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Nu Indi

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For the star previously named Nu Indi, see Nu Microscopii.
Nu Indi
Observation data
Epoch J2000      Equinox J2000
Constellation Indus[1]
Right ascension 22h 24m 36.88539s[2]
Declination −72° 15′ 19.4882″[2]
Apparent magnitude (V) 5.278±0.005[3]
Characteristics
Evolutionary stage Subgiant[4][5][6][7][8]
Spectral type G9V Fe-3.1CH-1.5[9]
Astrometry
Radial velocity (Rv)+32.51±0.16[10] km/s
Proper motion (μ) RA: +1,303.872 mas/yr[2]
Dec.: −674.186 mas/yr[2]
Parallax (π)35.1281±0.0640 mas[2]
Distance92.8 ± 0.2 ly
(28.47 ± 0.05 pc)[2]
Absolute magnitude (MV)+2.70±0.05[6]
Details
Mass0.85±0.04[4] M☉
Radius2.95±0.12[6] R☉
Luminosity6.28±0.23[5] L☉
Surface gravity (log g)3.43±0.10[6] cgs
Temperature5,318±80[6] K
Metallicity [Fe/H]−1.54±0.07[6] dex
Rotational velocity (v sin i)2.67[11] km/s
Age11.0±0.7[4] Gyr
Other designations
ν Indi, CD−72°1742, GJ 855.1, HD 211998, HIP 110618, HR 8515
Database references
SIMBADdata

Nu Indi is a star in the southern constellation of Indus. With an apparent visual magnitude of +5.278, it is faintly visible to the naked eye in sufficiently dark skies. Based upon parallax measurements, the star is 92.8 light-years distant.

Characteristics

[edit]

The spectrum of this star matches a classification of G9V Fe-3.1CH-1.5,[9] with the notation G9V suggesting it is a late-type G-type main sequence star. However, it is actually a subgiant,[4][5][6][7][8] a star which is running out of hydrogen in its core and expanding in size. The "Fe-3.1CH-1.5" indicate an underabundance of methylidyne radical and iron. The star has an overabundance of alpha elements, that is, elements heavier than carbon produced by nuclear reactions involving helium.[4] The metallicity indicators classify it as a Population II star.[6]

Nu Indi has been a target of asteroseismic studies since it displays solar-like oscillations.[7][8][4] It was the first metal-poor star of which asteroseismology has been applied.[8] Using this method, its mass and age have been measured at 0.85 solar masses and 11 billion years.[4] As a subgiant, it has expanded in size and become brighter, with a current radius of three solar radii[6] and a luminosity 6.3 times that of the Sun.[5] The effective temperature is 5,318 K,[6] giving it the yellow hue typical of G-type stars.[12]

It is a native member of the galactic halo which is currently crossing the galactic disk. The orbital eccentricity is somewhat high, at 0.60. It reaches a minimum distance of 8,000 light-years from the Galactic Center, and its distance relative to the galactic plane is no more than 4,900 ly.[4] It does not make part of any stellar association or moving group.[13]

Nu Indi was once thought to be a binary star whose components have spectral types of A3V and F9V, but this claim has since been disproven.[14] However, there is evidence it may be an astrometric binary.[6]

