Rho Ophiuchi (ρ Ophiuchi) is a
multiple star system in the
constellationOphiuchus. The central system has an apparent magnitude of 4.63.
[2] Based on the central system's
parallax of 9.03 mas,
[1] it is located about 360 light-years (110 parsecs) away.
[1] The other stars in the system are slightly farther away.The central pair is known as Rho Ophiuchi AB. It consists of at least two blue-colored
subgiants or
main-sequence stars, designated Rho Ophiuchi A and B, respectively.
[11] Rho Ophiuchi AB is a
visual binary, and the sky-projected distance between the two stars appears to be 3.1″, corresponding to a separation of at least 344
astronomical units (au).
[11] However, the actual separation is larger, and the two take about 2,400 years to complete an orbit.
[7] The two stars dominate the radiation field around the Rho Ophiuchi cloud complex.
[9]Rho Ophiuchi A emits
X-rays, and exhibits strong variability in emission over periods of about 1.2 days, corresponding to its
rotation period. The exact origin of its X-ray variability is unknown: it could be an magnetically active spot on its surface, or it could be a small low-mass companion.
[12] Related to this is its extremely strong
magnetic field; its dipole strength is at least Bd = 1.9 ± 0.2 kG.
[9]Several other stars are located close to Rho Ophiuchi AB. HD 147932 is located 2.5 arcminutes away (at least 17,000 au), and is known as Rho Ophiuchi C.
[11] HD 147888 is located 2.82 arcminutes away (at least 19,000 au), and is known as Rho Ophiuchi DE.
[11] Stars C and D are both
B-type main-sequence stars,
[11] and D itself is another binary with an orbital period of around 680 years
Comments