AZ Phoenicis

AZ Phoenicis (HR 239) is a variable star in the constellation of Phoenix. It has an average visual apparent magnitude of 6.47,[2] so it is at the limit of naked eye visibility. From parallax measurements by the Gaia spacecraft, it is located at a distance of 322 light-years (99 parsecs) from Earth.[1] Its absolute magnitude is calculated at 1.65.[5]

AZ Phoenicis
Observation data
Epoch J2000      Equinox J2000
Constellation Phoenix
Right ascension 00h 50m 03.77s[1]
Declination −43° 23′ 41.92″[1]
Apparent magnitude (V) 6.47[2]
Characteristics
Spectral type A9/F0III[3]
Variable type δ Scuti[2]
Astrometry
Radial velocity (Rv)11.9[4] km/s
Proper motion (μ) RA: 6.65[1] mas/yr
Dec.: 25.03[1] mas/yr
Parallax (π)10.1141 ± 0.0578[1] mas
Distance322 ± 2 ly
(98.9 ± 0.6 pc)
Absolute magnitude (MV)1.65 ± 0.30[5]
Details
Radius2.70[1] R☉
Luminosity18.6+5.9
−4.5[5] L☉
Surface gravity (log g)3.78 ± 0.08[5] cgs
Temperature7,278 ± 34[5] K
Metallicity[Z] = +0.52 ± 0.15[5]
Other designations
AZ Phe, CD−44°216, HD 4849, HIP 3903, HR 239, SAO 215254[6]
Database references
SIMBADdata

AZ Phoenicis is a Delta Scuti variable that pulsates with a single period of 79.3 minutes,[7] causing its visual brightness to vary with an amplitude of 0.015 magnitudes.[2] Its variability was discovered by Werner Weiss in 1977, from observations with the 50-cm telescope at La Silla Observatory.[8] AZ Phoenicis has also been classified as a possible Ap star, which remains uncertain, even though the star has a large concentration of metals;[7] the overall metallicity of the star has been measured to about 3 times the solar metallicity.[5]

This star is classified with a spectral type of A9/F0III,[3] corresponding to a giant of type A or F. With an estimated radius of 2.7 times the solar radius,[1] it is shining with 19 times the solar luminosity at an effective temperature of 7,280 K.[5] The astrometric observations by the Hipparcos spacecraft detected a significant acceleration in the proper motion of AZ Phoenicis, indicating it is an astrometric binary.[9]

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. Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  3. Houk, N. (1978). "Michigan atalogue of two dimensional spectral types for the HD stars, Vol. 2". Michigan Spectral Survey. 2. Bibcode:1978mcts.book.....H.
  4. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  5. Paunzen, E.; Handler, G.; Weiss, W. W.; Nesvacil, N.; Hempel, A.; Romero-Colmenero, E.; Vuthela, F. F.; Reegen, P.; Shobbrook, R. R.; Kilkenny, D. (2002). "On the Period-Luminosity-Colour-Metallicity relation and the pulsational characteristics of λ Bootis type stars". Astronomy and Astrophysics. 392 (2): 515–528. arXiv:astro-ph/0207494. Bibcode:2002A&A...392..515P. doi:10.1051/0004-6361:20020854. S2CID 54666586.
  6. "AZ Phe". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2 February 2019.
  7. Kreidl, T. J. (1985). "Differential photometry of the δ Sct stars HR 151 and HR 239". Monthly Notices of the Royal Astronomical Society. 216 (4): 1017–1023. Bibcode:1985MNRAS.216.1017K. doi:10.1093/mnras/216.4.1017.
  8. Weiss, W. W. (1977). "HR 239 and HR 8676: Two delta Scuti-Type Variables". Information Bulletin on Variable Stars. 1364: 1. Bibcode:1977IBVS.1364....1W.
  9. Makarov, V. V.; Kaplan, G. H. (May 2005), "Statistical Constraints for Astrometric Binaries with Nonlinear Motion", The Astronomical Journal, 129 (5): 2420–2427, Bibcode:2005AJ....129.2420M, doi:10.1086/429590.
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