OU Andromedae
The light curve of an X-ray flare observed in 2001 by the Chandra X-ray Observatory is shown. This flare is believed to have been produced by a coronal mass ejection. (Adapted from Argiroffi et al., 2019) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 23h 49m 40.9595s |
| Declination | +36° 25′ 31.013″ |
| Apparent magnitude (V) | 5.87 - 5.94 |
| Characteristics | |
| Evolutionary stage | subgiant |
| Spectral type | G1 IIIe |
| Apparent magnitude (G) | 5.638 |
| Apparent magnitude (J) | 4.723 |
| Apparent magnitude (H) | 4.208 |
| Apparent magnitude (K) | 4.097 |
| B−V color index | 0.79 |
| Variable type | FK Com |
| Astrometry | |
| Radial velocity (Rv) | −1.79±0.14 km/s |
| Proper motion (μ) | RA: −0.634±0.046 mas/yr Dec.: −47.740±0.028 mas/yr |
| Parallax (π) | 7.2647±0.0411 mas |
| Distance | 449 ± 3 ly (137.7 ± 0.8 pc) |
| Details | |
| Mass | 2.85 M☉ |
| Radius | 9.46 R☉ |
| Luminosity | 71.2 L☉ |
| Surface gravity (log g) | 2.8 cgs |
| Temperature | 5,360 K |
| Metallicity [Fe/H] | −0.07 dex |
| Rotation | 24.3 days |
| Rotational velocity (v sin i) | 21.5 km/s |
| Age | 346 Myr |
| Other designations | |
| 2MASS J23494097+3625309, FK5 3914, HIP 117503, SAO 73535, BD+35°5110, HR 9024, HD 223460, PPM 89159 | |
| Database references | |
| SIMBAD | data |
OU Andromedae (also HR 9024) is a rotationally variable star in the constellation Andromeda. Varying between magnitudes 5.87 and 5.94, it has been classified as an FK Comae Berenices variable, but the classification is still uncertain. It has a spectral classification of G1IIIe, meaning that it is a giant star that shows emission lines in its spectrum. It is considered to be on the subgiant branch, contracting across the Hertzsprung gap towards the red giant branch.
In 1985, Jeffrey Hopkins et al. discovered that HR 9024 is a variable star, with a period of ~23.3 days. It was given the variable star designation OU Andromedae in 1986. Paola Testa et al. reported that the star showed X-ray flare activity, in 2007.