21 Arietis

Last updated
21 Arietis
Observation data
Epoch J2000       Equinox J2000
Constellation Aries
Right ascension 02h 15m 42.77662s [1]
Declination +25° 02 34.9627 [1]
Apparent magnitude  (V)5.57 [2] (6.40/6.48) [3]
Characteristics
Spectral type F6 V [4]
U−B color index +0.00 [5]
B−V color index +0.50 [5]
Astrometry
Radial velocity (Rv)44.3 km/s
Proper motion (μ)RA: 89.72 [1]   mas/yr
Dec.: 86.42 [1]   mas/yr
Parallax (π)19.58 ± 0.61  mas [1]
Distance 167 ± 5  ly
(51 ± 2  pc)
Absolute magnitude  (MV)2.03 [2]
Orbit [6]
Period (P)23.70 ± 0.12 yr
Semi-major axis (a)0.2353 ± 0.0011
Eccentricity (e)0.6816 ± 0.0037
Inclination (i)104.52 ± 0.16°
Longitude of the node (Ω)236.44 ± 0.22°
Periastron epoch (T)1986.192 ± 0.012
Argument of periastron (ω)
(secondary)
84.16 ± 0.16°
Details
21 Ari A
Mass 1.338 ± 0.032 [7]   M
Surface gravity (log g)4.12 [8]   cgs
Temperature 6,299 [8]   K
Metallicity [Fe/H]+0.02 [8]   dex
Rotational velocity (v sin i)12.6 [9]  km/s
Age 2.2 [2]   Gyr
21 Ari B
Mass 1.374 ± 0.027 [7]   M
Other designations
BD+24 329, FK5 1059, HD 13872, HIP 10535, HR 657, SAO 75238, WDS J02157+2503. [5]
Database references
SIMBAD data

21 Arietis (abbreviated 21 Ari) is a binary star [3] system in the northern constellation of Aries. 21 Arietis is the Flamsteed designation. It has a combined apparent visual magnitude is 5.57; [2] the brighter member is magnitude 6.40 while the fainter star is magnitude 6.48. [3] The distance to this star system, based upon an annual parallax shift of 19.58  mas, [1] is 167 light-years (51 parsecs ). The pair orbit each other with a period of 23.70 years and an eccentricity of 0.68. [3]

The system was initially thought to be a triple system in 1981, since the orbit of the system predicted a mass greater than would be expected from its F6V spectral type. [10] This was later rejected because the distance to the system was overestimated. However, while observing the spectrum of the system, it was found that a giant planet may be causing radial velocity variations. The purported planet would have a mass of 1.40 ± 0.36 MJ, an orbital period of 925 days and orbit the primary star. [7]

Related Research Articles

<span class="mw-page-title-main">Beta Arietis</span> Binary star system in the constellation Aries

Beta Arietis, officially named Sheratan, is a star system and the second-brightest star in the constellation of Aries, marking the ram's second horn.

<span class="mw-page-title-main">Gamma Arietis</span> Star in the constellation Aries

Gamma Arietis is a binary star in the northern constellation of Aries. The two components are designated γ1 Arietis or Gamma Arietis B and γ2 Arietis or Gamma Arietis A. γ1 Arietis may itself be a spectroscopic binary with a low mass companion.

Kappa1 Sculptoris is a binary star system in the southern constellation of Sculptor. It is faintly visible to the naked eye, with a combined apparent visual magnitude of +5.51. Based upon an annual parallax shift of 12.91 mas as measured from Earth, it is located roughly 250 light years from the Sun.

<span class="mw-page-title-main">Beta Scuti</span> Star in the constellation Scutum

Beta Scuti, Latinized from β Scuti, is a binary star system in the southern constellation Scutum. Based upon an annual parallax shift of 3.56 mas as seen from Earth, it is located approximately 920 light years from the Sun. The primary component has an apparent visual magnitude of +4.22 and is radiating about 1,270 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 4,622 K. This yellow-hued star is a G-type bright giant with a stellar classification of G4 IIa.

<span class="mw-page-title-main">Epsilon Arietis</span> Binary star system in the constellation Aries

Epsilon Arietis is the Bayer designation for a visual binary star system in the northern constellation of Aries. It has a combined apparent visual magnitude of 4.63 and can be seen with the naked eye, although the two components are too close together to be resolved without a telescope. With an annual parallax shift of 9.81 mas, the distance to this system can be estimated as 330 light-years, give or take a 30 light-year margin of error. It is located behind the dark cloud MBM12.

<span class="mw-page-title-main">Kappa Arietis</span> Binary star system in the constellation Aries

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.

<span class="mw-page-title-main">Iota Arietis</span> Binary star system in the constellation Aries

Iota Arietis, Latinized from ι Arietis, is the Bayer designation for a binary star system in the northern constellation of Aries. It has an apparent visual magnitude of 5.117; bright enough to be dimly seen with the naked eye. Parallax measurements made during the Hipparcos mission yield an estimated distance of 520 light-years from Earth. The variable radial velocity of this system was announced by W. W. Campbell in 1922. K. C. Gordon published orbital elements for this single-lined spectroscopic binary system in 1946, giving an orbital period of 4.29 years and an eccentricity (ovalness) of 0.36.

