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70 Ophiuchi

Location of 70 Ophiuchi in the constellation Ophiuchus
Observation data Epoch J2000      Equinox
Constellation	Ophiuchus
70 Ophiuchi
Right ascension	18 05 27.285
Declination	+02° 29′ 00.36″
Apparent magnitude (V)	4.00 - 4.03
A
Right ascension	18 05 27.371
Declination	+02° 29′ 59.32″
Apparent magnitude (V)	4.13
B
Right ascension	18 05 27.462
Declination	+02° 29′ 56.22″
Apparent magnitude (V)	6.07
Characteristics
Spectral type	K0V + K4V
Apparent magnitude (B)	4.97/7.26
Apparent magnitude (R)	3.6/5.6
U−B color index	+0.69
B−V color index	+0.84/+1.19
Variable type	BY Dra or RS CVn
Astrometry
70 Oph A
Radial velocity (Rv)	−6.87 km/s
Proper motion (μ)	RA: 206.525±0.246 mas/yr Dec.: −1107.492±0.164 mas/yr
Parallax (π)	195.5674 ± 0.1964 mas
Distance	16.68 ± 0.02 ly (5.113 ± 0.005 pc)
Absolute magnitude (MV)	+5.49
70 Oph B
Proper motion (μ)	RA: 333.292±0.264 mas/yr Dec.: −1068.354±0.215 mas/yr
Parallax (π)	195.2166 ± 0.1012 mas
Distance	16.707 ± 0.009 ly (5.123 ± 0.003 pc)
Orbit
Period (P)	88.38±0.017 yr
Semi-major axis (a)	4.554±0.0052″
Eccentricity (e)	0.4992±0.00039
Inclination (i)	121.16±0.078°
Longitude of the node (Ω)	302.12±0.097°
Periastron epoch (T)	1895.94
Argument of periastron (ω) (secondary)	14.0±0.14°
Details
70 Oph A
Mass	0.90 ± 0.04 M☉
Radius	0.831±0.004 R☉
Luminosity (bolometric)	0.59 ± 0.02 L☉
Habitable zone inner limit	0.623 AU
Habitable zone outer limit	1.242 AU
Surface gravity (log g)	4.5 cgs
Temperature	5,300 K
Metallicity	+0.04 dex
Rotation	19.7 days
Age	1.9 Gyr
70 Oph B
Mass	0.70 ± 0.07 M☉
Radius	0.670±0.009 R☉
Luminosity (bolometric)	0.13 ± 0.03 L☉
Habitable zone inner limit	0.359 AU
Habitable zone outer limit	0.712 AU
Temperature	4,350 ± 150 K
Other designations
p Ophiuchi, V2391 Ophiuchi, BD+02 3482, Gl 702, HD 165341, HIP 88601, HR 6752, 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 is a binary star system located 16.6 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.

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.

Variability

70 Ophiuchi is a variable star with a magnitude range for the two stars combined of 4.00 to 4.03. 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 or an RS Canum Venaticorum variable, and a period of 1.92396 days has been measured.

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. 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, with one orbit taking 88.38 years to complete.

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". 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.

T. J. J. See made a stronger claim for the existence of a dark companion in this system in 1899, but Forest Ray Moulton soon published a paper proving that a three-body system with the specified orbital parameters would be highly unstable. The claims by Jacob and See have both been shown to be erroneous.

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. 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. This caused quite a sensation at the time but later observations have gradually discredited this claim.

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.

See also

• 61 Cygni
• Barnard's Star
• List of nearest stars and brown dwarfs

References

1. ^ 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
2. ^ "V2391 Oph". International Variable Star Index. AAVSO. Retrieved 2018-10-07.
3. ^ 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.
4. ^ 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.
5. ^ 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.
6. 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.
7. ^ "GCVS Query= V2391 Oph". General Catalog of Variable Stars. Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2018-03-08.
8. ^ 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.
9. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
10. Holmberg, J.; et al. (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.
11. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
12. 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.
13. ^ 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. doi:10.1088/0004-637X/757/2/112. ISSN 0004-637X.
14. ^ Fernandes, J.; Lebreton, Y.; Baglin, A.; Morel, P. (1998), "Fundamental stellar parameters for nearby visual binary stars: eta Cas, XI Boo, 70 OPH and 85 Peg", Astronomy and Astrophysics, 338: 455–464, Bibcode:1998A&A...338..455F
15. Bruntt, H.; et al. (July 2010), "Accurate fundamental parameters for 23 bright solar-type stars", Monthly Notices of the Royal Astronomical Society, 405 (3): 1907–1923, arXiv:1002.4268, Bibcode:2010MNRAS.405.1907B, doi:10.1111/j.1365-2966.2010.16575.x, S2CID 118495267
16. ^ 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
17. ^ 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
18. Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008), "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics", The Astrophysical Journal, 687 (2): 1264–1293, arXiv:0807.1686, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785, S2CID 27151456
19. "Star Catalogue of Ptolemaios". Vizier.cfa.harvard.edu. 2016-01-16. Retrieved 2022-03-27.
20. Ian Ridpath. "Taurus Poniatovii". Star Tales. Retrieved 2023-11-01.
21. "/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.
22. Solstation article giving details of orbital mechanics of the system
23. 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.
24. "The First Exoplanet Claim: Captain William S Jacob". YouTube. 2 December 2016.
25. 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.
26. Sherrill, Thomas J. (1999). "A Career of controversy: the anomaly OF T. J. J. See" (PDF). Journal for the History of Astronomy. 30: 25–50. Bibcode:1999JHA....30...25S. doi:10.1177/002182869903000102. S2CID 117727302. Archived (PDF) from the original on 25 September 2007. Retrieved 2007-08-27.
27. ^ Heintz, W.D. (June 1988). "The Binary Star 70 Ophiuchi Revisited" (PDF). Journal of the Royal Astronomical Society of Canada. 82 (3): 140. Bibcode:1988JRASC..82..140H.
28. 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.
29. Reuyl, Dirk; Holmberg, Erik (January 1943). "On the Existence of a Third Component in the System 70 Ophiuchi" (PDF). The Astrophysical Journal. 97: 41–46. Bibcode:1943ApJ....97...41R. doi:10.1086/144489.
30. 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.
31. 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.
32. 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" (PDF). The Astronomical Journal. 132 (1): 177–188. arXiv:astro-ph/0604171. Bibcode:2006AJ....132..177W. doi:10.1086/504942. S2CID 16755455.

