A survey for variable young stars with small telescopes: II -- Mapping a
  protoplanetary disk with stable structures at 0.15 AU
  The HOYS citizen science project conducts long term, multifilter, high
cadence monitoring of large YSO samples with a wide variety of professional and
amateur telescopes. We present the analysis of the light curve of V1490Cyg in
the Pelican Nebula. We show that colour terms in the diverse photometric data
can be calibrated out to achieve a median photometric accuracy of 0.02mag in
broadband filters, allowing detailed investigations into a variety of
variability amplitudes over timescales from hours to several years. Using
GaiaDR2 we estimate the distance to the Pelican Nebula to be
870$^{+70}_{-55}$pc. V1490Cyg is a quasi-periodic dipper with a period of
31.447$\pm$0.011d. The obscuring dust has homogeneous properties, and grains
larger than those typical in the ISM. Larger variability on short timescales is
observed in U and R$_c-$H$\alpha$, with U-amplitudes reaching 3mag on
timescales of hours, indicating the source is accreting. The H$\alpha$
equivalent width and NIR/MIR colours place V1490Cyg between CTTS/WTTS and
transition disk objects. The material responsible for the dipping is located in
a warped inner disk, about 0.15AU from the star. This mass reservoir can be
filled and emptied on time scales shorter than the period at a rate of up to
10$^{-10}$M$_\odot$/yr, consistent with low levels of accretion in other T
Tauri stars. Most likely the warp at this separation from the star is induced
by a protoplanet in the inner accretion disk. However, we cannot fully rule out
the possibility of an AA Tau-like warp, or occultations by the Hill sphere
around a forming planet.
