2 Scorpii

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2 Scorpii
Observation data
Epoch J2000       Equinox J2000
Constellation Scorpius
Right ascension 15h 53m 36.71880s [1]
Declination −25° 19 37.7087 [1]
Apparent magnitude  (V)4.69 + 6.98 [2]
Characteristics
Spectral type B2.5 Vn [3]
B−V color index −0.11/+0.07 [2]
Astrometry
Radial velocity (Rv)−9.3±1.6 [4]  km/s
Proper motion (μ)RA: −15.12 [1]   mas/yr
Dec.: −25.18 [1]   mas/yr
Parallax (π)6.49 ± 0.51  mas [1]
Distance 500 ± 40  ly
(150 ± 10  pc)
Absolute magnitude  (MV)−1.33 [5]
Details
2 Sco A
Mass 6.9±0.1 [6]   M
Luminosity 457.40 [5]   L
Temperature 20,350 [7]   K
Rotational velocity (v sin i)320 [8]  km/s
Age 30.4±4.6 [6]   Myr
Other designations
A Sco, 2 Sco, CD−24° 12352, HD  142114, HIP  77840, HR  5904, SAO  183896, WDS J15536-2520 [9]
Database references
SIMBAD data

2 Scorpii (A Scorpii) is a double star in the southern zodiac constellation of Scorpius. The brighter component has an apparent visual magnitude of 4.69, which is bright enough to be visible to the naked eye, while the fainter star is of magnitude 6.98. [2] The distance to this pair can be estimated from the annual parallax shift of 6.49±0.51  mas , [1] which places it roughly 500  light years away. It has a peculiar velocity of 16.5±2.4 km/s and is moving closer to the Sun with a heliocentric radial velocity of about −9 km/s, [4] which will bring it to a perihelion distance of 450 ly (139 pc) in about 2.9 million years. [5] This is a probable (73% chance) member of the Lower Centaurus–Crux group of the nearby Scorpius–Centaurus association (Sco OB2), or else (27% chance) it is a member of the Gould's Belt. [10]

With high likelihood (>95%), this is a binary star system. As of 2014, the pair had an angular separation of 2.061″±0.001″ along a position angle of 268.28°±0.02°. [7] The brighter member, component A, is a B-type main-sequence star with a stellar classification of B2.5 Vn. [3] The 'n' suffix indicates broad (nebulous) absorption lines due to rapid rotation. It is spinning with a projected rotational velocity of 320 km/s, giving the star an oblate shape with an equatorial bulge that is 15% larger than the polar radius. [8] Roughly 30 [6]  million years old, it has an estimated 6.9 [6] times the mass of the Sun and is radiating 457 [5] times the Sun's luminosity from its photosphere at an effective temperature of 20,350 K. [7]

Related Research Articles

<span class="mw-page-title-main">Kappa Scorpii</span> Star in the constellation Scorpius

Kappa Scorpii, Latinized from κ Scorpii, is a binary star system in the southern constellation of Scorpius. With an apparent visual magnitude of 2.4, this star system is readily visible to the naked eye. Parallax measurements place it at an estimated distance of roughly 480 light-years from the Earth.

<span class="mw-page-title-main">Sigma Scorpii</span> Multiple star system in the constellation of Scorpius

Sigma Scorpii, is a multiple star system in the constellation of Scorpius, located near the red supergiant Antares, which outshines it. This system has a combined apparent visual magnitude of +2.88, making it one of the brighter members of the constellation. Based upon parallax measurements made during the Hipparcos mission, the distance to Sigma Scorpii is roughly 696 light-years (214 parsecs). North et al. (2007) computed a more accurate estimate of 568+75
−59
 light years.

<span class="mw-page-title-main">Pi Scorpii</span> Triple star system in the constellation of Scorpius

Pi Scorpii or π Scorpii, is a triple star system in the southern constellation of Scorpius. With a combined apparent magnitude of 2.9, it can be easily seen with the naked eye. Parallax measurements yield an estimated distance of around 590 light-years from the Sun.

<span class="mw-page-title-main">Rho Scorpii</span>

Rho Scorpii is a double star in the constellation of Scorpius. It has an apparent visual magnitude of +3.87, which is bright enough to be seen with the naked eye. Based upon parallax measurements, it is located approximately 472 light years from the Sun. At that distance, the visual magnitude of the system is reduced by 0.07 due to extinction from interstellar dust. It is a member of the Upper Scorpius OB association.

Omicron Scorpii is a star in the zodiac constellation of Scorpius. With an apparent visual magnitude of +4.57, it is visible to the naked eye. Parallax measurements indicate a distance of roughly 900 light years. It is located in the proximity of the Rho Ophiuchi dark cloud.

Psi Scorpii, which is Latinized from ψ Scorpii, is a star in the zodiac constellation of Scorpius. It is white in hue and has an apparent visual magnitude of 4.94, which is bright enough to be faintly visible to the naked eye. Based upon parallax measurements, it is located at a distance of around 162 light years from the Sun. Data collected during the Hipparcos mission suggests it is an astrometric binary, although nothing is known about the companion. The system is drifting closer to the Sun with a radial velocity of −5 km/s.

Chi Scorpii, Latinized from χ Scorpii, is a single star in the zodiac constellation of Scorpius. It has an orange hue and can be faintly seen with the naked eye with an apparent visual magnitude of 5.22. Based upon parallax measurements, this star is around 409 light years from the Sun. The star is drifting closer with a radial velocity of −23.6 km/s.

