Eta Carinae is the most massive and luminous star system within 10,000 light years of Earth. New UMBC research published in Nature Astronomy concludes for the first time that the system is emitting cosmic rays, some of which may reach Earth.

Producing cosmic rays, which also happens following a supernova, requires that particles be accelerated nearly to the speed of light. “We found that the accelerated particles are really energetic, which is much more than we expected from this star,” says Kenji Hamaguchi, the lead author on the study. Hamaguchi is a researcher at UMBC’s Center for Space Sciences and Technology, a partnership with NASA. The fourth author is Neetika Sharma, Ph.D. ’16, physics, who worked on the project as a postdoctoral fellow.

The new research takes advantage of NASA’s powerful NuSTAR satellite, which can detect and locate high-energy x-rays with remarkable accuracy. Different instruments have been tracking relatively low-energy x-rays from Eta Carinae for decades, and another instrument suggested Eta Carinae might be the source of the high-energy x-rays and even higher-energy gamma rays. However, those instruments haven’t been powerful enough to conclusively determine the source of the rays that they detect.

“That’s why we proposed the observations with NuSTAR,” says Hamaguchi. “NuSTAR can image x-rays in the high-energy range for the first time. So we can pinpoint the location of high-energy emissions.”

Eta Carinae is a binary star system, meaning two stars are orbiting each other. As they orbit, the stars come within 140 million miles of each other every five and half years. This is about the distance from Mars to the Sun, and very, very close for two stars.

Stars are constantly throwing off particles, creating what is known as the “stellar wind.” Based on their findings, the researchers explain that Eta Carinae generates high-energy x-rays and gamma rays when the two stars’ stellar winds collide. The rays’ intensity depends on the relative position of the two stars. Those cosmic rays then travel through the universe, and some of them may end up near Earth—but until now scientists haven’t been able to clearly identify their source.

Beyond confirming Eta Carinae as a source of cosmic rays, this new research also shows for the first time that a binary system like Eta Carinae is capable of accelerating particles to extreme speeds. Previously, that kind of acceleration had only been proven in the debris resulting from supernovae. This helps expand knowledge of how particles can accelerate in space, which is relevant for studies of the birth of the universe and a variety of other extreme situations in the cosmos.

Hamaguchi is already looking forward to the next new instrument beyond NuSTAR, as he works to increase understanding of how stellar winds interact, accelerate particles, and generate cosmic rays. He is drawn to analyzing complex data about the universe “because we can find something nobody knows,” he says. “Every time you get something new.”

Image: The supermassive star Eta Carinae is at the center of two huge and expanding clouds of dust and other material, the result of an eruption about 150 years ago. Nathan Smith/NASA.

It’s official: UMBC is one of the best universities to work for in the nation, for the ninth year in a row.

UMBC is one of a select set of universities across the country to be named to the Chronicle of Higher Education’s 2018 “Great Colleges to Work For” list. The university is also distinguished as an exceptional “honor roll” university for the eighth year in a row, excelling in nearly every measured category.

This year, UMBC’s categories of top achievement include:

• Collaborative Governance
• Compensation and Benefits
• Confidence in Senior Leadership
• Diversity
• Job Satisfaction
• Professional/Career Development Programs
• Respect and Appreciation
• Teaching Environment
• Work/Life Balance

“This honor is meaningful for us because it reflects how UMBC is truly a supportive and inclusive community,” says President Freeman Hrabowski. “This is a place where we believe in mutual respect and in achieving great things when we combine our strengths and work together toward our shared vision.”

The Chronicle describes the “Great Colleges to Work For” survey as the “most comprehensive workplace study in higher education.” All accredited U.S. institutions with enrollment of at least 500 students were invited to participate, and 253 colleges and universities did so this year. The 2018 findings are based on survey responses from more than 53,000 faculty, staff, and administrators.

UMBC is the only research university in Maryland to be recognized as a Chronicle of Higher Education “Great College to Work For” this year.

See more rankings coverage through UMBC News.

Banner image: UMBC in spring 2018. All photos by Marlayna Demond ’11 for UMBC.