17 Lyrae

17 Lyrae is a multiple star system in the constellation Lyra, approximately 136 light years away from Earth.

17 Lyrae AB
Location of 17 Lyrae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lyra
AB
Right ascension 19h 07m 25.58012s[1]
Declination +32° 30′ 6.2599″[1]
Apparent magnitude (V) 5.221[2]
A
Right ascension 19h 07m 25.5s[3]
Declination +32° 30′ 07″[3]
Apparent magnitude (V) 5.26[3]
B
Right ascension 19h 07m 24.9s[4]
Declination +32° 30′ 07″[4]
Apparent magnitude (V) 9.1[4]
Characteristics
Spectral type F0V[5]
U−B color index +0.044[6]
B−V color index +0.351[6]
Astrometry
AB
Radial velocity (Rv)4.0[7] km/s
Proper motion (μ) RA: 122.42[1] mas/yr
Dec.: 32.36[1] mas/yr
Parallax (π)24.05 ± 0.31[1] mas
Distance136 ± 2 ly
(41.6 ± 0.5 pc)
Orbit[8]
PrimaryA
Period (P)42.857 days
Eccentricity (e)0.0
Semi-amplitude (K1)
(primary)		13.10 km/s
Details
A
Mass1.6[8] M☉
Luminosity16.4[9] L☉
Surface gravity (log g)3.57[6] cgs
Temperature6,887[9] K
Metallicity [Fe/H]0.0[10] dex
Rotational velocity (v sin i)138[9] km/s
Age1.4[10] Gyr
Other designations
17 Lyrae, HR 7261, BD+32°3326, HD 178449, SAO 67835, HIP 93917, GC 26340, CCDM J19075+3231, IDS 19036+3221
Database references
SIMBADdata

Components

The 17 Lyrae system contains two visible components, designated A and B, separated by 2.48" in 1997. The primary star is a single-lined spectroscopic binary with a period of 42.9 days.[6]

There was once thought to be a fourth star in the system, the red dwarf binary Kuiper 90, designated 17 Lyrae C, until it was evident that the star's parallax and proper motions were too different for it to be part of the system.[11] The separation between 17 Lyrae AB and C is increasing rapidly, from less than 2' in 1881 to nearly 5' in 2014.[12]

A number of other visual companions have been catalogued. The closest is the 11th magnitude star at 39", and the brightest is BD+32 3325 just over 2' away.[12]

Properties

The primary component, 17 Lyrae A, is a 5th magnitude main sequence star of the spectral type F0, meaning it has a surface temperature of about 6,750 K. It is about 60% more massive than the sun and 16 times more luminous. It has been catalogued as an Am star but is now believed to be a relatively normal quickly-rotating star.[6]

The visible companion 17 Lyrae B is a 9th magnitude star of an unknown spectral type. The spectroscopic companion cannot be detected in the spectrum and its properties are uncertain. Faint sharp spectral lines contrasting with the broadened lines of the primary may originate in a shell of material around the stars.[6]

References
  1. Van Leeuwen, F (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. Høg, E; Fabricius, C; Makarov, V. V; Urban, S; Corbin, T; Wycoff, G; Bastian, U; Schwekendiek, P; Wicenec, A (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H.
  3. "CCDM Vizier entry". Retrieved 2017-11-29.
  4. "CCDM Vizier entry". Retrieved 2017-11-29.
  5. Cowley, Anne; Fraquelli, Dorothy (1974). "MK Spectral Types for Some Bright F Stars". Publications of the Astronomical Society of the Pacific. 86: 70. Bibcode:1974PASP...86...70C. doi:10.1086/129562.
  6. Budaj, J; Iliev, I. Kh (2003). "Abundance analysis of Am binaries and search for tidally driven abundance anomalies - I. HD 33254, HD 178449 and HD 198391". Monthly Notices of the Royal Astronomical Society. 346: 27. Bibcode:2003MNRAS.346...27B. doi:10.1046/j.1365-2966.2003.07071.x.
  7. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
  8. Ducati, J. R; Penteado, E. M; Turcati, R (2011). "The mass ratio and initial mass functions in spectroscopic binaries" (PDF). Astronomy and Astrophysics. 525: A26. Bibcode:2011A&A...525A..26D. doi:10.1051/0004-6361/200913895.
  9. Zorec, J; Royer, F (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691.
  10. Trilling, D. E; Stansberry, J. A; Stapelfeldt, K. R; Rieke, G. H; Su, K. Y. L; Gray, R. O; Corbally, C. J; Bryden, G; Chen, C. H; Boden, A; Beichman, C. A (2007). "Debris disks in main-sequence binary systems". The Astrophysical Journal. 658 (2): 1289. arXiv:astro-ph/0612029. Bibcode:2007ApJ...658.1289T. doi:10.1086/511668.
  11. Slocum, Frederick (1929). "The parallax of 17 Lyrae C (abstract)". Popular Astronomy. 37: 328. Bibcode:1929PA.....37..328S.
  12. Mason, Brian D; Wycoff, Gary L; Hartkopf, William I; Douglass, Geoffrey G; Worley, Charles E (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
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