Pi2 Cygni

For other stars with this Bayer designation, see π Cygni.
Pi2 Cygni
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cygnus
Right ascension 21h 46m 47.60832s[1]
Declination +49° 18′ 34.4511″[1]
Apparent magnitude (V) 4.24[2]
Characteristics
Spectral type B2.5 III[3]
U−B color index −0.79[2]
B−V color index −0.125[2]
Variable type β Cep[4]
Astrometry
Radial velocity (Rv)−12.3[5] km/s
Proper motion (μ) RA: +2.77[1] mas/yr
Dec.: −2.00[1] mas/yr
Parallax (π)2.95 ± 0.34 mas[1]
Distanceapprox. 1,100 ly
(approx. 340 pc)
Absolute magnitude (MV)−3.39[6]
Orbit[7]
Period (P)72.0162 d
Eccentricity (e)0.34
Periastron epoch (T)2428410.6 JD
Argument of periastron (ω)
(secondary)		238.1°
Semi-amplitude (K1)
(primary)		7.8 km/s
Details
π2 Cyg A
Mass8.4±0.4[8] M☉
Radius7.1[9] R☉
Luminosity (bolometric)8,442[10] L☉
Surface gravity (log g)3.69±0.16[11] cgs
Temperature20,815±1,057[11] K
Metallicity [Fe/H]0.04±0.09[11] dex
Rotational velocity (v sin i)50±5[4] km/s
Age33.2±5.8[8] Myr
Other designations
π2 Cyg, 81 Cygni, BD+48° 3504, FK5 821, HD 207330, HIP 107533, HR 8335, SAO 51293.[12]
Database references
SIMBADdata

Pi2 Cygni, Latinized from π2 Cygni, is a triple star[13] system in the northern constellation of Cygnus. It is visible to the naked eye about 2.5° east-northeast of the open cluster M39,[14] having an apparent visual magnitude of 4.24.[2] Based upon an annual parallax shift of 2.95 mas,[1] it is located at a distance of roughly 1,100 light years from the Sun.

The inner pair of stars in this system form a single-lined[15] spectroscopic binary with an orbital period of 72.0162 days and an eccentricity of 0.34.[7] The primary, component A, is a B-type giant star with a stellar classification of B2.5 III.[3] It is a Beta Cephei variable[4] with an estimated 8.4[8] times the mass of the Sun and around 7.1[9] times the Sun's radius. The star is roughly 33[8] million years old and is spinning with a projected rotational velocity of 50[4] km/s. It is radiating 8,442[10] times the solar luminosity from its outer atmosphere at an effective temperature of around 20,815[11] K.

The third member of this system is a magnitude 5.98 star at an angular separation of 0.10 arc seconds along a position angle of 129°, as of 1996.[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 d Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference walborn1971 was invoked but never defined (see the help page).
  4. ^ a b c d Cite error: The named reference Silvester2009 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Wilson1953 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Pourbaix2004 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference Tetzlaff2011 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference aaa367_521 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Hohle2010 was invoked but never defined (see the help page).
  11. ^ a b c d Cite error: The named reference Prugniel2011 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 Eggleton2008 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference OMeara92 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Abt2002 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).