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Post Info TOPIC: TYC 8241 2652
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2MASS J12090225-5120410
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Title: TYC 8241 2652 1 and the case of the disappearing disk: no smoking gun yet
Author: Hans Moritz Günther, Stefan Kraus, Carl Melis, Michel Curé, Tim Harries, Michael Ireland, Samer Kanaan, Katja Poppenhaeger, Aaron Rizzuto, David Rodriguez, Christian P. Schneider, Michael Sitko, Gerd Weigelt, Matthew Willson, Scott Wolk

TYC 8241 2652 1 is a young star that showed a strong mid-infrared (mid-IR, 8-25 mu) excess in all observations before 2008 consistent with a dusty disk. Between 2008 and 2010 the mid-IR luminosity of this system dropped dramatically by at least a factor of 30 suggesting a loss of dust mass of an order of magnitude or more. We aim to constrain possible models including removal of disk material by stellar activity processes, the presence of a binary companion, or other explanations suggested in the literature. We present new X-ray observations, optical spectroscopy, near-IR interferometry, and mid-IR photometry of this system to constrain its parameters and further explore the cause of the dust mass loss. In X-rays TYC 8241 2652 1 has all properties expected from a young star: Its luminosity is in the saturation regime and the abundance pattern shows enhancement of O/Fe. The photospheric Ha line is filled with a weak emission feature, indicating chromospheric activity consistent with the observed level of coronal emission. Interferometry does not detect a companion and sets upper limits on the companion mass of 0.2, 0.35, 0.1 and 0.05 M_sun at projected physical separations of 0.1-4 AU,4-5 AU, 5-10 AU, and 10-30 AU, respectively (assuming a distance of 120.9 pc). Our mid-IR measurements, the first of the system since 2012, are consistent with the depleted dust level seen after 2009. The new data confirms that stellar activity is unlikely to destroy the dust in the disk and shows that scenarios where either TYC 8241 2652 1 heats the disk of a binary companion or a potential companion heats the disk of TYC 8241 2652 1 are unlikely.

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Blobrana


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Posts: 131433
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TYC 8241 2652 1
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The Mysterious Case of the Disappearing Dust 

Imagine if the rings of Saturn suddenly disappeared. Astronomers have witnessed the equivalent around a young sun-like star called TYC 8241 2652. Enormous amounts of dust known to circle the star are unexpectedly nowhere to be found. 
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The scientists observed the same star in 2008 using a mid-infrared imager at the Gemini South Observatory in Chile and again with the same ground-based telescope in 2009. The 2008 observation revealed an infrared emission pattern similar to the 1983 measurement, but something surprising happened in 2009: The infrared emission dropped by nearly two-thirds.
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Blobrana


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RE: TYC 8241 2652
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Title: Rapid disappearance of a warm, dusty circumstellar disk 
Authors: Carl Melis, B. Zuckerman, Joseph H. Rhee, Inseok Song, Simon J. Murphy, Michael S. Bessell

Stars form with gaseous and dusty circumstellar envelopes, which rapidly settle into disks that eventually give rise to planetary systems. Understanding the process by which these disks evolve is paramount in developing an accurate theory of planet formation that can account for the variety of planetary systems discovered so far. The formation of Earth-like planets through collisional accumulation of rocky objects within a disk has mainly been explored in theoretical and computational work in which post-collision ejecta evolution is typically ignored, although recent work has considered the fate of such material. Here we report observations of a young, Sun-like star (TYC 8241 2652 1) where infrared flux from post-collisional ejecta has decreased drastically, by a factor of about 30, over a period of less than two years. The star seems to have gone from hosting substantial quantities of dusty ejecta, in a region analogous to where the rocky planets orbit in the Solar System, to retaining at most a meagre amount of cooler dust. Such a phase of rapid ejecta evolution has not been previously predicted or observed, and no currently available physical model satisfactorily explains the observations.

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Position (J2000): R.A. 12 09 02.25 | Dec. -51° 20' 41.0''



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Blobrana


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PLANET-FORMING DISK TURNS OFF LIGHTS

The star -- designated TYC 8241 2652 and a young analogue of our Sun -- only a few years ago displayed all of the characteristics of hosting a solar system in the making. Now, it has transformed completely: very little of the warm dusty material thought to originate from collisions of rocky planets is apparent - it's a mystery that has astronomers baffled. Carl Melis of the University of California, San Diego, led the discovery team, whose report is published in the July 5th issue of the journal Nature.
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