Pi Aquarii

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Template:Short description

π Aquarii
Template:Location mark
Location of π Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius[1]
Right ascension Template:RA[2]
Declination Template:DEC[2]
Apparent magnitude (V) 4.42 - 4.87[3]
Characteristics
Spectral type B1III-IVe[4]
U−B Template:Engvar −0.98[5]
B−V Template:Engvar −0.03[5]
Variable type γ Cas[3]
Astrometry
Radial velocity (Rv)+4.0[6] km/s
Proper motion (μ) RA: +17.518 mas/yr[2]
Dec.: +2.563 mas/yr[2]
Parallax (π)2.9761±0.1129 mas[2]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−2.09[1]
Orbit[7]
Period (P)Script error: No such module "val".
Semi-major axis (a)Script error: No such module "val".
Eccentricity (e)0.0 (fixed)
Periastron epoch (T)Script error: No such module "val".
Argument of periastron (ω)
(secondary)		0.0 (fixed)°
Semi-amplitude (K1)
(primary)		Script error: No such module "val". km/s
Semi-amplitude (K2)
(secondary)		Script error: No such module "val". km/s
Details[8]
A
MassScript error: No such module "val". Template:Solar mass
RadiusScript error: No such module "val". (equatorial)
Script error: No such module "val". (polar) Template:Solar radius
LuminosityScript error: No such module "val". Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val". (equatorial)
Script error: No such module "val". (polar) cgs
TemperatureScript error: No such module "val". (equatorial)
Script error: No such module "val". (polar) K
Metallicity [Fe/H]−0.02[1] dex
Rotational velocity (v sin i)Script error: No such module "val". km/s
AgeScript error: No such module "val".[9] Myr
B
MassScript error: No such module "val".[10] Template:Solar mass
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[11]
Database references
SIMBADdata

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Pi Aquarii is a binary star system in the equatorial constellation of Aquarius. Its name is a Bayer designation that is Latinized from π Aquarii, and abbreviated Pi Aqr or π Aqr. This system has a combined apparent visual magnitude of +4.57,[5] which is bright enough to be faintly visible to the naked eye. Based upon parallax measurements, it is located at a distance of approximately Script error: No such module "convert". from the Sun.[2] It is drifting further away with a radial velocity of Script error: No such module "val"..[6]

Properties

File:PiAqrLightCurve.png
A white-light light curve for Pi Aquarii, adapted from Nazé et al. (2020)[12]

This is a binary star system with a period of 84.1 days in a circular orbit.[13][14] The primary component is a B1 giant or subgiant star.[4] This is a massive star with 11 times the mass of the Sun, and is luminous with 8,300 times the Sun's luminosity. It is spinning rapidly with a projected rotational velocity of Script error: No such module "val".. The fast rotation make the star ellipsoidal rather than spherical, its radius at equator is 5.8 times that of the Sun, while its polar radius is 5.0 times solar. Gravity darkening make the temperature at the equator to be about Script error: No such module "val". colder than the temperature at the poles.[15]

The secondary is likely a white dwarf star with a strong magnetic field and a mass of Script error: No such module "val".. It is an X-ray source which is probably coming from accretion onto this object, making this an intermediate polar system. The accretion rate is Script error: No such module "val".·yr−1.[10]

Pi Aquarii is notable for having undergone a transition from a Be star (showing hydrogen emission lines) into an ordinary B-type star.[14] It is classified as a Gamma Cassiopeiae type[3] variable star and its brightness varies from magnitude +4.45 to +4.71; a range of 0.28. The dominant variability period, Script error: No such module "val". days, is nearly the same as the orbital period.[14] Pi Aquarii has a reasonable chance of becoming a supernova some day.[13]

In culture

Pi Aquarii was called Seat Template:IPAc-en by Grotius in the 17th century, but the name has rarely been used since.[13]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Tomb, refers to an asterism consisting of π Aquarii, γ Aquarii, ζ Aquarii, η Aquarii.[16] Consequently, the Chinese name for π Aquarii itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[17]

In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Wasat al Achbiya (وسط الأخبية - wasath al ahbiyah), which was translated into Latin as Media Tabernaculorum, meaning the middle of luck of the homes (tents).[18] This star, along with γ Aqr (Sadachbia), ζ Aqr (Sadaltager / Achr al Achbiya) and η Aqr (Hydria), were al Aḣbiyah (الأخبية), the Tent.[19][20][21]

References

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  1. ↑ a b c Script error: No such module "citation/CS1".
  2. ↑ a b c d e Template:Cite Gaia DR3
  3. ↑ a b c Script error: No such module "citation/CS1". Note: type = GCAS.
  4. ↑ a b Script error: No such module "citation/CS1".
  5. ↑ a b c Script error: No such module "citation/CS1".
  6. ↑ a b Script error: No such module "citation/CS1".
  7. ↑ Script error: No such module "citation/CS1".
  8. ↑ Script error: No such module "citation/CS1".
  9. ↑ Script error: No such module "citation/CS1".
  10. ↑ a b Script error: No such module "citation/CS1".
  11. ↑ Template:Cite simbad
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ a b c Script error: No such module "citation/CS1".
  14. ↑ a b c Script error: No such module "citation/CS1".
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
  17. ↑ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 16 日 Template:Webarchive
  18. ↑ Script error: No such module "citation/CS1".
  19. ↑ Script error: No such module "citation/CS1".
  20. ↑ Script error: No such module "citation/CS1".
  21. ↑ γ Aqr as Aoul al Achbiya or Prima Tabernaculorum (the first of luck of the homes or tents), π Aqr as Wasat al Achbiya or Media Tabernaculorum (the middle of luck of the homes or tents) and ζ Aqr as Achr al Achbiya or Postrema Tabernaculorum (the end of luck of the homes or tents). η Aqr should be designated as al Achbiya consistently, but it was not designated as the Arabic name except the name Hydria (Greek) or Deli (Hebrew)

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External links

Template:Stars of Aquarius

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