Alpha Piscium

From Wikipedia, the free encyclopedia
(Redirected from Al Rischa)
Jump to navigation Jump to search

Template:Short descriptionTemplate:Sky

α Piscium
Template:Location mark
Location of α Piscium (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Pisces
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 3.82 (4.33 + 5.23)[2]
Characteristics
Spectral type kA0hA7 Sr + kA2hF2mF2 (IV)[3]
Variable type α2 CVn[4]
Astrometry
Proper motion (μ) RA: +32.45[1] mas/yr
Dec.: +0.04[1] mas/yr
Parallax (π)21.66±1.06 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)+0.50[5]
Orbit[6]
Period (P)3267.4 yr
Semi-major axis (a)7.4″
Eccentricity (e)0.465
Inclination (i)113.4°
Longitude of the node (Ω)3.70°
Periastron epoch (T)2188.6
Argument of periastron (ω)
(secondary)		147.9°
Details
α Psc A
MassTemplate:Val[7] Template:Solar mass
Radius2.45[8] Template:Solar radius
LuminosityTemplate:Val[7] Template:Solar luminosity
Surface gravity (log g)3.85[8] cgs
TemperatureTemplate:Val[7] K
Rotational velocity (v sin i)81[9] km/s
α Psc B
MassTemplate:Val[10] Template:Solar mass
RadiusTemplate:Val[10] Template:Solar radius
LuminosityTemplate:Val[10] Template:Solar luminosity
Surface gravity (log g)Template:Val[10] cgs
TemperatureTemplate:Val[10] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Rotational velocity (v sin i)84[9] km/s
AgeTemplate:Val[10] Myr
Other designations
Template:Odlist[11][12]
α Psc A: Template:Odlist[13]
α Psc B: Template:Odlist[14]
Database references
SIMBADα Psc
α Psc A
α Psc B

Script error: No such module "Check for unknown parameters".

Alpha Piscium (α Piscium) is a binary star[6] system in the equatorial constellation of Pisces. Based upon parallax measurements made by the Hipparcos spacecraft, it is about Template:Val from the Solar System.

The two components are designated Alpha Piscium A (officially named Alrescha Template:IPAc-en, the traditional name of the system)[15][16] and B.

Nomenclature

α Piscium (Latinised to Alpha Piscium) is the star's Bayer designation. The designations of the two components as Alpha Piscium A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[17]

The system bore the traditional name Alrescha (alternatively Al Rescha, Alrischa, Alrisha) derived from the Arabic الرشآء ar-Rishā’ "the cord" and less commonly Kaitain and Okda, the latter from the Arabic عقدة ʽuqdah "knot" (see Ukdah.[18] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[19] to catalog and standardize proper names for stars. The WGSN approved the name Alrescha for the component Alpha Piscium A on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[16]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Outer Fence, refers to an asterism consisting of Alpha Piscium, Delta Piscium, Epsilon Piscium, Zeta Piscium, Mu Piscium, Nu Piscium and Xi Piscium. Consequently, the Chinese name for Alpha Piscium itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx).[20]

Properties

Alpha Piscium comprises a close binary with angular separation of presently 1.8" between the components. The main star or primary (Alpha Piscium A) is of magnitude +4.33 and spectral type A0p, while the companion or secondary (Alpha Piscium B) is magnitude 5.23 and belongs to spectral class A3m. The two stars take more than 3,000 years to orbit one another and they will make their closest approach to each other around 2060. One or both of the stars may be a spectroscopic binary as well. The stars have masses of 2.55 and 2.64 solar masses respectively and shine with a total luminosity of 55 and 63 times that of the Sun.

File:AlphaPscLightCurve.png
A light curve for Alpha Piscium, plotted from TESS data[21]

Alpha Piscium is catalogued as an α2 Canum Venaticorum variable, a type of variable star where the brightness changes are caused by the rotation of the star. The brightness varies by about 1/100 of a magnitude, identified from Hipparcos photometry.[4] The primary component is thought to be the source of the variations, and it has a period of 0.845 days which corresponds to the rotation period of the star. Variations with a period of 6.65 days have also been identified in the variations.[22]

Long-exposure observation

Stars that can set (not in a circumpolar constellation for the viewer) culminate at midnight – where viewed away from any polar region experiencing midnight sun – when at opposition, meaning they can be viewed from dusk until dawn. This applies to α Piscium on 21 October, in the current astronomical epoch.[23]

Half of the year from this date, 22 April, the star will be at conjunction above or below, the sun – apart by the star's declination (angle set out in table, right). The nearby days and months have most of the star's risen time during daylight.

References

Template:Reflist

Template:Stars of Pisces

  1. ↑ a b c d e Cite error: Invalid <ref> tag; no text was provided for refs named vanLeeuwen2007
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Cowley1969
  3. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Gray1989
  4. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named gcvs
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Anderson2012
  6. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Hartkopf2006
  7. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named netopil2017
  8. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named glagolevskij2019
  9. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Royer2002
  10. ↑ a b c d e f Cite error: Invalid <ref> tag; no text was provided for refs named sikora2019
  11. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SIMBAD
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SIMBAD_A
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SIMBAD_B
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named IAU-LSN
  17. ↑ Script error: No such module "citation/CS1".
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named allen1899
  19. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named WGSN
  20. ↑ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日 Template:Webarchive
  21. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named MAST
  22. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named wraight2011
  23. ↑ Ephemera table, rising and setting times In-the-Sky.org. Dominic C. Ford, 2011–2020; Cambridge UK.
Retrieved from "http://debianws.lexgopc.com/wiki143/index.php?title=Alpha_Piscium&oldid=1507157"