摘要：Context. TYC8241 2652 1 is a young star that showed a strong mid-infrared (mid-IR, 8–25 μm) excess in all observations before 2008, which is 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 the 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 TYC8241 2652 1 has all the properties expected from a young star: Its luminosity is in the saturation regime and the abundance pattern shows enhancement of O/Fe. The photospheric Hα line is filled with a weak emission feature, indicating chromospheric activity that is 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 confirm that stellar activity is unlikely to destroy the dust in the disk and shows that scenarios, in which either TYC8241 2652 1 heats the disk of a binary companion or a potential companion heats the disk of TYC8241 2652 1, are unlikely.
关键词：stars: formation;stars: individual: TYC 8241 2652 1;stars: variables: general
