Nu Indi

Nu Indi
Location of ν Indi (circled in red)
Observation data
Epoch J2000      Equinox J2000
Constellation Indus
Right ascension 22h 24m 36.88539s
Declination −72° 15′ 19.4882″
Apparent magnitude (V) 5.278±0.005
Characteristics
Evolutionary stage Subgiant
Spectral type G9V Fe-3.1CH-1.5
Astrometry
Radial velocity (Rv)+32.51±0.16 km/s
Proper motion (μ) RA: +1,303.872 mas/yr
Dec.: −674.186 mas/yr
Parallax (π)35.1281±0.0640 mas
Distance92.8 ± 0.2 ly
(28.47 ± 0.05 pc)
Absolute magnitude (MV)+2.70±0.05
Details
Mass0.85±0.04 M☉
Radius2.95±0.12 R☉
Luminosity6.28±0.23 L☉
Surface gravity (log g)3.43±0.10 cgs
Temperature5,318±80 K
Metallicity [Fe/H]−1.54±0.07 dex
Rotational velocity (v sin i)2.67 km/s
Age11.0±0.7 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

The spectrum of this star matches a classification of G9V Fe-3.1CH-1.5, with the notation G9V suggesting it is a late-type G-type main sequence star. However, it is actually a subgiant, 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. The metallicity indicators classify it as a Population II star.

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

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. It does not make part of any stellar association or moving group.

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. However, there is evidence it may be an astrometric binary.

References

  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. 1 2 3 4 5 6 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. 1 2 3 4 5 6 7 8 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. 1 2 3 4 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. 1 2 3 4 5 6 7 8 9 10 11 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. 1 2 3 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. 1 2 3 4 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. 1 2 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.