Delta Tucanae
Star in the constellation Tucana
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Delta Tucanae (δ Tuc, δ Tucanae) is a common proper motion[3] pair of stars located in the southwestern corner of the southern constellation of Tucana.[9] Based upon an annual parallax shift of 13.00 mas as seen from Earth, is approximately 250 light years from the Sun. It is visible to the naked eye with a combined apparent visual magnitude of +4.48.[2] As of 2013, the two components had an angular separation of 7.0 arc seconds along a position angle of 282°.[10]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Tucana |
| Right ascension | 22h 27m 19.96745s[1] |
| Declination | −64° 57′ 58.8775″[1] |
| Apparent magnitude (V) | +4.48[2] (A: 4.52, B: 8.85)[3] |
| Characteristics | |
| Spectral type | B9 Vn + G0 V Fe−2[3] |
| U−B color index | A: −0.07, B: −0.02[3] |
| B−V color index | A: −0.02, B: +0.51[3] |
| Astrometry | |
| Proper motion (μ) | RA: +68.45[1] mas/yr Dec.: +10.06[1] mas/yr |
| Parallax (π) | 13.00±0.48 mas[1] |
| Distance | 251 ± 9 ly (77 ± 3 pc) |
| Absolute magnitude (MV) | A: 0.20, B: 4.50[3] |
| Details | |
| δ Tuc A | |
| Mass | 2.99[4] M☉ |
| Radius | 2.7[5] R☉ |
| Surface gravity (log g) | 4.11±0.14[4] cgs |
| Temperature | 11,271±383[4] K |
| Rotation | 2.8535[6] d |
| Rotational velocity (v sin i) | 224[7] km/s |
| Age | 232[4] Myr |
| Other designations | |
| δ Tuc, CPD−65°4044, HD 212581, HIP 110838, HR 8540, SAO 255222, WDS J22273-6458AB[8] | |
| Database references | |
| SIMBAD | data |
The brighter primary, component A, is blue-white hued star a visual magnitude of 4.52.[3] It is a B-type main-sequence star with a stellar classification of B9 Vn,[3] where the 'n' suffix indicates "nebulous" absorption lines due to the star's rotation. It is spinning rapidly with a projected rotational velocity of 224 km/s,[7] which is giving the star an oblate shape with an equatorial bulge that is an estimated 12% larger than the polar radius.[11] The star has about three times the mass of the Sun and is around 232 million years old.[4]
The magnitude 8.85[3] companion, component B, is a G-type main-sequence star. It has a classification of G0 V Fe−2,[3] with the suffix indicating an underabundance of iron in the star's photosphere.