X-ray bursts (XRBs) are violent explosions that occur on the surface of a neutron star as it absorbs material from a companion star. These explosions are fueled by a series of thermonuclear reactions that take place due to the increasing temperatures and densities on the surface of the neutron star.
A recent study published in Physical Review Letters delves into the 22Mg(α,p)25Al reaction, which involves magnesium-22 and helium-4 producing a proton and aluminum-25. This reaction plays a crucial role in informing models of XRBs and understanding the reaction mechanisms that drive these explosions.
New Findings in the Study
The researchers found that the rate of the 22Mg(α,p)25Al reaction is four times higher than the previous direct measurement. This higher rate suggests that the 22Mg waiting point, where the reaction slows down, may be bypassed by this reaction. Additionally, the study revealed that the reaction begins to occur at lower temperatures than previously believed.
Experimental Methodology
To measure the 22Mg(α,p)25Al reaction, scientists utilized the Argonne Tandem Linac Accelerator System (ATLAS), a Department of Energy user facility. They created an in-flight radioactive beam and directed it to the MUlti-Sampling Ionization Chamber (MUSIC) detector filled with pure helium gas to mimic conditions relevant to XRBs.
The new direct measurement of the angle and energy-integrated cross-section of the 22Mg(α,p)25Al reaction provides valuable insights into the nucleosynthesis reaction flow through the 22Mg waiting point in XRBs. By accurately determining the rates of reactions at these waiting points, scientists can enhance their understanding of the processes driving X-ray bursts.
The 22Mg(α,p)25Al reaction has a significant impact on the dynamics of X-ray bursts by influencing the synthesis of heavy chemical elements on the surface of neutron stars. The recent study sheds light on the reaction mechanisms fueling these explosions and highlights the importance of accurate measurements in enhancing our knowledge of XRBs.