V532 Oph has been found to be a member of the rare , hydrogen-deficient R Coronae Borealis ( RCB ) stars from new photometric and spectroscopic data reported in this paper .
The lightcurve of V532 Oph shows the sudden , deep , irregularly spaced declines characteristic of RCB stars .
Its optical spectrum is typical of a warm ( T _ { eff } \sim 7000 K ) RCB star , showing weak or absent hydrogen lines , the C _ { 2 } Swan bands , and no evidence for ^ { 13 } C. In addition , the star shows small pulsations typical of an RCB star and an infrared excess due to circumstellar dust .
It also appears to be significantly reddened by foreground dust .
The distance to V532 Oph is estimated to be 5.5-8.7 kpc .
These new data show that this star was misclassified as an eclipsing binary in the General Catalog of Variable Stars .
The new data presented here for V532 Oph reveal the power of high-quality , high-cadence all-sky photometric surveys , such as ASAS-3 , to identify new RCB candidates on the basis of lightcurve data alone , now that they have been collecting data for durations sufficiently long to reveal multiple declines .
Despite their small numbers , RCB stars may be of great importance in understanding the late stages of stellar evolution .
In particular , their measured isotopic abundances imply that many , if not most , RCB stars are produced by WD mergers , which may be the low-mass counterparts of the more massive mergers thought to produce type Ia supernovae .
Therefore , establishing the population of RCB stars in the Galaxy will help constrain the frequency of these WD mergers .