70 Ophiuchi: Wikis

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70 Ophiuchi
Observation data
Epoch J2000      Equinox
Constellation Ophiuchus
'70 Oph'[1]
Right ascension 18h 05m 27.285s[1]
Declination +02° 30′ 00.36″[1]
Apparent magnitude (V) 4.03[1]
'70 Oph B'[2]
Right ascension 18h 05m 27.421s[2]
Declination +02° 29′ 56.42″[2]
Apparent magnitude (V) 6.00[2]
Characteristics
Spectral type K0V[1]/K4V[2]
Apparent magnitude (B) ~4.89[1]/~7.15[2]
Apparent magnitude (V) ~4.03[1]/~6.00[2]
Apparent magnitude (R) -/~5.6[2]
U-B color index 0.57/?
B-V color index 0.78/?
Variable type BY[3]/-
Astrometry
Radial velocity (Rv) -6.9 km/s
Proper motion (μ) RA: 124.56 mas/yr
Dec.: -962.66 mas/yr
Parallax (π) 195.96 ± 0.87 mas
Distance 16.64 ± 0.07 ly
(5.1 ± 0.02 pc)
Absolute magnitude (MV) 5.48/7.51
Orbit
Companion 70 Oph B
Period (P) 88.3 yr
Semimajor axis (a) 4.56"
Eccentricity (e) 0.495
Inclination (i) 120.8°
Longitude of the node (Ω) 13.2°
Periastron epoch (T) 301.4
Details
Mass 0.92/0.70 M
Radius 0.89/0.73 R
Surface gravity (log g) 4.5[4]/–
Luminosity 0.43/0.08 L
Temperature 5,300[4]/– K
Age 0.8 × 109[4] years
Other designations
70 Oph
V2391 Oph, GJ 702, HR 6752, BD +02°3482, HD 165341, GCTP 4137.00, LHS 458/9, SAO 123107, Struve 2272, HIP 88601

2E 4004, IDS 18004+0232 AB, TD1 21598, 70 Oph, 1ES 1802+02.5, IRC +00335, UBV 15379, STF 2272AB, 2EUVE J1805+02.4, JP11 2926, UBV M 22611, ADS 11046 AB, EUVE J1805+02.4, N30 4015, UBV M 22609, ADS 11046, GC 24641, PLX 4137, uvby98 100165341 AB, AG+02 2199, GEN# +1.00165341J, PPM 165145, [B10] 4571, BD+02 3482, GJ 702, ROT 5812, p. WDS J1805.5+0230, CCDM J18055+0230AB, HD 165341, SAO 123107, p. WDS J18054+0232AB, Ci 20 1073, HIC 88601, SBC7 660, CSI+02 3482 1, HIP 88601, SBC9 1022, 2E 1802.9+0230, HR 6752, SKY# 32844
70 Oph B
LHS 459, CCDM J18055+0230B, IDS 18004+0232 B, ROT 3570, 70 Oph B, CSI+02 3482 11, LFT 1391, TDSC 46270 B, STF 2272B, 1E 1802.9+0229, LSPM J1805+0229b, TYC 434-5212-1, ADS 11046 B, GCRV 10532, LTT 15338, UBV 15378,

ASCC 1153898, GJ 702 B, NLTT 45900 , Zkh 272, BD+02 3482B, HD 165341B, 8pc 196.62B

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Database references
SIMBAD data

70 Ophiuchi is the primary star of a binary star system relatively close at 16.6 light years away from the Earth. It is in the constellation Ophiuchus. At magnitude 4 it is a typical less bright star usually visible to the unaided eye away from city lights.[1]

Contents

Binary star

The primary star is a yellow-orange main sequence dwarf BY Draconis variable[3] of spectral type K0, and the secondary star is an orange main sequence dwarf of spectral type K4.[2] The two stars orbit each other at an average distance of 23.2 AUs. But since the orbit is highly elliptical (at e=0.499), the separation between the two varies from 11.4 to 34.8 AUs, with one orbit taking 83.38 years to complete.[5]

