| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| 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
[edit]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
[edit]- ^ 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 BJ, Bok PF, Miller EW (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, Brown AG, Prusti T, De Bruijne JH, Arenou F, Babusiaux C, 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.
{{cite journal}}: CS1 maint: overridden setting (link) Gaia DR3 record for this source at VizieR. - ^ a b Zacharias N, Finch CT, Girard TM, Henden A, Bartlett JL, Monet DG, et al. (February 2013). "The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)". The Astronomical Journal. 145 (2): 44. Bibcode:2013AJ....145...44Z. doi:10.1088/0004-6256/145/2/44. ISSN 0004-6256.
- ^ a b Gray RO, Corbally CJ, Garrison RF, McFadden MT, Bubar EJ, McGahee CE, 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.
- ^ Evans DS (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten AH, Heard JF (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 JI, Jenkins JS (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 AD, Ireland MJ, White TR, Casagrande L, 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 KK, Apai D, Bergsten GJ, Pascucci I, López-Morales M (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 R (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 K, Chini R (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.[permanent dead link]
- ^ Mallik SV, Parthasarathy M, Pati AK (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 JB. "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 PK (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.
