*3.2. Iron Region*

In a case of magic numbers, κ = 0 (see Figure 1a). The dependence on the magnetic field in the synthesis of nuclei is due to a change in the energy of an interaction of free nucleons with a field. The magnetization of a nondegenerate nucleon gas and the arising component of magnetic pressure lead to an e ffective decrease in the binding energy of magic nuclei and, as a result, to the suppression of the yield of corresponding chemical elements. However, we notice that the suppression factor is less significant in the case of realistic magnetic field geometry, see [2]. A significant magnetic moment and parameter κ contribute to an increase in binding of nucleons for ultramagnetized antimagic nuclei in a field. The increase in nucleosynthesis products caused by such an enhancement is weakly sensitive to the structure of a magnetic field [2].

Let us consider the normalized yield coe fficient of antimagic even–even symmetric nuclei of the 1 *f*7/2 and 2*p*3/2 shells and the double magic nucleus 56Ni, i.e., [*i*/Ni] ≡ *yi*/*y*Ni. As is seen in Figure 2, the volume of synthesis of 44Ti and 48Cr increases sharply with increasing magnetic induction, whereas the output of 52Fe varies relatively insignificantly, and the total mass of 60Zn is almost constant. It is important to recall the mysteriously large abundance of titanium obtained in direct observations of SN-type II remnants; see refs. [2,5,9]. Observational data sugges<sup>t</sup> a 44Ti nucleus yield for type II SNe far exceeding model predictions and similar results for type I SNe. As one can see from Equations (3) and (4) and Figure 1b, the magnetic increase in the synthesis of nuclides by an order of magnitude corresponds to a field strength of several TT. Such magnetic induction is consistent with simulation predictions and an explosion energy of SNe [1,2].

**Figure 1.** Magnetic effects for nuclei in the iron region: (**a**) Dependence on the number of protons and neutrons of the magnetic susceptibility for nuclei with filled 1 *f*7/2 shell. The minimum values <sup>κ</sup>magic = 0 correspond to double magic nuclei at *Z*(&*N*) = 20 or 28, the maximum value κmax ≈ 17.51 for the antimagic nucleus 48Cr at *Z* = *N* = 24; (**b**) Magnetic field dependence of the yield ratio [*i*/Ni] (see text) for 56Ni and 44Ti—2, 48Cr—1, 52Fe—3, 60Zn—4, at *kT*=0.5 MeV.

Accounting for Equations (1) and (4) and Figure 1b, we notice that such conditions sugges<sup>t</sup> even stronger enrichment of 48Cr, since the maximum magnetic susceptibility corresponds to a half-filled shell. In the case of the filling of shell 1 *f*7/2 (iron group nuclei), this condition is satisfied at *Z* = *N* =24 (see Section 3.1). Then, a significant value of parameter κCr = 17.51 leads to a noticeable magnetic amplification of the synthesis of 48Cr nuclide. The chain of radioactive decay 48Cr → 48V → 48 Ti generates an excess of the dominant titanium isotope.

#### *3.3. The r-Process Nuclides*

r-process nuclides can plausibly originate from neutron star mergers. In a single event, such sites produce 100 times larger nuclide volumes than Type II SN events. In the first stage of the production of r-process nuclei, matter undergoes explosive burning and is heated to conditions of NSE equilibrium [11]; the abundance is given by Equation (1). Significantly amplified magnetic induction can affect nucleosynthesis processes in both cases. As is seen in Equation (4), a noticeable magnetic modification in nuclear properties is expected for mass numbers corresponding to pronounced magic numbers, i.e., N&Z = 50, 82, and 126.

As is illustrated in Figure 2a, for mass numbers *A* = 40—100, considerable values of magnetic susceptibility are displayed for nuclei corresponding to 1*f* 7/2 and <sup>1</sup>*g*9/2 shells. Neutron number *N* = 50 gives a magic number for the concentration of nuclear material, as with r-process scenarios. Such a mass enhancement also originates from a small cross section of (*<sup>n</sup>*, γ) reactions on magic nuclei, see [17]. The normalized yield coefficients of some nuclei of the <sup>1</sup>*g*9/2 shell and the double magic nucleus 100Sn, i.e., [*i*/Sn] = *yi*/*y*Sn are presented in Figure 2b. As is shown in Figure 2b, the magnetic effects give rise to an enrichment of nuclear components with smaller mass numbers. However, *N* = 50 isotone 95Rn displays more pronounced enrichment, indicating that a large volume of isotones with *N* = 50 remains robust. Such a property is due to larger magnetic susceptibility for protons than for neutrons. Following arguments of waiting point approximation, one would expect some slight magnetic effect in the r-process peak with an enhanced portion of small mass number nuclides.

**Figure 2.** Nuclear magnetic effects: (**a**) Dependence on numbers of protons and neutrons of the magnetic susceptibility for symmetric nuclei in region *A*=40—100; (**b**) Magnetic field dependence of the yield ratio [*i*/Sn] (see text) for **<sup>100</sup>**Sn and96Cd—1, 92Pd—2, 95Rn—3 at kT=0.5 MeV.
