Published July 12, 2013
| public
Journal Article
Voyager 1 Observes Low-Energy Galactic Cosmic Rays in a Region Depleted of Heliospheric Ions
Abstract
On 25 August 2012, Voyager 1 was at 122 astronomical units when the steady intensity of low-energy ions it had observed for the previous 6 years suddenly dropped for a third time and soon completely disappeared as the ions streamed away into interstellar space. Although the magnetic field observations indicate that Voyager 1 remained inside the heliosphere, the intensity of cosmic ray nuclei from outside the heliosphere abruptly increased. We report the spectra of galactic cosmic rays down to ~3 × 10^6 electron volts per nucleon, revealing H and He energy spectra with broad peaks from 10 × 10^6 to 40 × 10^6 electron volts per nucleon and an increasing galactic cosmic-ray electron intensity down to ~10 × 10^6 electron volts.
Additional Information
© 2013 American Association for the Advancement of Science. Received 11 February 2013; accepted 24 May 2013. Published online 27 June 2013. This work was supported by NASA (NNN12A012). This paper is dedicated to the memory of Frank McDonald, whose leadership in the cosmic-ray investigation on Voyager began in 1972. His contributions continued until the day of his passing, just after Voyager 1 durably entered the depletion region and fulfilled his vision of observing low-energy galactic cosmic rays from the local interstellar medium. This paper benefited substantially from discussions during meetings of the International Team on the Physics of the Heliopause at the International Space Science Institute in Bern, Switzerland.Additional details
- Eprint ID
- 39595
- Resolver ID
- CaltechAUTHORS:20130725-143748629
- NNN12A012
- NASA
- Created
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2013-07-29Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Space Radiation Laboratory