  | |
| Observation data Epoch J2000 Equinox | |
|---|---|
| Constellation | Ophiuchus |
| 70 Ophiuchi | |
| Right ascension | 18h 05m 27.285s[1] |
| Declination | +02° 29′ 00.36″[1] |
| Apparent magnitude (V) | 4.00 - 4.03[2] |
| A | |
| Right ascension | 18h 05m 27.248s[3] |
| Declination | +02° 30′ 00.53″[3] |
| Apparent magnitude (V) | 4.13[4] |
| B | |
| Right ascension | 18h 05m 27.463s[5] |
| Declination | +02° 29′ 56.21″[5] |
| Apparent magnitude (V) | 6.07[4] |
| Characteristics | |
| Spectral type | K0V + K4V[6] |
| Apparent magnitude (B) | 4.97/7.26[4] |
| Apparent magnitude (R) | 3.6/5.6[4] |
| U−B color index | +0.69[7] |
| B−V color index | +0.82/+1.15[8] |
| Variable type | BY Dra[9] or RS CVn[2] |
| Astrometry | |
| 70 Oph A | |
| Radial velocity (Rv) | −5.73±0.18[3] km/s |
| Proper motion (μ) | RA: 206.525 mas/yr[3] Dec.: −1107.492 mas/yr[3] |
| Parallax (π) | 195.5674±0.1964 mas[3] |
| Distance | 16.68 ± 0.02 ly (5.113 ± 0.005 pc) |
| Absolute magnitude (MV) | +5.627[8] |
| 70 Oph B | |
| Radial velocity (Rv) | −9.47±0.22[5] km/s |
| Proper motion (μ) | RA: 333.292 mas/yr[5] Dec.: −1068.354 mas/yr[5] |
| Parallax (π) | 195.2166±0.1012 mas[10] |
| Distance | 16.707 ± 0.009 ly (5.123 ± 0.003 pc) |
| Absolute magnitude (MV) | +7.427[8] |
| Orbit[11] | |
| Period (P) | 88.435±0.017 yr |
| Semi-major axis (a) | 4.526″±0.007″[11] (23.6±0.5 AU[8]) |
| Eccentricity (e) | 0.5005±0.0006 |
| Inclination (i) | 121.1±0.1° |
| Longitude of the node (Ω) | 121.7±0.2° |
| Periastron epoch (T) | 45,809±14 |
| Argument of periastron (ω) (secondary) | 193.4±0.3° |
| Semi-amplitude (K1) (primary) | 3.51±0.04 km/s |
| Semi-amplitude (K2) (secondary) | 4.25±0.05 km/s |
| Details | |
| 70 Oph A | |
| Mass | 0.834±0.055[8] M☉ |
| Radius | 0.831±0.004[12] R☉ |
| Luminosity (bolometric) | 0.51±0.01[8] L☉ |
| Habitable zone inner limit | 0.623[12] AU |
| Habitable zone outer limit | 1.242[12] AU |
| Surface gravity (log g) | 4.5[13] cgs |
| Temperature | 5,282[8] K |
| Metallicity [Fe/H] | 0.04±0.05[11] dex |
| Rotation | 19.7[14] days |
| Age | 6.2±1.0[11] Gyr |
| 70 Oph B | |
| Mass | 0.782±0.064[8] M☉ |
| Radius | 0.670±0.009[12] R☉ |
| Luminosity (bolometric) | 0.15±0.02[11] L☉ |
| Habitable zone inner limit | 0.359[12] AU |
| Habitable zone outer limit | 0.712[12] AU |
| Temperature | 4,623[8] K |
| Metallicity [Fe/H] | 0.04±0.05[11] dex |
| Age | 6.2±1.0[11] Gyr |
| Other designations | |
| p Oph, 70 Oph, V2391 Oph, BD+02 3482, GJ 702, HD 165341, HIP 88601, HR 6752, SAO 123107, PLX 4137 | |
| 70 Oph A: LHS 458 | |
| 70 Oph B: LHS 459 | |
| Database references | |
| SIMBAD | The system |
| A | |
| B | |
| Exoplanet Archive | data |
| ARICNS | data |
70 Ophiuchi (p Ophiuchi)[15] is a binary star system located 16.7 light-years away from the Earth. It is in the constellation Ophiuchus. At magnitude 4 it appears as a dim star visible to the unaided eye away from city lights.
History
In Ptolemy's 2nd-century Almagest star catalogue this star system is listed as a 4th magnitude star, the 28th (or 4th outside the constellation figure) in Ophiuchus. It is star No. 261 in this catalogue.[16]
This star system was first catalogued as a binary star by William Herschel in the late 18th century in his study of binary stars. Herschel proved that this system is a gravitationally bound binary system where the two stars orbit around a common center of mass. This was an important contribution to the proof that Newton's law of universal gravitation applied to objects beyond the Solar System.
