Collaborative Research: SHINE: Understanding the Connection between the Abundance of Helium in the Interplanetary Medium and the Origin of the Solar Wind in the Corona

Department Of Energy Albuquerque Operations Office, Albuquerque NM

Investigators

Abstract

Two new features in the variation of the relative abundance of helium to hydrogen in the solar wind have recently been observed by the WIND spacecraft: (i) This ratio is a linear function of the solar wind speed in the range from 250 km/s to 550 km/s, and (ii) The ratio undergoes a six-month periodic modulation in the sense that the maximum in He/H at a fixed solar wind speed occurs at the times when the Earth is most distant from the heliographic equator. This study will use this newly discovered effect as the basis for a thorough investigation of the connection between coronal and solar wind plasmas spanning observations by five different spacecraft taken over the last 30 years. Collaborations will be developed with investigators from these other spacecraft and with theorists and numerical modelers to connect the interplanetary observations of the He/H ratio back to its solar origins. These features present challenges to the currently accepted paradigm of solar wind. The abundance of helium is a sensitive test of models of solar wind formation and of the underlying connections between solar photospheric, coronal and interplanetary magnetic fields.