The astronomer Rafael Bachiller reveals to us in this series the most spectacular phenomena of the Cosmos.
Topics of exciting research, astronomical adventures and scientific news about the Universe analyzed in depth.
New panoramic images of the Milky Way show spectacular filaments of hot gas dominated by strong magnetic fields.
In the galactic center
Like gigantic ecosystems, galaxies are made up of large communities of interdependent stars. For example, at the center of each galaxy there is a supermassive black hole that unleashes complex activity throughout its environment. Their influence is so great that such central black holes largely determine galactic evolution.
Thus, in the core of the Milky Way, some 26,000 light years from our modest solar system, an extremely intense source of X-rays and radio waves, called Sagittarius A *, marks the position of a black hole that has a mass 4 millions of times greater than that of our Sun. This enormous mass is concentrated in a region smaller than the size of our planetary system.
Both X-ray and radio wave emissions mark the violent phenomena that occur in gas subjected to the devastating effects of this monstrous central black hole.
Panoramic of the galactic center with numerous filamentsNASA / CXC / UMass / NRF / SARAO / MeerKAT / QD Wang
X-rays and radio waves
Using data from NASA's Chandra X-ray space telescope and the large MeerKAT radio telescope, located in South Africa, astronomer Q. Daniel Wang (University of Massachusetts, USA) has just published spectacular panoramic images of the center of our Galaxy.
The new images cover a wide region that extends considerably above and below the galactic plane, that is, the disk where the vast majority of stars in the Milky Way are located.
The images produced by Wang, which illustrate this article, represent the X-ray emission in orange, green, blue and purple colors, while the radio wave emission is represented in violet and gray colors.
The annotated version of the panorama points out the most characteristic objects of the region.
Magnetic filaments
Perhaps the most striking of these images are the gigantic filaments that emerge from the vicinity of the galactic center to rise great distances from the disk.
For example, there is one of these large threads (labeled G0.17-0.41) that features entangled emissions of X-rays and radio waves and that rises more than 20 light-years above the galactic disk.
It is a very fine filament: its width is barely one hundredth of its length.
This and a similar filament are marked with red rectangles in the accompanying figure.
The G017-0.41 filament |
NASA / CXC / UMass / NRF / SARAO / MeerKAT / QD Wang
Wang believes that these filaments are created by the lines of the magnetic fields by phenomena similar to those that take place in our Sun. When two magnetic fields of different polarities approach each other a magnetic reconnection takes place that rearranges the fields by releasing large amounts of energy.
This is how the large mass ejections from its corona are created in the Sun.
In the vicinity of the galactic center, supernova explosions, very massive star winds, and hot gas ejections near the black hole are the source of the gas that is redirected by magnetic fields to form these filamentous structures.
The importance of magnetic reconnection
In addition to these spectacular strands of magnetized gas, Wang has also identified huge plumes of hot gas that rise about 700 light-years above and below the galactic plane. They appear to be large pieces of gas similar in nature to the jets of particles emerging from the Sun. Wang estimates that magnetic reconnection phenomena release enough energy to heat this gas and cause it to emit X-rays.
The explanation in terms of the magnetic reconnection of the large filaments and columns of hot gas is very attractive and seems well founded. But these physical phenomena of reconnection only seem to gain great magnitude in the surroundings of the galactic center. In other areas of the Milky Way, the magnetic fields are much weaker and do not give rise to such filaments, but the magnetic reconnection does seem to play an important role in the creation of cosmic rays, very energetic atomic nuclei, that permeate the large interstellar clouds that reach the earth's atmosphere.
Q. Daniel Wang's article, entitled "Chandra large-scale mapping of the Galactic Center: probing high-energy structures around the central molecular zone", has been published in a recent issue of the British magazine
Monthly Notices of the Royal Astronomical Society
, the manuscript can be consulted here.
____________________________________________________________________________
Rafael Bachiller is director of
the National Astronomical Observatory
(National Geographic Institute) and academic of the
Royal Academy of Doctors of Spain
.
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