This star was once considered part of the obsolete constellation Taurus Poniatovii, but after the International Astronomical Union officially recognized constellations, it was placed in Ophiuchus.[17]
Variability
70 Ophiuchi is a variable star with a magnitude range for the two stars combined of 4.00 to 4.03.[2] The type of variability is uncertain and it is not clear which of the two components causes the variations. It has been suspected of being either a BY Draconis variable[9] or an RS Canum Venaticorum variable, and a period of 1.92396 days has been measured.[2]
Binary star
The primary star is a yellow-orange main sequence dwarf of spectral type K0, while the secondary is an orange dwarf of spectral type K4.[6] The two stars orbit each other at an average distance of 23.2 AU. But since the orbit is highly elliptical (at e=0.499), the separation between the two varies from 11.4 to 34.8 AU,[19] with one orbit taking 88.38 years to complete.[20]
Claims of a planetary system
In 1855, William Stephen Jacob of the Madras Observatory claimed that the orbit of the binary showed an anomaly, and it was "highly probable" that there was a "planetary body in connection with this system".[21] This is the first known attempt to use astrometric methods to detect an exoplanet, although Friedrich Bessel had applied similar methods 10 years earlier to deduce the existence of Sirius B.[22]
T. J. J. See made a stronger claim for the existence of a dark companion in this system in 1899,[23] but Forest Ray Moulton soon published a paper proving that a three-body system with the specified orbital parameters would be highly unstable.[24] The claims by Jacob and See have both been shown to be erroneous.[25]
Discovery of a "third dark companion" was announced by Louis Berman in 1932. This "dark body" around 70 Oph A was thought to have an 18-year period and a mass of 0.1 to 0.2 the Sun's mass.[26] A claim of a planetary system was again made, this time by Dirk Reuyl and Erik Holberg in 1943. The companion was estimated to have a mass 0.008 to 0.012 that of the Sun and a 17-year period.[27] This caused quite a sensation at the time but later observations have gradually discredited this claim.[25][28][29]
The negative results of past studies does not completely rule out the possibility of planets. In 2006 a McDonald Observatory team set limits to the presence of one or more planets around 70 Ophiuchi with masses between 0.46 and 12.8 Jupiter masses and average separations spanning between 0.05 and 5.2 AU.[30]
See also
References
- ^ a b 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 "V2391 Oph". International Variable Star Index. AAVSO. Retrieved 2018-10-07.
- ^ 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.
- ^ a b c d Fabricius, C.; Høg, E.; Makarov, V. V.; Mason, B. D.; Wycoff, G. L.; Urban, S. E. (2002). "The Tycho double star catalogue". Astronomy and Astrophysics. 384: 180–189. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822.
- ^ a b c d 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 Cowley, A. P.; Hiltner, W. A.; Witt, A. N. (1967). "Spectral classification and photometry of high proper motion stars". The Astronomical Journal. 72: 1334. Bibcode:1967AJ.....72.1334C. doi:10.1086/110413.
- ^ Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". VizieR On-line Data Catalog. 2237. Bibcode:2002yCat.2237....0D.
- ^ a b c d e f g h i Piccotti, Luca; Docobo, José Ángel; Carini, Roberta; Tamazian, Vakhtang S.; Brocato, Enzo; Andrade, Manuel; Campo, Pedro P. (2020-02-01). "A study of the physical properties of SB2s with both the visual and spectroscopic orbits". Monthly Notices of the Royal Astronomical Society. 492 (2): 2709–2721. Bibcode:2020MNRAS.492.2709P. doi:10.1093/mnras/stz3616. ISSN 0035-8711. 70 Ophiuchi's database entry at VizieR.
- ^ a b "GCVS Query= V2391 Oph". General Catalog of Variable Stars. Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2018-03-08.
- ^ 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.
- ^ a b c d e f g Eggenberger, P.; Miglio, A.; Carrier, F.; Fernandes, J.; Santos, N. C. (2008-05-01). "Analysis of 70 Ophiuchi AB including seismic constraints". Astronomy & Astrophysics. 482 (2): 631–638. arXiv:0802.3576. Bibcode:2008A&A...482..631E. doi:10.1051/0004-6361:20078624. ISSN 0004-6361.
