Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Eridanus |
Right ascension | 05h 06m 45.65314s [1] |
Declination | −04° 39′ 18.5939″ [1] |
Apparent magnitude (V) | 5.12 [2] |
Characteristics | |
Spectral type | B9V [3] |
U−B color index | -0.16 [4] |
B−V color index | -0.06 [4] |
Variable type | α2 CVn |
Astrometry | |
Radial velocity (Rv) | 32.28 ± 0.10 [5] km/s |
Proper motion (μ) | RA: 10.70 [1] mas/yr Dec.: -0.78 [1] mas/yr |
Parallax (π) | 10.56 ± 0.34 [1] mas |
Distance | 309 ± 10 ly (95 ± 3 pc) |
Absolute magnitude (MV) | 0.37 [6] |
Orbit [5] | |
Period (P) | 5.5226013 ± 0.0000020 d |
Eccentricity (e) | 0.0844 ± 0.0013 |
Periastron epoch (T) | 2441356.499 ± 0.017 |
Argument of periastron (ω) (secondary) | 160.9 ± 1.1° |
Semi-amplitude (K1) (primary) | 102.83 ± 0.20 km/s |
Semi-amplitude(K2) (secondary) | 100.35 ± 0.19 km/s |
Details [5] | |
66 Eri A | |
Mass | 2.629 ± 0.032 M☉ |
Radius | 1.948 ± 0.063 R☉ |
Luminosity | 51.3 ± 3.3 L☉ |
Surface gravity (log g) | 4.28 ± 0.03 cgs |
Temperature | 11077 K |
Rotational velocity (v sin i) | 17.1 ± 0.2 km/s |
Age | 30 Myr |
66 Eri B | |
Mass | 2.566 ± 0.032 M☉ |
Radius | 1.919 ± 0.061 R☉ |
Luminosity | 46.9 ± 3.0 L☉ |
Surface gravity (log g) | 4.28 ± 0.03 cgs |
Temperature | 10914 K |
Rotational velocity (v sin i) | 16.9 ± 0.2 km/s |
Other designations | |
Database references | |
SIMBAD | data |
66 Eridani is a binary star in the constellation of Eridanus. The combined apparent magnitude of the system is 5.12 on average. [2] Parallax measurements by Hipparcos put the system at some 309 light-years (95 parsecs) away. [1]
This is a spectroscopic binary: the two stars cannot be individually resolved, but periodic Doppler shifts in its spectrum mean there must be orbital motion. The two stars orbit each other every 5.5226013 days. [5] Their orbit is fairly eccentric, at 0.0844. [5]
The combined spectrum of 66 Eridani matches that of a B-type main-sequence star, [3] and the two stars have similar masses. [5] The spectrum also shows excess of mercury and manganese, as it is a type of chemically peculiar star called a mercury-manganese star. [5] 66 Eridani is an Alpha2 Canum Venaticorum variable. For this reason, it has been given the designation EN Eridani. [7]
Atlas, designation 27 Tauri, is a triple star system in the constellation of Taurus. It is a member of the Pleiades, an open star cluster (M45). It is 431 light-years away, and is 3.92 degrees north of the ecliptic.
Chi Serpentis is a solitary star in the Serpens Caput section of the equatorial constellation Serpens. Based upon an annual parallax shift of 14.84 mas as seen from Earth, it is located around 220 light years from the Sun. The star is bright enough to be faintly visible to the naked eye, having an apparent visual magnitude of +5.30.
Omega Ursae Majoris is the Bayer designation for a binary star system in the northern circumpolar constellation of Ursa Major. It is visible to the naked eye with an apparent visual magnitude of 4.61. Based upon an annual parallax shift of 13.24 mas, it is roughly 246 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.11 due to interstellar dust.
Tau Ursae Majoris (τ UMa) is the Bayer designation for a binary star in the northern circumpolar constellation of Ursa Major. It is visible to the naked eye, having an apparent visual magnitude of 4.66. With an annual parallax shift of 25.82 mas, it is located about 126 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.19 due to interstellar dust.
