Upsilon Tauri
Star in the constellation of Taurus
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Upsilon Tauri (υ Tauri) is a solitary,[11] white-hued star in the zodiac constellation of Taurus, and is a member of the Hyades star cluster.[8] It is faintly visible to the naked eye with an apparent visual magnitude of +4.3. Based upon an annual parallax shift of 21.21 mas seen from Earth, it is around 154 light years from the Sun.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Taurus |
| Right ascension | 04h 26m 18.46368s[1] |
| Declination | +22° 48′ 48.8885″[1] |
| Apparent magnitude (V) | 4.28 – 4.31[2] |
| Characteristics | |
| Spectral type | A8 Vn[3] |
| U−B color index | +0.14[4] |
| B−V color index | +0.25[4] |
| Variable type | δ Scuti[2] |
| Astrometry | |
| Radial velocity (Rv) | 32.2±1.1[5] km/s |
| Proper motion (μ) | RA: +108.81[1] mas/yr Dec.: −46.80[1] mas/yr |
| Parallax (π) | 21.21±0.25 mas[1] |
| Distance | 154 ± 2 ly (47.1 ± 0.6 pc) |
| Absolute magnitude (MV) | +0.91[6] |
| Details | |
| Mass | 1.55[7] M☉ |
| Radius | 1.803[8] R☉ |
| Luminosity | 32.5[9] L☉ |
| Surface gravity (log g) | 3.50[7] cgs |
| Temperature | 7,398±252[7] K |
| Rotation | 0.415 d[8] |
| Rotational velocity (v sin i) | 243[3] km/s |
| Age | 827[7] Myr |
| Other designations | |
| υ Tau, υ1 Tau, 69 Tauri, BD+22 696, FK5 2326, HD 28024, HIP 20711, HR 1392, SAO 76608[10] | |
| Database references | |
| SIMBAD | data |
Properties
This is an A-type main sequence star with a stellar classification of A8 Vn.[3] It is classified as a Delta Scuti type variable star and its brightness varies from magnitude +4.28 to +4.31 with a period of 3.56 hours.[2] At an estimated age of 827 million years,[7] it is spinning rapidly with a rotation period of just 0.415 days.[8] This is giving the star an oblate shape with an equatorial bulge that is 9% larger than the polar radius.[13]
Occasionally this star system shares the Bayer designation υ Tauri with 72 Tauri, which is separated from it by 0.29° in the sky.[14]
Naming
With φ, κ1, κ2 and χ, it composed the Arabic were the Arabs' Al Kalbain, the Two Dogs.[15] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Kalbain were the title for five stars : φ as Alkalbain I, χ as Alkalbain II, κ1 as Alkalbain III, κ2 as Alkalbain IV and this star (υ) as Alkalbain V.[16]