PDS 110

PDS 110 is a young 11th magnitude star located approximately 1130 ly away in the constellation Orion. A series of eclipses was observed in 2008 and 2011, which may have been caused by dust from the star's circumstellar disk.

Description
PDS 110 is a young star still approaching the main sequence. It has been classified as a T Tauri star, or as a pre-main sequence star. The emission lines indicative of a T Tauri classification are somewhat weaker than a typical T Tauri star, interpreted as a post-T Tauri stage.

PDS 110 hosts a circumstellar disk.

2008-2011 eclipses
Brightness measurements from SuperWASP and KELT showed two similar reductions in brightness in November 2008 and January 2011, both with a maximal luminosity reduction of 30% and a duration of 25 days. These events were interpreted as transits of a structure with a period of 808 ± 2 days, corresponding to an orbital distance of about 2 AU. The large reduction in brightness could have happened due to a planet or brown dwarf with a circum-secondary disk of dust with a radius of 0.3 AU around a central object with a mass between 1.8 and 70 times the mass of Jupiter.

Another transit was predicted for September 2017, but nothing similar to the previous events was seen, ruling out a periodic event. A search of 50 years of archival data also did not find any similar eclipses. The eclipses may have been caused by dust around PDS 110 itself. Larger-scale aperiodic dimmings have been observed as UX Orionis variables, and PDS 110 may be similar.

An independent 2021 study, assuming that the eclipses were caused by a ringed object in orbit around the star, attempted to constrain the properties of such an object, with their preferred solution being a brown dwarf on a nearly circular orbit. However, this does not explain the fact that no eclipse was observed in 2017.