The solar system does not end with Pluto or the asteroid ice belt in the Oort cloud. In fact, it is so huge that Voyager 1 – the most distant object created by man and sent into space – has been surfacing space for more than 40 years, but still has not left the sphere of influence of our star. The robotic spacecraft is about 22.5 billion kilometers from our star. This is about four times the average distance from the Sun to icy Pluto. And while much of the solar system looks like empty space, it is actually inhabited by the solar wind and other electromagnetic radiation emanating from the star. The Sun’s sphere of influence is divided into various key regions, one of which is the heliosphere – the bubble region of the solar system that moves with the Sun through interstellar space. The heliosphere is filled with the solar magnetic field, protons and electrons from the solar wind (charged particles emanating from a star). In a new study, astronomers are finally able to determine the shape of the heliosphere and create a three-dimensional map showing the effect of the solar wind on the surrounding space.
The boundaries of the solar system
At its core, the heliosphere is a massive bubble that surrounds the solar system and extends tens of billions of miles. This bubble also protects us from harmful interstellar radiation. Recently, according to Science Alert, researchers have discovered some new details about this complex region of the Universe – they managed to create the first ever map of the heliosphere, where solar winds are stopped by the interstellar medium.
Астрономы из Лос-Аламосской национальной лаборатории также определили форму гелиосферы и создали трехмерную карту, отображающую влияние солнечного ветра нашей звезды на окружающую Вселенную.
Using data from NASA’s Interstellar Boundary Explorer or IBEX satellite, which measures charged particles ejected from the outermost region of the heliosphere, the authors of a new study published in the Astrophysical Journal have mapped the region in unprecedented detail. The new 3D map will allow scientists to better understand how solar and interstellar winds interact.
It is noteworthy that earlier the NASA New Horizons mission provided measurements of captured ions – particles that are ionized in space, captured and moved with the solar wind. These trapped ions are much hotter than other particles in the solar wind.
“Physics models have assumed this boundary for many years, but this is the first time we’ve actually been able to measure it and create a 3D map,” said lead author Dan Reisenfeld of Los Alamos National Laboratory.
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Detailed map of the heliosphere
Reisenfeld used a clever technique similar to that used by bats (sonar) to detect their surroundings. Instead of detecting reflected acoustic waves, astronomers measured energetic neutral atoms (ENAS) – particles produced by collisions between solar and interstellar winds – to create a map of the heliosphere. Where the amount of ENA increases, its boundary is most likely.
As the researchers explain, the solar wind “signal” sent by the sun varies in strength, forming a unique pattern. They also managed to determine the distance to the ENA source area in a certain direction.
“We can now see the boundary of the heliosphere in the same way that a bat uses sonar to ‘see’ the walls of a cave,” the authors of the scientific paper write.
Earlier simulations, in the course of which figures were obtained from measurements of galactic cosmic rays (an indirect indicator of ENAs), showed that the heliosphere of the solar system is shaped like a croissant, not comets. However, a recently published 3D map suggests that the solar wind bubble is still looks like a comet, although uncertainties about the true shape of the heliosphere still exist.
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The new map shows that the shortest distance between the Sun and the heliopause in the direction facing the interstellar wind is 120 AU (one AU is the distance from the Earth to the Sun). In the opposite direction, the heliopause extends at least 350 astronomical units from the Sun. But that’s not all.
Сигнал солнечного ветра, посылаемый Солнцем, варьируется по силе, образуя уникальную картину, отмечают авторы научной работы.
The heliosphere may indeed have a stranger shape, and its definition is incredibly important from a practical point of view. The fact is that the heliosphere blocks 75% of galactic cosmic rays, which can damage spaceships, vehicles and even the DNA of astronauts.