Ten billion years ago, the Milky Way violently merged with Gaia-Enceladus and giant stars are evidence of the impact.
In classical antiquity, the Greeks believed that the Milky Way had been the product of the breasts of the goddess Era, consort of Zeus. At the time of breastfeeding Heracles, the baby bit her. From that accident, star-spattered path of milk had scattered across the sky. Beyond the myth, little is known about the origins of our galaxy. Today, we have evidence of the moment when it joined with a satellite galaxy. As a havoc, giant stars remained.
A star-spattered milk path
A recent study sheds new evidence of the date the Milky Way merged with a nearby galaxy. The fusion wreaked havoc on its cosmic history, as seen in nearby giant stars. With them, scientists became aware of the phenomena that occurred at that moment of fusion.
This crash is estimated to have happened 10 billion years ago. It was between the Milky Way and Gaia-Enceladus, according to the results published in Nature Astronomy this week. According to Fiorenzo Vincenzo, co-author of the study and a member of the Center for Cosmology and Astroparticle Physics at Ohio State University, “our evidence suggests that when the merger occurred, the Milky Way had already formed a large population of its own stars.”
A large population of giant stars
The stars Vincenzo is referring to originate from the Milky Way, and they hit the thick disk in the middle of the galaxy. Most of them, however, were trapped by the outer halo of Gaia-Enceladus, and have remained there to this day. According to the study, this is the most important event in the history of both cosmic bodies.
This conclusion was biased from the age of the observed giant stars, which were captured by the satellite galaxy around the same time. They are known to be slightly more recent than those that were born within the Milky Way. As a result of this violent event, in addition, the orbits of the celestial bodies within both were notably altered.
According to Vincenzo, it is now possible to apply this detailed information to “even more subtle characteristics of the frequency spectra,” he notedin the article. Eventually, this ability will give a sharper view of the history of our own galaxy, and the cosmic path it has traveled up to this day.