Nu1 Sagittarii

Nu¹ Sagittarii (ν¹ Sagittarii, abbreviated Nu¹ Sgr, ν¹ Sgr) is a triple star system[7] lying approximately 1,100 light-years from Earth. Its three components are designated Nu¹ Sagittarii A (officially named Ainalrami /ɛnəlˈreɪmi/, the traditional name for the system),[8] B and C.[9] A and B themselves form a spectroscopic binary.[7]

For other stars with this Bayer designation, see ν Sagittarii.

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Nu¹ Sagittarii
Location of ν¹ Sagittarii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension  18h 54m 10.17695s[1]
Declination −22° 44′ 41.4247″[1]
Apparent magnitude (V) +4.86[2]
Characteristics
Spectral type G2/K1 Ib/II + B9.2p[3]
U−B color index +1.34[2]
B−V color index +1.43[2]
Astrometry
Radial velocity (Rv)−11.57[4] km/s
Proper motion (μ) RA: +4.291[4] mas/yr
Dec.: −7.786[4] mas/yr
Parallax (π)2.3170 ± 0.2139[4] mas
Distance1,400 ± 100 ly
(430 ± 40 pc)
Absolute magnitude (MV)−3.91[5]
Details
Radius101[4] R☉
Luminosity3,464[4] L☉
Temperature4,401[4] K
Other designations
Ainalrami, ν¹ Sgr, 32 Sgr, BD−22°4907, HD 174974, HIP 92761, HR 7116, SAO 187426, WDS J18542-2245[6]
Database references
SIMBADdata

Nomenclature

ν¹ Sagittarii (Latinised to Nu¹ Sagittarii) is the system's Bayer designation.

Nu¹ and Nu² Sagittarii (together designated Nu Sagittarii) bore the traditional name Ain al Rami, which is from the Arabic عين الرامي ʽain al-rāmī meaning 'eye of the archer'.[10] In 2016, the IAU organized a Working Group on Star Names (WGSN)[11] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[12] It approved the name Ainalrami for the component Nu¹ Sagittarii A on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[8]

Nu¹ and Nu² Sagittarii, together with Tau Sagittarii, Psi Sagittarii, Omega Sagittarii, 60 Sagittarii and Zeta Sagittarii were Al Udḥiyy, the Ostrich's Nest.[10]

Properties

Nu¹ Sagittarii A is a spectral type K1 bright giant which has an apparent magnitude of +4.86. It is a microvariable with a frequency of 0.43398 cycles per day and an amplitude of 0.0078 magnitude.[13] In 1982 it was found to have a hotter companion, Nu¹ Sagittarii B, a rapidly rotating B9 type star.[14] The pair orbit with a period of around 370 days.[7] A magnitude +11.2 companion, component C,[9] is orbiting further out at an angular separation of 2.5 arcseconds from the primary.[7]

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References
  1. van Leeuwen, F. (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.
  2. Lutz, T. E.; Lutz, J. H. (June 1977), "Spectral classification and UBV photometry of bright visual double stars", Astronomical Journal, 82: 431–434, Bibcode:1977AJ.....82..431L, doi:10.1086/112066.
  3. Parsons, Sidney B.; Ake, Thomas B. (1998), "Ultraviolet and Optical Studies of Binaries with Luminous Cool Primaries and Hot Companions. V. The Entire IUE Sample", The Astrophysical Journal Supplement Series, 119: 83, Bibcode:1998ApJS..119...83P, doi:10.1086/313152.
  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. Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics, 430: 303–311, arXiv:astro-ph/0409683, Bibcode:2005A&A...430..303C, doi:10.1051/0004-6361:20041440.
  6. "nu01 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-06.
  7. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  8. "Naming Stars". IAU.org. Retrieved 16 December 2017.
  9. "Washington Double Star Catalog". United States Naval Observatory. Archived from the original on 14 February 2011. Retrieved 2 January 2018.
  10. Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 355. ISBN 0-486-21079-0. Retrieved 2012-09-04.
  11. "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  12. "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  13. Koen, Chris; Eyer, Laurent (2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society, 331: 45, arXiv:astro-ph/0112194, Bibcode:2002MNRAS.331...45K, doi:10.1046/j.1365-8711.2002.05150.x.
  14. Kondo, Y.; et al. (August 1982), "The early-type component in ν¹ Sagittarii", Publications of the Astronomical Society of the Pacific, 94: 647–649, Bibcode:1982PASP...94..647K, doi:10.1086/131037.
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