The asymmetric structure of the inner disc around HD 142527 A with VLTI/MATISSE

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
² Fakultät für Physik und Astronomie, Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
³ HUN-REN Research Centre for Astronomy and Earth Sciences, Konkoly Observatory, MTA Centre of Excellence, KonkolyThege Miklós út 15-17., 1121 Budapest, Hungary
⁴ Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Boulevard de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
⁵ Ludwig-Maximilians-Universität München, Universitäts-Sternwarte, Scheinerstr. 1, 81679 München, Germany
⁶ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA, Leiden, The Netherlands
⁷ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
⁸ I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
⁹ Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands
¹⁰ SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands
¹¹ Institute for Mathematics, Astrophysics and Particle Physics, Radboud University, PO Box 9010, MC 62 6500 GL Nijmegen, The Netherlands
¹² Center for Astrophysics Harvard & Smithsonian : 60 Garden Street, Cambridge, MA 02138, USA
¹³ NASA Goddard Space Flight Center, Astrophysics Division, Greenbelt, MD, 20771, USA
¹⁴ STAR Institute, University of Liège, Quartier Agora - Bât. B5c Allée du Six AoÛt 19C, 4000 Liège, Belgium
¹⁵ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
¹⁶ Institute of Theoretical Physics and Astrophysics, University of Kiel, Leibnizstraße 15, 24118 Kiel, Germany

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Received: 8 August 2025
Accepted: 2 February 2026

Abstract

Context. Circumstellar discs, and especially their inner regions, which cover ranges from less than 1 au to a few au, are the birthplaces of terrestrial planets. The inner regions are thought to be as diverse in structure as the well-observed outer regions probed by ALMA.

Aims. By combining data and results from previous studies using the VLTI/PIONIER and VLTI/GRAVITY instruments with new, multi-epoch VLTI/MATISSE observations, we aim to provide a comprehensive picture of the structure of the inner regions of the circumstellar disc around the F-type Herbig Ae/Be star HD 142527 A, the primary of a binary star system.

Methods. We modelled the multi-wavelength interferometric data using a parametrised, geometrically thin disc model, allowing for azimuthal asymmetry, and exploring a first-order disc modulation and an off-centre Gaussian component.

Results. We find time-variable structures in the N-band observables, which we reproduce with time-dependent models. This variability manifests as azimuthally asymmetric emission, evidenced by strong, non-zero closure phases in the N-band data. Fits to individual epochs of the N-band observations yield better χ²_r values than fits to all epochs simultaneously. This suggests substantial changes in the geometry of the inner disc emission from ∼1 au up to a few astronomical-unit scales from one year to the next. Moreover, our models produce a very close-in inner disc rim R_rim ≈ 0.1 au. Altogether, we find a very complex, substantially non-point symmetric and temporally variable disc (r_out ≲ 6 au) around the primary.

Conclusions. The very close-in inner rim indicates the presence of material within the typical wall-like sublimation radius, R_{rim,literature} ≈ 0.3 au. The complex, temporally variable inner-disc geometry is likely affected, or even caused by, the close passage (∼5 au) and short orbit (P ≈ 24 yr) of the companion HD 142527 B.