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One Quasar, Two Quasar, Red Quasar, Blue Quasar: A Seuss-Like Space Color Mystery Explained

While the colors of weird astronomical objects known as quasars might seem elementary, the science behind these colors is rather complicated.

A team at Durham University in the UK say they have discovered a phase in the evolution of quasars — galaxies with a very active black hole in the center — that could provide more insight into the curious life of these objects. 

Like a children's book from Dr. Seuss, quasars have simple names: red quasar and blue quasar.

Related: The Mighty Quasar: The Science Behind These Galactic Lighthouses

Most quasars have a blue-ish tinge, Durham officials said in a statement.. But there's an astronomical mystery here to consider: many quasars appear more red if they are viewed through obscuring clouds of gas and dust. "The conventional view of red quasars is that they are actually blue quasars that are angled away from our line-of-sight," according to the statement. But a new science team led by doctoral student Lizelke Klindt argues that there is a much different explanation.

Specifically, Durham says that red quasars "are likely to be the result of a brief, but violent, phase in the evolution of galaxies when their black holes are ejecting large amounts of energy into the surrounding dust and gas." This energy emission carries away any gas and dust in the vicinity, leaving a blue quasar behind. 

The team reached this new conclusion  by studying 10,000 red and blue quasars in various stages of evolution. Their findings may also shed light on how galaxies form in general, according to the statement.

"[Scientists] expect that the massive burst of energy from the black hole would burn off the gas needed to form stars," Durham stated. "Without gas, the galaxies can't grow — so the quasar is effectively ending the life of the galaxy by destroying the very thing that it needs to survive."

A study based on this research was published in the Monthly Notices of the Royal Astronomical Society.

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Elizabeth Howell
Elizabeth Howell

Elizabeth Howell, Ph.D., is a staff writer in the spaceflight channel since 2022. She was contributing writer for Space.com (opens in new tab) for 10 years before that, since 2012. As a proud Trekkie and Canadian, she also tackles topics like diversity, science fiction, astronomy and gaming to help others explore the universe. Elizabeth's on-site reporting includes two human spaceflight launches from Kazakhstan, three space shuttle missions in Florida, and embedded reporting from a simulated Mars mission in Utah. She holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, and a Bachelor of Journalism from Canada's Carleton University. Elizabeth is also a post-secondary instructor in communications and science since 2015. Her latest book, Leadership Moments from NASA, is co-written with astronaut Dave Williams. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday.