Eta Indi
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Indus |
| Right ascension | 20h 44m 02.33404s[1] |
| Declination | −51° 55′ 15.4970″[1] |
| Apparent magnitude (V) | 4.52[2] |
| Characteristics | |
| Spectral type | A9IV[3] |
| B−V color index | +0.26[2] |
| Astrometry | |
| Radial velocity (Rv) | −1.6±0.8[4] km/s |
| Proper motion (μ) | RA: +155.80[1] mas/yr Dec.: −53.86[1] mas/yr |
| Parallax (π) | 41.37 ± 0.25 mas[1] |
| Distance | 78.8 ± 0.5 ly (24.2 ± 0.1 pc) |
| Absolute magnitude (MV) | 2.59[5] |
| Details | |
| Mass | 1.60[6] M☉ |
| Radius | 2.27[7] R☉ |
| Luminosity | 7.60[5] L☉ |
| Temperature | 7,694[6] K |
| Rotational velocity (v sin i) | 75[8] km/s |
| Age | 100±50[7] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta Indi, Latinised from η Indi, is a single, white-hued star in the southern constellation Indus. It is a faint star but visible to the naked eye with an apparent visual magnitude of 4.52.[2]
Measurements with the Hipparcos spacecraft showed the star, which is single,[9] appears to move against the deep sky backdrop by a mean biannual parallax shift of around 41.37 mas,[1] which equates to 79 light-years' distance. Its radial vector to our system's own trajectory (radial velocity) shows it to be in a phase of a narrowing of the gap, at a rounded −2 km/s, net.[4] η Indi appears to be a member of the Octans association, a group of 62 stars that are around 30−50 million years old and have common motion.[10]
The spectrum of this star matches a stellar classification of A9 IV[3] which suggests it is an evolving subgiant star of type A. The star is estimated 1.6 M☉ (masses of the Sun),[6] and 2.27 R☉ (its radius).[7] It is shines with 7.60[5] times the Sun's luminosity, which is radiated from its photosphere at an effective temperature of 7,694 K.[6] The star is spinning with a projected rotational velocity of 75 km/s.[8] It is very likely to be a hybrid Delta Scuti/Gamma Doradus variable.[8]
References[edit]
- ^ a b c d e f 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. Vizier catalog entry
- ^ a b c d "Eta Indi". SIMBAD Astronomical Database. Retrieved 2016-08-23.
- ^ a b Gray, R. O.; et al. (July 2006). "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. S2CID 119476992.
- ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
- ^ a b c Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644. Vizier catalog entry
- ^ a b c d David, Trevor J.; Hillenbrand, Lynne A. (May 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): 146–184. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. S2CID 33401607. Vizier catalog entry
- ^ a b c Plavchan, Peter; et al. (June 2009), "New Debris Disks Around Young, Low-Mass Stars Discovered with the Spitzer Space Telescope", The Astrophysical Journal, 698 (2): 1068–1094, arXiv:0904.0819, Bibcode:2009ApJ...698.1068P, doi:10.1088/0004-637X/698/2/1068, S2CID 51417657.
- ^ a b c Koen, C.; van, Wyk F.; Laney, C. D.; Kilkenny, D. (2017), "HR 7920: a very bright new Delta Scuti star with possible Gamma Doradus variations", MNRAS, 466 (1): 122–128, Bibcode:2017MNRAS.466..122K, doi:10.1093/mnras/stw3062
- ^ Rodriguez, David R.; et al. (May 2015), "Stellar multiplicity and debris discs: an unbiased sample", Monthly Notices of the Royal Astronomical Society, 449 (3): 3160–3170, arXiv:1503.01320, Bibcode:2015MNRAS.449.3160R, doi:10.1093/mnras/stv483.
- ^ Torres, C. A. O.; Quast, G. R.; da Silva, L .; de la Reza, R.; Melo, C. H. F.; Sterzik, M. (2006). "Search for associations containing young stars (SACY)". Astronomy and Astrophysics. 460 (3): 695–708. arXiv:astro-ph/0609258. Bibcode:2006A&A...460..695T. doi:10.1051/0004-6361:20065602. ISSN 0004-6361. S2CID 16080025.
