These vivid peacock clouds were created by violent galactic interactions
Two colorful gas clouds shaped like peacocks have been spotted in the Large Magellanic Cloud, a neighboring dwarf galaxy about 163,000 light years away.
In the vastness of space, it’s nice to have a neighbor. For our galaxy, the Milky Way, that’s the Large Magellanic Cloud and its sibling, the Small Magellanic Cloud. These dwarf galaxies act like satellites of our own galaxy.
The clouds were spotted by the Atacama Large Millimeter/submillimeter Array, known as ALMA, consisting of 66 radio telescopes in Chile. But their beauty may mask a violent past between the two dwarf galaxies.
Both clouds, made up of complex gas filaments, contain several massive baby stars. Astronomers who made the discovery said that this matches with previous computer simulations that model the collision of gas clouds.
The gas and the young stars act like evidence from a crime scene, suggesting a confrontation by the Large and Small Magellanic Clouds 200 million years ago, the researchers estimate.
Stars themselves form from clouds of gas and dust. But astronomers don’t entirely understand how giant stars, weighing in at 10 times more massive than our sun, or larger, can form in small regions because they require so much material.
But when galaxies interact with each other, it’s the perfect setting for massive stars to form. The gravity of both galaxies interacting is immense, causing gaseous clouds within them to collide. This creates a large amount of gas in a small area. Then, massive stars can form.
The researchers used ALMA to take a closer look at a star-forming region in the Large Magellanic Cloud called N159, along with detailed looks at clouds in two parts of it.
In this case, both clouds are shaped similarly, resembling peacocks with their tailfeathers outstretched in a fan.
“It is unnatural that in two regions separated by 150 light years, clouds with such similar shapes were formed and that the ages of the baby stars are similar,” said Kazuki Tokuda, a researcher at Osaka Prefecture University and the National Astronomical Observatory of Japan. “There must be a common cause of these features. Interaction between the LMC and SMC is a good candidate.”
Previous research investigating the movement of gas in the Large Magellanic Cloud suggested that a boom of star formation may be fed by a glow of gas coming from the Small Magellanic Cloud. This new observation lines up.
“For the first time, we uncovered a link between massive star formation and galaxy interactions in very sharp detail,” said Yasuo Fukui, a professor at Nagoya University. “This is an important step in understanding the formation process of massive star clusters in which galaxy interactions have a big impact.”
The Large Magellanic Cloud will catastrophically collide with the Milky Way in 2 billion years, according to a study published in January in the Monthly Notices of the Royal Astronomical Society. The impact, which they believe is long overdue, has a chance of sending our solar system “hurtling through space.”
Our galaxy is orbited by smaller satellite galaxies, the kind of dance that can go on undisturbed for billions of years. Other times, things take a violent turn and satellite galaxies can migrate toward the Milky Way until they collide and are gobbled up.
The Large Magellanic Cloud is fairly new to orbiting the Milky Way, entering our corner of the universe 1.5 billion years ago. It’s now the brightest satellite galaxy we have. Previously, astronomers thought it would hang out in a quiet, long orbit or speed away from the gravity of the Milky Way and move on.
But new measurements suggest that this little satellite galaxy was hiding a big secret, and it has a much larger mass than expected. This means the Large Magellanic Cloud is losing energy, which will trigger it to collide with the Milky Way.