Billion years ago, galaxies like our Milky Way underwent an era of prolific star formation, churning out stars at a frenzy rate, 30 times faster than they do today.
However, our sun was a bit of a late bloomer, not forming until roughly 5 billion years ago, a new study has found. By that time, Milky Way’s peak period of star formation had plunged to a trickle.
Missing the party certainly was no bad thing after all, the Sun’s late may actually facilitated the growth of planets in our solar system. Elements heavier than hydrogen and helium were more abundant during the frenzied period of star birth. These elements are believed to have enriched the galaxy with the “building blocks” of planets and even life on Earth.
In order to learn a bit more about Milky Way’s formative years, astronomers studied spiral galaxies with properties comparable to the Milky Way, found in deep surveys of the universe. From those surveys, astronomers build up a database of almost 2,000 images of of Milky Way-like galaxies. This new census provided the scientists with the most complete picture yet of the evolution of Milky Way-like galaxies over the past 10 billion years.
This study allows us to see what the Milky Way may have looked like in the past.
Said Casey from the Texas A&M University & lead author of the study.
It shows that these galaxies underwent a big change in the mass of its stars over the past 10 billion years, bulking up by a factor of 10, which confirms theories about their growth. And most of that stellar-mass growth happened within the first 5 billion years of their birth.
The study reinforces earlier research that showed Milky Way-like galaxies started off as small clumps of stars, which grew by gobbling huge amounts of gas which spurred rapid star births. The findings also suggest that once these “star-making factories” calmed down, the growth of galaxies decreased as well.
I think the evidence suggests that we can account for the majority of the buildup of a galaxy like our Milky Way through its star formation.
When we calculate the star-formation rate of a Milky Way galaxy and add up all the stars it would have produced, it is pretty consistent with the mass growth we expected. To me, that means we’re able to understand the growth of the ‘average’ galaxy with the mass of a Milky Way galaxy.
The study combined observations from NASA’s Hubble and Spitzer space telescopes, the European Space i\gencN/s Herschel Space Observatory and ground-based telescopes, including the Magellan Baade Telescope at the Las Campanas Observatory in Chile.