History

This star system was first cataloged by William Herschel in the late 18th century in his study of binary stars. Herschel proved that this system as a gravitationally bound Binary star system where the two stars orbited 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. He commented at the time that there was a possible third unseen companion affecting the orbit of the two visible stars.[6]

Claims of a planetary system

In 1855, Capt. W. S. Jacob of the Madras Observatory of the East India Company 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".[7] T. J. J. See made a stronger claim for the existence of a dark companion in this system in 1899,[6] but Forest Ray Moulton soon published a paper proving that a three-body system with the specified orbital parameters would be highly unstable.[8] The claims by Jacob and See have both been shown to be erroneous.[9] Jacob's claim was probably one of the first for an exoplanet based on astrometric evidence.
A claim of a planetary system was again made by Dirk Reuyl and Erik Holberg in 1943. The companion was estimated to have a mass one tenth the mass of the Sun.[10] This caused quite a sensation at the time but later observations have gradually discredited this claim.[11]

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Refining planetary boundaries

The negative results of past studies does not completely rule out the possibility of planets. In 2006 a McDonald Observatory team has 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 Astronomical Units.[12]

See also

References

  1. ^ a b c d e f g h "SIMBAD query result: V* V2391 Oph -- Spectroscopic binary". Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=GJ+702. Retrieved 2009-06-04.  
  2. ^ a b c d e f g h i "SIMBAD query result: LHS 459 -- High proper-motion Star". Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Gl+702+B. Retrieved 2009-06-04.  
  3. ^ a b "GCVS Query= V2391 Oph". General Catalog of Variable Stars. Sternberg Astronomical Institute, Moscow, Russia. http://www.sai.msu.su/groups/cluster/gcvs/cgi-bin/search.cgi?search=V2391+Oph. Retrieved 2009-06-04.  
  4. ^ a b c 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. http://adsabs.harvard.edu/abs/1992A&A...259..543M. Retrieved 2007-06-05.  
  5. ^ Solstation article giving details of orbital mechanics of the system
  6. ^ a b 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. doi:10.1086/102368.  
  7. ^ Jacob, W.S. (1855). "On Certain Anomalies presented by the Binary Star 70 Ophiuchi". Monthly Notices of the Royal Astronomical Society 15: 228. http://books.google.nl/books?id=pQsAAAAAMAAJ&printsec=frontcover&dq=editions:0B0EaWqbmirpeTa2sds.  
  8. ^ Sherrill, Thomas J. (1999). "A Career of controversy: the anomaly OF T. J. J. See" (PDF). Journal for the history of astronomy 30. http://www.shpltd.co.uk/jha.pdf. Retrieved 2007-08-27.  
  9. ^ Heintz, W.D. (June 1988). "The Binary Star 70 Ophiuchi Revisited". Journal of the Royal Astronomical Society of Canada 82 (3). http://adsabs.harvard.edu/abs/1988JRASC..82..140H. Retrieved 2007-08-27.  
  10. ^ Reuyl, Dirk; Holmberg, Erik (January 1943). "On the Existence of a Third Component in the System 70 Ophiuchi". The Astrophysical Journal 97: 41–46. doi:10.1086/144489. Bibcode1943ApJ....97...41R. http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1943ApJ....97...41R&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf.  
  11. ^ Heintz, W. D. (June 1988). "The binary star 70 Ophiuchi revisited". Royal Astronomical Society of Canada, Journal (ISSN 0035-872X) 82: 140–145. Bibcode1988JRASC..82..140H. http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1988JRASC..82..140H&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf.  
  12. ^ Wittenmyer, et al.; 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. doi:10.1086/504942. http://www.iop.org/EJ/article/1538-3881/132/1/177/205213.web.pdf?request-id=07bc0d13-46f9-401e-afa4-5f9928b3da46.  

External links

Coordinates: Sky map 18h 05m 27.3s, −02° 30′ 00″


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