- ^ a b c d e f Boyajian, Tabetha S.; von Braun, Kaspar; van Belle, Gerard; McAlister, Harold A.; Brummelaar, Theo A. ten; Kane, Stephen R.; Muirhead, Phil; Jones, Jeremy; White, Russel; Schaefer, Gail; Ciardi, David; Henry, Todd; López-Morales, Mercedes; Ridgway, Stephen; Gies, Douglas (2012-10-01). "Stellar Diameters and Temperatures II. Main Sequence K & M Stars". The Astrophysical Journal. 757 (2): 112. arXiv:1208.2431. Bibcode:2012ApJ...757..112B. doi:10.1088/0004-637X/757/2/112. ISSN 0004-637X.
- ^ Morell, O.; Kallander, D.; Butcher, H. R. (1999). "The age of the Galaxy from thorium in G dwarfs, a re-analysis". Astronomy and Astrophysics. 259 (2): 543–548. Bibcode:1992A&A...259..543M.
- ^ Maldonado, J.; et al. (October 2010). "A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups". Astronomy and Astrophysics. 521: A12. arXiv:1007.1132. Bibcode:2010A&A...521A..12M. doi:10.1051/0004-6361/201014948. S2CID 119209183.
- ^ Gore, J. G. (March 1888). "On the Orbit of 70 (p) Ophiuchi". Monthly Notices of the Royal Astronomical Society. 48: 257. Bibcode:1888MNRAS..48..257G. doi:10.1093/mnras/48.5.257.
- ^ "Star Catalogue of Ptolemaios". Vizier.cfa.harvard.edu. 2016-01-16. Retrieved 2022-03-27.
- ^ Ian Ridpath. "Taurus Poniatovii". Star Tales. Retrieved 2023-11-01.
- ^ "/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.
- ^ Solstation article giving details of orbital mechanics of the system
- ^ Pourbaix, D. (2000). "Resolved double-lined spectroscopic binaries: A neglected source of hypothesis-free parallaxes and stellar masses". Astronomy and Astrophysics Supplement Series. 145 (2): 215–222. Bibcode:2000A&AS..145..215P. doi:10.1051/aas:2000237.
- ^ Jacob, W.S. (1855). "On Certain Anomalies presented by the Binary Star 70 Ophiuchi". Monthly Notices of the Royal Astronomical Society. 15 (9): 228–230. Bibcode:1855MNRAS..15..228J. doi:10.1093/mnras/15.9.228.
- ^ "The First Exoplanet Claim: Captain William S Jacob". YouTube. 2 December 2016.
- ^ See, Thomas Jefferson Jackson (1896). "Researches on the Orbit of F.70 Ophiuchi, and on a Periodic Perturbation in the Motion of the System Arising from the Action of an Unseen Body". The Astronomical Journal. 16: 17. Bibcode:1896AJ.....16...17S. doi:10.1086/102368.
- ^ Sherrill, Thomas J. (1999). "A Career of controversy: the anomaly OF T. J. J. See". Journal for the History of Astronomy. 30: 25–50. Bibcode:1999JHA....30...25S. doi:10.1177/002182869903000102. S2CID 117727302.
- ^ a b Heintz, W.D. (June 1988). "The Binary Star 70 Ophiuchi Revisited". Journal of the Royal Astronomical Society of Canada. 82 (3): 140. Bibcode:1988JRASC..82..140H.
- ^ Berman, Louis (1932). "70 Ophiuchi as a Triple System". Lick Observatory Bulletin. 16 (443): 24–30. Bibcode:1932LicOB..16...24B. doi:10.5479/ADS/bib/1932LicOB.16.24B.
- ^ Reuyl, Dirk; Holmberg, Erik (January 1943). "On the Existence of a Third Component in the System 70 Ophiuchi". The Astrophysical Journal. 97: 41–46. Bibcode:1943ApJ....97...41R. doi:10.1086/144489.
- ^ van de Kamp, Peter (February 1945). "Stars Nearer than Five Parsecs". Publications of the Astronomical Society of the Pacific. 57 (334): 34–41 (38*). Bibcode:1945PASP...57...34V. doi:10.1086/125679.
- ^ Worth, M.D. (November 1974). "Parallax, orbit, and mass of the binary star 70 Ophiuchi". Astrophysical Journal. 193: 647–650. Bibcode:1974ApJ...193..647W. doi:10.1086/153202.
- ^ Wittenmyer; Endl, Michael; Cochran, William D.; Hatzes, Artie P.; Walker, G. A. H.; Yang, S. L. S.; Paulson, Diane B. (7 April 2006). "Detection Limits from the McDonald Observatory Planet Search Program". The Astronomical Journal. 132 (1): 177–188. arXiv:astro-ph/0604171. Bibcode:2006AJ....132..177W. doi:10.1086/504942. S2CID 16755455.
External links
- "70 Ophiuchi". SolStation. Archived from the original on August 24, 2000. Retrieved October 24, 2005.
