Pi2 Columbae

π2 Columbae, Latinized as Pi2 Columbae, is a binary star[9] system in the southern constellation of Columba, near the southern constellation border with Pictor. It is white-hued and dimly visible to the naked eye with a combined apparent visual magnitude of 5.50.[2] Based upon an annual parallax shift of 12.8 mas as seen from Earth,[1] this system is located about 254 light years from the Sun. They are receding with a heliocentric radial velocity of +31 km/s.[4]

For other stars with this Bayer designation, see π Columbae.
Pi2 Columbae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Columba
Right ascension  06h 07m 52.86009s[1]
Declination −42° 09′ 14.5488″[1]
Apparent magnitude (V) 5.50[2]
Characteristics
Spectral type A0 V + A[3]
B−V color index +0.00[2]
Astrometry
Radial velocity (Rv)+31.0±3.7[4] km/s
Proper motion (μ) RA: −10.612[1] mas/yr
Dec.: −16.928[1] mas/yr
Parallax (π)12.8296 ± 0.1132[1] mas
Distance254 ± 2 ly
(77.9 ± 0.7 pc)
Absolute magnitude (MV)+1.17[5]
Details[6]
Mass2.64 M☉
Luminosity31[7] L☉
Surface gravity (log g)4.38±0.14 cgs
Temperature11,223±382 K
Rotational velocity (v sin i)274 km/s
Age98 Myr
Other designations
π2 Col, CD−42° 2351, HD 42303, HIP 29064, HR 2181, SAO 217730[8]
Database references
SIMBADdata

The pair have an angular separation of 0.1[3] arc seconds with the primary being an A-type main-sequence star of spectral class A0 V,[3] while the secondary component is a similar A-type star.[9] The primary is 98 million years old with 2.6 times the mass of the Sun and is spinning rapidly with a projected rotational velocity of 274 km/s.[6] It is radiating 31[7] times the luminosity of the Sun from its photosphere at an effective temperature of 11,223 K. The system is a source of X-ray emission with a luminosity of 184.3×1020 W, which is considered unusual since A-type stars are not expected to display magnetic activity.[3]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa, 27: 11, Bibcode:1968MNSSA..27...11C.
  3. Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677–684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.
  4. 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, A61.
  5. Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035.
  6. 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.
  7. 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.
  8. "pi02 Col". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-28.
  9. Eggleton, 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.
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