I tried to research but what I found is pretty limited. A very tiny but non zero percentage of primordial matter was Helium-3 or 3He.

Stars produce 3He as part of the proton-proton chain but they also consume 3He. It has about a 400 year half life in our sun. From Wikipedia.

In the Sun, each helium-3 nucleus produced in these reactions exists for only about 400 years before it is converted into helium-4.[6] Once the helium-3 has been produced, there are four possible paths to generate 4He

My question is 2-fold. Is the primordial amounts of 3He significant or insignificant compared to what stars produce and eject by coronal mass ejections or blowing up into nebulas, and are there specific stars, due to the internal heat and rate of reaction that product and eject more 3He into their mass ejections.

For example, would airless, rocky, magnetic field free worlds around red dwarfs be more saturated with 3He or would you find more around larger, hotter stars that undergo fusion faster. If I wanted to go He3 mining, would I set my ship to a red dwarf system or a blue star system or a nebula?

It's not for a book or anything, I'm just personally curious, as 3He is potentially very useful stuff.

I'm aware that primordial isn't particularly easy to collect, as anything gaseous and primordial would spread out and only collect in large gravity wells, gas giants or larger. But primordial 3He could, for example, exist in Jupiter or Saturn from formation, though the formation of their magnetic fields probably prevents them from absorbing any ejected from stars. Hence the primordial vs star ejected ratio and the type of star that produced the most question are somewhat related, so I thought one question rather than two, but I can split into two questions if desired.


1 Answer 1


My question is 2-fold:

1. Is the primordial amounts of $^3$He significant or insignificant compared to what stars produce and eject by coronal mass ejections or blowing up into nebulas, and ...

The $^3$He composition of CMEs can vary significantly, see: "Unusual composition of the solar wind in the 2-3 May 1998 CME observed with SWICS on ACE" (Jan 1999), by G. Gloeckler, L. A. Fisk, S. Hefti, N. A. Schwadron, T. H. Zurbuchen, F. M. Ipavich, J. Geiss, P. Bochsler, and R. F. Wimmer-Schweingruber, DOI: 10.1029/1998GL900166

"Early work [Bame, et al., 1979; Schwenn et al., 1980; and Zwickl et al., 1982] showed that He and heavier elements are overabundant in CMEs and there is enhanced He$^{+}$. Observations from the SWICS instrument on Ulysses revealed some compositional differences in CMEs, such as a high O$^{7+}/\,$O$^{6+}$ ratio, indicating significant heating in the corona [Galvin, 1997].


SWICS is especially well suited to measure solar wind $^4$He$^+$ and the isotopic helium ratio, $^3$He$^{++}/\,^4$He$^{++}$, as described by Gloeckler' and Geiss [1998a].".


2. are there specific stars, due to the internal heat and rate of reaction that product and eject more $^3$He into their mass ejections.

Most of $^3$He was originally produced by stellar processes, but see also my answer above. Each star produces varying amounts at various times, see: "The Origin of Helium and the Other Light Elements" (Nov 4 1998), by G. Burbidge and F. Hoyle:

4. D and $^3$He
The light isotope $^3$He is produced in large quantities in dwarf stars where the masses are not large enough for it to be destroyed by $^3$He ($^3$He, 2$p$) $^4$He. It is also the case that there is a class of stars in which it has been shown from measurements of the isotope shift that most of the helium in their atmospheres is $^3$He. These stars include 21 Aquilae, three Centaurus A, and several others (Burbidge & Burbidge 1956; Sargent & Jugaku 1961; Hartoog & Cowley 1979; Stateva, Ryabchikov, & Iliev 1998). The stars are peculiar A, F, and B stars having He/H abundances that are $\sim \frac{1}{10}$ of the normal helium abundance. The $^3$He$/\,^4$He ratio can range from 2.7 to 0.5. These stars occupy narrow strip in the (log $g$, T$_{eff}$)-plane between the B stars with strong helium lines and those with weak helium lines that show no evidence for the presence of $^3$He. However, the detection of $^3$He from the isotope shift will fail if the $^3$He$/\,^4$He ratio is $\le$ 0.1. Thus, many of the weak helium-line stars may well have $^3$He$/\,^4$He abundance ratios far higher than the abundance ratio that is normally assumed to be present, namely, $^3$He$/\,^4$He $\approx$ 2 x 10$^{-4}$.

