Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Hydra [2] |
Right ascension | 09h 22m 50.856s [3] |
Declination | −09° 50′ 19.66″ [3] |
Apparent magnitude (V) | 6.75 [4] |
Characteristics | |
Spectral type | Ap EuCrSr [5] |
U−B color index | +0.11 [6] |
B−V color index | +0.22 [6] |
Variable type | α2 CVn |
Astrometry | |
Radial velocity (Rv) | 19.6 ± 5.0 km/s |
Proper motion (μ) | RA: −27.94 ± 0.61 [3] mas/yr Dec.: −13.01 ± 0.36 [3] mas/yr |
Parallax (π) | 6.92 ± 0.61 mas [3] |
Distance | 470 ± 40 ly (140 ± 10 pc) |
Orbit [7] | |
Companion | KU Hya B |
Period (P) | 52.98(37) yr |
Semi-major axis (a) | 0.169(1)″ |
Eccentricity (e) | 0.074(8) |
Inclination (i) | 68.5(6)° |
Longitude of the node (Ω) | 202.4(4)° |
Periastron epoch (T) | 2020.20(45) |
Argument of periastron (ω) (secondary) | 58.7(3.3)° |
Details [8] | |
KU Hya A | |
Mass | 2.07 M☉ |
KU Hya B | |
Mass | 2.05 M☉ |
Other designations | |
Database references | |
SIMBAD | data |
KU Hydrae is a binary star in the constellation Hydra. The primary star is an Alpha2 Canum Venaticorum variable with its apparent magnitude varying from 0.05 magnitudes over a period of 33.97 days. [8]
This star was discovered to be a visual binary star by Robert Grant Aitken in 1906 and was given the double star designation A 1342. [9] Additional measurements of the position angle and angular separation showed a rapid orbital motion. [10]
70 Ophiuchi is a binary star system located 16.6 light years away from the Earth. It is in the constellation Ophiuchus. At magnitude 4 it appears as a dim star visible to the unaided eye away from city lights.
Upsilon Sagittarii is a spectroscopic binary star system in the constellation Sagittarius. Upsilon Sagittarii is the prototypical hydrogen-deficient binary (HdB), and one of only four such systems known. The unusual spectrum of hydrogen-deficient binaries has made stellar classification of Upsilon Sagittarii difficult.
Gamma Tucanae, Latinized from γ Tucanae, is a star in the constellation Tucana, marking the toucan's beak. It is faintly visible to the naked eye with an apparent visual magnitude of +3.99. Based upon an annual parallax shift of 43.37 mas as seen from Earth, this star is located about 75 light years from the Sun. It is moving away from the Sun with a radial velocity of +18 km/s.
Kappa Arietis, Latinized from κ Arietis, is the Bayer designation for a binary star in the northern constellation of Aries. The combined apparent visual magnitude of the pair is 5.02, making the system bright enough for it to be dimly visible to the naked eye as a white-hued point of light. It is located approximately 181 light-years from the Sun based on parallax, and is drifting further away with a radial velocity of +11.5 km/s.
36 Andromedae is a visual binary star system in the northern constellation of Andromeda. The designation is from the star catalogue of English astronomer John Flamsteed, first published in 1712. It is faintly visible to the naked eye with an apparent visual magnitude of 5.45. An annual parallax shift of 26.33 mas yields a distance estimate of about 124 light years. The system is moving closer to the Sun with a radial velocity of −0.8 km/s.
Xi2 Centauri, Latinized from ξ2 Centauri, is a triple star system in the southern constellation of Centaurus. It is visible to the naked eye with an apparent visual magnitude of 4.30, and forms a wide optical double with the slightly dimmer ξ1 Centauri. Based upon an annual parallax shift of 6.98 mas, Xi2 Centauri lies roughly 470 light years from the Sun. At that distance, the visual magnitude is diminished by an interstellar extinction factor of 0.32 due to intervening dust.
