| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Triangulum |
| Right ascension | 02h 03m 47.11380s[1] |
| Declination | +35° 35′ 28.6692″[1] |
| Apparent magnitude (V) | 8.1 – 8.7[2] |
| Characteristics | |
| Evolutionary stage | red giant branch[3] |
| Spectral type | K0 III[4] |
| U−Bcolor index | +0.78[2] |
| Variable type | RS CVn[2] |
| Astrometry | |
| Radial velocity (Rv) | −26.35±0.18[5] km/s |
| Proper motion (μ) | RA: −53.222[1]mas/yr Dec.: −14.160[1]mas/yr |
| Parallax (π) | 5.0820±0.0497 mas[1] |
| Distance | 642 ± 6 ly (197 ± 2 pc) |
| Orbit | |
| Period (P) | 23.9674±0.0005[6] days |
| Inclination (i) | 60±10[3]° |
| Details[6] | |
| Mass | 1.1+0.2 −0.3 M☉ |
| Radius | 8.95±0.23 R☉ |
| Luminosity | 337±2 L☉ |
| Surface gravity (log g) | 2.82±0.05 cgs |
| Temperature | 4,627±46 K |
| Metallicity[Fe/H] | −0.13±0.04 dex |
| Rotation | 23.470–24.716 days |
| Rotational velocity (v sin i) | 20.0±0.6 km/s |
| Age | 7.4+2.3 −3.2 Gyr |
| Other designations | |
| XX Tri,BD+34°363,GJ 3130,HD 12545,HIP 9630,SAO 55233[7] | |
| Database references | |
| SIMBAD | data |
XX Trianguli, abbreviated XX Tri, is avariable star in the northernconstellation ofTriangulum, about 1.5° to the WNW ofBeta Trianguli along the constellation border withAndromeda.[8] It is classified as aRS Canum Venaticorum variable and ranges in brightness from magnitude 8.1 down to 8.7,[2] which is too faint to be visible to thenaked eye. The system is located at a distance of approximately 642 light years from theSun based onparallax,[1] but is drifting closer with aradial velocity of −26 km/s.[5]
The variability of the star's brightness was probably first noticed in 1985 by Brian Skiff atLowell Observatory.[2] It was given itsvariable star designation, XX Trianguli, in 1993.[10] This is a single-linedspectroscopic binary with anorbital period of 23.96924 days.[4] The visible component is an orange-huedK-typegiant star with astellar classification of K0 III,[4] indicating it has exhausted the supply of hydrogen at itscore then cooled and expanded off themain sequence. It is around eight billion years old with 26% more mass than the Sun and has expanded to 11 times the Sun's radius. It is radiating roughly 30 times the luminosity of the Sun from itsphotosphere at aneffective temperature of 4,620 K.[3]
The star is "covered with large high-latitude and even polarspots and with occasional small equatorial spots".[3] XX Tri is notable for having a hugestarspot larger than the diameter of theSun, discovered usingDoppler imaging.[11] For its size, the star has a rapid rotation rate of about 24 days. It has a weak, Sun-likedifferential rotation. The star appears to show amagnetic activity cycle of26±6 years, although only a single cycle has been observed as of 2015.