Tau Virginis is a single star in the zodiac constellation Virgo. With an apparent visual magnitude of 4.28, it is faintly visible to the naked eye. The distance to Tau Virginis, based upon parallax measurements, is approximately 225 light years with a margin of error of ±3 light years.
Pi Virginis is a binary star in the zodiac constellation of Virgo. It is visible to the naked eye with an apparent visual magnitude of 4.64. The distance to this star, based upon parallax measurements, is roughly 380 light years.
40 Aurigae is a binary star in the constellation Auriga. Its apparent magnitude is 5.345, meaning it can just barely be seen with the naked eye. Based on parallax estimates made by the Hipparcos spacecraft, the system is located some 340 light-years away.
Tau4 Eridani is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.65. The distance to this star can be estimated using the parallax method, which yields a value of roughly 300 light years.
Theta1 Crucis is a spectroscopic binary star system in the southern constellation of Crux. It is visible to the naked eye with an apparent visual magnitude of 4.30m. The distance to this star, as determined using parallax measurements, is around 235 light years.
HR 9038 is a triple star system located thirty-five light-years away, in the constellation Cepheus. Component A is a spectroscopic binary system with an orbital period of 7.753 days and a combined stellar classification of K3 V. Component B is a red dwarf star that orbits the primary pair every 290 years.
EZ Canis Majoris is binary system in the constellation of Canis Major. The primary is a Wolf-Rayet star and it is one of the ten brightest Wolf-Rayet stars, brighter than apparent magnitude 7.
88 Tauri, also known as d Tauri, is a multiple star system in the constellation Taurus. It has an apparent magnitude of about 4.25, meaning that it is visible to the naked eye. Based upon parallax measurements made by the Hipparcos spacecraft, the star system is some 156 light-years from the Sun.
HD 106112, also known as CO Camelopardalis, is a star in the constellation Camelopardalis. It has an apparent magnitude of about 5.1, meaning that it is just barely visible to the naked eye. Based upon parallax measurements made by the Hipparcos spacecraft, this star is around 177 light years away from the Sun.
20 Ceti is a single star located around 590 light years away in the equatorial constellation of Cetus. It is faintly visible to the naked eye with apparent magnitude is 4.76. The Bright Star Catalogue has this star classified as M0III, matching an aging red giant star that has consumed the hydrogen at its core and expanded. Houk and Swift (1999) listed an earlier class of K5 III. It has around 56 times the Sun's radius and is radiating 1,044 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,920 K.
Upsilon4 Eridani is a close binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.56. Based upon parallax measurements, the pair are located around 54.6 parsecs (178 ly) from the Sun.
Omega Eridani is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude is 4.37. The distance to this star, as determined by the parallax method, is around 235 light years.
15 Lyncis is a binary star system in the northern constellation of Lynx. It is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.35. Based on the system's parallax, it is located 178 light-years away. The pair are moving away from the Earth with a heliocentric radial velocity of +2 km/s.
90 Tauri is a star in the zodiac constellation of Taurus, located 144 light years away from the Sun. It is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.27. 90 Tauri is a member of the Hyades cluster and is listed as a double star.
66 Tauri, also known as r Tauri, is a binary star in the constellation of Taurus. The combined apparent magnitude of the system is 5.098, with the magnitudes of the two components being 5.8 and 5.9, respectively. Parallax measurements by Hipparcos put 66 Tauri at some 400 light-years away.
Rho3 Eridani, Latinized from ρ3 Eridani, is a star located in the constellation Eridanus. It forms an asterism with Rho1 and Rho2 Eridani, south of Cetus, in the upper north east portion of Eridanus. The star has an apparent visual magnitude of 5.26, which is bright enough to be seen with the naked eye on a dark, clear night. The distance to this star, as determined via the parallax method, is about 136 light years.