The Magellanic Clouds are Now Forming New Stars at a Faster Pace

Magellanic Clouds, the galactic neighbors of the Milky Way, have picked up the rate of their star formation.

The Small and Large Magellanic Clouds are the closest companion galaxies of the Milky Way. Both of these galactic neighbors are named after Ferdinand Magellan, the man who led the first European expedition to circumnavigate the world. These galaxies can only be seen from the Southern Hemisphere while they appear in form of bright, wispy clouds. The first detailed chemical maps made of galaxies beyond the Milky Way led to this amazing discovery about the Magellanic Clouds.

Chemical Compositions of the Stars of Magellanic Clouds

For the first time ever in the astronomical history of humanity, scientists have created a detailed map of the chemical compositions of the star within the Clouds. The Sloan Digital Sky Survey (SDSS) took this initiative of carrying out this revolutionary project. These maps mark the first major discovery that has come out of the new southern operations of the Apache Point Observatory Galaxy Evolution Experiment 2 (APOGEE-2) survey. David Nidever, a Research Professor of Physics at the Montana State University who also works as an astronomer for NOAO, was selected to lead this research. He talked about these maps in the following words:

“We mapped the positions, movements, and chemical make-up of thousands of stars in the Magellanic Clouds. Reading these maps helps us reconstruct the history of when these galaxies formed their stars.”

Stellar Spectra

The researching team collected several stellar spectra from these clouds as a spectrum holds key information about the star. For instance, spectra encode the motion of stars, the chemical elements they contain, their temperature, and their current stage in the stellar lifecycle. The chemical history of the stars of a particular galaxy allows the astronomers to determine a rough estimate of the rate at which stars formed over time. The differences in the lifetimes of stars of different masses make sure that the reconstruction process is possible. Similarly, the role of massive stars is also instrumental in re-visiting the history of galaxies.

The journey of a star comes to an end with a massive explosion called Supernova. When stars more massive than the Sun explode, they spread heavy elements into the galaxy while lower mass stars carry on with their respective lives. This ejected mixture of elements enriches the surrounding gas to form new generations of stars while less massive stars record the overall enrichment of the galaxy. In order to study the star formation history of the galaxy, astronomers need to map the abundances of such stars in it.

Star Formation History of Magellanic Clouds

The latest research revealed that the star formation history of the Small and Large Magellanic Clouds is a complete opposite of what happened in our galaxy. Sten Hasselquist, a representative from the University of Utah, explained that the rate of star formation declined with time in Milky Way. On the other hand, the Magellanic Clouds made a slow start but accelerated rapidly in the last couple of billion years. He referred to that trend by saying,

“In the Milky Way, star formation began like gangbusters and later declined. In contrast, in the Magellanic Clouds, stars formed extremely slowly at early times, at a rate only 1/50th of the star formation rate in the Milky Way, but that rate has skyrocketed in the last 2 billion years.”

Nidever mentioned that this dramatic increase could have been caused by the mutual interaction of the Magellanic Clouds. He said,

“Reading these maps helps us reconstruct the history of when these galaxies formed their stars. But in the last few billion years, the close interactions that the Clouds have had with each other and with the Milky Way is causing the gas in the Clouds to transform into stars.”

Exciting Future

According to an estimate of the researchers, the rate of star formation in the Magellanic Clouds will continue to increase in the next several billion years. The gravitational force of the Milky Way is pulling them in continuously and it is believed that the Large Magellanic Cloud will be completely consumed by our galaxy in the next 2.5 billion years. In these circumstances, a lot of fireworks is expected to happen in coming times.