Scientists generally believe that cosmic rays originate from exploding stars (supernovae), but neutron stars or very massive stars could be other potential sources.Īn instrument like CALET is important for answering questions about how cosmic rays accelerate and travel, and where they come from. "Something that needs to be emphasized is that the way the elements get from the sources to us is different, but it may be that the sources are different as well," adds Michael Cherry, physics professor emeritus at Louisiana State University (LSU) and a co-author on the new paper. The cosmic rays could accelerate and travel through the galaxy differently, although scientists generally believe they understand the latter, Krizmanic says. There are several possibilities to explain the differences between iron and the three lighter elements. The spectra for carbon, oxygen, and hydrogen cosmic rays are very similar, but the key finding from the new paper is that the spectrum for iron is significantly different. A graph called a cosmic ray spectrum shows how many cosmic rays are arriving at the detector at each energy level. The CALET instrument is one of extremely few in space that is able to deliver fine detail about the cosmic rays it detects. The American, Italian, and Japanese teams that manage CALET, including UMBC's Krizmanic and postdoc Nick Cannady, collaborated on the new research.Ĭosmic rays arrive at Earth from elsewhere in the galaxy at a huge range of energies - anywhere from 1 billion volts to 100 billion billion volts. The data include details such as how many and what kinds of atoms are arriving, and how much energy they're arriving with. Information about these cosmic rays can give scientists clues about where they came from in the galaxy and what kind of event generated them.Īn instrument on the International Space Station (ISS) called the Calorimetric Electron Telescope (CALET) has been collecting data about cosmic rays since 2015. They enter Earth's atmosphere at extremely high energies.
And what that something interesting is we're going to have to see."Ĭosmic rays are atomic nuclei - atoms stripped of their electrons - that are constantly whizzing through space at nearly the speed of light. "These are indicators of something interesting happening. "So what does this finding mean?" asks John Krizmanic, a senior scientist with UMBC's Center for Space Science and Technology (CSST). Learning more about how cosmic rays move through the galaxy helps address a fundamental, lingering question in astrophysics: How is matter generated and distributed across the universe? New findings published this week in Physical Review Letters suggest that carbon, oxygen, and hydrogen cosmic rays travel through the galaxy toward Earth in a similar way, but, surprisingly, that iron arrives at Earth differently.
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