# The PDS 110 observing campaign - photometric and spectroscopic observations reveal eclipses are aperiodic

## TL;DR

This study investigates the young star PDS 110, revealing that its previously observed eclipses are irregular and not periodic, with no evidence of a companion causing the dimmings, suggesting stochastic dust obscuration events.

## Contribution

The paper provides extensive photometric and spectroscopic data showing the eclipses are aperiodic and rules out close binary companions, offering new insights into the star's variability mechanisms.

## Key findings

- Eclipses are aperiodic and not caused by a companion.
- No deep eclipses found in archival data over 50 years.
- Star exhibits stochastic dimmings similar to UX Ori variables.

## Abstract

PDS 110 is a young disk-hosting star in the Orion OB1A association. Two dimming events of similar depth and duration were seen in 2008 (WASP) and 2011 (KELT), consistent with an object in a closed periodic orbit. In this paper we present data from a ground-based observing campaign designed to measure the star both photometrically and spectroscopically during the time of predicted eclipse in September 2017. Despite high-quality photometry, the predicted eclipse did not occur, although coherent structure is present suggesting variable amounts of stellar flux or dust obscuration. We also searched for RV oscillations caused by any hypothetical companion and can rule out close binaries to 0.1 $M_\odot$. A search of Sonneberg plate archive data also enabled us to extend the photometric baseline of this star back more than 50 years, and similarly does not re-detect any deep eclipses. Taken together, they suggest that the eclipses seen in WASP and KELT photometry were due to aperiodic events. It would seem that PDS 110 undergoes stochastic dimmings that are shallower and shorter-duration than those of UX Ori variables, but may have a similar mechanism.