The high abundance of $^3$He in these stars has been attributed by G. Michaud and his colleagues to diffusion (Michaud et al. 1979 and earlier references). Whether or not this is the correct explanation, what these results do tell us is that stellar winds from such stars will enrich the interstellar gas with He in large amounts. This $^3$He is in addition to the $^3$He that will be injected from dwarf stars. The final abundance required is $^3$He$/\,$H $\; \approx \;$ 2 x 10$^{-5}$. It has been argued by those who believe that $^3$He is a product of big bang nucleosynthesis that there has not been time to build up the required abundance by astrophysical processes.

However, not only do we not know what the rate of injection from stars is, but in the QSSC, the timescale for all of this stellar processing is $\sim 10^{11}$ rather than H$_0^{-1}$ $\approx$ 10$^{-10}$ yr. Thus, we believe that He may very well have been produced by stellar processes.

Another Wikipedia link not mentioned in your question is: "Helium-3 - Natural abundance - Solar nebula (primordial) abundance":

"Solar nebula (primordial) abundance

One early estimate of the primordial ratio of $^3$He to $^4$He in the solar nebula has been the measurement of their ratio in the atmosphere of Jupiter, measured by the mass spectrometer of the Galileo atmospheric entry probe. This ratio is about 1:10,000,$^{[43]}$ or 100 parts of $^3$He per million parts of $^4$He. This is roughly the same ratio of the isotopes as in lunar regolith, which contains 28 ppm helium-4 and 2.8 ppb helium-3 (which is at the lower end of actual sample measurements, which vary from about 1.4 to 15 ppb). However, terrestrial ratios of the isotopes are lower by a factor of 100, mainly due to enrichment of helium-4 stocks in the mantle by billions of years of alpha decay from uranium and thorium.

Terrestrial abundance
Main article: Isotope geochemistry

$^3$He is a primordial substance in the Earth's mantle, considered to have become entrapped within the Earth during planetary formation. The ratio of $^3$He to $^4$He within the Earth's crust and mantle is less than that for assumptions of solar disk composition as obtained from meteorite and lunar samples, with terrestrial materials generally containing lower $^3$He$/\,^4$He ratios due to ingrowth of $^4$He from radioactive decay.

$^3$He has a cosmological ratio of 300 atoms per million atoms of $^4$He (at. ppm),$^{[44]}$ leading to the assumption that the original ratio of these primordial gases in the mantle was around 200-300 ppm when Earth was formed. A lot of $^4$He was generated by alpha-particle decay of uranium and thorium, and now the mantle has only around 7% primordial helium,$^{[44]}$ lowering the total 3He/4He ratio to around 20 ppm. Ratios of $^3$He$/\,^4$He in excess of atmospheric are indicative of a contribution of $^3$He from the mantle. ...".

[43] "The Galileo Probe Mass Spectrometer: Composition of Jupiter's Atmosphere" (Science 10 May 1996: Vol. 272, Issue 5263, pp. 846-849) by Hasso B. Niemann, Sushil K. Atreya, George R. Carignan, Thomas M. Donahue, John A. Haberman, Dan N. Harpold, Richard E. Hartle, Donald M. Hunten, Wayne T. Kasprzak, Paul R. Mahaffy, Tobias C. Owen, Nelson W. Spencer, and Stanley H. Way, DOI: 10.1126/science.272.5263.846

[44] "Non-Lunar $\underline{^3}$He Resources" (Presented at the Second Wisconsin Symposium on Helium-3 and Fusion Power, 19–21 July 1993, Madison WI), by LJ Wittenberg - fti.neep.wisc.edu


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