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Pi Arae

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Pi Arae
Location of π Arae (dot within red circle)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ara[1]
Right ascension 17h 38m 05.515s[2]
Declination −54° 30′ 01.56″[2]
Apparent magnitude (V) +5.25[3]
Characteristics
Spectral type A5 IV-V[4]
B−V color index +0.20[3]
Astrometry
Radial velocity (Rv)−2.11±0.22[2] km/s
Proper motion (μ) RA: −50.775 mas/yr[2]
Dec.: −149.745 mas/yr[2]
Parallax (π)24.3817±0.0805 mas[2]
Distance133.8 ± 0.4 ly
(41.0 ± 0.1 pc)
Absolute magnitude (MV)+2.01[1]
Details
Mass1.73[5] M☉
Radius1.90[6] R☉
Luminosity13.3[1] L☉
Surface gravity (log g)4.36[5] cgs
Temperature8,215±279[5] K
Metallicity [Fe/H]+0.13[1] dex
Rotational velocity (v sin i)54.1±0.4[7] km/s
Age319[5] Myr
Other designations
π Ara, CPD−54°8403, GC 23862, GJ 683, HD 159492, HIP 86305, HR 6549, SAO 244896, PPM 346165[8]
Database references
SIMBADdata

Pi Arae is a star in the southern constellation of Ara. Its name is a Bayer designation that is Latinized from π Arae, and abbreviated Pi Ara or π Ara. This star is faintly visible to the naked eye with an apparent visual magnitude of +5.25.[3] Based upon an annual parallax shift of 24.38 mas as seen from Earth,[2] it is located 134 light-years (41 pc) from the Sun. It is moving closer to the Sun with a radial velocity of −2 km/s.[2]

The stellar classification of this star is A5 IV-V,[4] indicating the spectrum displays the hybrid features of both a main sequence and a more evolved subgiant star. Pi Arae is an estimated 319[5] million years old and is spinning with a projected rotational velocity of 54.1 km/s.[7] The star has 1.73[5] times the mass of the Sun and 1.90[6] times the Sun's radius. It is radiating 13.3[1] times the Sun's luminosity from its photosphere at an effective temperature of about 8,215 K.[5]

Pi Arae displays an excess emission of infrared radiation, which may be explained by circumstellar dust.[9] The thermal emission matches a two component model, consisting of an inner disk of warm crystalline silicate dust and an outer colder disk of dirty ice. The inner disk has a temperature of 173 K and is orbiting roughly 9.1 AU from the host star. The outer disk is 77 K and orbits at a distance of about 117.3 AU. The small size of some of the dust grains indicate the inner disk may have formed relatively recently from collisions between orbiting planetesimals.[10]

Located 55 arc minutes to the north of Pi Arae is the globular cluster NGC 6397.[11]

References

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  1. ^ a b c d e 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, S2CID 119257644.
  2. ^ a b c d e f g 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. ^ a b c Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  4. ^ a b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 1, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1975mcts.book.....H.
  5. ^ a b c d e f g 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.
  6. ^ a b Patel, Rahul I.; et al. (May 2014), "A Sensitive Identification of Warm Debris Disks in the Solar Neighborhood through Precise Calibration of Saturated WISE Photometry", The Astrophysical Journal Supplement Series, 212 (1): 23, arXiv:1403.3435, Bibcode:2014ApJS..212...10P, doi:10.1088/0067-0049/212/1/10, S2CID 119219094, 10.
  7. ^ a b Díaz, C. G.; et al. (July 2011), "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum", Astronomy & Astrophysics, 531: A143, arXiv:1012.4858, Bibcode:2011A&A...531A.143D, doi:10.1051/0004-6361/201016386, S2CID 119286673.
  8. ^ "pi. Ara", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-09-26.
  9. ^ Morales, Farisa Y.; et al. (April 2011), "Common Warm Dust Temperatures Around Main-sequence Stars" (PDF), The Astrophysical Journal Letters, 730 (2): L29, Bibcode:2011ApJ...730L..29M, doi:10.1088/2041-8205/730/2/L29, S2CID 2360696.
  10. ^ Morales, F. Y.; et al. (October 2013), "Herschel-resolved Outer Belts of Two-belt Debris Disks around A-type Stars: HD 70313, HD 71722, HD 159492, and F-type: HD 104860", The Astrophysical Journal, 776 (2): 13, Bibcode:2013ApJ...776..111M, doi:10.1088/0004-637X/776/2/111, 111.
  11. ^ O'Meara, Stephen James (2013), Deep-Sky Companions: Southern Gems, Cambridge University Press, p. 358, Bibcode:2013dcsg.book.....O, ISBN 978-1139851541.
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