Speaker
Description
The Solar system travels in the interstellar medium and may encounter so-called clouds, regions of the enhanced density of matter relative to the surrounding space. Such passages can in theory affect the size of the heliosphere around the Sun and lead to a significant change of the space climate around the Earth. As one of the changes, a reduced heliospheric size can make the solar modulation of galactic cosmic ray (GCR) intensity less effective. The energetic particle radiation significantly increases due to that, and it should be reflected in the enhanced production of cosmogenic nuclides in lunar regolith and rocks. The present study assesses how an encounter of an interstellar cloud in the past could affect the present content of cosmogenic nuclide $^{26}$Al with the lifetime of 1.0 Myr, one of the nuclides most suitable for such studies. For that, we made an assumption about how the heliospheric size affects the GCR modulation and calculated the nuclide content as a function of the GCR modulation. The case of the Local Leo Cold Cloud has been applied to the presented model, and it showed that although it is theoretically possible to identify a such transient in the lunar nuclide data, the uncertainties of the existing experimental data (old measurements of samples from Apollo missions) do not allow to resolve the event. As a result of this work, we present the limit of detection of transiting interstellar clouds with long-living lunar cosmogenic nuclides and call for new measurements of existing lunar samples with modern techniques, as this can significantly improve the sensitivity of the method and may potentially lead to new discoveries.
| Do you plan to attend in-person or online? | In-person |
|---|
