Over the last decade, the pre-main-sequence star KH 15D has exhibited periodic eclipses that are surprisingly deep (∼3 mag) and long-lasting (∼40% of the 48.4 day period). The cause of the eclipses is unknown, but it could be a feature in a nearly edge-on protoplanetary disk. Here we report on an analysis of archival photographs of KH 15D from the Harvard College Observatory plate collection, most of which were taken during the years 1913-1951. During this time range, the data are consistent with no eclipses; the duty cycle of 1 mag eclipses was less than 20%. The decadal timescale of this change in eclipse behavior is compatible with the expected timescale of protoplanet/disk interactions. Archival images from more recent epochs should reveal the onset of the eclipses.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- Open clusters and associations: individual (NGC 2264)
- Planetary systems: protoplanetary disks
- Stars: individual (KH 15D)
- Stars: pre-main-sequence