The Historical Lightcurve of the R Coronae Borealis Star, V854 Cen, from 1890 to 2026

TL;DR

This paper reconstructs the century-long historical lightcurve of V854 Cen, revealing its faint states caused by dust clouds before its discovery in the 1980s, and provides insights into its variability over time.

Contribution

It presents the first detailed historical lightcurve of V854 Cen from 1890 to 2026, based on archival photographic plates, showing its long-term faintness and variability.

Findings

V854 Cen was faint (16th-17th magnitude) from 1890 to 1980.

The star experienced deep declines due to dust clouds.

Historical data extends understanding of RCB star variability.

Abstract

The R Coronae Borealis (RCB) Star, V854 Cen, was not discovered until the 1980's even though it is 7th magnitude at maximum light. This is because it was in a faint state due to the presence of thick circumstellar dust clouds for nearly a century. RCB stars are known for having deep declines of up to 9 magnitudes at irregular intervals. The declines are caused by dust clouds which block the light from the star. The historical lightcurve of V854 Cen before discovery was investigated by examining plates taken by Harvard College Observatory and other observatories beginning in 1889. These observations show that V854 Cen was well below 7th magnitude from 1890 to 1980, often as faint as 16th or 17th magnitude.