Pi Cephei is a trinary star located in the constellation Cepheus. With a combined apparent magnitude of about 4.4, the system is faintly visible to the naked eye. The inner pair of stars orbits in 1.5 years while the outer companion completes one orbit in about 160 years.
Rho Ophiuchi is a multiple star system in the constellation Ophiuchus. The central system has an apparent magnitude of 4.63. Based on the central system's parallax of 9.03 mas, it is located about 360 light-years away. The other stars in the system are slightly farther away.
Xi Piscium (ξ Piscium) is an orange-hued binary star system in the zodiac constellation of Pisces. In 1690, the astronomer Johannes Hevelius in his Firmamentum Sobiescianum regarded the constellation Pisces as being composed of four subdivisions. Xi Piscium was considered to be part of the Linum Austrinum, the South Cord. The star is visible to the naked eye, having an apparent visual magnitude of 4.60. Based upon an annual parallax shift of 11.67 mas as seen from Earth, it is located about 280 light years from the Sun. It is moving away from the Sun, having a radial velocity of +26 km/s.
Lambda Cygni is a class B5V star in the constellation Cygnus. Its apparent magnitude is 4.54 and it is approximately 770 light years away based on parallax.
Nu Cygni, Latinized from ν Cygni, is a binary star system in the constellation Cygnus. Its apparent magnitude is 3.94 and it is approximately 374 light years away based on parallax. The brighter component is a magnitude 4.07 A-type giant star with a stellar classification of A0III n, where the 'n' indicates broad "nebulous" absorption lines due to rapid rotation. This white-hued star has an estimated 3.6 times the mass of the Sun and about 1.9 times the Sun's radius. It is radiating 412 times the Sun's luminosity from its photosphere at an effective temperature of 9,462 K. The magnitude 6.4 companion has an angular separation of 0.24" from the primary.
Phi Ophiuchi, a name Latinized from φ Ophiuchi, is a single star in the equatorial constellation of Ophiuchus. It has a yellow hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.27. The star is located at a distance of approximately 244 light-years from the Sun based on parallax, but it is drifting closer with a radial velocity of −33.5 km/s.
ν Pegasi, Latinized as Nu Pegasi is a single star in the northern constellation of Pegasus. It is an orange-hued star that is faintly visible to the naked eye with an apparent visual magnitude of 4.84. The star is located approximately 261 light years away based on parallax, but is drifting closer with a radial velocity of −19 km/s.
μ Phoenicis, Latinized as Mu Phoenicis, is a suspected astrometric binary star system in the southern constellation of Phoenix. It is visible to the naked eye as a faint, yellow-hued star with an apparent visual magnitude of 4.59. This system is located approximately 246 light years distant from the Sun based on parallax, and is drifting further away with a radial velocity of +17.4 km/s.
33 Piscium is a binary star system in the zodiac constellation of Pisces. It is visible to the naked eye with an apparent visual magnitude of 4.61. The distance to this system, as determined from an annual parallax shift of 25.32±0.53 mas, is about 129 light years. It is moving closer to the Sun with a heliocentric radial velocity of −6.6 km/s.
HD 69142 is a class K1II-III star in the constellation Puppis. Its apparent magnitude is 4.44 and it is approximately 298 light years away based on parallax.
HD 61330 is a class B8IV star in the constellation Puppis. Its apparent magnitude is 4.53 and it is approximately 360 light years away based on parallax.
HD 56456 is a class B8.5V star in the constellation Puppis. Its apparent magnitude is 4.76 and it is approximately 377 light years away based on parallax.
HD 172910 is a class B2.5V star in the constellation Sagittarius. Its apparent magnitude is 4.87 and it is approximately 467 light years away based on parallax.
Kepler-13 or KOI-13 is a stellar triple star system consisting of Kepler-13A, around which an orbiting hot Jupiter exoplanet was discovered with the Kepler spacecraft in 2011, and Kepler-13B a common proper motion companion star which has an additional star orbiting it.