Scientists determined most galaxies went through a "baby boom" in which they created stars 30 times faster than they do today, but our own Sun was a "late bloomer."
This massive star birth is believed to have taken place about 10 billion years ago, but the Sun has only existed for about five billion years, the European Southern Observatory reported. This delayed birth may not have necessarily been a bad thing; the timing may have facilitated the growth of planets in our solar system.
During the period of the Sun's birth elements such as hydrogen and helium were more abundant. These elements are believed to have served as the "building blocks" of planets and other objects.
To make their findings the researchers studied the way galaxies similar to the Milky Way evolved. A large survey of the universe revealed 2,000 "snapshots" of the development of these types of galaxies and the star births that took place within them. This new census led to the most complete picture of how galaxies similar to our own grew up 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 Papovich of Texas A&M University in College Station, lead author on the paper that describes the study's results. "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 backs up past research that showed Milky Way-like galaxies started off as relatively small clumps of stars, and grew by absorbing gas, which spurred rapid star births. The findings also suggest that once these "star-making factories" calmed down, the galaxy growth spurt slowed 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," Papovich said. "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 findings were published in a recent edition of the Astrophysical Journal.
