Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Taurus |
88 Tau A | |
Right ascension | 04h 35m 39.25910s [1] |
Declination | +10° 09′ 38.8396″ [1] |
Apparent magnitude (V) | 4.250 [2] |
88 Tau B | |
Right ascension | 04h 35m 35.1775s [3] |
Declination | +10° 10′ 13.572″ [3] |
Apparent magnitude (V) | 7.84 [4] |
Characteristics | |
88 Tau A | |
Spectral type | A6m / F5 / G2-3: / G2-3: [5] |
U−B color index | +0.08 [4] |
B−V color index | +0.19 [4] |
88 Tau B | |
Spectral type | F8V / M? [6] |
U−B color index | +0.04 [7] |
B−V color index | +0.54 [7] |
Astrometry | |
88 Tau A | |
Radial velocity (Rv) | 23.97 [8] km/s |
Proper motion (μ) | RA: 43.13 [1] mas/yr Dec.: -52.71 [1] mas/yr |
Parallax (π) | 20.88 ± 0.94 mas [1] |
Distance | 156 ± 7 ly (48 ± 2 pc) |
88 Tau B | |
Radial velocity (Rv) | 23.97 [9] km/s |
Proper motion (μ) | RA: 51.8 [2] mas/yr Dec.: -49.4 [2] mas/yr |
Orbit [5] | |
Primary | 88 Tau Aa |
Companion | 88 Tau Ab |
Period (P) | 6585 ± 12 d |
Semi-major axis (a) | 240.1 ± 5.3 mas 12.17 ± 0.17 AU |
Eccentricity (e) | 0.0715 ± 0.0026 |
Inclination (i) | 69.923 ± 0.048° |
Longitude of the node (Ω) | 146.734 ± 0.067° |
Periastron epoch (T) | 2455261 ± 22 |
Argument of periastron (ω) (secondary) | 205.7 ± 1.2° |
Orbit [5] | |
Primary | 88 Tau Aa1 |
Companion | 88 Tau Aa2 |
Period (P) | 3.571096 ± 0.000003 d |
Semi-major axis (a) | 1.359 ± 0.034 mas 0.0689 ± 0.0012 AU |
Eccentricity (e) | 0 |
Inclination (i) | 110.6 ± 2.7° |
Longitude of the node (Ω) | 287.5 ± 1.8° |
Periastron epoch (T) | 2453389.3824 ± 0.0030 |
Argument of periastron (ω) (secondary) | 0° |
Orbit [5] | |
Primary | 88 Tau Ab1 |
Companion | 88 Tau Ab2 |
Period (P) | 7.886969 ± 0.000066 d |
Semi-major axis (a) | 1.967 ± 0.054 mas 0.0997 ± 0.0021 AU |
Eccentricity (e) | 0 |
Inclination (i) | 27.23 ± 0.72° |
Longitude of the node (Ω) | 34.0 ± 8.2° |
Periastron epoch (T) | 2452507.31 ± 0.02 |
Argument of periastron (ω) (secondary) | 0° |
Orbit [6] | |
Primary | 88 Tau Ba |
Companion | 88 Tau Bb |
Period (P) | 1350 ± 35 d |
Semi-major axis (a) | 0.057″ |
Eccentricity (e) | 0.663 ± 0.075 |
Periastron epoch (T) | 2450498 ± 34 |
Argument of periastron (ω) (secondary) | 223 ± 9° |
Semi-amplitude (K1) (primary) | 3.24 ± 0.44 km/s |
Details | |
88 Tau Aa1 | |
Mass | 2.06 ± 0.11 [5] M☉ |
Rotational velocity (v sin i) | 37 ± 2 [5] km/s |
88 Tau Aa2 | |
Mass | 1.361 ± 0.073 [5] M☉ |
Rotational velocity (v sin i) | 17 ± 2 [5] km/s |
88 Tau Ab1 | |
Mass | 1.069 ± 0.069 [5] M☉ |
Rotational velocity (v sin i) | 5 ± 3 [5] km/s |
88 Tau Ab2 | |
Mass | 1.057 ± 0.068 [5] M☉ |
Rotational velocity (v sin i) | 5 ± 3 [5] km/s |
88 Tau Ba | |
Mass | 1.2 [6] M☉ |
88 Tau Bb | |
Mass | >0.15 [6] M☉ |
Other designations | |
88 Tau A: d Tau, 88 Tau, BD+09° 607, HD 29140, HIP 21402, SAO 94026, HR 1458, GC 5599 [10] | |
88 Tau B: BD+09° 606, HD 286909, SAO 94024, GC 5596, TYC 673-1487-1 [11] | |
Database references | |
SIMBAD | 88 Tau |
88 Tau A | |
88 Tau B |
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 (48 parsecs ) from the Sun. [1]