References

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  1. ^ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
  2. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. ^ Paunzen, E. (August 2015). "A new catalogue of Strömgren-Crawford uvbyβ photometry". Astronomy and Astrophysics. 580: A23. arXiv:1506.04568. Bibcode:2015A&A...580A..23P. doi:10.1051/0004-6361/201526413. ISSN 0004-6361.
  4. ^ a b c d e f g h Chaplin, William J.; Serenelli, Aldo M.; Miglio, Andrea; Morel, Thierry; Mackereth, J. Ted; Vincenzo, Fiorenzo; Kjeldsen, Hans; Basu, Sarbani; Ball, Warrick H.; Stokholm, Amalie; Verma, Kuldeep; Mosumgaard, Jakob Rørsted; Silva Aguirre, Victor; Mazumdar, Anwesh; Ranadive, Pritesh (April 2020). "Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi". Nature Astronomy. 4 (4): 382–389. arXiv:2001.04653. Bibcode:2020NatAs...4..382C. doi:10.1038/s41550-019-0975-9. ISSN 2397-3366.
  5. ^ a b c d Bruntt, H.; Bedding, T. R.; Quirion, P.-O.; Lo Curto, G.; Carrier, F.; Smalley, B.; Dall, T. H.; Arentoft, T.; Bazot, M.; Butler, R. P. (2010-05-11). "Accurate fundamental parameters for 23 bright solar-type stars". Monthly Notices of the Royal Astronomical Society. 405 (3): 382–389. arXiv:1002.4268. Bibcode:2010MNRAS.405.1907B. doi:10.1111/j.1365-2966.2010.16575.x. ISSN 0035-8711.
  6. ^ a b c d e f g h i j k Fuhrmann, Klaus; Chini, Rolf (2021-03-11). "On ancient solar-type stars – II". Monthly Notices of the Royal Astronomical Society. 501 (4): 4903–4916. doi:10.1093/mnras/staa3942. ISSN 0035-8711.
  7. ^ a b c Carrier, F.; Kjeldsen, H.; Bedding, T. R.; Brewer, B. J.; Butler, R. P.; Eggenberger, P.; Grundahl, F.; McCarthy, C.; Retter, A.; Tinney, C. G. (2007-08-01). "Solar-like oscillations in the metal-poor subgiant ν Indi - II. Acoustic spectrum and mode lifetime". Astronomy & Astrophysics. 470 (3): 1059–1063. arXiv:0706.0795. Bibcode:2007A&A...470.1059C. doi:10.1051/0004-6361:20066901. ISSN 0004-6361.
  8. ^ a b c d Bedding, Timothy R.; Butler, R. Paul; Carrier, Fabien; Bouchy, Francois; Brewer, Brendon J.; Eggenberger, Patrick; Grundahl, Frank; Kjeldsen, Hans; McCarthy, Chris; Nielsen, Tine Bjorn; Retter, Alon; Tinney, Christopher G. (2006-08-10). "Solar-like Oscillations in the Metal-poor Subgiant ν Indi: Constraining the Mass and Age Using Asteroseismology". The Astrophysical Journal. 647 (1): 558–563. arXiv:astro-ph/0604453v1. Bibcode:2006ApJ...647..558B. doi:10.1086/505295. ISSN 0004-637X.
  9. ^ a b Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2006-06-02). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. ISSN 0004-6256.
  10. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  11. ^ Perdelwitz, V.; Trifonov, T.; Teklu, J. T.; Sreenivas, K. R.; Tal-Or, L. (2024). "Analysis of the public HARPS/ESO spectroscopic archive. Ca II H&K time series for the HARPS radial velocity database". Astronomy and Astrophysics. 683. arXiv:2311.12438. Bibcode:2024A&A...683A.125P. doi:10.1051/0004-6361/202348263.
  12. ^ "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. Archived from the original on 2013-12-03. Retrieved 2012-01-16.
  13. ^ Navarrete, Camila; Chanamé, Julio; Ramírez, Iván; Meza, Andrés; Anglada-Escudé, Guillem; Shkolnik, Evgenya (July 2015). "The Kapteyn Moving Group Is Not Tidal Debris From ω Centauri". The Astrophysical Journal. 808 (1): 103. arXiv:1506.02041. Bibcode:2015ApJ...808..103N. doi:10.1088/0004-637X/808/1/103. ISSN 0004-637X.
  14. ^ Lambert, D. L.; McWilliam, A. (May 1986). "Isotopic Abundances of Magnesium in the Metal-poor Subgiant ν Indi". The Astrophysical Journal. 304: 436. Bibcode:1986ApJ...304..436L. doi:10.1086/164178. ISSN 0004-637X.
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