Typical disks contain a mass of 10 −3 to 10 −1 M ⊙ and disperse within a few Myr (see review by Alexander et al. Disks regulate the angular momentum of the star and may launch a disk wind. Low-mass stars (<3 M ⊙) at this stage are called classical T Tauri stars (CTTS), and their circumstellar disks are the sites of planet formation. After the initial collapse of the cloud, an accretion disk forms around the central protostar. The formation of stars and planetary systems from large-scale molecular clouds is a complicated process with many interacting components. We speculate that a breakup of planetesimals or a terrestrial planet could supply large grains, causing gray absorption some of these grains would be accreted and enrich the stellar corona with iron, which could explain the inferred high abundance. Given the high column density coupled with changes in the X-ray spectral shape, this absorber is probably located in the inner disk. Comparing X-ray absorbing column density N H and optical extinction A V, we find that either the gas-to-dust ratio in the absorber is orders of magnitude higher than in the ISM, or the absorber has undergone significant dust evolution. Furthermore, a new emission feature at 6.63 ± 0.02 keV (statistic) ☐.02 keV (systematic) appeared, indicating an Fe abundance an order of magnitude above solar, in contrast with previous sub-solar Fe abundance measurements. In 2017, the X-ray spectrum is more absorbed than it was in the optically bright state ( ) and shows significantly more hot plasma than in X-ray observations taken before. In 2017, when the optical brightness was almost 2 mag below the long-term average, we triggered a Chandra observation to measure the absorbing column density N H and to constrain dust properties and the gas-to-dust ratio of the absorber. This dimming is also associated with changes in the outflow. Visual and IR observations indicate a gray absorber that moved into the line of sight. RW Aur is a binary system composed of two young, low-mass stars.
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