New constraints on the HR 8799 planetary system from mid-infrared direct imaging

Abstract

Direct imaging is a tried and tested method of detecting exoplanets in the near infrared, but has so far not been extended to longer wavelengths. New data at mid-IR wavelengths (8-20μm) canprovide additional constraints on planetary atmospheric models. We use the VISIR instrumenton the VLT to detect or set stringent limits on the 8.7μm flux of the four planets surrounding HR8799, and to search for additional companions. We use a novel circularised PSF subtractiontechnique to reduce the stellar signal and obtain instrument limited background levels andobtain optimal flux limits. The BT SETTL isochrones are then used to determine the resultingmass limits. We find flux limits between 0.7 and 3.3 mJy for the J8.9 flux of the differentplanets at better than5σlevel and derive a new mass limit of 30 MJupfor any objects beyond40 AU. While this work has not detected planets in the HR 8799 system at 8.7μm, it has foundthat an instrument with the sensitivity of VISIR is sufficient to detect at least 4 known hotplanets around close stars, including\b{eta}Pictoris b (1700 K, 19 pc), with more than5σcertaintyin 10 hours of observing time in the mid-IR.

arXiv commentPublished in MNRAS, 5 pages, 5 figures

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Cited by in corpus (9)

• Four-of-a-kind? Comprehensive atmospheric characterisation of the HR 8799 planets with VLTI/GRAVITY
• A detailed characterization of HR 8799's debris disk with ALMA in Band 7
• On the Chemical Abundance of HR 8799 and the Planet c
• Retrieving C and O Abundance of HR 8799 c by Combining High- and Low-Resolution Data
• Direct emission spectroscopy of exoplanets with the medium resolution imaging spectrometer on board JWST MIRI: I. Molecular mapping and sensitivity to instrumental effects
• Imaging detection of the inner dust belt and the four exoplanets in the HR8799 system with JWST's MIRI coronagraph
• JWST-TST High Contrast: Living on the Wedge, or, NIRCam Bar Coronagraphy Reveals CO${}_2$ in the HR 8799 and 51 Eri Exoplanets' Atmospheres
• Constraints on the nearby exoplanet $\epsilon$ Ind Ab from deep near/mid-infrared imaging limits
• New Mid-Infrared Imaging Constraints on Companions and Protoplanetary Disks around six Young Stars