TYC 8241 2652 1 and the case of the disappearing disk: no smoking gun yet
Astronomy and Astrophysics
EDP Sciences for European Southern Observatory (ESO)
© ESO 2016
Context. TYC 8241 2652 1 is a young star that showed a strong mid-infrared (mid-IR, 8-25 m) 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. Aims. 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. Methods. 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. Results. 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 H 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 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. Conclusions. 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.
We thank Michael Bessell from Mt. Stromlo/ANU and B. Bowler from Caltech for their help in obtaining and reducing optical spectra for this work. This research has made use of data obtained from the Chandra Data Archive, and software provided by the Chandra X-ray Center (CXC) in the application packages CIAO and Sherpa as well as data obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. This research also used the AAVSO Photometric All-Sky Survey (APASS), funded by the Robert Martin Ayers Sciences Fund. Support for H. M. G. was provided by the National Aeronautics and Space Administration through Chandra Award Number GO4-15009X issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060. S.K. acknowledges support from an STFC Rutherford Fellowship (ST/J004030/1) and Marie Sklodowska-Curie CIG grant (Ref. 618910). C.M. was supported by NASA grant 13-ADAP13-0178. M.Curé and S.Kanaan acknowledges financial support from Centro de Astrofísica de Valparaíso. S. Kanaan thank the support of Fondecyt iniciacíon grant N 11130702. S.J.W. was supported by NASA contract NAS8-03060 (Chandra). We want to thank the referee for help specifically with the discussion section of the paper.
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