Delta Tucanae

Delta Tucanae A/B

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Tucana
Right ascension	22^h 27^m 19.96745^s[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, CP−65° 4044, HD 212581, HIP 110838, HR 8540, SAO 255222, WDS J22273-6458AB[8]
Database references
SIMBAD	data

Delta Tucanae (δ Tuc, δ Tucanae) is a common proper motion^[3] pair 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]

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.

References

1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
2. Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
3. Corbally, C. J. (1984), "Close visual binaries. I - MK classifications", Astrophysical Journal Supplement Series, 55: 657, Bibcode:1984ApJS...55..657C, doi:10.1086/190973.
4. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
5. Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (3rd ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
6. Barraza, L. F.; Gomes, R. L.; Messias, Y. S.; Leão, I. C.; Almeida, L. A.; Janot-Pacheco, E.; Brito, A. C.; Brito, F. A. C.; Santana, J. V.; Gonçalves, N. S.; Das Chagas, M. L.; Teixeira, M. A.; De Medeiros, J. R.; Canto Martins, B. L. (2022). "Rotation Signature of TESS B-type Stars. A Comprehensive Analysis". The Astrophysical Journal. 924 (2): 117. arXiv:2202.01022. Bibcode:2022ApJ...924..117B. doi:10.3847/1538-4357/ac3335. S2CID 246030494.
7. Royer, F.; et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897–911, arXiv:astro-ph/0205255, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943, S2CID 14070763.
8. "del Tuc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-04-22.
9. Streicher, Magda (2005), "Deepsky Delights", Monthly Notes of the Astronomical Society of Southern Africa, 64 (9–10): 172–74, Bibcode:1907GOAMM..67G...2C.
10. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
11. Belle, G. T. (2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.