Nav: Home

The cosmic ray gun duel of Eta Carinae

July 29, 2018

An international collaboration operating NASA's NuSTAR satellite has revealed that two of the biggest stars in the galaxy are capable of creating cosmic rays. Their results were published in Nature Astronomy this month.

In the time it takes you to read this sentence, hundreds of cosmic rays have pummeled through our bodies. Cosmic rays are mostly made of protons and electrons, with the smallest fraction made of X-rays and gamma rays. These jets of high-energy particles not only make up a sizable portion of radiation astronauts and airplane pilots receive, but they also can reach the ends of the galaxy.

Scientists have found that cosmic rays can come from places like supernova remnants, neutron stars, or solar flares from the sun. Still, their origins are a mystery. They could come from other parts of outer space. However, it has not been easy figuring out where.

"Since these particles are electrically charged, they wander when in the presence of magnetic fields," Hiromitsu Takahashi said. "This means we could not tell precisely where they are coming from when observed them from Earth." Takahashi is an astrophysicist at Hiroshima University and coauthor on this study.

Takahashi and his team were interested in Eta Carinae, a binary star system 7,500 light years away from Earth. The two stars are massive - one is thirty times heavier than our sun, the other ninety - and thought to be a source of cosmic rays. The team built upon findings from an experiment conducted with the Fermi Gamma-ray telescope, in which they discovered a source of gamma rays coming from around the area of Eta Carinae.

However, the resolution of the images they collected was not clear enough to confirm whether these rays were coming this star system or somewhere else. "We had to come up with a different way of finding their source - by measuring X-rays and gamma rays with a more sensitive detector," Takahashi said.

For this experiment, Takahashi and his colleagues observed Eta Carinae through NuSTAR, a recently launched X-ray satellite from NASA. Fermi can resolve images at about one degree, or twice as large as the angular diameter of a full moon as viewed from Earth. NuSTAR, on another hand, has a one-twentieth more precise angular resolution of Fermi - similar to that of the human eye.

Because of NuSTAR, Takahashi's team not only confirmed that the gamma rays are coming from Eta Carinae - as they suspected in the Fermi mission - but they also deduce how cosmic rays come out of Eta Carinae.

The stars of Eta Carinae revolve around one another about every five years. The stars are so massive and hot that they emit a never-ending stream of charged particles called stellar winds. As they approach one another, their winds collide and form hot plasma that can emit X-rays. This time, Takahashi's team confirmed the collision also forms shock waves. The energy of the particles shooting back and forth gets higher and higher, and they accelerate to nearly the speed of light. Then, these ultrahigh-energy particles, or cosmic rays, escape the shock region and scatter throughout space.

Takahashi's findings establish binary star systems as a source of cosmic rays. He predicts that future studies on the origins of cosmic rays could lead to further understanding of the fundamentals of physics and our universe.
Since its foundation in 1949, Hiroshima University has strived to become one of the most prominent and comprehensive universities in Japan for the promotion and development of scholarship and education. Consisting of 12 schools and 11 graduate schools, ranging from International Development and Cooperation to Integrated Arts and Sciences, the university has grown into one of the most distinguished research universities in Japan. English website:

Hiroshima University

Related Cosmic Rays Articles:

Study: Collateral damage from cosmic rays increases cancer risks for Mars astronauts
The cancer risk for a human mission to Mars has effectively doubled following a UNLV study predicting a dramatic increase in the disease for astronauts traveling to the red planet or on long-term missions outside the protection of Earth's magnetic field.
Physicists leapfrog accelerators with ultrahigh energy cosmic rays
An international team of physicists has developed a pioneering approach to using Ultrahigh Energy Cosmic Rays (UHECRs) -- the highest energy particles in nature since the Big Bang -- to study particle interactions far beyond the reach of human-made accelerators.
Chorus of black holes radiates X-rays
The NuSTAR mission is identifying which black holes erupt with the highest-energy X-rays.
NASA instrument to use X-rays to map an asteroid
NASA's OSIRIS-REx spacecraft will launch September 2016 and travel to the near-Earth asteroid Bennu to harvest a sample of surface material and return it to Earth for study.
Microscopic 'clocks' time distance to source of galactic cosmic rays
Most of the galactic cosmic rays reaching Earth come from nearby clusters of massive stars, according to new observations from NASA's ACE spacecraft.
New use for X-rays: A radar gun for unruly atoms
Using coherent X-rays, a new technique has been discovered for sensing motion and velocity of small groups of atoms.
Nature: KIT simulation analyzes cosmic rays
When cosmic rays hit the Earth's atmosphere, their high-energy primary particles generate an 'air shower' of secondary particles.
How skates and rays got their wings
The evolution of the striking, wing-like pectoral fins of skates and rays relied on repurposed genes, according to new research by scientists from the University of Chicago.
Study finds metal foams capable of shielding X-rays, gamma rays, neutron radiation
Research shows lightweight composite metal foams are effective at blocking X-rays, gamma rays and neutron radiation, and are capable of absorbing the energy of high impact collisions.
Using muons from cosmic rays to find fraying infrastructure
Seeking a better way to identify faulty energy infrastructure before it fails, researchers at Los Alamos National Laboratory are using subatomic particles called muons to analyze the thickness of concrete slabs and metal pipes.

Related Cosmic Rays Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Moving Forward
When the life you've built slips out of your grasp, you're often told it's best to move on. But is that true? Instead of forgetting the past, TED speakers describe how we can move forward with it. Guests include writers Nora McInerny and Suleika Jaouad, and human rights advocate Lindy Lou Isonhood.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...