Astrophysics

What are the little red dots deep in space?

Rachel Sauer — Fri, 16 Jan 2026 15:28:58 +0000

What are the little red dots deep in space? Rachel Sauer Fri, 01/16/2026 - 08:28

Blake Puscher

�Թ�� of Colorado researchers work with an international team to uncover more about the mysterious objects detected by the James Webb Space Telescope

As the largest telescope in outer space, the James Webb Space Telescope (JWST) has been able to view celestial objects that are too dim or distant for its predecessors to detect. As a result, it has helped astronomers look deeper into topics like galaxy formation. However, the JWST can see only so far, and at the edge of its vision some of the most interesting recent astronomical observations have been made, in the form of strange, seemingly impossible objects.

They are small, red-tinted spots of light and were descriptively named little red dots (LRDs). Information on them is limited, though they are known to be extremely dense and to have existed twelve to thirteen billion years ago (for context, the Big Bang was slightly less than fourteen billion years ago). What can be seen of them now are afterimages, because looking so far into space also means looking back in time; even light takes a while to make it between galaxies. There are several theories about what LRDs are, but none of them can completely reconcile the evidence with established astronomical principles.

CU Boulder astrophysicist Erica Nelson and an international team of research colleagues found evidence that the little red dot dubbed Irony is a growing supermassive black hole, which suggests that at least some of the other little red dots are as well.

Erica Nelson, an assistant professor of astrophysics at the �Թ�� of Colorado Boulder and one of the researchers who first discovered LRDs, recently published a study that focuses on a specific LRD dubbed Irony. The study was co-led by Francesco D’Eugenio at Cambridge �Թ�� and included CU Boulder PhD student Vanessa Brown as well as an international team of scientists. They found evidence that Irony is a growing supermassive black hole, which suggests that at least some of the other LRDs are as well.

Little red dots

According to Nelson, there are two main interpretations of what little red dots are. “Either they are really massive galaxies, or they are growing supermassive black holes,” she says. The two can be difficult to distinguish because both are very luminous. Massive galaxies are luminous because they typically have more stars, but “contrary to what most people expect, supermassive black holes are incredibly luminous” too, Nelson continues, “especially when they’re growing.”

Either of these possibilities would have implications for our understanding of the history of the universe. If LRDs are massive galaxies, “it could mean that early galaxies grow much more rapidly than we think they should be able to,” Nelson explains. That could be because their stars formed in a different way than how scientists have observed stars to form previously.

If they are supermassive black holes, they could be a phase in the development of black holes long hypothesized by CU Boulder professor Mitch Begelman, though never observed. “For a long time, we have tried to understand how supermassive black holes can grow so fast,” Nelson says. If LRDs represent an early phase of supermassive black hole growth, it could help narrow down the possibilities for how they form, “which has been a mystery for a really, really long time.”

Regardless of what the answer is, if it falls into one of these interpretations, it will provide insight into a broader question: whether galaxies or supermassive black holes formed first. That matters because most large galaxies, including the Milky Way, seem to have supermassive black holes at their centers. So, even if LRDs are black holes, that fact will have implications for galaxy formation.

The Irony is…

Irony is the name of the LRD with the deepest medium-resolution JWST spectroscopy to date. Spectroscopy is a way of determining what elements objects are made of, along with other characteristics like density and heat, based on the light coming from them. Irony is an incredibly bright object, giving off more light than other LRDs, so the researchers were able to get more details about it using spectroscopy. Upon examination, these details reveal several oddities.

Images of little red dots captured by the James Webb Space Telescope. (Photo: NASA)

“One is that it was the first time we have detected forbidden iron lines in any distant object,” Nelson says. Spectroscopy uses lines in a spectrum to represent the types of light coming from an object, and this pattern of lines corresponds to iron. The reason they are considered forbidden is technical and not immediately relevant; their detection is significant because scientists do not expect to find iron in something as old as an LRD. “The universe began with just hydrogen and helium,” Nelson explains. “There was no carbon, no oxygen and no iron.”

Heavier elements like iron were produced in the cores of stars over several generations through nuclear fusion. When older generations of stars went supernova, they launched heavier elements than what they formed out of into space, to be picked up by newer generations of stars and fused into even heavier elements. “So, seeing a lot of iron at very early cosmic times means that there had to have been a lot of generations of star formation very rapidly,” Nelson says. Iron in particular is the heaviest element that a star can create during normal hydrogen fusion (the others are only made during supernovae), so it is strange to find iron in older objects.

Another oddity is the strength of Irony’s Balmer breaks, which are breaks in the spectrum of light coming from an object. “The thing we have started to find in some of these little red dots, and especially in Irony, is that the breaks are too strong and too smooth to be produced by stars,” Nelson explains. “No model we can generate produces a break like that, so we think, instead of the atmospheres of a bunch of old stars, it is actually this single atmosphere around a growing supermassive black hole.”

