Alpha Indi

Alpha Indi (α Ind, α Indi) is a third magnitude giant star in the constellation Indus, located about 98 light years from the Earth.[1] The stellar classification of this star is K0 III-IV,[5] so it has exhausted the hydrogen at its core and evolved away from the main sequence. It has about double the mass of the Sun and is an estimated billion years old.[4] As a giant star it has expanded to about 12 times the radius of the Sun.[6] The effective temperature of the photosphere is 4,893 K,[7] giving it the characteristic orange hue of a K-type star.[9] It may have two nearby M-type companion stars, which are located at least 2,000 Astronomical Units from the primary.[10]

α Indi
Location of α Indi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Indus
Right ascension  20h 37m 34.03201s[1]
Declination –47° 17′ 29.4026″[1]
Apparent magnitude (V) 3.11[2]
Astrometry
Radial velocity (Rv)−1.3[3] km/s
Proper motion (μ) RA: +49.24[1] mas/yr
Dec.: +66.53[1] mas/yr
Parallax (π)33.17 ± 0.18[1] mas
Distance98.3 ± 0.5 ly
(30.1 ± 0.2 pc)
Absolute magnitude (MV)0.65[4]
Characteristics
Spectral type K0 III–IV[5]
U−B color index +0.79[2]
B−V color index +1.00[2]
Details
Mass2.0[4] M☉
Radius12[6] R☉
Surface gravity (log g)3.00[7] cgs
Temperature4,893[7] K
Metallicity [Fe/H]+0.03[7] dex
Age1[4] Gyr
Other designations
HD 196171, HR 7869, SAO 230300, FK5 769, CD −47 13477, HIP 101772.[8]
Database references
SIMBADdata

In China, this star is called Pe Sze where it also was known as the Persian, a title from the Jesuit missionaries.[11] The term Pe Sze is from the name of asterism 波斯 (Bō Sī, English: Persia). In Chinese astronomy, consequently, α Indi itself is known as 波斯二 (Bō Sī èr, English: the Second Star of Persia)[12]

References
  1. van Leeuwen, F. (November 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.
  2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J
  3. Evans, D. S. (June 20–24, 1966), "The revision of the general catalogue of radial velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, 30, University of Toronto: International Astronomical Union, p. 57, Bibcode:1967IAUS...30...57E
  4. Thorén, P.; Edvardsson, B.; Gustafsson, B. (October 2004), "Subgiants as probes of galactic chemical evolution", Astronomy and Astrophysics, 425: 187–206, arXiv:astro-ph/0407260, Bibcode:2004A&A...425..187T, doi:10.1051/0004-6361:20040421
  5. Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637
  6. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451
  7. Gratton, R. G.; Ortolani, S. (November 1986), "The forbidden O/Fe ratio in metal-poor late-type stars", Astronomy and Astrophysics, 169 (1–2): 201–207, Bibcode:1986A&A...169..201G
  8. "alf Ind -- Star in double system", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2011-12-12
  9. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 10, 2012, retrieved 2012-01-16
  10. Kaler, James B., "THE PERSIAN (Alpha Indi)", Stars, University of Illinois, retrieved 2011-12-23
  11. Star Name - R.H.Allen p. 246
  12. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 30 日)
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