Pi Chamaeleontis

Pi Chamaeleontis, its name Latinized from π Chamaeleontis, is a binary star[12][13] system located in the southern circumpolar constellation of Chamaeleon. It is dimly visible to the naked eye with an apparent visual magnitude of 5.64.[2] Parallax measurements by Hipparcos put the system approximately 135 light-years (41.5 parsecs) away.[1] It is drifting closer with a radial velocity of −10 km/s.[6]

π Chamaeleontis
Observation data
Epoch J2000      Equinox J2000
Constellation Chamaeleon
Right ascension 11h 37m 15.63631s[1]
Declination −75° 53′ 47.5626″[1]
Apparent magnitude (V) 5.64[2]
Characteristics
Spectral type A9 IV[3] or F1 III[4]
U−B color index −0.01[5]
B−V color index +0.35[5]
Astrometry
Radial velocity (Rv)−9.8±3.7[6] km/s
Proper motion (μ) RA: −127.94[1] mas/yr
Dec.: −1.82[1] mas/yr
Parallax (π)24.09 ± 0.33 mas[1]
Distance135 ± 2 ly
(41.5 ± 0.6 pc)
Absolute magnitude (MV)2.56[7]
Orbit[1]
Period (P)223.1845±1.9460 d
Semi-major axis (a)7.86±0.83 mas
Eccentricity (e)0.3244±0.1375
Inclination (i)104.88±5.52°
Details
Mass1.52[8] M☉
Radius2.2[9] R☉
Luminosity8[9] L☉
Surface gravity (log g)4.08[8] cgs
Temperature6,853±80[6] K
Metallicity [Fe/H]−0.28[6] dex
Rotational velocity (v sin i)50[10] km/s
Age1.8±0.1[7] Gyr
Other designations
π Cha, CPD−75°744, FK5 438, HD 101132, HIP 56675, HR 4479, SAO 256857[11]
Database references
SIMBADdata

The Hipparcos satellite mission derived a 223 d orbit on the basis of its motion caused by an unseen companion.[1] The visible component is an A-type subgiant[3] or F-type giant star with an effective temperature of about 6,900 K.[6] It has an absolute magnitude of 2.56,[7] a mass of 1.52 M☉,[8] and a radius of 2.2 M☉.[9] It is roughly 1.8 billion years old.[7]

References
  1. van Leeuwen, F.; et al. (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. Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A.
  3. Houk, N.; Cowley, A. P. (1975). "University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations -90°.0 to -53°.0". Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. 1. Bibcode:1975mcts.book.....H.
  4. Kharchenko, N. V.; et al. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. S2CID 119323941.
  5. Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
  6. Casagrande, L.; Schönrich, R.; Asplund, M.; Cassisi, S.; Ramírez, I.; Meléndez, J.; Bensby, T.; Feltzing, S. (2011). "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey". Astronomy & Astrophysics. 530: A138. arXiv:1103.4651. Bibcode:2011A&A...530A.138C. doi:10.1051/0004-6361/201016276. S2CID 56118016.
  7. Holmberg, J.; Nordström, B.; Andersen, J. (2009). "The Geneva-Copenhagen survey of the solar neighbourhood". Astronomy & Astrophysics. 501 (3): 941. arXiv:0811.3982. Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191. S2CID 118577511.
  8. Lambert, David L.; Reddy, Bacham E. (2004). "Lithium abundances of the local thin disc stars". Monthly Notices of the Royal Astronomical Society. 349 (2): 757. arXiv:astro-ph/0401259. Bibcode:2004MNRAS.349..757L. doi:10.1111/j.1365-2966.2004.07557.x. S2CID 118931004.
  9. Chandler, Colin Orion; McDonald, Iain; Kane, Stephen R. (2016). "The Catalog of Earth-Like Exoplanet Survey Targets (CELESTA): A Database of Habitable Zones Around Nearby Stars". The Astronomical Journal. 151 (3): 59. arXiv:1510.05666. Bibcode:2016AJ....151...59C. doi:10.3847/0004-6256/151/3/59. S2CID 119246448.
  10. Balachandran, Suchitra (1990). "Lithium depletion and rotation in main-sequence stars". The Astrophysical Journal. 354: 310. Bibcode:1990ApJ...354..310B. doi:10.1086/168691.
  11. "pi Cha". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-31.
  12. 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. S2CID 14878976.
  13. Bartkevicius, A.; Gudas, A. (2001). "Kinematics of Hipparcos Visual Binaries. I. Stars with Orbital Solutions". Baltic Astronomy. 10 (4): 481–587. Bibcode:2001BaltA..10..481B. doi:10.1515/astro-2001-0402. S2CID 117700350.
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