These features suggest that Irony is a supermassive black hole rather than a massive galaxy. Other LRDs may not be the same as Irony, but making this determination about Irony strengthens the argument that some LRDs are supermassive black holes.

Black hole sun

All of this raises a question: What does it mean for Irony and potentially other LRDs to be black holes if LRDs do not fit cleanly into the category of either galaxies or black holes? “The kind of supermassive black holes that these things might be, and that a subset of them likely are, is nothing like any supermassive black holes we’ve seen before,” Nelson answers. They could be a new class of object, called black hole stars or quasi-stars that have been hypothesized by CU Boulder professors Mitch Begelman and Jason Dexter, that in some ways look like incredibly large stars but function differently.

“Instead of being powered by nuclear fusion like our sun and all other stars are, they’re being powered by the energy that is radiated when matter falls into the supermassive black hole,” Nelson explains. This energy comes from the gravitational potential of the objects. Similar to how charging a battery allows it to release energy later, moving an object into a place like the edge of a cliff “charges” it with energy that will be released when it falls. This gravitational potential would be especially strong because of how much gravity black holes of this size exert.

“It’s been a really cool time in extragalactic astrophysics because a big segment of our field is pitching in and collaborating to try to figure out a true mystery that the universe has shown us."

Another telling detail is the mention of an atmosphere around the supermassive black hole, which is not part of the common image of a black hole. “Normally,” Nelson says, “you have the supermassive black hole, and then an accretion disk around it.” The accretion disk is the glowing ring and halo that has appeared in many depictions of black holes in popular culture. “The new theory of these black hole stars is that there is almost spherical accretion.” However, this is a more theoretical aspect of the research, and there are different opinions about the structure that this type of black hole would have.

More research is planned to help resolve these ambiguities, and several JWST proposals for next year are designed to help. Two major points that Nelson identifies are collecting data on more LRDs to understand the variations that exist between them and collecting new data to see if previously observed LRDs have changed since they were first documented.

“Maybe some of them are massive galaxies, maybe some of them are black hole stars, maybe some of them are something else entirely,” she says. “It also helps to have information at different times because things as compact as black holes should show variation on very short timescales, so that will tell us a lot about the nature of the object.

“It’s been a really cool time in extragalactic astrophysics,” Nelson continues, “because a big segment of our field is pitching in and collaborating to try to figure out a true mystery that the universe has shown us. It’s also a strange time, because a lot of funding has been cut from astrophysics in particular. But with support, it could be a golden era in astrophysics. A lot of new discoveries will be made with James Webb. We really are just at the beginning of the data that we’re getting.”

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�Թ�� of Colorado researchers work with an international team to uncover more about the mysterious objects detected by the James Webb Space Telescope.

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CU grad Erin Macdonald makes it so

Rachel Sauer — Tue, 15 Apr 2025 22:18:50 +0000

CU grad Erin Macdonald makes it so Rachel Sauer Tue, 04/15/2025 - 16:18

Bradley Worrell

The 2009 math and astrophysics double major has successfully transformed herself from a scientist to an educator to a storyteller sailing with the enterprise known as Star Trek

As she worked toward completing her bachelor’s degrees in astrophysics and mathematics at the �Թ�� of Colorado Boulder in the late 2000s, Erin Macdonald often enjoyed watching Star Trek: The Next Generation with her college friends. Today, she is a science advisor for the entire Star Trek franchise.

“I don’t think I could have ever conceived it, that being able to work in television and movies was a real thing that people could actually do,” Macdonald says in retrospect. “And if you told me that I would see my name in TV credits—not to mention in the Star Trek font with the Star Trek theme playing—it’s almost unbelievable.”

It’s been a remarkable journey from academia to Hollywood, Macdonald acknowledges. Still, she is quick to add that in a multiverse of possibilities, the outcome was never assured, and it did not happen at warp speed.

CU Boulder alumnus Erin Macdonald, who double majored in mathematics and astrophysics, is a science advisor for the Star Trek franchise and author of Star Trek: My First Book of Space. (Photo: Bradley Worrell)

Raised in Fort Collins, Colorado, Macdonald did not grow up watching Star Trek. However, she was deeply motivated to study science after being inspired by the protagonist astronomer Ellie Arroway in the movie Contact, as well as by fictional FBI agent and medical doctor Dana Scully in the popular TV show The X-Files.

“I watched The X-Files growing up, and Dana Scully for me was just the coolest woman who ever existed. That really sparked an excitement to be a scientist,” she says. “And then when Contact came out, watching Dr. Ellie Arroway use a telescope to find aliens, and seeing her legitimately work as an astronomer was the first time I ever saw that as a career.”

Still, there were some obstacles to overcome, Macdonald says, including the fact that math did not come naturally to her.

“In high school, I had friends who were taking classes that seemed to get it. And for me, I felt like I was trudging through mud trying to understand things—but knowing that I had to get through the math,” she says. Finally, when taking a Calculus 3 course at CU Boulder, she says she experienced a breakthrough when she came to understand how math worked with physics, and then “everything just clicked.” It prompted her to immediately declare a double major in mathematics and astrophysics.