ω1 Scorpii, Latinised as Omega1 Scorpii, is a star in the zodiac constellation of Scorpius. With an apparent visual magnitude of 3.95 it can be seen with the naked eye, 0.22 degree north of the ecliptic. Parallax measurements of this star give an estimated distance of around 470 light years from the Sun. It is a member of the Scorpius–Centaurus association.

Mu<sup>2</sup> Scorpii B-type star in the constellation of Scorpius

Mu² Scorpii, also named Pipirima, is a star in the zodiac constellation of Scorpius. It has an apparent visual magnitude of +3.56, which is bright enough to be seen with the naked eye. Its distance from the Sun is about 474 light-years, as determined by parallax measurements. It is a member of the Upper Centaurus–Lupus subgroup of the Scorpius–Centaurus association.

<span class="mw-page-title-main">Lambda Centauri</span> Star in the constellation Centaurus

Lambda Centauri, Latinized from λ Centauri, is a star in the southern circumpolar constellation of Centaurus. It has an apparent visual magnitude of +3.13, which is bright enough to be seen with the naked eye from the Southern Hemisphere and places it among the brighter members of this constellation. The star is close enough that its distance can be determined directly using the parallax technique, which gives a value of approximately 470 light-years from the Sun. Although a putative solitary star, it has a candidate proper motion companion at an angular separation of 0.73 arcseconds along a position angle of 135°. The nebula IC 2944 lies nearby.

Pi Centauri, Latinized from π Centauri, is a binary star system in the southern constellation of Centaurus. It has a blue-white hue and is visible to the naked eye with a combined apparent visual magnitude of +3.90. The system is located at a distance of approximately 360 light years from the Sun based on parallax, and is drifting further away with a radial velocity of around +9 km/s. It is a member of the Lower Centaurus–Crux subgroup of the Scorpius–Centaurus association.

Sigma Centauri, Latinized from σ Centauri, is the Bayer designation for a solitary star in the southern constellation of Centaurus. It is visible to the naked eye with an apparent visual magnitude of 3.91. A visual companion at an angular separation of 88.11±0.37 mas along a position angle of 14.33°±2.59° was detected in 2010 using interferometry, but its association with Sigma Centauri remains undetermined as of 2013. The distance to Sigma Centauri, based upon an annual parallax shift of 7.92 mas, is around 412 light years.

Xi<sup>2</sup> Centauri Triple star system in the constellation Centaurus

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.

<span class="mw-page-title-main">HD 125823</span> Star in the constellation Centaurus

HD 125823, also known as V761 Centauri or a Centauri, is a variable star in the constellation Centaurus. It is a blue-white star that is visible to the naked eye with a mean apparent visual magnitude of +4.41. The distance to this star is approximately 460 light years based on parallax measurements. It is a member of the Upper Centaurus–Lupus subgroup of the Scorpius–Centaurus association.

1 Scorpii, or b Scorpii, is a single star in the southern zodiac constellation of Scorpius. It has an apparent magnitude of 4.63, which is bright enough to be faintly visible to the naked eye on a dark night. The star shows an annual parallax shift of 6.59 mas from Earth's orbit, which equates to a distance of roughly 490 light years. It is a probable member of the Sco OB2 moving group.

<span class="mw-page-title-main">4 Scorpii</span> A-type main sequence star in the constellation Scorpius

4 Scorpii is a single star in the southern zodiac constellation of Scorpius. With an apparent visual magnitude of +5.6, it is dimly visible to the naked eye under good viewing conditions. The distance to this star can be estimated from its annual parallax shift of 7.99±0.77 mas, which yields a value of around 410 light years. It is moving closer to the Sun with a heliocentric radial velocity of −29 km/s and will reach perihelion in about two million years at an estimated distance of 280 ly (86 pc).

Theta Lupi, Latinized from θ Lupi, is a solitary star in the southern constellation of Lupus. It is visible to the naked eye with an apparent visual magnitude of 4.22. Based upon an annual parallax shift of 7.87 mas as seen from Earth, it is located roughly 410 light years away from the Sun. Relative to its neighbors, this star has a peculiar velocity of 16.7±3.7 km/s. It is a member of the nearby Sco OB2 association.

Tau<sup>1</sup> Lupi Star in the constellation Lupus

Tau1 Lupi, Latinized from τ1 Lupi, is a solitary star in the southern constellation of Lupus. It is visible to the naked eye with an apparent visual magnitude of 4.5. Based upon an annual parallax shift of only 2.99 mas as seen from Earth, it is located about 1,090 light years from the Sun. Tau1 Lupi may be a runaway star having a peculiar velocity of 32.6±3.6 km/s. It is a member of the Upper Centaurus–Lupus sub-group of the nearby Sco OB2 association.

HD 143699 is a single star in the southern constellation of Lupus. It is a dim star but visible to the naked eye with an apparent visual magnitude of 4.90. Based upon an annual parallax shift of 9.2 mas, it is located around 350 light years away. It is most likely a member of the Upper Centaurus–Lupus subgroup of the Sco OB2 moving group.

<span class="mw-page-title-main">N Scorpii</span> Star in the constellation of Scorpius

N Scorpii, also known as HD 148703, is a solitary, bluish-white hued star located in the southern constellation Scorpius. It has an apparent magnitude of 4.23, making it readily visible to the naked eye. N Scorpii was initially given the Bayer designation Alpha Normae by Lacaille but it was later moved from Norma to Scorpius. N Scorpii is currently located 550 light years away based on parallax measurements from the Hipparcos satellite and is part of the Upper Scorpius–Centaurus region of the Scorpius–Centaurus association.

References

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