<span class="mw-page-title-main">Theta Arietis</span> Binary star system in the constellation Aries

Theta Arietis, Latinised from θ Arietis, is the Bayer designation for a binary star system in the northern constellation of Aries. It is faintly visible to the naked eye with an apparent visual magnitude of 5.58. With an annual parallax shift of 7.61 mas, the distance to this star is an estimated 429 light-years with a 10-light-year margin of error. It is drifting further away with a radial velocity of +6 km/s.

<span class="mw-page-title-main">Mu Arietis</span> Star system in the constellation Aries

Mu Arietis, Latinized from μ Arietis, is the Bayer designation for a star system in the northern constellation of Aries. It is approximately 340 light-years distant from Earth, give or take a 30 light-year margin of error, and has a combined apparent visual magnitude of 5.74. According to the Bortle Dark-Sky Scale, this means it is faintly visible to the naked eye from dark suburban skies.

<span class="mw-page-title-main">35 Arietis</span> Star in the constellation Aries

35 Arietis is a binary star in the northern constellation of Aries. 35 Arietis is the Flamsteed designation. It is approximately 340 light-years distant from the Earth, based upon an annual parallax shift of 9.51 mas. This star is visible to the naked eye with an apparent visual magnitude of 4.64.

33 Arietis is a binary star in the northern constellation of Aries. 33 Arietis is the Flamsteed designation. The combined apparent magnitude of 5.33 is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 14.09 mas, the distance to this system is approximately 231 light-years.

31 Arietis is a binary star in the northern constellation of Aries. 31 Arietis is the Flamsteed designation. The two members of this system orbit each other with a period of 3.80 years and an eccentricity of 0.017. Both components of the system are F-type main sequence stars with a stellar classification of F7 V. The pair have an apparent visual magnitude of 5.75, which is just bright enough to be faintly visible to the naked eye. Based upon an annual parallax shift of 28.79 mas, the distance to this system is approximately 113 light-years. The system is located near the ecliptic, so it is subject to occultation by the Moon. The dynamical mass of the system is 3.36 ± 0.04 M.

10 Arietis is a binary star system in the northern constellation of Aries. 10 Arietis is the Flamsteed designation. It is visible to the naked eye as a dim, yellow-white hued star with a combined apparent visual magnitude of 5.63. Based upon parallax measurements, it is located around 159 light years away from the Sun. The system is receding from the Earth with a heliocentric radial velocity of +12.9 km/s.

<span class="mw-page-title-main">30 Arietis</span> Multiple star system in the constellation Aries

30 Arietis is a 6th-apparent-magnitude multiple star system in the constellation of Aries. 30 Arietis is the Flamsteed designation. 30 Arietis A and B are separated by 38.1″ or about 1,500 AU at a distance of 130 light years away. The main components of both systems are both binaries with a composite spectra belonging to F-type main-sequence stars, meaning they are fusing hydrogen in their cores. The 30 Arietis system is 910 million years old, one fifth the age of the Sun.

<span class="mw-page-title-main">23 Vulpeculae</span> Star in the constellation Vulpecula

23 Vulpeculae is a triple star system in the northern constellation of Vulpecula. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.52 and it is located approximately 327 light years away from the Sun based on parallax. The system is moving further from the Earth with a heliocentric radial velocity of +1.47 km/s.

HD 6114 is a visual binary star system in the northern constellation of Andromeda. With a combined apparent magnitude of 6.46, the star can only be seen with the naked eye by keen-eyed observers even on the best of nights. Based upon an annual parallax shift of 10.4 mas as seen from Earth's orbit, the system is located approximately 108 parsecs (350 ly) distant.

29 Arietis is a triple star system in the northern constellation of Aries. 29 Arietis is the Flamsteed designation. Its annual parallax shift of 34.86±0.13 mas indicates a distance of about 94 light-years from Earth. The system is barely visible to the naked eye with an apparent visual magnitude of 6.0; it is 0.02 degree north of the ecliptic. It is moving further from Earth with a heliocentric radial velocity of 9 km/s.

<span class="mw-page-title-main">UX Arietis</span> Trinary star system in the constellation Aries

UX Arietis is a triple star system located in the northern zodiacal constellation of Aries. Based upon parallax measurements from the Gaia satellite, it is roughly 165 light years away. The primary, component Aa, is a variable star of the RS CVn type. The variability of the star is believed due to a combination of cool star spots and warm flares, set against the baseline quiescent temperature of the stellar atmosphere. The variability appears to be cyclical with a period of 8−9 years. The star varies in brightness from magnitude 6.35 to 6.71, meaning it may be intermittently visible to the unaided eye under ideal dark-sky conditions.

<span class="mw-page-title-main">Mu Orionis</span> Quadruple star system in the constellation Orion

μ Orionis is a quadruple star system in the constellation Orion, similar to Mizar and Epsilon Lyrae with combined visual magnitude of 4.13. The four stars are known as Mu Orionis Aa, Mu Orionis Ab, Mu Orionis Ba, and Mu Orionis Bb. The A and B systems are several tenths of an arcsecond apart. The entire system is located approximately 150 light years from the Sun.

<span class="mw-page-title-main">27 Piscium</span> Star in the constellation Pisces

27 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 4.88. Based upon an annual parallax shift of 13.91±0.28 mas, it is located about 234 light years away. The system is positioned near the ecliptic and so is subject to occultation by the Moon.

References

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