The Absolute Cosmos: Voyagers detected a new type of electron burst in interstellar space

Image Credit: NASA

Even after more than forty years in space, NASA’s Voyager twins are still doing wonders. A recent study has reported a new type of electron burst spotted by Voyager twins in the interstellar space.

The bursts occur when shock waves which are generated by solar eruptions push cosmic ray electrons- fast moving charged particles likely originated from faraway supernovae. Further, these cosmic ray electrons accelerate to extremely high speeds along the cosmic magnetic lines.

According to scientists, the possibility of shock waves accelerating particles is already known. But for the first time it has been detected in interstellar medium, where the environment is totally different.

The primary stage of creating the electron bursts starts with coronal mass ejections (CMEs). CMEs are large ejection of plasma and accompanying magnetic field from Sun’s corona.

While blasting plasma, CMEs create shock waves which move outward through our Solar System. The shock waves accelerate the high speed cosmic ray electrons.

These cosmic ray electrons again get accelerated in interstellar medium (space between stars) along the magnetic field lines.

Finally, these magnetic field lines push the cosmic ray electrons to almost the light speed. That speed is almost 670 times greater than the solar shock waves that pushed them first.

As per scientists, solar shock waves travel at approximately 1.6 million kilometers per hour.

Scientists think that these cosmic ray electrons in the interstellar medium are reflected off a scaled up magnetic field at the boundary of the shock wave and later get accelerated by the motion of the shock wave.

These reflected cosmic ray electrons then move along the interstellar magnetic field lines, achieving speed as the distance between them and shock wave increases.

Within days of their acceleration, electron bursts were spotted by both the Voyagers. And later the twins detected slower and low energy plasma wave oscillations through the interstellar space created by the electron bursts.

The Voyagers also spotted the originating shock wave up to a year after the event happened. The cause of this time delay is the distance of probes from the Sun.

Voyager 1 is some 22.7 billion kilometres away from Sun, whereas Voyager 2 is about 18.8 billion kilometres away. For comparison average distance between Sun and Earth is approximately 150 million kilometres.

For more details: A Foreshock Model for Interstellar Shocks of Solar Origin: Voyager 1 and 2 Observations

In short: Voyager program

Voyager program is NASA’s scientific program that employs two space probes, Voyager 1 and Voyager 2.

The probes were launched in 1977 while taking the advantage of a favourable alignment of outer planets (gas giants Saturn and Jupiter, and ice giants Uranus and Neptune).

The probes were built to last for five years. Their primary mission was to study Jupiter, Saturn and its rings and the larger moons of these gas giants.

After several mission extensions, probes are now exploring the outer boundary of heliosphere in interstellar space, and transmitting data back to home.

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