 The visual band light curve of FO Aquarii. The main plot shows the dimming which occurred in 2016, and the inset plot shows the short-term variation that occurs during an orbital period. Adapted from Littlefield et al. (2016) [1] | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 22h 17m 55.38s [2] |
| Declination | −08° 21′ 04.6″ [2] |
| Apparent magnitude (V) | 12.7 [3] |
| Characteristics | |
| Apparent magnitude (B) | 13.70 [2] |
| Apparent magnitude (R) | 13.60 [2] |
| Apparent magnitude (J) | 12.87 [2] |
| Apparent magnitude (H) | 12.75 [2] |
| Apparent magnitude (K) | 12.51 [2] |
| Variable type | DQ [4] |
| Orbit | |
| Period (P) | 4.85 hr [5] |
| Other designations | |
| 2E 4588, 1RXS J221753.9-082115, CS 22886-0021, H 2215-086 | |
| Database references | |
| SIMBAD | data |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) | |
FO Aquarii is an intermediate polar [4] star system in the constellation Aquarius. The white dwarf and companion star orbit each other with a period of approximately 4.85 hours. [5] The system is famous for a very strong optical pulsation which occurs every 20.9 minutes, corresponding with the rotational period of the accreting white dwarf. [6] Prior to 2016, the system's long-term optical brightness varied between apparent magnitude 12.7 and 14.2, [7] but in early 2016, it faded to magnitude 15.8 and thereafter began a slow recovery to its normal brightness, behavior which is indicative of a temporary dropoff in the mass-transfer rate between the two stars. [8]
The variable nature of FO Aquarii was discovered in 1983 by Joseph Patterson and João Evangelista Steiner. [6] It was given its variable star designation in 1985. [9]
