The size of the Solar System extends well beyond Pluto’s orbit and into the heliosphere, a region dominated by the Sun. The solar system’s neighborhood extends even further, into the interstellar medium, a region between the Sun and nearby stars. Our system is located in one of the arms of the Milky Way where we find gas, plasma and dust.
One of these structures is the so-called local hot bubblewhich is a region of low density hot gas. This bubble surrounds the solar system and a few other nearby stars. Its origin is believed to be linked to supernovae that occurred in the past and warmed the environment. This bubble measures approximately 300 light years in diameter and is one of the components of the Sun’s neighborhood.
Last month, astronomers discovered an interstellar tunnel that connects the Sun to neighboring stars. This tunnel, located in the local hot bubbleis a hole in the middle of interstellar gas. The discovery was made using data from eRosita, which mapped the vicinity of the solar system on a 3D map. The researchers also added information about dust, supernova remnants, and more.
Local Hot Bubble
he Solar System is surrounded by a bubble called the “Local Hot Bubble” which is so named because it is a region of hot, low density gas. This bubble is estimated to be about 300 light years across and its origin is associated with supernovas that took place near the Solar System. It would be made up of residues of matter expelled by supernovas which heated the interstellar medium
Supernovae are important because they play a role in the diffusion of elements into the interstellar medium when they expel matter.
Dense, cold clouds are found in the interstellar medium, but the local hot bubble is distinguished by the fact that it is very hot and its density is relatively low. This bubble also serves as a transition between the heliosphere and the distant interstellar medium. This is why studying the properties of this bubble is important to understand the neighborhood in which we find ourselves.
eRosita
To study energy structures in space, Germany and Russia launched the eRosita project, which explores X-ray structures. The observatory consists of X-ray telescopes launched aboard the SRG satellite. The observatory consists of X-ray telescopes that were launched aboard the SRG satellite. The idea is to map all directions in X-rays that are associated with energetic events consisting of supernovae, black holes and other phenomena.
In addition, eRosita also contributes to the study of dark matter by observing galaxy clusters and the distribution of visible matter. By understanding the dynamics of these objects, astronomers can estimate the amount of dark matter. Another important point of study for eRosita is the influence of supermassive black holes. Thanks to the observation of X-rays, it is possible to understand the correlation and evolution of these objects at the center of galaxies.
3D map of the solar system neighborhood
In an article published in Astronomy & Astrophysicsa group of astronomers from the Max Planck Institute used data from eRosita and its predecessor ROSAT. In their work, they divided the data into 2,000 regions, extracting and analyzing the spectrum from each one. Using data from both projects, they were able to extract X-ray information from the hot gas present in the local hot bubble.
The data also showed what the structure of the local hot bubble and made it possible to create a 3D map of the vicinity of the solar system. Additionally, they discovered an asymmetry where the southern hemisphere appears warmer than the northern hemisphere. This phenomenon could be due to the explosion of supernovas which heat the gas asymmetrically. You can view the 3D map iteratively on the magazine’s website.
Interstellar tunnel
However, one of the biggest discoveries of this study is an interstellar tunnel that extends into the constellation Centaurus. The tunnel is a sort of arm that stands out in the colder interstellar medium. The hypothesis is that the tunnel is part of a larger network of hot gases that spans different regions. This network would be powered by the stars themselves which are connected to it.
The idea of this network of hot gases connecting stars through tunnels in the interstellar medium has existed since the 1970s. However, more sensitive data, like that from eRosita, is needed to be able to map this network. In the absence of such data, the idea of this network remains a question in astronomy and the tunnel towards the constellation Centaurus could be one of the first pieces of evidence.
Other discoveries
In addition to the discovery of this tunnel, there is another one which is located in the direction of the constellation Canis Major and which connects the Local Hot Bubble to the Gum Nebula. It is also possible that this tunnel connects another bubble called GSH238+00+09. Denser molecular clouds were also discovered in the published study.
Another curiosity is that the Sun did not stay so long in the local hot bubble and that he began to enter there a few million years ago. This matches the estimate that supernovae have also occurred in the last few million years. Interestingly, the Sun is at the center of the local hot bubblewhich seems to be a coincidence.
Article reference:
Yeung et al. 2024 The SRG/eROSITA diffuse soft X-ray background Astronomy & Astrophysics
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