70 Ophiuchi
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| Data pengamatan Epos J2000 Ekuinoks | |
|---|---|
| Rasi bintang | Ophiuchus |
| '70 Oph'[1] | |
| Asensio rekta | 18j 05m 27.285d[1] |
| Deklinasi | +02° 30′ 00.36″[1] |
| Magnitudo semu (V) | 4.03[1] |
| '70 Oph B'[2] | |
| Asensio rekta | 18j 05m 27.421d[2] |
| Deklinasi | +02° 29′ 56.42″[2] |
| Magnitudo semu (V) | 6.00[2] |
| Ciri-ciri | |
| Kelas spektrum | K0V[1]/K4V[2] |
| Magnitudo semu (B) | ~4.89[1]/~7.15[2] |
| Magnitudo semu (V) | ~4.03[1]/~6.00[2] |
| Magnitudo semu (R) | -/~5.6[2] |
| Indeks warna U−B | 0.57/? |
| Indeks warna B−V | 0.78/? |
| Jenis variabel | BY[3]/- |
| Astrometri | |
| Kecepatan radial (Rv) | -6.9 km/s |
| Gerak diri (μ) | RA: 124.56 mdb/thn Dek.: -962.66 mdb/thn |
| Paralaks (π) | 195,96±0,87 mdb |
| Jarak | 16,64 ± 0,07 tc (5,10 ± 0,02 pc) |
| Magnitudo mutlak (MV) | 5.48/7.51 |
| Orbit bintang ganda visual | |
| Bintang sekunder | 70 Oph B |
| Periode (P) | 88.3 tahun |
| Sumbu semi-mayor (a) | 4.56" |
| Eksentrisitas (e) | 0.495 |
| Inklinasi (i) | 120.8° |
| Bujur node (Ω) | 13.2° |
| Epoch periastron (T) | 301.4 |
| Detail | |
| Massa | 0.92/0.70 M☉ |
| Radius | 0.89/0.73 R☉ |
| Luminositas | 0.43/0.08 L☉ |
| Gravitasi permukaan (log g) | 4.5[4]/– |
| Suhu | 5,300[4]/– K |
| Usia | 0.8 × 109[4] tahun |
| Penamaan lain | |
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 | |
| Referensi basis data | |
| SIMBAD | data |
70 Ophiuchi adalah komponen utama dari sistem bintang ganda yang berada cukup dekat dengan Bumi, yaitu 16.6 tahun cahaya dari Bumi, berada di rasi Ophiuchus. Dengan magnitudo 4.00, bintang ini merupakan bintang cemerlang yang paling redup yang dapat dilihat dalam cahaya kota.[1]
Bintang ganda
Komponen utamanya merupakan bintang katai kuning-jingga (yellow-orange dwarf) variable[3] of spectral type K0, and the secondary star is an orange main sequence dwarf of spectral type K4.[2]
Sejarah pengamatan
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.[5]
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".[6] T. J. J. See made a stronger claim for the existence of a dark companion in this system in 1899,[5] but Forest Ray Moulton soon published a paper proving that a three-body system with the specified orbital parameters would be highly unstable.[7] The claims by Jacob and See have both been shown to be erroneous.[8] 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.[9] This caused quite a sensation at the time but later observations have gradually discredited this claim.[10]
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.[11]
See also
References
- ^ a b c d e f g h "SIMBAD query result: V* V2391 Oph -- Spectroscopic binary". Centre de Données astronomiques de Strasbourg. Diakses tanggal 2009-06-04.
- ^ a b c d e f g h i "SIMBAD query result: LHS 459 -- High proper-motion Star". Centre de Données astronomiques de Strasbourg. Diakses tanggal 2009-06-04.
- ^ a b "GCVS Query= V2391 Oph". General Catalog of Variable Stars. Sternberg Astronomical Institute, Moscow, Russia. Diakses tanggal 2009-06-04.
- ^ 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. Diakses tanggal 2007-06-05.
- ^ 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.
- ^ Jacob, W.S. (1855). "On Certain Anomalies presented by the Binary Star 70 Ophiuchi". Monthly Notices of the Royal Astronomical Society. 15: 228.
- ^ Sherrill, Thomas J. (1999). "A Career of controversy: the anomaly OF T. J. J. See" (PDF). Journal for the history of astronomy. 30. Diakses tanggal 2007-08-27.
- ^ Heintz, W.D. (1988). "The Binary Star 70 Ophiuchi Revisited". Journal of the Royal Astronomical Society of Canada. 82 (3). Diakses tanggal 2007-08-27.
- ^ Reuyl, Dirk; Holmberg, Erik (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.
- ^ Heintz, W. D. (1988). "The binary star 70 Ophiuchi revisited" (PDF). Royal Astronomical Society of Canada, Journal (ISSN 0035-872X). 82: 140–145. Bibcode:1988JRASC..82..140H.
- ^ Wittenmyer; et al. (7 April 2006). "Detection Limits from the McDonald Observatory Planet Search Program" (PDF). The Astronomical Journal. 132 (1): 177–188. doi:10.1086/504942.
External links
- Detection Limits from the McDonald Observatory Planet Search Program
- "70 Ophiuchi". SolStation. Diakses tanggal October 24 2005.
