Alpha Ophiuchi

Location of α Ophiuchi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension 17
Declination +12° 33′ 36.1346″
Apparent magnitude (V) 2.07
Characteristics
Spectral type A5 III
U−B color index +0.10
B−V color index +0.15
Astrometry
Radial velocity (Rv) +12.6 km/s
Proper motion (μ) RA: 108.07 mas/yr
Parallax (π) 67.13 ± 1.06mas
Distance 48.6 ± 0.8 ly
(14.9 ± 0.2 pc)
Absolute magnitude (MV) 1.30
Orbit
Period (P) 3,148.4 days
Semimajor axis (a) 427+20
−13
 mas
Eccentricity (e) 0.92 ± 0.03
Inclination (i) 125+6
−9
°
Longitude of the node (Ω) 232 ± 9°
Periastron epoch (T) 2452888 ± 53 JD
Argument of periastron (ω)
(secondary)
162 ±14°
Details
α Oph A
Mass 2.40+.23
−.37
M
Radius 2.6R
Luminosity 25.1–25.6L
Surface gravity (log g) 3.91
Temperature 7,880–8,050K
Rotational velocity (v sin i) 240 km/s
Age 0.77 ± 0.03Gyr
α Oph B
Mass 0.85+.06
−.04
M
Other designations
Ras Alhague, Rasalhague, 55 Ophiuchi, BD +12° 3252, FK5 656, GCTP 4000.00, Gl 681, HD 159561, HIP 86032, HR 6556, SAO 102932.

Get more info about Rasalhague in Wikipedia

This article uses material from the Wikipedia article
Rasalhague, which is released under the Creative Commons Attribution-Share-Alike License 3.0