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The transiting dust clumps in the evolved disc of the Sun-like UXor RZ Psc

Published version
Peer-reviewed

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Authors

Kennedy, GM 
Kenworthy, MA 
Pepper, J 
Rodriguez, JE 
Siverd, RJ 

Abstract

RZ Psc is a young Sun-like star, long associated with the UXor class of variable stars, which is partially or wholly dimmed by dust clumps several times each year. The system has a bright and variable infrared excess, which has been interpreted as evidence that the dimming events are the passage of asteroidal fragments in front of the host star. Here, we present a decade of optical photometry of RZ Psc and take a critical look at the asteroid belt interpretation. We show that the distribution of light curve gradients is non-uniform for deep events, which we interpret as possible evidence for an asteroidal fragment-like clump structure. However, the clumps are very likely seen above a high optical depth midplane, so the disc's bulk clumpiness is not revealed. While circumstantial evidence suggests an asteroid belt is more plausible than a gas-rich transition disc, the evolutionary status remains uncertain. We suggest that the rarity of Sun-like stars showing disc-related variability may arise because (i) any accretion streams are transparent and/or (ii) turbulence above the inner rim is normally shadowed by a flared outer disc.

Description

Keywords

circumstellar matter, debris discs, protoplanetary discs, variable stars

Journal Title

Royal Society Open Science

Conference Name

Journal ISSN

2054-5703
2054-5703

Volume Title

4

Publisher

The Royal Society Publishing
Sponsorship
Royal Society (UF140298)
Science and Technology Facilities Council (ST/N000927/1)
European Research Council (279973)
G.M.K. is supported by the Royal Society as a Royal Society University Research Fellow. J.E.R. is supported as a Future Faculty Leaders Fellow at the Harvard-Smithsonian Center for Astrophysics. M.C.W. acknowledges support from the European Union through ERC grant no. 279973. Early work on KELT-North was supported by NASA grant no. NNG04GO70G.