Eta Scorpii
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Scorpius |
| η Sco A | |
| Right ascension | 17h 12m 09.19565s[1] |
| Declination | −43° 14′ 21.0905″[1] |
| Apparent magnitude (V) | 3.33[2] |
| η Sco B | |
| Right ascension | 17h 12m 51.49828s[3] |
| Declination | −43° 20′ 31.0692″[3] |
| Apparent magnitude (V) | 11.23±0.01[4] |
| Characteristics | |
| η Sco A | |
| Spectral type | F5 IV[5] |
| U−B color index | +0.09[2] |
| B−V color index | +0.41[2] |
| Astrometry | |
| η Sco A | |
| Radial velocity (Rv) | −27.0[6] km/s |
| Proper motion (μ) | RA: +24.47 mas/yr[1] Dec.: −288.55 mas/yr[1] |
| Parallax (π) | 44.39±0.16 mas[1] |
| Distance | 73.5 ± 0.3 ly (22.53 ± 0.08 pc) |
| Absolute magnitude (MV) | +1.58[7] |
| η Sco B | |
| Radial velocity (Rv) | −23.36±0.18[3] km/s |
| Proper motion (μ) | RA: +24.01 mas/yr[3] Dec.: −288.55 mas/yr[3] |
| Parallax (π) | 44.7788±0.0324 mas[3] |
| Distance | 72.84 ± 0.05 ly (22.33 ± 0.02 pc) |
| Details | |
| η Sco A | |
| Mass | 1.60+0.01 −0.23[8] M☉ |
| Radius | 3.307±0.050[9] R☉ |
| Luminosity | 17.94±0.45[9] L☉ |
| Surface gravity (log g) | 3.65±0.20[9] cgs |
| Temperature | 6,533±46[9] K |
| Metallicity [Fe/H] | −0.29±0.10[9] dex |
| Rotational velocity (v sin i) | 150[9] km/s |
| Age | 1.1[7] Gyr |
| η Sco B | |
| Mass | 0.527±0.017[10] M☉ |
| Radius | 0.524±0.017[10] R☉ |
| Luminosity | 0.050±0.001[10] L☉ |
| Temperature | 3,643±121[10] K |
| Other designations | |
| η Sco, CD−43 11485, FK5 638, GJ 657, HD 155203, HIP 84143, HR 6380, SAO 227707, WDS J17122-4314[11] | |
| Database references | |
| SIMBAD | Eta Scorpii A |
| Eta Scorpii B | |
Eta Scorpii, Latinized from η Scorpii, is a binary star in the southern zodiac constellation of Scorpius. With an apparent visual magnitude of 3.33,[2] this is one of the brighter members of the Scorpius and is the furthest south of the constellation stars with a Bayer designation.[12] The distance to this system can be estimated using parallax measurements, yielding values of 73.48 ± 0.26 light-years (22.53 ± 0.08 parsecs) for the primary[1] and 72.84 ± 0.05 ly (22.333 ± 0.015 pc) for the secondary.[3]
Characteristics
The two components of this system are separated by 9.87" in the sky, and were identified as a gravitationally bound pair in 2018 with data from the Gaia spacecraft.[13]
The stellar classification of the primary star, Eta Scorpii A, has undergone some revision over time, with the star being classified anywhere from an F-type main sequence star to a giant star.[11] In 2006, the NStars program assigned it a class of F5 IV,[5] where the luminosity class of 'IV' indicates this is a subgiant star that is exhausting the supply of hydrogen at its core and is in the process of evolving into a giant star. It has around 1.6 times the Sun's mass[8] with an estimated age of 1.1 billion years.[7] The star is radiating about 18 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 6,533 K.[9] It is this heat that gives it a yellow-white hue that is typical for an F-type star.[14]
Eta Scorpii A is rotating rapidly, with a projected rotational velocity of 150 km s−1.[15] This is causing the star to spin on its axis with a period of less than a day.[16] It is an X-ray emitter with its stellar corona giving off an X-ray luminosity of 4.4×1028 ergs s−1.[17] In 1991 it was identified as a possible barium star, as it displays an enhanced abundance of the element barium in its spectrum.[18] Overall, the abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, is similar to the abundance in the Sun.[7]
The secondary component, Eta Scorpii B, also designated L 413-148,[19] has a much fainter apparent magnitude of +11.23.[4] It has no published spectral type.[19] The star has roughly 0.53 times the mass of the Sun and 0.52 times the radius. It is radiating about 5% of the Sun's luminosity at an effective temperature of approximately 3,600 K.[10]
References
- ^ a b c d e 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. S2CID 18759600.
