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Post Info TOPIC: RZ Piscium
Blobrana


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Posts: 131433
Date:
TYC 1753-1498-1
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Title: The transiting dust clumps in the evolved disk of the Sun-like UXor RZ Psc
Author: Grant M. Kennedy, Matthew A. Kenworthy, Joshua Pepper, Joseph E. Rodriguez, Robert J. Siverd, Keivan G. Stassun, Mark C. Wyatt

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 mid-plane, so the disk's bulk clumpiness is not revealed. While circumstantial evidence suggests an asteroid belt is more plausible than a gas-rich transition disk, the evolutionary status remains uncertain. We suggest that the rarity of Sun-like stars showing disk-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 disk.

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Blobrana


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Posts: 131433
Date:
RE: RZ Piscium
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Title: An active asteroid belt causing the UX Ori phenomenon in RZ Psc
Authors: W.J. de Wit, V.P. Grinin, I.S. Potravnov, D.N. Shakhovskoi, A. Müller, M. Moerchen

We report the discovery of mid-infrared excess emission in the young object RZ Psc. The excess constitutes ~8% of its Lbol, and is well fit by a single 500K black-body implying a dust free region within 0.7AU for optically thick dust. The object displays dust obscuration events (UXOR behaviour) with a time-scale that suggests dusty material on orbits of 0.5AU. We also report a 12.4 year cyclical photometric variability which can be interpreted as due to perturbations in the dust distribution. The system is characterised by a high inclination, marginal extinction (during bright photometric states), a single temperature for the warm dust, and an age estimate which puts the star beyond the formation stage. We propose that the dust occultation events present a dynamical view of an active asteroid belt whose collisional products sporadically obscure the central star.

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Blobrana


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Posts: 131433
Date:
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Title: The evolutionary status of the UX Orionis star RZ Piscium
Authors: V. P. Grinin, I. S. Potravnov, F. A. Musaev

The star RZ Psc is one of the most enigmatic members of the UX Ori star family. It shows all properties that are typical for these stars (the light variability, high linear polarization in deep minima, the blueing effect) except for one: it lacks any signatures of youth. With the Li I line, as a rough estimate for the stellar age, we show that the "lithium" age of RZ Psc lies between the age of stars in the Pleiades (approximately 70 Myr) and the Orion (approximately 10 Myr) clusters. We also roughly estimated the age of RZ Psc based on the proper motion of the star using the Tycho-2 catalogue. We found that the star has escaped from its assumed birthplace near to the Galactic plane about 30-40 Myr ago. We conclude that RZ Psc is a post-UXOr star, and its sporadic eclipses are caused by material from the debris disk.

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Position (J2000):     R.A. 01 09 42.05  |  Dec. +27° 57' 02.0''



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