HR 7703

HR 7703 (Gliese 783, 279 G. Sagittarii) is a binary star system in the constellation of Sagittarius. The brighter component has an apparent visual magnitude of 5.31,[2] which means it is visible from suburban skies at night. The two stars are separated by an angle of 7.10″, which corresponds to an estimated semimajor axis of 56.30 AU for their orbit.[10]

HR 7703
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 20h 11m 11.93827s[1]
Declination –36° 06′ 04.3610″[1]
Apparent magnitude (V) 5.31[2]/11.50[3]
Characteristics
Spectral type K2.5 V[4] + M4 V[5]
U−B color index +0.43[2]
B−V color index +0.85[2]
Astrometry
Radial velocity (Rv)–129.4[6] km/s
Proper motion (μ) RA: +456.99[1] mas/yr
Dec.: –1574.64[1] mas/yr
Parallax (π)166.25 ± 0.27[1] mas
Distance19.62 ± 0.03 ly
(6.015 ± 0.010 pc)
Absolute magnitude (MV)6.53[7]
Details
HR 7703 A
Mass0.65[8] M☉
Radius0.66[8] R☉
Luminosity0.26[8] L☉
Surface gravity (log g)4.48 ± 0.17[8] cgs
Temperature5,075 ± 43[8] K
Metallicity [Fe/H]–0.56 ± 0.04[8] dex
Rotational velocity (v sin i)1.8 ± 0.2[7] km/s
Age7.7[9] Gyr
HR 7703 B
Mass0.24[10] M☉
Radius0.28[3] R☉
Other designations
279 G. Sagittarii, Gliese 783, CD –36°13940, GCTP 4782.00, HD 191408, HIP 99461, SAO 211885.[11]
HR 7703 A: LHS 486, LFT 1529, LTT 7988
HR 7703 B: LHS 487, LFT 1530, LTT 7989
Database references
SIMBADThe system
A
B

Based upon an annual parallax shift of 0.16625 arc seconds as measured by the Hipparcos satellite, this system is 19.62 light-years (6.015 parsecs) from Earth. It is approaching the Solar System at a velocity of approximately 129 kilometers per second.[6] At this rate, it will make its closest approach in 41,100 years when it comes to within 6.7 light-years (2.05 parsecs) of the Sun.[12]

This star system has been examined for an excess of radiation in the infrared. The presence of an infrared excess can be taken as an indication of a debris disk orbiting the star. However, no such excess was discovered around HR 7703.[13] Radial velocity data collected over a period of 12 years was examined for signs of periodicity caused by a planet orbiting at a distance of 3–6 AU, but none was detected.[14] A slight linear trend in the radial velocities of the primary is probably due to the companion star.[15]

In the Defiance TV series episode "Of a Demon in My View", the Omec ship Tsuroz was in this system in 1978 when they picked up a radio signal from Earth.

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. Feinstein, A. (1966), "Photoelectric observations of Southern late-type stars", The Information Bulletin for the Southern Hemisphere, 8: 30, Bibcode:1966IBSH....8...30F.
  3. Pasinetti-Fracassini, L. E.; et al. (February 2001), "Catalogue of Stellar Diameters (CADARS)", Astronomy and Astrophysics, 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
  4. Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992.
  5. Turnbull, M. C.; Tarter, J. C. (December 2003), "Target Selection for SETI. II. Tycho-2 Dwarfs, Old Open Clusters, and the Nearest 100 Stars", The Astrophysical Journal Supplement Series, 149 (2): 423–436, Bibcode:2003ApJS..149..423T, doi:10.1086/379320.
  6. Nordström, B.; et al. (May 2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs", Astronomy and Astrophysics, 418 (3): 989–1019, arXiv:astro-ph/0405198, Bibcode:2004A&A...418..989N, doi:10.1051/0004-6361:20035959, S2CID 11027621.
  7. Ammler-von Eiff, M.; Reiners, A. (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics, 542: A116, arXiv:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724, S2CID 53666672.
  8. Ghezzi, L.; et al. (September 2010), "Stellar Parameters and Metallicities of Stars Hosting Jovian and Neptunian Mass Planets: A Possible Dependence of Planetary Mass on Metallicity", The Astrophysical Journal, 720 (2): 1290–1302, arXiv:1007.2681, Bibcode:2010ApJ...720.1290G, doi:10.1088/0004-637X/720/2/1290, S2CID 118565025.
  9. 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.
  10. Bonavita, M.; Desidera, S. (June 2007), "The frequency of planets in multiple systems", Astronomy and Astrophysics, 468 (2): 721–729, arXiv:astro-ph/0703754, Bibcode:2007A&A...468..721B, doi:10.1051/0004-6361:20066671, S2CID 18907128.
  11. "HD 191408". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2014-01-10.
  12. Bobylev, Vadim V. (March 2010), "Searching for Stars Closely Encountering with the Solar System", Astronomy Letters, 36 (3): 220–226, arXiv:1003.2160, Bibcode:2010AstL...36..220B, doi:10.1134/S1063773710030060, S2CID 118374161.
  13. Trilling, D. E.; et al. (February 2008), "Debris Disks around Sun-like Stars", The Astrophysical Journal, 674 (2): 1086–1105, arXiv:0710.5498, Bibcode:2008ApJ...674.1086T, doi:10.1086/525514, S2CID 54940779.
  14. Wittenmyer, Robert A.; et al. (February 2011), "On the Frequency of Jupiter Analogs", The Astrophysical Journal, 727 (2): 102, arXiv:1011.4720, Bibcode:2011ApJ...727..102W, doi:10.1088/0004-637X/727/2/102, S2CID 56204861.
  15. Howard, Andrew W.; Fulton, Benjamin J. (2016). "Limits on Planetary Companions from Doppler Surveys of Nearby Stars". Publications of the Astronomical Society of the Pacific. 128 (969). 114401. arXiv:1606.03134. Bibcode:2016PASP..128k4401H. doi:10.1088/1538-3873/128/969/114401. S2CID 118503912.
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