OW Geminorum, an unusual star system
Posted: 25.03.2020, 14:41
Hi everyone! While I was researching, I came across a star system that was very unique, and I knew I had to share it.
OW Geminorum (OW Gem) is an eclipsing binary consisting of two supergiants: one is F2Ib-II and the other is G8IIb (technically a bright giant). The two stars orbit each other every 3 and a half years, so eclipses are very rare.
This unusual configuration poses a conundrum to stellar evolutionary theory, according to Terrell et al. (2003), since it is impossible for the two stars to have formed at the same time. However, they say it's possible that OW Geminorum was once a triple system and two stars in a close binary system merged.
Physical and orbital parameters are from the aforementioned Terrell et al. (2003), while the primary minimum is set to occur at the 2008 primary eclipse. Approximate rotation periods are from Griffin & Duquennoy (1993). Below is the STC code:
Regards, Luke
OW Geminorum (OW Gem) is an eclipsing binary consisting of two supergiants: one is F2Ib-II and the other is G8IIb (technically a bright giant). The two stars orbit each other every 3 and a half years, so eclipses are very rare.
This unusual configuration poses a conundrum to stellar evolutionary theory, according to Terrell et al. (2003), since it is impossible for the two stars to have formed at the same time. However, they say it's possible that OW Geminorum was once a triple system and two stars in a close binary system merged.
Physical and orbital parameters are from the aforementioned Terrell et al. (2003), while the primary minimum is set to occur at the 2008 primary eclipse. Approximate rotation periods are from Griffin & Duquennoy (1993). Below is the STC code:
Code: Select all
# Terrell et al. (2003), AJ 126 (2), 902
# "The Double Supergiant Binary OW Geminorum"
# https://iopscience.iop.org/article/10.1086/376479
# Period and eclipse minimum from Dvorak (2009), OEJVS 100, 1
# "The 2008 Primary Eclipse of OW Gem"
# http://var.astro.cz/oejv/oejv.php?oejv=100
# Rotation periods from Griffin & Duquennoy (1993), The Obs. 113, 53
# "Spectroscopic binary orbits from photoelectric radial velocities. Paper 109:
# HDE 258878 (OW Gem)"
# https://ui.adsabs.harvard.edu/abs/1993Obs...113...53G/abstract
Barycenter 1004901332 "OW Gem"
{
RA 97.92404853
Dec 17.08231543
Distance 6876.576 # from Gaia DR2 parallax
}
"OW Gem A"
{
OrbitBarycenter "OW Gem"
SpectralType "F2Ib-II"
AbsMag -3.5 # from bolometric magnitude and temperature
Radius 21497130
EllipticalOrbit {
Period 3.445807
SemiMajorAxis 1.9528 # mass ratio 5.8:3.9
Eccentricity 0.51718
Inclination 93.04 # inclination to plane of sky:
AscendingNode 96.36 # 89.08 +/- 0.02 mas
ArgOfPericenter 46.87
MeanAnomaly 344.00
Epoch 2415779.0 # primary minimum
}
RotationPeriod 3912 # 163 d
}
"OW Gem B"
{
OrbitBarycenter "OW Gem"
SpectralType "G8IIb"
AbsMag -1.5 # from bolometric magnitude and temperature
Radius 22053690
EllipticalOrbit {
Period 3.445807
SemiMajorAxis 2.9042 # mass ratio 5.8:3.9
Eccentricity 0.51718
Inclination 93.04 # inclination to plane of sky:
AscendingNode 96.36 # 89.08 +/- 0.02 mas
ArgOfPericenter 226.87
MeanAnomaly 344.00
Epoch 2415779.0
}
RotationPeriod 2928 # 122 d
}
Regards, Luke