In a new study, an international team of researchers, including several from the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics (LASP), report the first evidence of a coronal mass ejection (CME) carrying both hot and cool plasma from a young star that may represent the properties of our own Sun in its infancy.
The finding, reported in an Oct. 27 Nature Astronomy paper, supports the idea that huge CMEs from the early Sun may have severely impacted the early environments of Earth, Mars, and Venus, affecting the chemistry of the planets’ atmospheres and, therefore, the emergence and evolution of life on Earth.
“Stellar CMEs, if they exist, could catalyze early life on Earth and would likely lead to extreme space weather on extrasolar planets. These new observations present one of the stronger cases for an observational signature of a CME on another star,” says co-author Kevin France, LASP researcher and associate professor of Astrophysical and Planetary Sciences at CU Boulder, and the principal investigator on the Hubble Space Telescope observations used in this work.
CMEs often occur together with sudden brightenings called flares, and sometimes extend far enough to disturb Earth’s magnetosphere, generating space weather phenomena including auroras or geomagnetic storms, and even damaging power grids on occasion.
Previous studies have revealed that young Sun-like stars, proxies of our Sun in its youth, frequently produce powerful flares that far exceed the largest solar flares in modern history. However, to what extent flares from these young stars include large particle eruptions associated with CMEs remains unclear. The team, led by Kosuke Namekata of Kyoto University, Japan, sought to test whether young Sun-like stars produce solar-like CMEs.
The new analysis included simultaneous ultraviolet observations by the Hubble Space Telescope and optical observations by ground-based telescopes in Japan and Korea. Their target was the young solar analogue EK Draconis. Hubble observed far-ultraviolet emission lines sensitive to hot plasma, while the three ground-based telescopes simultaneously observed the hydrogen Hα line, which traces cooler gases. These simultaneous, multi-wavelength spectroscopic observations allowed the research team to capture both the hot and cool components of the ejection in real time.
These observations led to the first evidence of a multi-temperature coronal mass ejection from a young Sun.
The team found that hot plasma of 180,000 degrees Fahrenheit was ejected at 0.7 million to 1.2 million miles per hour, followed about 10 minutes later by a cooler gas of about 18,000 degrees F ejected at 160,000 mph. The hot plasma carried much greater energy than the cool plasma, suggesting that frequent strong CMEs in the past could have driven strong shocks and energetic particles capable of eroding or chemically altering early planetary atmospheres.
Theoretical and experimental studies support the critical role that strong CMEs and energetic particles can play in initiating biomolecules and greenhouse gases, which are essential for the emergence and maintenance of life on an early planet. Therefore, this discovery has major implications for understanding planetary habitability and the conditions under which life emerged on Earth, and possibly elsewhere.
The research team noted that the success of this study was achieved through international teamwork and precise coordination between space- and ground-based observatories.
“What inspired us most was the long-standing mystery of how the young Sun’s violent activity influenced the nascent Earth,” says lead author Namekata. “By combining space- and ground-based facilities across Japan, Korea, and the United States, we were able to reconstruct what may have happened billions of years ago in our own solar system.”
Other CU Boulder/LASP co-authors include Adam Kowalski, Yuta Notsu, and Cole Tamburri.
Founded a decade before NASA, the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder (LASP) is revolutionizing human understanding of the cosmos. LASP is deeply committed to inspiring and educating the next generation of space explorers. From the first exploratory rocket measurements of Earth’s upper atmosphere to trailblazing observations of every planet in the solar system, LASP continues to build on its remarkable history with a nearly $1 billion portfolio of new research and engineering programs.
-Adapted from Kyoto University press materials. For more information, contact media@lasp.colorado.edu.
