Iota Tucanae

Iota Tucanae (ι Tuc, ι Tucanae) is a solitary^[10] star in the southern constellation of Tucana. Based upon an annual parallax shift of 10.72 mas as seen from Earth,^[2] it is located around 304 light years from the Sun. With an apparent visual magnitude of +5.33,^[3] it is faintly visible to the naked eye.

Iota Tucanae

A light curve for Iota Tucanae, plotted from Hipparcos data[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Tucana
Right ascension	01h 07m 18.66365s[2]
Declination	−61° 46′ 31.0434″[2]
Apparent magnitude (V)	+5.33[3]
Characteristics
Spectral type	G5 III[4]
B−V color index	+0.89[3]
Variable type	SRV[5]
Astrometry
Radial velocity (Rv)	−7.80[5] km/s
Proper motion (μ)	RA: +73.80[2] mas/yr Dec.: −11.55[2] mas/yr
Parallax (π)	10.72 ± 0.23 mas[2]
Distance	304 ± 7 ly (93 ± 2 pc)
Absolute magnitude (MV)	0.70[6]
Details
Mass	2.20[5] M☉
Radius	11[7] R☉
Luminosity	65[5] L☉
Surface gravity (log g)	3.15±0.13[8] cgs
Temperature	5,039±63[5] K
Metallicity [Fe/H]	−0.02±0.08[8] dex
Rotational velocity (v sin i)	5.8±3.5[6] km/s
Age	1.69[5] Gyr
Other designations
ι Tuc, CPD−62° 89, FK5 39, HD 6793, HIP 5268, HR 332, SAO 248324[9]
Database references
SIMBAD	data

This is a yellow-hued G-type giant star with a stellar classification of G5 III.^[4] It is classified as a semiregular variable star, showing a periodicity of 66.8 days with an amplitude of 0.0202 in visual magnitude.^[11] Iota Tucanae is an X-ray source with a luminosity of 817.6×10²⁸ erg s⁻¹.^[12] It has an estimated 2.2^[5] times the mass of the Sun, and, at the age of 1.69 billion years,^[5] it has evolved away from the main sequence, expanding to 11^[7] times the Sun's radius. The star radiates 65^[5] times the solar luminosity from its photosphere at an effective temperature of 5,039 K.^[5]

References

1. "/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.
2. 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.
3. Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa, 27: 11, Bibcode:1968MNSSA..27...11C.
4. Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
5. Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 23, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114, 88.
6. Ammler-von Eiff, Matthias; Reiners, Ansgar (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics, 542: A116, arXiv:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724, S2CID 53666672.
7. Pasinetti Fracassini, L. E.; et al. (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.
8. Alves, S.; et al. (April 2015), "Determination of the spectroscopic stellar parameters for 257 field giant stars", Monthly Notices of the Royal Astronomical Society, 448 (3): 2749–2765, arXiv:1503.02556, Bibcode:2015MNRAS.448.2749A, doi:10.1093/mnras/stv189.
9. "iot Tuc -- Long-period variable star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-04-22.
10. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
11. Koen, Chris; Eyer, Laurent (2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society, 331 (1): 45–59, arXiv:astro-ph/0112194, Bibcode:2002MNRAS.331...45K, doi:10.1046/j.1365-8711.2002.05150.x, S2CID 10505995.
12. Pizzolato, N.; et al. (September 2000), "Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases", Astronomy and Astrophysics, 361: 614–628, Bibcode:2000A&A...361..614P.