Lynne A. Hillenbrand, Adam A. Miller, Kevin R. Covey, John M. Carpenter, S. Bradley Cenko, Jeffrey M. Silverman, Philip Muirhead, William Fischer, Justin R. Crepp, Joshua S. Bloom, Alexei V. Filippenko
[abbreviated] We report extensive photometry and spectroscopy of the highly variable young stellar object PTF 10nvg including optical, near-infrared, mid-infrared, and millimeter data. Following the 2010 maximum and subsequent fade, during 2011 and 2012 the source underwent additional episodes of brightening followed by several magnitude dimming events consistent with extinction variations. Further, a ~221 day period is derived; 2010 data taken when the source was near maximum brightness do not phase well to this period, however. Spectral evolution includes changes in slope and correlated changes in the prominence of TiO/VO/CO and atomic emission. These are anticorrelated with changes in forbidden emission which, along with H_2, dominate at faint epochs. Notably, night-to-night variations in several forbidden doublet strengths and ratios are observed. High-dispersion spectra in a variety of photometric states reveal line profiles for atomic species likely formed in an accretion flow and/or impact. The origin of zero-velocity Li I 6707 in emission is unknown. Forbidden line profiles are all blueshifted and likely arise from an outflow/jet. Several of these lines are also seen in a shocked region that is spatially offset from the continuum source position. Blueshifted absorption components similarly are formed in the outflow. CARMA maps resolve a spatially extended outflow in mm-wavelength CO. We attribute the observed photometric and spectroscopic behavior to rotating circumstellar disk material located at approximately 0.5-0.7 AU from the continuum source, causing the semi-periodic dimming. Occultation of the central star as well as the bright inner disk and the accretion/outflow zones renders shocked gas in the inner part of the jet amenable to observation at the faint epochs. We discuss PTF 10nvg as a source exhibiting both accretion-driven and extinction-driven phenomena.
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http://arxiv.org/abs/1208.2066
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