This star was first recorded byBenjamin Apthorp Gould on April 29, 1873, and catalogued as the 10th star of Zone 257 with right ascension of11h 31m 32.89s and declination of −46° 01′ 08″ (at epoch 1875.0) and apparent magnitude of 8.5.[16]
There have been many attempts to assign a conventional spectral class to this star. TheHenry Draper Catalogue gives a class of B5. More detailed analysis when the unusual nature of the star was discovered estimated a class of F8 or G0. Later studies gave classes of F0 or F5 to G0.[5] It is considered likely to be amain sequence star with a temperature somewhat hotter than theSun, but with itsspectral lines strongly blanketed by the extreme abundances of certain metals.[19] A catalogue ofchemically peculiar stars gives the type F3 Ho, indicating anAp star with an approximate spectral class of F3 and strongholmium lines.[6] Compared to neighboring stars, HD 101065 has a highpeculiar velocity of23.8±1.9 km/s.[20]
With a mass of about 1.5 M☉ and an age of around 1.5 billion years, HD 101065 is calculated to be right at the end of itsmain sequence life. It shines with abolometric luminosity of about 5.6 L☉ at aneffective temperature of6,131 K. It has a very slowprojected rotational velocity for a hot main sequence star of just3.5 km/s. Observations of its magnetic field suggest a possible rotation period of about 188 years, although this is considered a minimum possible value.[4] Ametallicity index ([Fe/H]) of −2.40 has been published (less than 1% that of the Sun), but this single value (for iron) does not adequately represent the chemical makeup shown in the star's unique spectrum. Levels of some other metals as derived from the spectrum are thousands of times higher than in the Sun.[11] Also, because the chemical peculiarities of Ap stars in general are largely due to stratification of elements allowed by very slow rotation, the published metallicity presumably is not representative of the proportion of heavy elements in the whole star.[4]
A potential companion had also been detected, a 14th-magnitude star (in infrared) 8arc seconds away, indicating at the primary's distance a minimum separation of just1,000 AU (0.02 light-years);[22] however,Gaia Data Release 2 suggests that the pair is onlyoptical and the distance to this second star is890±90 light-years, more than twice the distance to Przybylski's Star.[23]
Przybylski's stellar atmosphere is "highlymagnetic, stratified and chemically peculiar."[24][25]: 13 Two different types of unusual spectroscopic observation have been reported.
Many different short-livedactinide elements, namely,actinium,protactinium,neptunium,plutonium,americium,curium,berkelium,californium, andeinsteinium have been reported in the absorption spectrum.[26][27] Radioactive elements have also been reported to includetechnetium andpromethium.[26][28] While the longest-lived knownisotopes of technetium have half-lives in the millions of years, the longest-lived knownpromethium isotope has a half-life of only 17.7 years. The presence of these elements in the stellar atmosphere would imply some process constantly replenishing it.[29]Models to explain such replenishment hypothesize continuous bombardment of the stellar atmosphere by magnetically accelerated particles[30] or from a companion neutron star.[31] However,more recent spectral analysis has not confirmed the existence of technetium[32] or of promethium.[29]
The other unusual spectroscopic observation is the abundance of elements with atomic numbers 35 < Z < 82 being a thousand times more than observed in theSolar System.[25][33] Przybylski's original observations found a very high abundance ofrare earth elements and holmium was confirmed in the atmosphere of this star even before it was found in the spectrum of the Sun.[34]While unusual diffusion processes (the normal cause of chemical peculiarity) may account for these observations, nuclear reactions caused by atmospheric particle bombardment could also explain the anomaly.[25]
Przybylski's star has occasionally attracted attention as aSETI candidate[35] insofar as it aligns with speculation that atechnological species may salt the photosphere of its star with unusual elements, either to signal its presence to other civilizations[36][37] or to dispose ofnuclear waste.[38]
^abSamus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)".VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S.1: B/GCVS.Bibcode:2009yCat....102025S.
^Kurtz, Don; Wegner, Gary (September 1979). "The nature of Przybylski's star: an Ap star model inferred from the light variations and temperature".The Astrophysical Journal.232:510–519.Bibcode:1979ApJ...232..510K.doi:10.1086/157310.
^Kurtz, D. W. (1978). "12.15 Minute Light Variations in Przybylski's Star, HD 101065".Information Bulletin on Variable Stars.1436: 1.Bibcode:1978IBVS.1436....1K.
^abGopka, V. F.; Yushchenko, A. V.; Yushchenko, V. A.; Panov, I. V.; Kim, Ch. (15 May 2008). "Identification of absorption lines of short half-life actinides in the spectrum of Przybylski's star (HD 101065)".Kinematics and Physics of Celestial Bodies.24 (2):89–98.Bibcode:2008KPCB...24...89G.doi:10.3103/S0884591308020049.S2CID120526363.
^Bidelman, W. P. (2005, September). Tc and other unstable elements in Przybylski's star. In Cosmic Abundances as Records of Stellar Evolution and Nucleosynthesis (Vol. 336, p. 309).
^Frank D. Drake (1965). "Chapter IX - The Radio Search for Intelligent Extraterrestrial Life". In Gregg Mamikunian; Michael H. Briggs (eds.).Current Aspects of Exobiology. Pergamon.doi:10.1016/B978-1-4832-0047-7.50015-0.ISBN978-1-4832-0047-7.
^Iosif S. Shklovskii; Carl Sagan (1966).Intelligent Life in the Universe. Holden-Day. pp. 406–407.
Cowley, C. R; Hubrig, S; Bord, D. J (2003). "Actinides in HD 101065 (Przybylski's Star)".American Astronomical Society Meeting Abstracts #202.202: 32.09.Bibcode:2003AAS...202.3209C.