External links

• Detection Limits from the McDonald Observatory Planet Search Program
• "70 Ophiuchi". SolStation. Retrieved October 24, 2005.

v t e Constellation of Ophiuchus
Ophiuchus in Chinese astronomy List of stars in Ophiuchus Taurus Poniatovii
Stars	Bayer α (Rasalhague) β (Cebalrai) γ (Muliphen) δ (Yed Prior) ε (Yed Posterior) ζ (Han) η (Sabik) θ ι κ λ (Marfik) μ ν ξ ο ρ σ τ υ φ χ ψ ω Flamsteed 12 14 15 16 18 19 20 21 23 24 26 28 29 30 31 36 (A, Guniibuu) 37 38 41 43 44 (b) 45 (d, θ Tel) 47 Oph 50 51 (c) 52 53 (f) 54 58 61 66 67 68 70 (p) 71 72 73 74 24 Sco Variable U V X Y RS RV RZ ST SW TT TW UU WZ XX BF IX KK V380 V426 V438 V442 V445 V451 V453 V502 V508 V566 V567 V716 V839 V841 V849 V986 V1010 V1054 V2051 V2052 V2076 V2105 V2112 V2113 V2114 V2118 V2126 V2129 V2213 V2214 V2247 V2291 V2292 V2293 V2295 V2301 V2306 V2307 V2324 V2368 V2388 V2393 V2400 V2487 V2500 (Barnard's Star) V2502 V2540 V2542 HR 5989 5990 6041 6067 6096 6124 6136 6137 6140 6144 6179 6189 6190 6193 6201 6202 6235 6248 6269 6284 6294 6296 6302 6308 6329 6340 6350 6353 6354 6358 6359 6361 6365 6367 6372 6375 6387 6390 6404 6413 6428 6433 6435 6439 6441 6465 6472 6473 6474 6476 6489 6490 6494 6497 6504 6507 6512 6516 6520 6521 6524 6532 6534 6575 6577 6578 6590 6593 6601 6633 6639 6650 6659 6667 6670 6686 6689 6690 6696 6706 6719 6784 6797 6800 6851 6857 6883 6902 6925 6976 6985 6987 7010 HD 148390 148427 (Timir) 148531 149143 (Rosalíadecastro) 149382 150052 150381 150433 150493 152581 (Mahsati) 154088 156992 157172 160042 160346 164509 167162 170469 171028 Other AS 239 BD-9 4395 CFHTWIR-Oph 98 CoRoT-6 CoRoT-25 CoRoT-26 DoAr 21 Elias 2-27 Gaia BH1 Gliese 673 GJ 1207 GJ 1214 (Okaria) GRS 1739-278 GX 1+4 GX 9+9 H 1705-250 Hen 3-1341 Great Annihilator IRAS 16293−2422 K2-32 LS IV-1 2 2MASS J16452211-1319516 MXB 1659-29 Oph-IRS 48 PG 1627-017 PSR B1929+10 TOI-677 Van Biesbroeck 8 VVV BD001 WISE 1800+0134 WISEP J180026.60+013453.1 Wolf 635 XTE J1739-285
Exoplanets CFHTWIR-Oph 98 b CoRoT-6b 25b 26b GJ 1214 b (Enaiposha) HD 149143 b (Riosar) ν Ophiuchi b c
Star clusters	NGC 6284 6287 6293 6304 6316 6325 6342 6355 6356 6366 6401 6426 6633 Other IC 4665 Melotte 186 Messier 9 Messier 10 Messier 12 Messier 14 Messier 19 Messier 62 Messier 107 Palomar 6
Nebulae	NGC 6309 6572 Other Dark Horse Double Helix Nebula Ophiuchus Superbubble Pipe Nebula Rho Ophiuchi cloud complex Serpens–Aquila Rift Snake Nebula
Galaxies	NGC 6240 6384 6509 6570 Other NeVe 1
Galaxy clusters Ophiuchus Supercluster
Astronomical events Kepler's Supernova
Category

• Binary stars
• Flamsteed objects
• Ophiuchus
• K-type main-sequence stars
• Solar analogs
• Gliese and GJ objects
• Objects with variable star designations
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects
• Bayer objects
• Durchmusterung objects
• Hypothetical planetary systems