KX Andromedae
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| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 23h 07m 06.21216s[2] |
| Declination | +50° 11′ 32.4886″[2] |
| Apparent magnitude (V) | 6.88 – 7.28 variable[3] |
| Characteristics | |
| Spectral type | B3pe+K1III[4] |
| Apparent magnitude (U) | 6.79[5] |
| Apparent magnitude (B) | 7.25[5] |
| Apparent magnitude (V) | 6.92[5] |
| Apparent magnitude (G) | 6.852[2] |
| Apparent magnitude (J) | 5.845[6] |
| Apparent magnitude (H) | 5.33[5] |
| Apparent magnitude (K) | 5.19[5] |
| Variable type | Be star |
| Astrometry | |
| Radial velocity (Rv) | −7.8±0.9[7] km/s |
| Proper motion (μ) | RA: +1.625(19) mas/yr[2] Dec.: −0.761(17) mas/yr[2] |
| Parallax (π) | 1.3172±0.0207 mas[2] |
| Distance | 2,480 ± 40 ly (760 ± 10 pc) |
| Orbit[8] | |
| Period (P) | 38.919 days |
| Eccentricity (e) | 0±0.03 |
| Inclination (i) | 50±5° |
| Periastron epoch (T) | HJD 2423220.25±0.09 |
| Semi-amplitude (K2) (secondary) | 86.2±0.8 km/s |
| Details | |
| Primary | |
| Mass | 9.0±0.1[9] M☉ |
| Age | 22.4±3.1[9] Myr |
| Secondary | |
| Radius | 19±4[8] R☉ |
| Surface gravity (log g) | 2.0±0.5[8] cgs |
| Temperature | 5000±400[8] K |
| Rotational velocity (v sin i) | 25±5[8] km/s |
| Other designations | |
| KX And, AAVSO 2302+49, BD+49 4045, HD 218393, HIP 114154, SAO 52701, TYC 3631-1533-1, 2MASS J23070621+5011324 | |
| Database references | |
| SIMBAD | data |
KX Andromedae (often abbreviated to KX And) is a spectroscopic binary star in the constellation Andromeda. Its apparent visual magnitude varies between 6.88 and 7.28.[3] It is at a distance of 2,480 light-years (760 parsecs).[2]
The primary component of the KX Andromedae system is a Be star with a spectral classification B3pe as of 2017,[3] although in historical records it has varied from B1 to B7.[12]
The secondary star is difficult to detect in the spectrum, but has been given a K1III spectral type. It is likely to be an asymptotic giant branch star that fills its Roche lobe, transferring mass to the primary star.[8]
The system is only about 25 million years old. The pair complete a circular orbit every 38.919 days at an inclination of 50°.[8]
KX Andromedae is surrounded by bipolar jets of ejected material, that extend 19 light-years (5.8 parsecs) out from it in each direction (angular size 20′). These faint jets, visible in hydrogen-alpha, were discovered in 2024 by astronomer Stefan Ziegenbalg.[1]
