A survey for variable stars with small telescopes: IX – Evolution of Spot Properties on YSOs in IC5070
arxiv(2024)
摘要
We present spot properties on 32 periodic young stellar objects in IC 5070.
Long term, ∼5 yr, light curves in the V, R, and I-bands are obtained
through the HOYS (Hunting Outbursting Young Stars) citizen science project.
These are dissected into six months long slices, with 3 months oversampling, to
measure 234 sets of amplitudes in all filters. We fit 180 of these with
reliable spot solutions. Two thirds of spot solutions are cold spots, the
lowest is 2150 K below the stellar temperature. One third are warm spots that
are above the stellar temperature by less than ∼2000 K. Cold and warm
spots have maximum surface coverage values of 40 percent, although only 16
percent of warm spots are above 20 percent surface coverage as opposed to 60
percent of the cold spots. Warm spots are most likely caused by a combination
of plages and low density accretion columns, most common on objects without
inner disc excess emission in K-W2. Five small hot spot solutions have <3
percent coverage and are 3000 - 5000 K above the stellar temperature. These are
attributed to accretion, and four of them occur on the same object. The
majority of our objects are likely to be accreting. However, we observe very
few accretion hot spots as either the accretion is not stable on our timescale
or the photometry is dominated by other features. We do not identify cyclical
spot behaviour on the targets. We additionally identify and discuss a number of
objects that have interesting amplitudes, phase changes, or spot properties.
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