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Abstract Transition disks, with inner regions depleted in dust and gas, could represent later stages of protoplanetary disk evolution when newly formed planets are emerging. The PDS 70 system has attracted particular interest because of the presence of two giant planets in orbits at tens of astronomical units within the inner disk cavity, at least one of which is itself accreting. However, the region around PDS 70 most relevant to understanding the planet populations revealed by exoplanet surveys of middle-aged stars is the inner disk, which is the dominant source of the system’s excess infrared emission but only marginally resolved by the Atacama Large Millimeter/submillimeter Array. Here we present and analyze time-series optical and infrared photometry and spectroscopy that reveal the inner disk to be dynamic on timescales of days to years, with occultation by submicron dust dimming the star at optical wavelengths, and 3–5μm emission varying due to changes in disk structure. Remarkably, the infrared emission from the innermost region (nearly) disappears for ∼1 yr. We model the spectral energy distribution of the system and its time variation with a flattened warm (T≲ 600 K) disk and a hotter (1200 K) dust that could represent an inner rim or wall. The high dust-to-gas ratio of the inner disk, relative to material accreting from the outer disk, means that the former could be a chimera consisting of depleted disk gas that is subsequently enriched with dust and volatiles produced by collisions and evaporation of planetesimals in the inner zone.
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RZ Piscium Hosts a Compact and Highly Perturbed Debris Disk
Abstract RZ Piscium (RZ Psc) is well known in the variable star field because of its numerous irregular optical dips in the past 5 decades, but the nature of the system is heavily debated in the literature. We present multiyear infrared monitoring data from Spitzer and WISE to track the activities of the inner debris production, revealing stochastic infrared variability as short as weekly timescales that is consistent with destroying a 90 km sized asteroid every year. ALMA 1.3 mm data combined with spectral energy distribution modeling show that the disk is compact (∼0.1–13 au radially) and lacks cold gas. The disk is found to be highly inclined and has a significant vertical scale height. These observations confirm that RZ Psc hosts a close to edge-on, highly perturbed debris disk possibly due to migration of recently formed giant planets that might be triggered by the low-mass companion RZ Psc B if the planets formed well beyond the snowlines.
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- Award ID(s):
- 2307920
- PAR ID:
- 10509350
- Publisher / Repository:
- The Astrophysical Journal
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 959
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 43
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3847/1538-4357/ad04d9