88 Tauri is a sextuple star system, meaning that it contains six stars in a hierarchical orbit. The brighter component, 88 Tauri A, is a quadruple system consisting of two spectroscopic binaries orbiting each other with an orbital period of 18 years. The fainter component, 88 Tauri B, is also a spectroscopic binary, and is about 69 arcseconds away, bringing up the total to six stars. [5]
Aa1 | |||||||||||||||
Period = 3.571d a = 1.36 mas | |||||||||||||||
Aa2 | |||||||||||||||
Period = 6585d a = 0.24″ | |||||||||||||||
Ab1 | |||||||||||||||
Period = 7.887d a = 1.97 mas | |||||||||||||||
Ab2 | |||||||||||||||
69.6″ separation | |||||||||||||||
Ba | |||||||||||||||
Period = 1350d a = 0.057 mas | |||||||||||||||
Bb | |||||||||||||||
Hierarchy of orbits in the 88 Tauri system
88 Tauri A is a fourth-magnitude star [10] with two components, 88 Tauri Aa and 88 Tauri Ab. 88 Tauri Aa and Ab orbit each other once every 18 years and are separated by about 0.28 arcseconds. Those two components themselves are spectroscopic binaries: binary stars that are too close to be resolved but can be detected by periodic Doppler shifts in their spectrum. In this case, variability in the radial velocity has been recognized as early as 1907. [12] The Aa pair has an orbital period of 3.57 days, the Ab pair has an orbital period of 7.89 days, and both have circular orbits with low orbital eccentricities. [5]
88 Tauri B, 69.56 arcseconds away, [11] is a seventh-magnitude star that is also a binary star system. It is another spectroscopic binary whose components (88 Tauri Ba and Bb) orbit each other every 3.69 years. [5] The orbit of 88 Tauri B around 88 Tauri A likely takes about 70,000 years. [6]
88 Tauri Aa has a spectral type of A6m, [5] indicating that it is an A-type star. The "m" in its spectral type means that it is an Am star, [5] also known as a metallic-line star. These types of stars have spectra indicating varying amounts of metals, like iron. [13] The rest of the stars in 88 Tauri A have spectral types ranging from F5 to G2-3, meaning that they are regular F-type or G-type main-sequence stars. The spectral types for 88 Tauri Ab1 and Ab2 are less certain, because their spectral lines are weaker, hence the colon after G2. Aa1 does not appears to be rotating synchronously with its companion (nor does it have a convective atmosphere), unlike Aa2. (It is not known if the two stars of 88 Tauri Ab are in synchronous rotation with each other, because of the relatively high errors in their measurements.) [5]
88 Tauri B consists of a F-type main sequence star, with another low-mass star. [6] The mass of the smaller component is at least 0.15 solar masses, so it is most likely a red dwarf. [6]
Mizar is a second-magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major. It has the Bayer designation ζ Ursae Majoris. It forms a well-known naked eye double star with the fainter star Alcor, and is itself a quadruple star system. The Mizar and Alcor system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite, and is part of the Ursa Major Moving Group.
Xi Scorpii is part of a quintuple star system in the constellation Scorpius. It was assigned this designation by Bayer, although Ptolemy had catalogued the star in Libra. Flamsteed assigned it the designation 51 Librae, but this has fallen out of use since modern constellation boundaries assign the star to Scorpius.
