap size, but also the spiral and streamer filaments, can be qualitatively explained by the gravitational interactions of a binary with a semimajor axis of 35 au on an orbit coplanar with the circumbinary ring. ∼ Key words. stars: individual: GG Tau A – protoplanetary disks – methods: observational – methods: numerical – techniques: high angular resolution – techniques: polarimetric 1. Introduction eccentricity) be dominated by the gravitational perturbation of the central binary. As a consequence, the binary-disk interac- Almost half of all main-sequence solar-type stars are found in tion has severe implications for the planet formation process. binary or higher-order multiple systems (e.g., Raghavan et al. Tidal interactions exerted by the binary are expected to trun- 2010; Duchêne & Kraus 2013), and it is thought that the fraction cate the individual circumstellar disks, reducing their masses, of multiple systems is even higher among pre-main sequence outer radii, and viscous timescales (e.g., Papaloizou & Pringle stars (e.g., Duchêne 1999; Kraus et al. 2011). More than 4000 1977; Artymowicz & Lubow 1994; Rosotti & Clarke 2018). In detections of extrasolar planets around single stars to date show addition, the tidal torques will truncate the circumbinary disk that the assembly of planetary bodies is a common byproduct of from the inner edge by opening a large inner cavity. Despite the star formation. The high abundance of multiple stars on the one resulting separation of circumbinary and circumstellar material, hand and planetary companions on the other hand thus raises the gas streams through the gap may form, supplying the circumstel- question about the possible formation pathways and prevalence lar disks with material from the outer circumbinary disk (e.g., of planets in multiple systems. Artymowicz & Lubow 1996; Muñoz et al. 2020). While obser- While our understanding of the building-up of planets vational trends infer binary interaction to be indeed destructive within protoplanetary disks around single stars has significantly for disks in many cases (e.g., Bouwman et al. 2006; Duchêne advanced in the past years, less is known about the condi- 2010; Harris et al. 2012; Cox et al. 2017; Akeson et al. 2019; tions of planet formation in multiple systems (e.g., Thebault Manara et al. 2019), potentially impeding the formation of plan- & Haghighipour 2015). In contrast to the single-star case, the ets, several massive disks around binary systems are known and evolution of material in the circumbinary and individual cir- have been observed at high angular resolution (e.g., UY Aur, cumstellar disks in multiple systems will (depending on the HD142527, HD 34700 A; Hioki et al. 2007; Tang et al. 2014; binary parameters such as mass ratio, orbital separation, and Avenhaus et al. 2017; Monnier et al. 2019). ? Based on observations performed with VLT/SPHERE under pro- Despite the potential complications for planet formation gram ID 198.C-0209(N). induced by the gravitational perturbations from the binary, more A62, page 1 of 15 Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Open Access funding provided by Max Planck Society. A&A 639, A62 (2020) than 100 planets in binary systems have already been discov- (e.g., Artymowicz & Lubow 1994), the knowledge of the binary ered (e.g., Martin 2018; Bonavita & Desidera 2020)1. Most of orbit is required in order to compare the observed gap size with these planets are found to orbit only one of the binary stars (i.e., theoretical predictions. Based on almost two decades of orbital “S-type”, i.e., circumstellar planets). The reason for this certainly monitoring, a best-fit orbit with a semimajor axis of 36 au and an is that the radial velocity and transit photometry methods, which eccentricity of 0.28 has been established (Köhler 2011). How- represent the most successful planet detection methods in terms ever, this orbital solution assumes that the orbit is coplanar of numbers, are strongly biased toward planets on short orbital with the circumbinary ring; when this assumption is relaxed, the periods. Nevertheless, about 20 planets have been discovered orbital solution is less well constrained and allows for larger orbit on orbits surrounding both binary components (i.e., “P-type”, sizes. Several theoretical studies have concluded that in order to i.e., circumbinary planets) (e.g., Doyle et al. 2011; Orosz et al. explain the observed gap size of 190 au, the binary orbit should 2019). The statistical analysis of the first direct-imaging survey have a semimajor axis of about ∼65 au, that is, about one-third of dedicated to finding planets orbiting two stars suggests that the the gap size. To still remain consistent∼ with the astrometric con- distributions of planets and brown dwarfs are indistinguishable straints, such a large binary orbit would have to be misaligned between single and binary stars within the error bars (Bonavita with respect to the circumbinary disk (e.g., Beust & Dutrey et al. 2016; Asensio-Torres et al. 2018). This implies that planet 2005; Cazzoletti et al. 2017; Aly et al. 2018). It is clear that the formation in multiple systems, and in particular, in circumbinary respective geometry and orientation of binary orbit and circum- disks indeed occurs.
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