Mu2 Scorpii

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For other star systems with a similar Bayer designation, see Mu Scorpii.
μ2 Scorpii
(Pipirima)
Location of μ2 Scorpii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 16h 52m 20.14532s[1]
Declination −38° 01′ 03.1258″[1]
Apparent magnitude (V) +3.56[2]
Characteristics
Spectral type B2 IV[3]
U−B color index −0.878[2]
B−V color index −0.219[2]
Distance
474 ± 8 ly
(145 ± 3 pc)
Absolute magnitude (MV)−2.25[5]
Details
Myr
HIP 82545, HR 6252, SAO 208116.[9]
Database references
SIMBADdata

Mu2 Scorpii (μ2 Scorpii, abbreviated Mu2 Sco, μ2 Sco), also named Pipirima /pɪˈpɪrɪmə/,[10] is a star in the zodiac constellation of Scorpius. It has an apparent visual magnitude of +3.56,[2] 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.[1] It is a member of the Upper Centaurus–Lupus subgroup of the Scorpius–Centaurus association.[11] A super-Jupiter or brown dwarf is known to orbit it, and another is suspected. [6]

Properties

Mu2 Scorpii is a blue-white B-type subgiant star with a stellar classification of B2 IV.[3] It has an estimated diameter of 5.6 solar radii and a mass of 9.1 times the Sun's mass,[6] and shines with 2,385 times the Sun's luminosity.[7] The large mass of this star make it a supernova progenitor. The outer atmosphere has an effective temperature of 21,700 K. It is some 20 million years old[6] and is spinning with a projected rotational velocity of 58 km/s.[8]

Nomenclature

μ2 Scorpii (Latinised to Mu2 Scorpii) is the star's Bayer designation.

In Tahiti, a

Lesath in the tip of the tail of Scorpio,[12] and in another they become Mu2 and Mu1 Scorpii.[citation needed] (In a similar version of the story told in the Cook Islands, they become Omega1 and Omega2 Scorpii).[12]

In 2016, the IAU organized a

Xamidimura for its partner) and it is now so included in the List of IAU-approved Star Names.[10]

In Chinese astronomy, Mu2 Scorpii is called 尾宿增二.[15]

Planetary system

Two sub-stellar objects slightly above deuterium burning limit (brown dwarfs) were found in 2022 by direct imaging near Mu2 Scorpii. The outer one, designated μ2 Scorpii b, is definitely an orbiting planet or brown dwarf, and the inner one is a planetary candidate.[6]

The Mu2 Scorpii planetary system[6]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(years) 		Eccentricity Inclination Radius
c (unconfirmed) 18.5±1.5 MJ 18.9+11.7
−5.0 		— 0.61+0.19
−0.32 		62.8+9.9
−16.6° 		—
b 14.4±0.8 MJ 242.4+114.5
−52.1 		— 0.56+0.27
−0.26 		96.6+21.5
−20.5° 		—

References

  1. ^
    S2CID 18759600
    .
  2. ^
    doi:10.1086/190168
    .
  3. ^
    doi:10.1086/150069
    .
  4. Bibcode:1967IAUS...30...57E
    .
  5. S2CID 119257644
    .
  6. ^
    S2CID 248524983
  7. ^
    S2CID 118665352
    .
  8. ^
    Bibcode:1970crvs.book.....U
    .
  9. ^ "mu.02 Sco". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-09-20.{{cite web}}: CS1 maint: postscript (link)
  10. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
  11. S2CID 15785349
    .
  12. ^ a b c Johannes Carl Andersen (1931) Myths and Legends of the Polynesians. 1995 Dover reprint, p.400ff.
  13. ^ Herbert John Davies, A Tahitian and English dictionary, with introductory remarks on the Polynesian language, and a short grammar of the Tahitian dialect. London Missionary Society, 1851.
  14. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  15. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 10 日 Archived 2011-05-22 at the Wayback Machine
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