In 2016, a team of scientists from New Jersey Institute of Technology detected a strange signal coming from the Sun. Now, seven years later, they have published in Nature Astronomy the study in which they finally explain the origin of said signal: a dawn.
This, seen this way, is surprising, since auroras are phenomena that take place both on Earth and on other planets in the Solar System and that are caused precisely by the Sun. Therefore, it could be said that the king star was causing an aurora to himself.
But, in reality, it is something more complex. We usually relate the auroras with the lights that we see in the sky of our planetespecially at the north and south poles, where the northern and southern lights, respectively. But the radiation emitted by these phenomena is not only in the visible light spectrum. There is also a high radio wave component. And that is precisely what these scientists have detected in the Sun.
What are the auroras we are familiar with?
Auroras are formed due to the emission of charged particles, coming from storms and winds originating in the sunspots of our star. This means that the higher the solar activity, the more auroras are produced.
In the case of the Earth, these particles first collide with the magnetic field, which prevents them from reaching the atmosphere, diverting them to their extremes. These extremes are those found above the poles, where the magnetic field is much weaker. At this point, the particles accelerate, amplifying the energy that subsequently excites the atoms present in the atmosphere. This excitation is what causes the emission of radiation, generally in the form of visible lightwhose shades depend on the composition of the atmosphere.
But there are also broadcasts in the form of radio. These are not seen, but they are measured and characterized, above all, because they are long-lasting bursts, which remain active for a long time.
It should be noted that visible auroras also occur on other planets in the solar system. They have even been detected in Galilean satellites of Jupiter. However, until nowhad never been measured in the Sun itself.
Mysterious gusts over the Sun
In 2016, the authors of this new study used the Karl Jansky Very Large Array (VLA) to measure solar activity with much higher resolution than ever before.
This made it possible to detect something that had not been found before. A radio source in the solar atmosphere, above a sunspot group, transmitting at frequencies up to 1.7 GHz during the 4.5 hours complete of your observation.
Generally, the bursts of this type that had been located at that frequency were very short, lasting a few minutes or, at most, an hour. It was something different.
Therefore, scientists got to work, searching for a possible origin. And to find it, they just had to compare the bursts with the radio patterns coming from the northern and southern lights.
It is no coincidence that it was detected right over sunspots or, in other words, over colder regions of the Sun’s surface and with a much more intense magnetic field than in the rest of the star. He explained it in a statement the lead author of the research, Sijie Yu.
“The cooler, more intensely magnetic areas of sunspots provide a favorable environment for ECM emission to occur, drawing parallels with the magnetic polar caps of planets and other stars and potentially providing a local solar analogue to study these phenomena.” .
Sijie Yu, astronomer and lead author of the study.
With ECM it refers to the electromagnetic emission generated by the electrons of the plasma due to their rotation around the magnetic field lines. In short, the sun’s own magnetic field can also trap the particles that cause auroras on other planets. In this case it does not give us the typical light show, but it does give us a pattern of radio bursts that had never been measured before. Every day we see more clearly how little we know about our star.