Pi Sagittarii

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Template:Short description

π Sagittarii
Template:Location mark
Location of π Sagittarii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sagittarius
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) +2.89[2]
Characteristics
Spectral type F2 II[2]
U−B Template:Engvar +0.22[3]
B−V Template:Engvar +0.35[3]
Astrometry
Radial velocity (Rv)−9.8[4] km/s
Proper motion (μ) RA: −1.36[1] mas/yr
Dec.: −36.45[1] mas/yr
Parallax (π)6.2410±0.2868 mas[5]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−3.08[6]
Details
MassTemplate:Val[2] Template:Solar mass
Radius28.4[7] Template:Solar radius
Luminosity1,285[7] Template:Solar luminosity
Surface gravity (log g)Template:Val[2] cgs
TemperatureTemplate:Val[2] K
Rotational velocity (v sin i)30[8] km/s
Age67[2] Myr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Albaldah, π Sgr, 41 Sgr, BD−21°5275, CCDM J19098-2101AB, FK5 720, GC 26386, HD 178524, HIP 94141, HR 7264, SAO 187756, WDS J19098-2101AB[9]
Database references
SIMBADdata

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Pi Sagittarii (π Sagittarii, abbreviated Pi Sgr, π Sgr) is a triple star system in the zodiac constellation of Sagittarius. It has an apparent visual magnitude of +2.89,[2] bright enough to be readily seen with the naked eye. Based upon parallax measurements, it is roughly Template:Convert from the Sun.[1]

The three components are designated Pi Sagittarii A (officially named Albaldah Template:IPAc-en, from the traditional name of the entire system),[10] B and C.[9]

Nomenclature

π Sagittarii (Latinised to Pi Sagittarii) is the system's Bayer designation. The designations of the three constituents as Pi Sagittarii A, B and C, derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[11]

The system bore the traditional name Albaldah,[12] which comes from the Arabic بلدة bálda 'the town'.[13] In 2016, the IAU organized a Working Group on Star Names (WGSN)[14] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[15] It approved the name Albaldah for the component Pi Sagittarii A on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[10]

In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Nir al Beldat, which was translated into Latin as Lucida Oppidi, meaning 'the brightest of the town'.[16]

This system, together with Zeta Sagittarii and Sigma Sagittarii may have been the Akkadian Gu-shi-rab‑ba, 'the Yoke of the Sea'.[12]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Establishment, refers to an asterism consisting of Pi Sagittarii, Xi² Sagittarii, Omicron Sagittarii, 43 Sagittarii, Ro¹ Sagittarii and Upsilon Sagittarii. Consequently, the Chinese name for Pi Sagittarii itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[17]

Properties

The spectrum of the system's primary, Pi Sagitarii A, matches a stellar classification of F2 II.[2] The 'II' luminosity class is for a bright giant star that has exhausted the hydrogen at its core and has followed an evolutionary track away from the main sequence of stars like the Sun. Because it has nearly six times the mass of the Sun,[2] it reached this stage in a mere 67 million years.[2] The outer envelope is radiating energy at an effective temperature of about 6,590 K,[2] giving it the yellow-white hue of an F-type star.[18]

Pi Sagittarii A has two nearby companions. The first is separated by 0.1 arcseconds, or at least 13 AUs. The second is 0.4 arcseconds away, which is 40 AU or more. Nothing is known about the orbits of these stars.[13]

Being 1.43 degrees north of the ecliptic, Pi Sagittarii can be occulted by the Moon, and, very rarely, by planets. The next occultation by a planet will be by Venus on 17 February 2035 over part of Antarctica and Southern Australia.[19][20]Template:Rp

References

Template:Reflist

Template:Stars of Sagittarius

  1. ↑ a b c d e Cite error: Invalid <ref> tag; no text was provided for refs named aaa474_2_653
  2. ↑ a b c d e f g h i j k Cite error: Invalid <ref> tag; no text was provided for refs named mnras402_2_1369
  3. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named aass34_1
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named gcrv1953
  5. ↑ Template:Cite Gaia EDR3
  6. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Anderson2012
  7. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Tycho-Gaia
  8. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named csrv
  9. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named SIMBAD
  10. ↑ a b Script error: No such module "citation/CS1".
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ a b Script error: No such module "citation/CS1".
  13. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Kaler
  14. ↑ Script error: No such module "citation/CS1".
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named mnras55_429
  17. ↑ Template:In lang Activities of Exhibition and Education in Astronomy 天文教育資訊網 2006 年 5 月 11 日 Template:Webarchive
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named csiro
  19. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named grego2008
  20. ↑ Script error: No such module "citation/CS1".
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