ο Tauri, Latinized as Omicron Tauri, is a binary star system in the constellation Taurus, near the constellation border with Cetus. It has a yellow hue and is visible to the naked eye with an apparent visual magnitude of 3.61. It is approximately 191 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −20 km/s. As the westernmost bright point of light in Taurus, this system has the Flamsteed designation 1 Tauri; Omicron Tauri is the Bayer designation.
19 Tauri is a double star in the constellation of Taurus and a member of the Pleiades open star cluster (M45).
Iota Trianguli Australis is a binary star system in the constellation Triangulum Australe. It is visible to the naked eye with a combined apparent visual magnitude of +5.27. Based upon an annual parallax shift of 25.77 mas as seen from the Earth, it is located around 127 light years from the Sun. The system appears to be moving closer to the Sun with a radial velocity of around −6 km/s.
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.
Delta¹ Tauri is a double star in the zodiac constellation of Taurus. Based upon an annual parallax shift of 20.96 mas as seen from Earth, it is located roughly 156 light-years distant from the Sun. The system is faintly visible to the naked eye with a combined apparent visual magnitude of +3.772. It is considered a member of the Hyades cluster.
Theta Virginis is a multiple star system in the zodiac constellation of Virgo. Based upon parallax measurements, it is about 320 light years from the Sun. The three stars in this system have a combined apparent visual magnitude of 4.37, bright enough to be seen with the naked eye.
5 Aquilae is a quadruple star system in the constellation of Aquila. 5 Aquilae is the Flamsteed designation. The combined apparent visual magnitude of the system is 5.9, which means it is faintly visible to the naked eye. With an annual parallax shift of 8.94 mas, the distance to this system is estimated as approximately 360 light-years, albeit with a 13% margin of error.
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.
S Monocerotis, also known as 15 Monocerotis, is a massive multiple and variable star system located in the constellation Monoceros. It is the brightest star in the Christmas Tree open cluster in the area catalogued as NGC 2264.
Phi Cygni, Latinized from φ Cygni, is a binary star system in the northern constellation of Cygnus. It is faintly visible to the naked eye with an apparent visual magnitude of 4.70. The annual parallax shift is 12.25 mas as measured from Earth, which yields a distance estimate of around 266 light years. It is moving further from the Sun with a radial velocity of +4.5 km/s.
39 Draconis is a wide binary star system in the northern circumpolar constellation of Draco. It has the Bayer designation b Draconis, while 39 Draconis is the Flamsteed designation. This system is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude of 5.0. Parallax measurements made by the Hipparcos spacecraft put it at a distance of 184 light-years, or 56 parsecs away from the Sun. The system is moving closer to the Earth with a heliocentric radial velocity of -24.5 km/s.
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.
Epsilon Librae is the Bayer designation for a binary star system in the zodiac constellation Libra. With an apparent visual magnitude of 4.922, it is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 32.02 mas, it is located about 102 light years away from the Sun.
Mu Lupi is a system of three or four stars in the southern constellation of Lupus. It is visible to the naked eye with an apparent visual magnitude of 4.29 and lies roughly 340 light-years from the Sun.
Zeta1 Lyrae, Latinized from ζ1 Lyrae, is a binary star in the northern constellation of Lyra. Based upon an annual parallax shift of 20.89 mas as seen from Earth, the pair are located about 156 light years from the Sun. It is visible to the naked eye with an apparent visual magnitude of 4.37.
HD 165590 is a quintuple system dominated by the binary Algol variable star known as V772 Herculis. The system lies in the constellation of Hercules about 123 light years from the Sun, and is suspected to be a part of the Pleiades moving group.
HD 202908, also known as HIP 105200, is a triple star located in the equatorial constellation Equuleus. It has an apparent magnitude of 7.01, making it readily visible in binoculars but not to the naked eye. When resolved, the components have apparent magnitudes of 7.25 and 8.87 respectively. The system is located relatively close at a distance of 169 light years based on Gaia DR3 parallax measurements but it is receding with a heliocentric radial velocity of 6.24 km/s.