18236-2610 HO 566 (HD 168991)

 
 
18h 23m 33.28s -26° 10' 17.6" P.A. 143.00 sep 0.5 mag 7.97,9.55 Sp F8V dist. 104.28 pc (340.16 l.y.)
 
 
Coord 2000 18236-2610 Discov num HO  566 Comp Coord arcsec 2000 18 23 33.28 -26 10 17.6
Date first 1889 Date last 2016 Obs 24
Pa first 140 Pa last 143.2 P.A. Now (θ) 143.2°
Sep first 0.5 Sep last 0.543 Sep. Now (ρ) 0.543"
Mag pri 7.97 Mag sec 9.55 delta mag (ΔM) 1.58 Spectral class F8V (yellow-white)
Pri motion ra +006 Sec motion ra +006
Pri motion dec -033 Sec motion dec -033
Notes N O (See Notes, Orbital solution)
This double is physical.
 
 
OTHER CATALOGS AND DESIGNATIONS
 
 
Name HD 168991 Constellation Sagittarius SAO 186752 HIP 90128
Tycho2 6848-02119-1 Gaia DR2 4052892326433799808 HD 168991 ADS 11296
CD CD-2613106 CP CP-26 6425 Distance 104.28 Distance ly 340.16
 
 
ORBITAL ELEMENTS
 
 
Period (P)119.87y Periastron (T)1968.65y Semi-major axis (a)0.376a
Eccentricity (e)0.784 Inclination (i)105.2° Longitude of periastron (ω)223.7°
Node (Ω)154.1° Notesn ReferenceMsn2017a
Equinox2000 Last observation2010 Grade4(1=Definitive, 9=Indet.)
label theta rho
2000 147.2 0.513
2001 146.9 0.517
2002 146.7 0.521
2003 146.4 0.524
2004 146.2 0.527
2005 145.9 0.529
2006 145.7 0.531
2007 145.4 0.533
2008 145.2 0.534
2009 144.9 0.536
2010 144.7 0.536
2011 144.4 0.537
2012 144.2 0.537
2013 144.0 0.537
2014 143.7 0.536
2015 143.5 0.536
2016 143.2 0.535
2017 143.0 0.533
2018 142.8 0.532
2019 142.5 0.530
2020 142.3 0.528
2021 142.0 0.526
2022 141.8 0.523
2023 141.5 0.520
2024 141.3 0.517
2025 141.0 0.514
2026 140.7 0.510
2027 140.5 0.506
2028 140.2 0.502
2029 139.9 0.498
2030 139.6 0.494


 
grafico orbita
Note: Theta is PA, Rho is Sep. For yearly orbits, data refer to Jan 1st.



 
 


wds18236-2610a.png orbit plot
Measures: green=micrometric, blue=interferometric, purple=photographic