The First Post-Kepler Brightness Dips of KIC 8462852

Abstract

<p><span>We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the <em>Kepler</em> space mission in 2013 May. Our regular photometric surveillance started in 2015 October, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1%-2.5% dips, named "<em>Elsie</em>," "<em>Celeste</em>," "<em>Skara Brae</em>," and "<em>Angkor</em>," which persist on timescales from several days to weeks. Our main results so far are as follows: (i) there are no apparent changes of the stellar spectrum or polarization during the dips and (ii) the multiband photometry of the dips shows differential reddening favoring non-gray extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale &lt;&lt;1 &mu;m, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term "secular" dimming, which may be caused by independent processes, or probe different regimes of a single process.</span></p>