Physics: discoveries of gravitational waves multiply
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.
A new study, in which the Spanish Jorge Peñarrubia (University of Edinburgh) participates, reveals that, during the approach of the Large Magellanic Cloud, which began a few hundred million years ago, the disk of the Milky Way is being displaced, elongated and twisted in a very violent way.
Galaxies in community
When contemplating the night sky, one can get the impression that the disk of the Milky Way, our popular Camino de Santiago, is a set of fixed stars that remains unchanged in the sky.
Nothing is further from reality.
The truth is that each star has its own movement that is invaluable to the naked eye due to the enormous distances that separate us from them.
In addition, the whole group behaves like a great cosmic swarm that can be subjected, as a whole, to the gravitational effects of other galaxies.
And it is that our galaxy is not alone, it is part of a set of fifty galaxies called the Local Group.
This small cluster is dominated by two large spiral galaxies: Andromeda and the Milky Way itself.
The other galaxies in the Local Group are smaller and many of these behave like satellites of the larger galaxies.
The Milky Way's main satellites are the Large Magellanic Clouds, a wonderful pair of weak luminosity that is visible to the naked eye in the southern constellation of the Toucan.
These galaxies owe their name to Fernando de Mgallanes who, after his circumnavigation of the globe, together with Elcano, was the one who disclosed the existence of such peculiar stars in the West.
Relative situation of the Milky Way and the Large Magellanic Cloud 30 million years agoPetersen and Peñarrubia
A galaxy that moves like a comet ...
Of the two Magellanic Clouds, the larger one is the closest to the Milky Way (it is only 163,000 light years distant) and it is the one that seems to have the most important interaction with our galaxy.
The Large Magellanic Cloud is thought to move around the Milky Way along a parabolic path reminiscent of those followed by nonperiodic comets approaching the Sun.
About 700 million years ago, the Large Cloud crossed the boundary of our galaxy and, as it approached, had a violent effect on the structure of the Milky Way disk.
And only 15 million years ago that the first one passed through the periaster in its parabolic orbit, that is, both galaxies are still very close to their point of closest approach.
It is also known that the two galaxies are surrounded by large halos of dark matter, that is, of some type of matter (whose nature is unknown) that is not visible but has very important effects on the movement of the galaxies and on that of the stars in its bosom.
Dark matter must therefore play a dominant role in this encounter between the Large Magellanic Cloud and the Milky Way.
... and faster than a bullet
The Spanish astronomer Jorge Peñarrubia, working at the University of Edinburgh together with postdoctoral researcher Michael Petersen, has now used a very sophisticated statistical numerical model to reproduce, also with the help of supercomputers, the movement of the stars in the Milky Way disk according to the Large Magellanic Cloud was closing in on her.
The models reveal the effects were quite devastating and that, to a large extent, they were dominated by the gravitational pull due to the enormous dark halo of the Large Cloud.
In this link you can see, in a very schematic way, an animation built from the numerical simulations that illustrates the progressive behavior of the two galaxies.
A snapshot of the meeting can be seen in the attached figure.
As a consequence of the encounter between galaxies, the disk of the Milky Way is being displaced, stretched and twisted, at a speed of about 115,000 kilometers per hour, towards a point in space that is located in the constellation of Pegasus.
It is surprising that the Milky Way is not moving towards the current position of the Large Magellanic Cloud, but towards a point in its past trajectory.
It is as if our galaxy is trying to point to a position that is moving so rapidly in the sky that it cannot accurately track it.
And, as the study results, the Large Magellanic Cloud moves, with respect to the Milky Way, at a dizzying speed that exceeds a million kilometers per hour, that is, literally much faster than a bullet.
Keep in mind that the Milky Way is much more massive than its satellite, that is, it has much greater inertia (it costs much more to move).
Our history in stellar movements
Astronomers are already preparing to analyze the new batch of stellar data from the Gaia satellite that was just made public just a few days ago.
By comparing the models with real observations, Peñarrubia and Petersen try to describe all the complexities of this complicated dance between galaxies.
If all these details are understood, it can be possible to reveal how the dark matter is distributed in both galaxies, something that is not directly observable.
But above all, these models help us understand the dynamic evolution of our galaxy.
In the current movements of its stars is written the account of its turbulent past.
Thanks to the statistical models of astronomers we can now read part of this complicated history which, of course, is part of the history of our planet and our planetary system.
The Petersen and Peñarrubia article entitled "Detection of the Milky Way reflex motion due to the Large Magellanic Cloud infall" has been published in a recent issue of the prestigious journal Nature Astronomy.
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.
According to the criteria of The Trust Project
Know more
Science and Health
science
Covid-19 The option to save Christmas: the Finnish model against the risks of the Swedish
ExplorationSuccessful launch of the Chinese space mission that will try to bring rocks from the Moon
Climate crisis Record CO2 concentration in the atmosphere despite the pandemic
See links of interest
News
Translator
Programming
Films
2021 calendar
2020 calendar
Topics
Coronavirus
Anadolu Efes Istanbul - TD Systems Baskonia
Zalgiris Kaunas - Barça
Hertha BSC - 1. FC Union Berlin
Real Madrid - Asvel Villeurbanne
Sevilla - Real Madrid, live