Z Apodis

Z Apodis

A visual band light curve for Z Apodis, plotted from ASAS-SN data[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Apus
Right ascension	14h 06m 54.82s[2]
Declination	−71° 22′ 16.7″[2]
Apparent magnitude (V)	10.8 to 12.0[3]
Characteristics
U−B color index	+0.5 - +1.5[4]
B−V color index	+1.5 - +1.75[4]
Variable type	RV Tau?[3]
Astrometry
Proper motion (μ)	RA: −3.841[2] mas/yr Dec.: −1.604[2] mas/yr
Parallax (π)	0.3135±0.0131 mas[2]
Distance	10,400 ± 400 ly (3,200 ± 100 pc)
Details
Mass	3.2[5] M☉
Radius	27.6[2] R☉
Luminosity	405[2] L☉
Surface gravity (log g)	2.12[2] cgs
Temperature	4,579[2] K
Metallicity [Fe/H]	−0.76[5] dex
Age	11[6] Gyr
Other designations
Z Aps, TYC 9252-1914-1, 2MASS J14065484-7122167, AAVSO 1358-70A
Database references
SIMBAD	data

Z Apodis (Z Aps) is a variable star in the constellation of Apus. It has an apparent visual magnitude which varies between 10.8 and 12.8,^[3] over a period of 39.37 days.^[3] Although described in the General Catalogue of Variable Stars as a cataclysmic variable star, it appears that it is a pulsating variable star,^[4] and has been classed as an RV Tauri variable star, type RVa.^[3] Other sources classify it is a type II (W Virginis) Cepheid.^[7]

Edna B. Florence discovered the variability of Z Apodis by examining photographic plates. The discovery was announced by Henrietta Hill Swope in 1931. Examination of 20 plates taken in 1925 allowed the derivation of a period of 19.5 days, almost exactly half of the currently accepted period. However, observations outside of that time window seemed "...too scattered to give any other indication of a period.", so the star was initially classified as an irregular variable.^[8]

1. ^ "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 6 January 2022.
2. ^ ^{a b c d e f g h i} 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 d e} Watson, Christopher (4 January 2010). "Z Apodis". The International Variable Star Index. American Association of Variable Star Observers. Retrieved 20 Nov 2022.
4. ^ ^{a b c} Marino, B. F.; Walker, W. S. G. (1991). "Z Apodis is a Pulsating - not a Cataclysmic - Variable Star". Information Bulletin on Variable Stars. 3664: 1. Bibcode:1991IBVS.3664....1M.
5. ^ ^{a b} Anders, F.; Khalatyan, A.; Queiroz, A. B. A.; Chiappini, C.; Ardevol, J.; Casamiquela, L.; Figueras, F.; Jimenez-Arranz, O.; Jordi, C.; Monguio, M.; Romero-Gomez, M.; Altamirano, D.; Antoja, T.; Assaad, R.; Cantat-Gaudin, T.; Castro-Ginard, A.; Enke, H.; Girardi, L.; Guiglion, G.; Khan, S.; Luri, X.; Miglio, A.; Minchev, I.; Ramos, P.; Santiago, B. X.; Steinmetz, M. (2022). "VizieR Online Data Catalog: StarHorse2, Gaia EDR3 photo-astrometric distances (Anders+, 2022)". Vizier Online Data Catalog. Bibcode:2022yCat.1354....0A.
6. ^ Fouesneau, M.; Andrae, R.; Dharmawardena, T.; Rybizki, J.; Bailer-Jones, C. A. L.; Demleitner, M. (2022). "Astrophysical parameters from Gaia DR2, 2MASS, and AllWISE". Astronomy and Astrophysics. 662: A125. arXiv:2201.03252. Bibcode:2022A&A...662A.125F. doi:10.1051/0004-6361/202141828. S2CID 245837778.
7. ^ Ripepi, V.; Molinaro, R.; Musella, I.; Marconi, M.; Leccia, S.; Eyer, L. (2019). "Reclassification of Cepheids in the Gaia Data Release 2. Period-luminosity and period-Wesenheit relations in the Gaia passbands". Astronomy and Astrophysics. 625: 625. arXiv:1810.10486. Bibcode:2019A&A...625A..14R. doi:10.1051/0004-6361/201834506. S2CID 119338608.
8. ^ Swope, Henrietta H. (June 1931). "New Variable Stars in Centaurus and Circinus". Harvard College Observatory Bulletin. 883: 23–30. Bibcode:1931BHarO.883...23S.

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