Przybylski's Star

Source: Wikipedia, the free encyclopedia.
HD 101065

A blue band light curve for V816 Centauri, adapted from Kurtz and Wegner (1979)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension 11h 37m 37.04096s[2]
Declination −46° 42′ 34.8779″[2]
Apparent magnitude (V) 7.996–8.020[3]
Characteristics
Spectral type F0, F5, or G0[4] (F3 Ho)[5]
U−B color index +0.20[6]
B−V color index +0.76[6]
Variable type roAp[3][7]
Distance
356.5 ± 0.8 ly
(109.3 ± 0.3 pc)
Details
Gyr
HIP 56709, SAO 222918[13]
Database references
SIMBADdata

Przybylski's Star (pronounced

radioactive isotopes
, but under-abundances of more common elements such as iron.

Observation history

In 1961, the Polish-Australian astronomer

spectrum, but higher amounts of unusual elements such as strontium, holmium, niobium, scandium, yttrium, caesium, neodymium, praseodymium, thorium, ytterbium, and uranium. In fact, at first Przybylski doubted that iron was present in the spectrum at all. Modern work shows that the iron group elements are somewhat below normal in abundance, but it is clear that the lanthanides and other exotic elements are highly over-abundant.[7]

Przybylski's Star possibly also contains many different short-lived actinide elements, with actinium, protactinium, neptunium, plutonium, americium, curium, berkelium, californium, and einsteinium being theoretically detected.[16] The longest-lived known isotope of einsteinium has a half-life of only 472 days, though according to astrophysicist Stephane Goriely, the evidence for such actinides is not strong, as "Przybylski's stellar atmosphere is highly magnetic, stratified and chemically peculiar, so that the interpretation of its spectrum remains extremely complex [and] the presence of such nuclei remains to be confirmed."[17] Furthermore, Vera F. Gopka, lead author of the actinide studies, admits that "the position of lines of the radioactive elements under search were simply visualized in synthetic spectrum as vertical markers because there are no atomic data for these lines except for their wavelengths . . . enabling one to calculate their profiles with more or less real intensities."[18] The signature spectra of einsteinium isotopes have since been comprehensively analyzed experimentally (in 2021),[19] though there is currently no published research confirming whether the theorized einsteinium signatures proposed to be found in the star's spectrum match the lab-determined results.

Radioactive elements verifiably identified in this star include technetium and promethium.[16] While the longest-lived known isotopes of technetium have half-lives in the millions of years, the longest-lived known promethium isotope has a half-life of only 17.7 years; for it to be still present in measurable quantities, some process must be constantly replenishing it.

There have been many attempts to assign a conventional spectral class to this star. The

Ap star with an approximate spectral class of F3 and strong holmium lines.[5]

Compared to neighboring stars, HD 101065 has a high peculiar velocity of 23.8±1.9 km/s.[21]

Hypotheses

Because of the odd properties of this star, there are numerous hypotheses about why the oddities occur. One such theory is that the star contains some long-lived nuclides from the island of stability (such as 298Fl or 304Ubn) and that the observed short-lived actinides are the daughters of these progenitors, occurring in secular equilibrium with their parents.[22][23]

It was suggested that stellar wind from a nearby neutron star companion could produce the observed radioactive elements, but subsequent radial velocity measurements appeared to exclude this possibility.[24] More recently it has been proposed that a companion may be present but impossible to observe with radial velocity methods if it orbits in the plane of sky. In that scenario it may still be detected as it would also produce deuterium,[25] but so far no deuterium has been found spectroscopically.[26]

Przybylski's star has occasionally attracted attention as a

nuclear waste.[29]

Properties

With a mass of about 1.5 

projected rotational velocity for a hot main sequence star of just 3.5 km/s. Observations of its magnetic field suggest a possible rotation period of about 188 years, although this is considered a minimum likely value.[7] A metallicity index ([Fe/H]) of −2.40 has been published, suggesting levels of metals just a few percent of the Sun's, but this single value 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 are largely due to stratification of elements allowed by very slow rotation, the published metallicity also probably does not represent the proportion of heavy elements in the whole star.[7]

HD 101065 is the prototype star of the rapidly oscillating Ap star (roAP) variable star class. In 1978, it was discovered to pulsate photometrically with a period of 12.15 min.[30]

A potential companion had also been detected, a 14th-magnitude star (in infrared) 8 arc seconds away. This could have meant a separation of just 1,000 

Gaia Data Release 2 suggests that while those two stars appear to us as separated by a very close angle, the actual distance separating us from this second star is 890±90 light-years, which is more than twice the distance to Przybylski's Star.[32]

References

  1. doi:10.1086/157310
    .
  2. ^
    S2CID 244398875
    . Gaia DR3 record for this source at VizieR.
  3. ^
    Bibcode:2009yCat....102025S
    .
  4. ^
    Bibcode:2014yCat....1.2023S
    .
  5. ^
    doi:10.1051/0004-6361/200810788
    .
  6. ^
    doi:10.1093/mnras/177.1.99
    .
  7. ^
    S2CID 55698015
    .
  8. S2CID 119231169
    .
  9. S2CID 53538833
    .
  10. doi:10.1093/mnras/178.2.71
    .
  11. ^
    doi:10.1093/mnras/sty1912
    .
  12. doi:10.1051/0004-6361:200809890
    .
  13. ^ "V* V816 Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2008-06-06.
  14. doi:10.1086/127965
    .
  15. ^ Powell, C. S.; Wright, J. (30 June 2017). "The Strangest (and Second-Strangest) Star in the Galaxy". Discover. Retrieved 12 December 2022.
  16. ^
    S2CID 120526363
    .
  17. ^ Jesse Empsak (23 March 2017). "Oddball star could be home to long-sought superheavy elements". New Scientist. Retrieved 29 May 2022.
  18. S2CID 122474778
    .
  19. S2CID 246603539
    .
  20. hdl:2027.42/74704
    .
  21. S2CID 118629873
  22. ^ Jason Wright (16 March 2017). "Przybylski's Star III: Neutron Stars, Unbinilium, and aliens". Astrowright. Retrieved 31 July 2018.
  23. S2CID 118956691
    .
  24. ^
    S2CID 119228548
    .
  25. S2CID 254907782
    .
  26. S2CID 256615832
    .
  27. ISBN 9781483200477
    .
  28. ^ Iosif S. Shklovskii; Carl Sagan (1966). Intelligent Life in the Universe. Holden-Day. pp. 406–407.
  29. doi:10.1016/0019-1035(80)90253-5
    .
  30. Bibcode:1978IBVS.1436....1K
    .
  31. S2CID 119311263
    .
  32. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .

External links
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