Scientists observed a secret to the galaxy's evolution through a telescope.
Galaxies that have stopped forming stars (called "quenched-galaxies), used to be much smaller, Space.com reported.
Scientists used to believe the quenched galaxies could have merged with smaller neighbors that were quenched as well.
This doesn't seem to be the case.
"We found that a large number of the bigger galaxies instead switch off at later times, joining their smaller quenched siblings and giving the mistaken impression of individual galaxy growth over time, "co-author Simon Lilly, of the Swiss Federal Institute of Technology, said.
Researchers studied information from Hubble's Cosmic Evolution Survey (COSMOS). They used observations from several telescopes to create a video of the unproductive galaxies.
After tracking eight billion years worth of history, the team concluded the quenched galaxies didn't grow at all, but rather stayed small and compact.
The researchers believe the older galaxies simply switched off their star-making abilities earlier.
"The apparent puffing up of quenched galaxies has been one of the biggest puzzles about galaxy evolution for many years," lead author Marcella Carollo, also from the Swiss Federal Institute of Technology, said. "Our study offers a surprisingly simple and obvious explanation to this puzzle. Whenever we see simplicity in nature amidst apparent complexity, it's very satisfying."
In contrast to these older, infertile galaxies; astronomers have discovered an interesting youthful stellar system, a NASA press release reported. The system "blinks" every 93 days.
The system, called YLW 16A, is believed to contain three developing stars. A "hula hoop" of leftover debris from the star-making process surrounds the stars.
The stars systematically peak out from behind the disk, which is what causes the blink.
The spinning disk could birth planets and other celestial objects.
"These blinking systems offer natural probes of the binary and circumbinary planet formation process," Peter Plavchan, a scientist at the NASA Exoplanet Science Institute and Infrared Processing and Analysis Center at the California Institute of Technology, said.
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