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Beta Scorpii

Beta Scorpii
Scorpius constellation map.svg
Red circle.svg

Location of β Scorpii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Scorpius
HR 5984
Right ascension 16h 05m 26.23198s
Declination –19° 48′ 19.6300″
Apparent magnitude (V) 2.62
HR 5985
Right ascension 16h 05m 26.57128s
Declination –19° 48′ 06.8556″
Apparent magnitude (V) 4.92
Characteristics
Spectral type B1V + B2V
U−B color index –0.08 / –0.70
B−V color index –0.08 / –0.02
Astrometry
HR 5984
Radial velocity (Rv) –1.0 km/s
Proper motion (μ) RA: –5.20 mas/yr
Dec.: –24.04 mas/yr
Parallax (π) 8.07 ± 0.78mas
Distance 400 ± 40 ly
(120 ± 10 pc)
HR 5985
Radial velocity (Rv) –3.6 km/s
Proper motion (μ) RA: –5.07 mas/yr
Dec.: –25.87 mas/yr
Parallax (π) 8.19 ± 1.17mas
Distance approx. 400 ly
(approx. 120 pc)
Details
HR 5984
Mass 10 M
Radius 19 R
Luminosity 20,000 L
Temperature 27,000 K
Rotational velocity (v sin i) 100 km/s
HR 5985
Temperature 22,000 K
Rotational velocity (v sin i) 65 km/s
Other designations
Acrab, Elacrab, Graffias, Grassias, 8 Scorpii, ADS 9913.
A: β1 Sco, BD–19 4307, HD 144217, HIP 78820, HR 5984, SAO 159682.
B: β2 Sco, BD–19 4308, HD 144218, HIP 78821, HR 5985.
Database references
SIMBAD data

Beta Scorpii (β Scorpii, abbreviated Beta Sco, β Sco) is a multiple star system in the southern zodiac constellation of Scorpius.

Hierarchy of orbits in the β Scorpii system

Observed through a small telescope, Beta Scorpii appears as a binary star with a separation between the two components of 13.5 arcseconds and a combined apparent magnitude of 2.50. This pair, designated β¹ Scorpii and β² Scorpii, form the top branches of the hierarchy of orbiting components in this system.

β¹ Scorpii, the brighter of the pair, consists of two sub-components, designated β Scorpii A and β Scorpii B, orbiting at an angular separation of 3.9 arcseconds with an orbital period of 610 years. β Scorpii A is itself a spectroscopic binary with the two components, designated β Scorpii Aa (also named Acrab) and β Scorpii Ab, separated by 1.42 milliarcseconds and an orbital period of 6.82 days.

β² Scorpii also has two sub-components, designated β Scorpii C and β Scorpii E, orbiting at an angular separation of 0.1328 arcseconds with an orbital period of 39 years. β Scorpii E in turn is a spectroscopic binary with components designated β Scorpii Ea and β Scorpii Eb and having an orbital period of 10.7 days.

This brings the total number of stars in the system to six. (There is no D component; this is now an artifact of earlier system models.)

β Scorpii (Latinised to Beta Scorpii) is the star's Bayer designation; β¹ and β² Scorpii, those of its two components. The designations of the sub-components - β Scorpii A, Aa, Ab, B, C, E, Ea and Eb - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).


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Wikipedia

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