- ^ a b c d Bok, B. J.; Bok, P. F.; Miller, E. W. (November 1972). "Photometric standards for the southern hemisphere. II". Astronomical Journal. 77: 733. Bibcode:1972AJ.....77..733B. doi:10.1086/111346.
- ^ a b c d e f 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.
- ^ a b Zacharias, N.; Finch, C. T.; Girard, T. M.; Henden, A.; Bartlett, J. L.; Monet, D. G.; Zacharias, M. I. (February 2013). "The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)". The Astronomical Journal. 145 (2): 44. arXiv:1212.6182. Bibcode:2013AJ....145...44Z. doi:10.1088/0004-6256/145/2/44. ISSN 0004-6256.
- ^ 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. (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.
- ^ 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. Vol. 30. University of Toronto: International Astronomical Union. p. 57. Bibcode:1967IAUS...30...57E.
- ^ a b c d Holmberg, J.; Nordstrom, B.; Andersen, J. (July 2009). "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics". Astronomy and Astrophysics. 501 (3): 941–947. arXiv:0811.3982. Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191. S2CID 118577511.
- ^ a b Vines, Jose I.; Jenkins, James S. (June 2022). "ARIADNE: measuring accurate and precise stellar parameters through SED fitting". Monthly Notices of the Royal Astronomical Society. 513 (2): 2719–2731. arXiv:2204.03769. Bibcode:2022MNRAS.513.2719V. doi:10.1093/mnras/stac956. ISSN 0035-8711.
- ^ a b c d e f g Rains, Adam D.; Ireland, Michael J.; White, Timothy R.; Casagrande, Luca; Karovicova, I. (April 2020). "Precision angular diameters for 16 southern stars with VLTI/PIONIER". Monthly Notices of the Royal Astronomical Society. 493 (2): 2377–2394. arXiv:2004.02343. Bibcode:2020MNRAS.493.2377R. doi:10.1093/mnras/staa282.
- ^ a b c d e Hardegree-Ullman, Kevin K.; Apai, Dániel; Bergsten, Galen J.; Pascucci, Ilaria; López-Morales, Mercedes (June 2023). "Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O2 Levels in Nearby Transiting Habitable-zone Exoplanets". The Astronomical Journal. 165 (6): 267. arXiv:2304.12490. Bibcode:2023AJ....165..267H. doi:10.3847/1538-3881/acd1ec. ISSN 0004-6256.
- ^ a b "LTT 6848 -- High proper-motion Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2012-02-10.
- ^ Burnham, Robert (1978). Burnham's celestial handbook: an observer's guide to the universe beyond the solar system. Dover books explaining science. Vol. 3 (2nd ed.). Courier Dover Publications. p. 1675. ISBN 0-486-23673-0.
- ^ Fuhrmann, Klaus; Chini, Rolf (2018-06-01). "Nearby Gaia DR2 Companions". Research Notes of the AAS. 2 (2): 56. Bibcode:2018RNAAS...2...56F. doi:10.3847/2515-5172/aacc72. ISSN 2515-5172.
- ^ "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. Retrieved 2012-02-10.
- ^ Mallik, Sushma V.; Parthasarathy, M.; Pati, A. K. (October 2003). "Lithium and rotation in F and G dwarfs and subgiants". Astronomy and Astrophysics. 409 (1): 251–261. Bibcode:2003A&A...409..251M. doi:10.1051/0004-6361:20031084.
- ^ Kaler, James B. "Eta Scorpii". Stars. University of Illinois. Retrieved 2012-02-10.
- ^ Pizzolato, N.; Maggio, A.; Sciortino, S. (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.
- ^ Lu, Phillip K. (June 1991). "Taxonomy of barium stars". Astronomical Journal. 101: 2229–2254. Bibcode:1991AJ....101.2229L. doi:10.1086/115845.
- ^ a b "NLTT 44329". SIMBAD. Centre de données astronomiques de Strasbourg.