Pi Pavonis
π Pavonis, Latinized as Pi Pavonis, is a binary star in the constellation Pavo. It is a white-hued star that is visible to the naked eye as a faint point of light with an apparent visual magnitude of 4.33. The distance to this object is 130 light years based on parallax, but it is drifting closer to the Sun with a radial velocity of −15.6 km/s. The primary component is an chemically peculiar star that displays an abundance anomaly of strontium. Gray & Garrison (1989) classify it as kA4hF0mF2 III, matching a giant Am star with the calcium K line of an A4 star, the hydrogen lines of a cooler F0 star, and the metal lines of a F2 star. However, Loden and Sundman (1989) don't consider it to be a giant and list it as an Ap star. It is 1.4 billion years old with 1.8 times the mass of the Sun and 2.8 times the Sun's radius. The star is radiating 24.7 times the Sun's luminosity from its photosphere at an effective temperature of 7,560 K. The secondary is a K-type main-sequence star, much smaller than its primary, at 0.76 solar masses and 0.7 solar radii. It has an effective temperature 4,710 K and is 3.63 magnitudes fainter than the primary in the H band. They are separated by 39.3 astronomical units and have an estimated orbital period of 150 years. There is evidence for another companion using Hipparcos-Gaia astrometry, which should be a star with less than 0.7 times the mass of the Sun, closer to the primary star.
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pavo |
| Right ascension | 18h 08m 34.81459s[1] |
| Declination | −63° 40′ 06.7906″[1] |
| Apparent magnitude (V) | 4.33[2] |
| Characteristics | |
| Spectral type | kA4hF0mF2 III[3] + KV[4] |
| U−B color index | +0.17[5] |
| B−V color index | +0.23[5] |
| Astrometry | |
| Radial velocity (Rv) | −15.60[6] km/s |
| Proper motion (μ) | RA: +18.02[1] mas/yr Dec.: -207.57[1] mas/yr |
| Parallax (π) | 25.09±0.17 mas[1] |
| Distance | 130.0 ± 0.9 ly (39.9 ± 0.3 pc) |
| Absolute magnitude (MV) | 1.33[2] |
| Details[4] | |
| A | |
| Mass | 1.80 M☉ |
| Radius | 2.80 R☉ |
| Luminosity | 24.69±0.36[7] L☉ |
| Surface gravity (log g) | 3.81[8] cgs |
| Temperature | 7,560 K |
| Metallicity [Fe/H] | 0.27[8] dex |
| Rotational velocity (v sin i) | 30.0[9] km/s |
| Age | 1.4 Gyr |
| B | |
| Mass | 0.76 M☉ |
| Radius | 0.70 R☉ |
| Temperature | 4,710 K |
| Position (relative to A)[4] | |
| Component | B |
| Angular distance | 959 mas |
| Projected separation | 39.3 AU |
| Other designations | |
| π Pav, CPD−63°4292, FK5 3437, GC 24665, HD 165040, HIP 88866, HR 6745, SAO 254147[10] | |
| Database references | |
| SIMBAD | data |
π Pavonis, Latinized as Pi Pavonis, is a binary star[4] in the constellation Pavo. It is a white-hued star that is visible to the naked eye as a faint point of light with an apparent visual magnitude of 4.33.[2] The distance to this object is 130 light years based on parallax,[1] but it is drifting closer to the Sun with a radial velocity of −15.6 km/s.[6]
The primary component is an chemically peculiar star that displays an abundance anomaly of strontium.[11][12] Gray & Garrison (1989) classify it as kA4hF0mF2 III,[3] matching a giant Am star with the calcium K line of an A4 star, the hydrogen lines of a cooler F0 star, and the metal lines of a F2 star. However, Loden and Sundman (1989) don't consider it to be a giant and list it as an Ap star.[11] It is 1.4 billion years old with 1.8 times the mass of the Sun and 2.8 times the Sun's radius.[4] The star is radiating 24.7[7] times the Sun's luminosity from its photosphere at an effective temperature of 7,560 K.[4]
The secondary is a K-type main-sequence star, much smaller than its primary, at 0.76 solar masses and 0.7 solar radii. It has an effective temperature 4,710 K and is 3.63 magnitudes fainter than the primary in the H band. They are separated by 39.3 astronomical units and have an estimated orbital period of 150 years.[4]
There is evidence for another companion using Hipparcos-Gaia astrometry, which should be a star with less than 0.7 times the mass of the Sun, closer to the primary star.[4]
References
[edit]- ^ a b c d e f Van Leeuwen, F. (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. Vizier catalog entry
- ^ a b c 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. Vizier catalog entry
- ^ a b Gray, R. O.; Garrison, R. F. (1989). "The early F-type stars - Refined classification, confrontation with Stromgren photometry, and the effects of rotation". Astrophysical Journal Supplement Series. 69: 301. Bibcode:1989ApJS...69..301G. doi:10.1086/191315.
- ^ a b c d e f g h Waisberg, Idel; Klein, Ygal; Katz, Boaz (2023-07-04). "Hidden Companions to Intermediate-mass Stars. VII. Discovery of a 0.76 M☉, 39 au Companion to the Ap Star HIP 88866 = π Pavonis". Research Notes of the AAS. 7 (7): 138. Bibcode:2023RNAAS...7..138W. doi:10.3847/2515-5172/ace2be. ISSN 2515-5172.
- ^ a b Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.Vizier catalog entry
- ^ a b Wilson, R. E. (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication. Carnegie Institution of Washington. Bibcode:1953GCRV..C......0W. LCCN 54001336.
- ^ a b 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.
- ^ a b Erspamer, D.; North, P. (February 2003). "Automated spectroscopic abundances of A and F-type stars using echelle spectrographs. II. Abundances of 140 A-F stars from ELODIE". Astronomy and Astrophysics. 398 (3): 1121–1135. arXiv:astro-ph/0210065. Bibcode:2003A&A...398.1121E. doi:10.1051/0004-6361:20021711. S2CID 1109164.
- ^ Glebocki, R.; Gnacinski, P. (2005). "VizieR Online Data Catalog: Catalog of Stellar Rotational Velocities (Glebocki+ 2005)". VizieR On-line Data Catalog: III/244. Originally Published in: 2005csss...13..571G; 2005yCat.3244....0G. 3244. Bibcode:2005yCat.3244....0G. Vizier catalog entry
- ^ "pi Pav". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-12.
- ^ a b Loden, L. O.; Sundman, A. (June 1989). "Giant CP stars?". Journal of Astrophysics and Astronomy. 10 (2): 183–196. Bibcode:1989JApA...10..183L. doi:10.1007/BF02719315. S2CID 121258394.
- ^ Renson, P.; Manfroid, J. (2009). "Catalogue of Ap, Hg Mn and Am stars". Astronomy and Astrophysics. 498 (3): 961. Bibcode:2009A&A...498..961R. doi:10.1051/0004-6361/200810788.
