Editing Einsteinium (section)

===Natural occurrence===
Due to the short half-life of all isotopes of einsteinium, any [[Primordial nuclide|primordial]] einsteinium—that is, einsteinium that could have been present on Earth at its formation—has long since decayed. Synthesis of einsteinium from naturally-occurring uranium and thorium in the Earth's crust requires multiple neutron capture, an extremely unlikely event. Therefore, all einsteinium on Earth is produced in laboratories, high-power nuclear reactors, or [[nuclear testing]], and exists only within a few years from the time of the synthesis.<ref name="em" />

The transuranic elements [[americium]] to [[fermium]], including einsteinium, were once created in the [[natural nuclear fission reactor]] at [[Oklo]], but any quantities produced then would have long since decayed away.<ref name="emsley">{{cite book|last=Emsley|first=John|title=Nature's Building Blocks: An A-Z Guide to the Elements|edition=New|date=2011|publisher=Oxford University Press|location=New York, NY|isbn=978-0-19-960563-7}}</ref>

Einsteinium was theoretically observed in the spectrum of [[Przybylski's Star]].<ref>{{cite journal | doi=10.3103/S0884591308020049 | volume=24 |issue = 2| title=Identification of absorption lines of short half-life actinides in the spectrum of Przybylski's star (HD 101065) | journal=Kinematics and Physics of Celestial Bodies | pages=89–98| bibcode=2008KPCB...24...89G |year = 2008|last1 = Gopka|first1 = V. F.|last2 = Yushchenko|first2 = A. V.|last3 = Yushchenko|first3 = V. A.|last4 = Panov|first4 = I. V.|last5 = Kim|first5 = Ch.| s2cid=120526363 }}</ref> However, the lead author of the studies finding einsteinium and other short-lived actinides in Przybylski's Star, Vera F. Gopka, admitted that "the position of lines of the radioactive elements under search were simply visualized in synthetic spectrum as vertical markers because there are not any atomic data for these lines except for their wavelengths (Sansonetti et al. 2004), enabling one to calculate their profiles with more or less real intensities."<ref>{{cite journal |last1=Gopka |first1=V. F. |last2=Yushchenko |first2=Alexander V. |last3=Shavrina |first3=Angelina V. |last4=Mkrtichian |first4=David E. |last5=Hatzes |first5=Artie P. |last6=Andrievsky |first6=Sergey M. |last7=Chernysheva |first7=Larissa V. |title=On the radioactive shells in peculiar main sequence stars: the phenomenon of Przybylski's star. |journal=Proceedings of the International Astronomical Union |year=2005 |volume=2004 |pages=734–742 |doi=10.1017/S174392130500966X |s2cid=122474778 |doi-access=free }}</ref> The signature spectra of einsteinium's isotopes have since been comprehensively analyzed experimentally (in 2021),<ref>{{cite journal | doi=10.1103/PhysRevC.105.L021302 |title = Nuclear structure investigations of {{sup|253−255}}Es by laser spectroscopy |journal = Physical Review C |volume = 105 |year = 2022 |last1 = Nothhelfer |first1 = S. |last2 = Albrecht-Schönzart |first2 = Th.E. |last3 = Block |first3 = M. |last4 = Chhetri |first4 = P. |last5 = Düllmann |first5 = Ch.E. |last6 = Ezold |first6 = J.G. |last7 = Gadelshin |first7 = V. |last8 = Gaiser |first8 = A. |last9 = Giacoppo |first9 = F. |last10 = Heinke |first10 = R. |last11 = Kieck |first11 = T. |last12 = Kneip |first12 = N. |last13 = Laatiaoui |first13 = M. |last14 = Mokry |first14 = Ch. |last15 = Raeder |first15 = S. |last16 = Runke |first16 = J. |last17 = Schneider |first17 = F. |last18 = Sperling |first18 = J.M. |last19 = Studer |first19 = D. |last20 = Thörle-Pospiech |first20 = P. |last21 = Trautmann |first21 = N. |last22 = Weber |first22 = F. |last23 = Wendt |first23 = K.|s2cid = 246603539 |doi-access = free }}</ref> though there is no published research confirming whether the theorized einsteinium signatures proposed to be found in the star's spectrum match the lab-determined results.