UX Arietis
Trinary star system in the constellation Aries
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UX Arietis is a triple star system located in the northern zodiacal constellation of Aries. Based upon parallax measurements from the Gaia satellite, it is roughly 165 light years away. The star varies in brightness from magnitude 6.35 to 6.71, meaning it may be intermittently visible to the unaided eye under ideal dark-sky conditions.[3]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aries |
| Right ascension | 03h 26m 35.37568s[2] |
| Declination | +28° 42′ 54.2264″[2] |
| Apparent magnitude (V) | 6.35 - 6.71[3] |
| Characteristics | |
| Spectral type | G5IV[4] |
| U−B color index | 0.43[5] |
| B−V color index | 0.90[5] |
| Variable type | RS CVn[6] |
| Astrometry | |
| Radial velocity (Rv) | +26.53[7] km/s |
| Proper motion (μ) | RA: +46.794[2] mas/yr Dec.: −102.876[2] mas/yr |
| Parallax (π) | 19.7836±0.1264 mas[2] |
| Distance | 165 ± 1 ly (50.5 ± 0.3 pc) |
| Absolute magnitude (MV) | 2.91[8] |
| Orbit[9] | |
| Primary | Aa |
| Name | Ab |
| Period (P) | 6.437888±0.000007 d |
| Semi-major axis (a) | 1.750±0.01 mas |
| Eccentricity (e) | 0 (fixed) |
| Inclination (i) | 125.0±0.5° |
| Longitude of the node (Ω) | 113.4±0.4° |
| Periastron epoch (T) | 2456238.134 ± 0.002 HJD |
| Argument of periastron (ω) (secondary) | 90 (fixed)° |
| Orbit[10] | |
| Primary | A |
| Name | B |
| Period (P) | 111.02 yr |
| Semi-major axis (a) | 648.0±0.8 mas |
| Eccentricity (e) | 0.77±0.01 |
| Inclination (i) | 93.3±0.6° |
| Longitude of the node (Ω) | 58.9±0.5° |
| Periastron epoch (T) | 2451664.9±34.3 HJD |
| Argument of periastron (ω) (secondary) | 274.9±0.8° |
| Details[9] | |
| UX Ari Aa | |
| Mass | 1.30±0.06 M☉ |
| Radius | 5.6±0.1 R☉ |
| Luminosity | 9.3±0.7 L☉ |
| Surface gravity (log g) | 3.06±0.04 cgs |
| Temperature | 4,560±100 K |
| Rotation | 6.44 d[4] |
| UX Ari Ab | |
| Mass | 1.14±0.06 M☉ |
| Radius | 1.6±0.2 R☉ |
| Luminosity | 2.34±0.28 L☉ |
| Surface gravity (log g) | 4.09±0.16 cgs |
| Temperature | 5,670±100 K |
| UX Ari B | |
| Mass | 0.75 M☉ |
| Radius | 0.8±0.1 R☉ |
| Luminosity | 0.38±0.08 L☉ |
| Surface gravity (log g) | 4.51±0.13 cgs |
| Temperature | 4,930±100 K |
| Other designations | |
| BD+28°532, CCDM 03266+2843, HD 21242, HIP 16042, SAO 75927 | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
In 1972, Robert E. Montle and Douglas S. Hall discovered that the star's brightness varies.[11] It was given its variable star designation in 1973.[12] The primary, component Aa, is the variable star, of the RS CVn type. The variability of the star is believed due to a combination of cool star spots and warm flares, set against the baseline quiescent temperature of the stellar atmosphere. The variability appears to be cyclical with a period of 8−9 years.[6]
A more distant companion, component C, shares a common proper motion and is at the same distance.[13] It is another cool dwarf star with an estimated spectral class of K2. Any orbit is estimated to require over 100,000 years.[14]