Yildun
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Minor |
| Right ascension | 17h 32m 12.99671s |
| Declination | +86° 35′ 11.2584″ |
| Apparent magnitude (V) | 4.36 |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | A1 Van |
| U−B color index | +0.03 |
| B−V color index | +0.02 |
| Astrometry | |
| Radial velocity (Rv) | −7.6±2.7 km/s |
| Proper motion (μ) | RA: +10.17 mas/yr Dec.: +53.97 mas/yr |
| Parallax (π) | 18.95±0.14 mas |
| Distance | 172 ± 1 ly (52.8 ± 0.4 pc) |
| Absolute magnitude (MV) | 0.62 |
| Details | |
| Mass | 2.35 M☉ |
| Radius | 2.8 R☉ |
| Luminosity | 47.77 L☉ |
| Surface gravity (log g) | 4.04 cgs |
| Temperature | 9,911±337 K |
| Rotation | 19 hours |
| Rotational velocity (v sin i) | 154 km/s |
| Age | 327 Myr |
| Other designations | |
| Yildun, Vildiur, Gildun, δ UMi, 23 Ursae Minoris, BD+86°269, FK5 913, GC 24236, HD 166205, HIP 85822, HR 6789, SAO 2937 | |
| Database references | |
| SIMBAD | data |
Delta Ursae Minoris, Latinized from δ Ursae Minoris, formally named Yildun /jɪlˈdʌn/, is a white-hued star in the northern circumpolar constellation of Ursa Minor, forming the second star in the bear's tail. It is visible to the naked eye with an apparent visual magnitude of 4.36. Based upon an annual parallax shift of 18.95 mas as seen from Earth, it is located 172 light years from the Sun. The star is moving closer to the Sun with a radial velocity of about −8 km/s.