HD 175535

HD 175535 is a binary star system in the northern circumpolar constellation of Draco. It has an apparent visual magnitude of 4.92,[2] which is bright enough to be faintly visible to the naked eye. The system is located about 302 light years away, as determined from its annual parallax shift of 10.8 mas.[1] It is moving further from the Earth with a heliocentric radial velocity of +8.5 km/s.[2]

HD 175535
Observation data
Epoch J2000      Equinox J2000
Constellation Draco
Right ascension  18h 53m 13.55478s[1]
Declination +50° 42′ 59.1821″[1]
Apparent magnitude (V) 4.92[2]
Characteristics
Spectral type G7 IIIa Fe−1[3]
U−B color index 0.57[4]
B−V color index 0.90[2]
Astrometry
Radial velocity (Rv)+8.5[2] km/s
Proper motion (μ) RA: 0.938 mas/yr
Dec.: −24.171 mas/yr
Parallax (π)10.7890 ± 0.2187[1] mas
Distance302 ± 6 ly
(93 ± 2 pc)
Absolute magnitude (MV)−0.78[5]
Orbit[4]
Period (P)972.84±0.35 d
Eccentricity (e)0.342±0.006
Periastron epoch (T)53,678.2±2.4
Argument of periastron (ω)
(secondary)		190.0±1.1°
Semi-amplitude (K1)
(primary)		5.83±0.04 km/s
Details
Mass3.27[2] M☉
Radius13[6] R☉
Luminosity219[2] L☉
Surface gravity (log g)2.85±0.15[7] cgs
Temperature5,024±74[2] K
Metallicity [Fe/H]−0.07±0.07[7] dex
Rotational velocity (v sin i)2.3[8] km/s
Age320[2] Myr
Other designations
BD+50° 2686, HD 175535, HIP 92689, HR 7137, SAO 31241[9]
Database references
SIMBADdata

The binary nature of this system was announced by W. W. Campbell of the Lick Observatory in 1911. It is a single-lined spectroscopic binary with an orbital period of 2.66 years (972.84 d) and an eccentricity of 0.342. The a sin i value for the visible component is 73.4±0.6 Gm, where a is the semimajor axis and i is the (unknown) orbital inclination.[4] This indicates that the actual semimajor axis is larger than 0.49 AU.[10]

The visible component appears to be an evolved giant star with a stellar classification of G7 IIIa Fe−1,[3] where the suffix notation indicates an underabundance of iron in the atmosphere. It is 320[2] million years old with 3.27[2] times the mass of the Sun and about 13[6] times the Sun's radius. The star is radiating 219[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,024 K.[2]

References
  1. 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.
  2. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88.
  3. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373
  4. Griffin, R. F. (October 2010), "Spectroscopic binary orbits from photoelectric radial velocities - Paper 214: HR 6790, HR 6886, HR 6901, and HR 7137", The Observatory, 130: 299–314, Bibcode:2010Obs...130..299G.
  5. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  6. Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition", Astronomy and Astrophysics, 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  7. Prugniel, P.; et al. (2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769.
  8. De Medeiros, J. R.; et al. (October 2002), "The Rotation of Binary Systems with Evolved Components", The Astrophysical Journal, 578 (2): 943–950, arXiv:astro-ph/0207288, Bibcode:2002ApJ...578..943D, doi:10.1086/342613.
  9. "HD 175535". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-19.
  10. The maximum value of the sine function is 1.0; hence, 'a' is no smaller than the value cited.
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