Pi Cassiopeiae

Pi Cassiopeiae

Map of the Bayer-designated stars in Cassiopeia. Pi Cassiopeiae is circled.
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cassiopeia
Right ascension 00h 43m 28.07045s[1]
Declination +47° 01′ 28.3694″[1]
Apparent magnitude (V) +4.949[2]
Characteristics
Spectral type A5V[3] + A5V[4]
B−V color index +0.171[2]
Variable type Ellipsoidal[5]
Astrometry
Radial velocity (Rv)+12.9±0.8[6] km/s
Proper motion (μ) RA: −23.71±0.23[1] mas/yr
Dec.: −36.84±0.18[1] mas/yr
Parallax (π)18.63 ± 0.32 mas[1]
Distance175 ± 3 ly
(53.7 ± 0.9 pc)
Absolute magnitude (MV)+1.30[7]
Orbit[8]
Period (P)1.9642 d
Eccentricity (e)0.00
Periastron epoch (T)2427535.74 JD
Argument of periastron (ω)
(secondary)		0.00°
Semi-amplitude (K1)
(primary)		120.5 km/s
Semi-amplitude (K2)
(secondary)		122.1 km/s
Details
A
Mass1.82[9] M☉
Radius1.9[4] R☉
Luminosity22[10] L☉
Surface gravity (log g)4.41[11] cgs
Temperature8,392±285[11] K
Rotational velocity (v sin i)60[4] km/s
Age251[11] Myr
B
Mass1.87[9] M☉
Radius1.9[4] R☉
Rotational velocity (v sin i)65[4] km/s
Other designations
π Cas, 20 Cas, BD+46°146, HD 4058, HIP 3414, HR 184, SAO 36602[12]
Database references
SIMBADdata

Pi Cassiopeiae, Latinized from π Cassiopeiae, is a close binary star[8] system in the constellation Cassiopeia. It is visible to the naked eye with an apparent visual magnitude of +4.949.[2] Based upon an annual parallax shift of 18.63 mas as seen from Earth,[1] this system is located about 175 light years from the Sun.

A light curve for Pi Cassiopeiae, plotted from TESS data[13]

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,[5] 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.[3] The two stars have similar masses and spectra.[4] A star at a projected separation of 1,700 AU 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.[14]

Pi Cassiopeiae has been given the spectral class of kA3hF1mA5, indicating an Am star,[15] but this is now considered doubtful.[16]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference Hog2000 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Cowley1969 was invoked but never defined (see the help page).
  4. ^ a b c d e f Cite error: The named reference howe2009 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference Pourbaix2004 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference dr3 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).
  11. ^ a b c Cite error: The named reference David2015 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference qiu2021 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference abt1995 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference renson2009 was invoked but never defined (see the help page).