B Detection of transuranic elements in astronomical events

[Deric Xavier]

Is it possible to detect transuranic elements that may eventually occur during big astronomical events? I know that transuranic elements are radioactive, so we could maybe measure the radiation that is being emited, but how could we separate the radiation that comes from the transuranic elements from the radiation that comes from the event itself?​

 

[Vanadium 50]

What is a cosmic event?

 

[Deric Xavier]

What is a cosmic event?

Sorry, I meant astronomical events

 

[malawi_glenn]

What do you mean by "occur"?

 

[mathman]

Spectrum may show up for longer living isotopes, which may be created in supernova events.

 

[snorkack]

One possible evidence is composition of solids.
Most Ca on earth is Ca-40. Only 2,1% of Ca on Earth is Ca-44.
Yet some grains in meteorites contain mostly Ca-44!
This is evidence that these grains were originally titanium minerals, which on solidification excluded Ca but contained Ti-44 that decayed to Ca-44.
Ti-44 half-life is just 60 years. Which means that within a few decades, supernovae must have cooled so much as to turn into dust rather than glowing interstellar plasma!
The longest lived isotopes of transuranium elements are as follows:
Np-237 (2,14 million years > Bi-209)
Pu-244 (80 million years > Th-232)
Am-243 (7400 years > U-235)
Cm-247 (15,6 million years > U-235)
Bk-247 (1400 years > U-235)
Cf-251 (900 years > U-235)
Now, note that in contrast to Th and U, which persistently have oxidation state +4 in reducing environments, transuranium elements preferentially have oxidation state +3. They should therefore form different minerals, which since decayed.
Do meteorites contain grains or rocks of decayed transuranium ores?

 

[Vanadium 50]

OK, then what is an "astronomical event"? I think I've gathered you are not talking about cosmic rays now, but if we have to exclude things one by one we will be here a very long time.

 

[vanhees71]

E.g., a kilonova is an "astronomical event", and indeed a lot of heavy elements are produced in those events. AFAIK no transuranian elements have been seen yet, and they are hard to detect:

https://link.springer.com/article/10.1007/s41114-019-0024-0 (open access)

 

[Vanadium 50]

a kilonova is an "astronomical event"

If that's what he means.

 

[Drakkith]

how could we separate the radiation that comes from the transuranic elements from the radiation that comes from the event itself?

The only way I know of to detect them is to use spectroscopy. Either by directly measuring their absorption/emission spectra, or by measuring the abundance of their decay products. But neither of these are easy to do. Either because transuranic elements aren't being produced or because they aren't being produced in large enough quantities to measure.

 

[Vanadium 50]

Well, the OP hasn't told us what an "event" is, and indeed, seems to have lost interest and wandered off Is Oklo an "event"?. Would evidence of a Martian Oklo "count"? I think in principle there is more than spectroscopy, but we'd stiill just be guessing what the OP is looking for.

 

[ORF]

Is it possible to detect transuranic elements that may eventually occur during big astronomical events? I know that transuranic elements are radioactive, so we could maybe measure the radiation that is being emited, but how could we separate the radiation that comes from the transuranic elements from the radiation that comes from the event itself?​

There are 2 approaches to determine if radioactive elements are newly produced in explosive astrophysical sites . One is based on the so-called optical transient: the opacity of the gas will change as the radioactive elements decay (beta or whatever), so the timescale of the change if given by the nuclear decay. This was already observed in the 2 neutron star merger event in 2017.
The spectroscopy of single elements is challenging but doable. In the same astrophysical event, Strontium lines were observed, I do not know if presence of other elements was determined as well.
Among the limitations are the low statistics needed for spectroscopy and the poor experimental data of some atomic transitions. Researchers working on theoretical simulations usually make predictions about the opacity transient.