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Pi Geminorum

From Wikipedia, the free encyclopedia
Star in the constellation Gemini
π Geminorum
Location of π Geminorum (circled)
Observation data
EpochJ2000.0      EquinoxJ2000.0 (ICRS)
ConstellationGemini
Right ascension07h 47m 30.32300s[1]
Declination+33° 24′ 56.5034″[1]
Apparent magnitude (V)5.14[2]
Characteristics
Evolutionary stageAGB[3]
Spectral typeM1 IIIa[4]
U−Bcolor index+1.90[2]
B−Vcolor index+1.59[2]
Variable typesuspected[5]
Astrometry
Radial velocity (Rv)−13.36±0.34[6] km/s
Proper motion (μ)RA: -19.59[1]mas/yr
Dec.: -29.33[1]mas/yr
Parallax (π)4.93±0.32 mas[1]
Distance660 ± 40 ly
(200 ± 10 pc)
Absolute magnitude (MV)−1.04[7]
Details
Mass1.1[8] M☉
Radius57[9] R☉
Luminosity676[9] L☉
Surface gravity (log g)0.90[8] cgs
Temperature3,915[9] K
Metallicity[Fe/H]0.07[8] dex
Other designations
π Gem,80 Geminorum,BD+33°1585,FK5 296,HD 62898,HIP 38016,HR 3013,SAO 60340.[10]
Database references
SIMBADdata

π Geminorum (Latinised asPi Geminorum, abbreviated to π Gem or pi Gem) is astar located in the constellationGemini, to the north ofCastor. With anapparent visual magnitude of 5.14,[2] it is faintly visible to the naked eye on a dark night. Based upon an annualparallax shift of 4.93 mas,[1] Pi Geminorum is located roughly 660 light years from theSun. At that distance, the visual magnitude of the star is diminished by aninterstellar absorption factor of 0.033 due to interstellar dust.[7]

This is anevolvedred giant star with astellar classification of M1 IIIa.[4] The measuredangular diameter of this star is2.58±0.20 mas.[11] At the estimated distance of this star, this yields a physical size of about 56 times theradius of the Sun.[12] It is radiating roughly a thousand times theluminosity of the Sun from itsouter atmosphere at aneffective temperature of 3,900 K.

Unexpected for a red giant, Pi Geminorum was found to be anX-ray source during theROSAT all-sky survey. The most likely source for this emission is a magnitude 11.4 star located at anangular separation of 21 arcseconds along aposition angle of 214°.[13] This is a background star, not gravitationally bound to Pi Geminorum.[14]

In a 1930 study, Pi Geminorum was suspected to vary in brightness by a few hundredths of a magnitude, but this has not been confirmed by modern measurements.[5]

References

[edit]
  1. ^abcdefvan Leeuwen, F. (2007), "Validation of the new Hipparcos reduction",Astronomy and Astrophysics,474 (2):653–664,arXiv:0708.1752,Bibcode:2007A&A...474..653V,doi:10.1051/0004-6361:20078357,S2CID 18759600.
  2. ^abcdMermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)",Catalogue of Eggen's UBV Data,SIMBAD,Bibcode:1986EgUBV........0M.
  3. ^Eggen, Olin J. (1992), "Asymptotic Giant Branch Stars Near the Sun",The Astronomical Journal,104: 275,Bibcode:1992AJ....104..275E,doi:10.1086/116239.
  4. ^abEggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems",Monthly Notices of the Royal Astronomical Society,389 (2):869–879,arXiv:0806.2878,Bibcode:2008MNRAS.389..869E,doi:10.1111/j.1365-2966.2008.13596.x,S2CID 14878976.
  5. ^abSamus, N. N.; Durlevich, O. V.; et al. (2004). "VizieR Online Data Catalog: Combined General Catalogue of Variable Stars (Samus+ 2004)".Vizier Online Data Catalog.Bibcode:2004yCat.2250....0S.
  6. ^Famaey, B.; et al. (2009), "Spectroscopic binaries among Hipparcos M giants. I. Data, orbits, and intrinsic variations",Astronomy and Astrophysics,498 (2):627–640,arXiv:0901.0934,Bibcode:2009A&A...498..627F,doi:10.1051/0004-6361/200810698,S2CID 18739721.
  7. ^abRyon, Jenna; et al. (August 2009), "Comparing the Ca ii H and K Emission Lines in Red Giant Stars",Publications of the Astronomical Society of the Pacific,121 (882):842–856,arXiv:0907.3346,Bibcode:2009PASP..121..842R,doi:10.1086/605456,S2CID 17821279.
  8. ^abcAnders, F.; Khalatyan, A.; Chiappini, C.; Queiroz, A. B.; Santiago, B. X.; Jordi, C.; Girardi, L.; Brown, A. G. A.; Matijevič, G.; Monari, G.; Cantat-Gaudin, T.; Weiler, M.; Khan, S.; Miglio, A.; Carrillo, I.; Romero-Gómez, M.; Minchev, I.; De Jong, R. S.; Antoja, T.; Ramos, P.; Steinmetz, M.; Enke, H. (2019), "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18",Astronomy and Astrophysics,628: A94,arXiv:1904.11302,Bibcode:2019A&A...628A..94A,doi:10.1051/0004-6361/201935765.
  9. ^abcFetherolf, Tara; Pepper, Joshua; Simpson, Emilie; Kane, Stephen R.; Močnik, Teo; English, John Edward; Antoci, Victoria; Huber, Daniel; Jenkins, Jon M.; Stassun, Keivan; Twicken, Joseph D.; Vanderspek, Roland; Winn, Joshua N. (2023), "Variability Catalog of Stars Observed during the TESS Prime Mission",The Astrophysical Journal Supplement Series,268 (1): 4,arXiv:2208.11721,Bibcode:2023ApJS..268....4F,doi:10.3847/1538-4365/acdee5.
  10. ^"pi. Gem",SIMBAD,Centre de données astronomiques de Strasbourg, retrieved2016-12-07.
  11. ^Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements",Astronomy and Astrophysics,431 (2):773–777,Bibcode:2005A&A...431..773R,doi:10.1051/0004-6361:20042039.
  12. ^Lang, Kenneth R. (2006),Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.),Birkhäuser,ISBN 3-540-29692-1.. The radius (R*) is given by:
    2⋅R∗=(203⋅2.58⋅10−3) AU0.0046491 AU/R⨀≈112.6⋅R⨀{\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(203\cdot 2.58\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 112.6\cdot R_{\bigodot }\end{aligned}}}
  13. ^Hunsch, Matthias; et al. (February 1998), "On the X-ray emission from M-type giants",Astronomy and Astrophysics,330:225–231,Bibcode:1998A&A...330..225H.
  14. ^Vallenari, A.; et al. (Gaia collaboration) (2023)."Gaia Data Release 3. Summary of the content and survey properties".Astronomy and Astrophysics.674: A1.arXiv:2208.00211.Bibcode:2023A&A...674A...1G.doi:10.1051/0004-6361/202243940.S2CID 244398875. Gaia DR3 record for this source atVizieR.
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