Resolving faint structures in the debris disk around TWA 7: Tentative detections of an outer belt, a spiral arm, and a dusty cloud
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Fecha
2018-09
Profesor/a Guía
Facultad/escuela
Idioma
en
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Título del volumen
Editor
EDP Sciences
Nombre de Curso
Licencia CC
CC BY 4.0
Licencia CC
Resumen
Context. Debris disks are the intrinsic by-products of the star and planet formation processes. Most likely due to instrumental limitations and their natural faintness, little is known about debris disks around low mass stars, especially when it comes to spatially resolved observations. Aims. We present new VLT/SPHERE IRDIS dual-polarization imaging (DPI) observations in which we detect the dust ring around the M2 spectral type star TWA 7. Combined with additional angular differential imaging observations we aim at a fine characterization of the debris disk and setting constraints on the presence of low-mass planets. Methods. We modeled the SPHERE DPI observations and constrain the location of the small dust grains, as well as the spectral energy distribution of the debris disk, using the results inferred from the observations, and performed simple N-body simulations. Results. We find that the dust density distribution peaks at ∼0.72′′ (25 au), with a very shallow outer power-law slope, and that the disk has an inclination of ∼13° with a position angle of ∼91° east of north. We also report low signal-to-noise ratio detections of an outer belt at a distance of ∼1.5′′ (∼52 au) from the star, of a spiral arm in the southern side of the star, and of a possible dusty clump at 0.11′′. These findings seem to persist over timescales of at least a year. Using the intensity images, we do not detect any planets in the close vicinity of the star, but the sensitivity reaches Jovian planet mass upper limits. We find that the SED is best reproduced with an inner disk at ∼0.2′′ (∼7 au) and another belt at 0.72′′ (25 au). Conclusions. We report the detections of several unexpected features in the disk around TWA 7. A yet undetected 100M· planet with a semi-major axis at 20-30 au could possibly explain the outer belt as well as the spiral arm. We conclude that stellar winds are unlikely to be responsible for the spiral arm. © 2018 ESO.
Notas
Indexación Scopus
Palabras clave
Exoplanets, Planet, Grain Dust, Instrumentation: high angular resolution, Circumstellar matter
Citación
Astronomy and Astrophysics Volume 6171 September 2018 Article number A109
DOI
10.1051/0004-6361/201832583