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Pi Cassiopeiae

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Variable star in the constellation Cassiopeia
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Pi Cassiopeiae
Location of π Cassiopeiae (circled)
Observation data
Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation Cassiopeia [1]
Right ascension 00h 43m 28.070s[2]
Declination +47°01′28.36′′[2]
Apparentmagnitude(V) +4.949[3]
Characteristics
Evolutionarystage Main sequence
Spectraltype A5V[4] + A5V[5]
B−V color index +0.171[3]
Variabletype Ellipsoidal [6]
Astrometry
Radial velocity (Rv)+12.9±0.8[7] km/s
Proper motion (μ) RA:−24.570 mas/yr [2]
Dec.:−36.886 mas/yr [2]
Parallax (π)18.6293±0.1142mas [2]
Distance 175 ± 1ly
(53.7 ± 0.3pc)
Absolutemagnitude(MV)+1.30[1]
Orbit [8]
Period (P)1.9642d
Eccentricity (e)0.00
Periastron epoch (T)2427535.74JD
Argument of periastron (ω)
(secondary)		0.00°
Semi-amplitude (K1)
(primary)		120.5km/s
Semi-amplitude (K2)
(secondary)		122.1km/s
Details
A
Mass 1.82[2] M☉
Radius 1.9[5] R☉
Luminosity 22[9] L☉
Surface gravity (logg)4.41[10] cgs
Temperature 8,392±285[10] K
Rotational velocity (vsini)60[5] km/s
Age 251[10] Myr
B
Mass 1.87[2] M☉
Radius 1.9[5] R☉
Rotational velocity (vsini)65[5] km/s
Other designations
πCas, 20Cas, BD+46°146, HD 4058, HIP 3414, HR 184, SAO 36602[11]
Database references
SIMBAD data

Pi Cassiopeiae is a close binary star [8] system in the constellation Cassiopeia, near the southern border with Andromeda. Its name is a Bayer designation that is Latinized from π Cassiopeiae, and abbreviated Pi Cas or π Cas. This system is visible to the naked eye as a point of light with a combined apparent visual magnitude of +4.949.[3] Based upon an annual parallax shift of 18.63mas as seen from Earth,[2] this system is located about 175 light-years (54 pc ) 175 light years from the Sun. It is drifting further away with a radial velocity of +13 km/s.[7]

A light curve for Pi Cassiopeiae, plotted from TESS data[12]

This is a double-lined spectroscopic binary system with an orbital period of nearly two days in a circular orbit.[8] It is classified as a rotating ellipsoidal variable star and its brightness varies by 0.02 magnitudes with a period of 23.57 hours,[6] which equals half of its orbital period. The spectrum matches that of an A-type main-sequence star with a stellar classification of A5 V.[4] The two stars have similar masses and spectra.[5] A star at a projected separation of 1,700AU has been identified as a possible white dwarf. It is at the same distance as Pi Cassiopeiae and shares a common proper motion. The age of the white dwarf is calculated to be about 500 million years.[13]

Pi Cassiopeiae has been given the spectral class of kA3hF1mA5, indicating an Am star,[14] but this is now considered doubtful.[15]

References

[edit ]
  1. 1 2 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters , 38 (5): 331, arXiv:1108.4971 , Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. XHIP record for this object at VizieR .
  2. 1 2 3 4 5 6 7 8 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 at VizieR .
  3. 1 2 3 Høg, E.; et al. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy and Astrophysics, 355: L27, Bibcode:2000A&A...355L..27H, doi:10.1888/0333750888/2862.
  4. 1 2 Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
  5. 1 2 3 4 5 6 Howe, K. S.; Clarke, C. J. (2009), "An analysis of v sin (I) correlations in early-type binaries", Monthly Notices of the Royal Astronomical Society, 392 (1): 448, Bibcode:2009MNRAS.392..448H, doi:10.1111/j.1365-2966.2008.14073.x , S2CID 120183969.
  6. 1 2 Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  7. 1 2 de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048 , Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  8. 1 2 3 Pourbaix, D.; et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics, 424: 727–732, arXiv:astro-ph/0406573 , Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
  9. ↑ McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037 , Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x , S2CID 118665352.
  10. 1 2 3 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154 , Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  11. ↑ "pi. Cas", SIMBAD , Centre de données astronomiques de Strasbourg , retrieved 2017年08月30日.
  12. ↑ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 8 December 2021.
  13. ↑ Qiu, Dan; et al. (2021), "Precise Ages of Field Stars from White Dwarf Companions in Gaia DR2", The Astrophysical Journal Supplement Series, 253 (2): 58, arXiv:2012.04890 , Bibcode:2021ApJS..253...58Q, doi:10.3847/1538-4365/abe468 , S2CID 234867350.
  14. ↑ Abt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement Series, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182 .
  15. ↑ Renson, P.; Manfroid, J. (2009), "Catalogue of Ap, HGMN and Am stars", Astronomy and Astrophysics, 498 (3): 961, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788 .

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