Gaining another role model

It also was in college that Macdonald was first exposed to Star Trek through a tightknit group of fellow students who were big fans of the TV shows.

“In the Venn diagram of physics majors and Star Trek fans, there is a big intersection,” she says with a laugh. “I was in my early 20s and (fictional) Voyager Captain Catherine Janeway became my new Scully. She was someone who had gone from being a science officer to a captain. At that point, I knew I wanted to get my PhD, but I didn’t necessarily want to be a researcher as a career. So, Janeway was a role model, how she was a leader and a problem-solver and a mentor. It was something I aspired to.”

After graduating from CU Boulder in May 2009, Macdonald enrolled at the �Թ�� of Glasgow in Scotland, where she earned her PhD in astrophysics in 2012. Normally, a master’s degree would be the next educational step after obtaining an undergraduate degree, but Macdonald credits the quality of the education she received at CU Boulder—and particularly the research opportunity and mentorship of astrophysics and planetary sciences Professor Jeremy Darling—with allowing her to immediately advance to working toward a doctorate.

After obtaining her PhD, Macdonald spent two years doing post-doctoral research at Cardiff �Թ�� in Wales, United Kingdom. She later moved back to Colorado, where she worked as an adjunct professor in the community college system and as an educator at the Denver Museum of Nature & Science for about a year, then transitioned to work as an aerospace engineer for a contractor based in the Denver area.

“In the Venn diagram of physics majors and Star Trek fans, there is a big intersection,” says CU Boulder alumnus Erin Macdonald. (Photo: Bradley Worrell)

It was during her time working for the contractor, and while attending pop culture conventions for fun, that Macdonald hit upon the idea that she could combine her deep knowledge of astrophysics with her love of science fiction to give talks on the science of science fiction TV shows, movies and videogames at fan conventions.

“After a while in the private sector, I found I really missed teaching. I was already going to conventions, so I proposed giving talks,” she says, adding that event organizers were receptive to the idea. “For topics, a popular one is physics and Star Trek. I’d say, ‘I did my PhD in gravitational physics, so let me explain how (theoretically) warp drives work, because I actually know the science of how warp drives work.’”

To boldly go …

In 2017, Macdonald moved to the Los Angeles area, where she continued to work in the aerospace industry while also giving science/science fiction talks at fan conventions, or as she describes herself in that time: “rocket scientist by day, warp engineering expert by evening.” It was during that period that she began meeting actors and writers at fan events, which ultimately led to industry connections with executives at CBS, the producer of all things Star Trek.

Macdonald was initially hired to give talks at CBS-sponsored events, including Star Trek Cruises. That led to an introduction with the co-executive producer of Star Trek Discovery, who asked Macdonald to serve as a science advisor for the show as season 3 began production.

“I believe I did a good job on that season, so I think the executives saw value in hiring a science advisor to be available to all of their shows to maintain consistency across the franchise, to understand all of the made-up technologies that we have in Star Trek and to be able to communicate that to the writers as well,” she says. “That’s been going on since 2019, so almost five years now.”

Meanwhile, Macdonald has written four screenplays, and she has done voice acting for Star Trek Prodigy, an animated Star Trek show, during which she had the opportunity to work with Kate Mulgrew, the actress who played Captain Janeway on Star Trek Voyager.

“When I started working on Star Trek Prodigy, they were bringing Captain Janeway back as a teacher for young kids. I was going to help write some of her lines, and that was when I had this huge epiphany of—I’m not meant to become Captain Janeway; I’m meant to write Captain Janeway and create characters that inspire kids to become scientists.”

“When I started working on Star Trek Prodigy, they were bringing Captain Janeway back as a teacher for young kids. I was going to help write some of her lines, and that was when I had this huge epiphany of—I’m not meant to become Captain Janeway; I’m meant to write Captain Janeway and create characters that inspire kids to become scientists,” she says. “And so now, I find that storytelling lets me sort of inspire and motivate the next generation of STEM professionals, and that’s what I want to do as a career.”

Macdonald has found her voice as a storyteller in several different ways. In 2022, she published Star Trek: My First Book of Space, an illustrate children’s board book that uses Star Trek to talk about science, technology, engineering, arts and math (STEAM), and she wrote and narrated the Audible Original “The Science of Sci-Fi” in collaboration with The Great Courses.

Additionally, in 2021, McDonald created Spacetime Productions, a film development and production company devoted to giving representation to traditionally marginalized voices, including those in the LGBTQIA+ community. The company has produced two short films including Identiteaze, released on the streaming service Nebula earlier this summer.

Reflecting on her journey from scientist to educator to storyteller, Macdonald says her success is the result of recognizing good opportunities, trusting her instincts, perseverance and, most importantly, putting in the time and work to achieve her goals.

“You know, I didn’t quit my PhD and move to LA with no plan. I took those important steps in between,” she says. “And it took me until well into my 30s for me to realize what I wanted, to be a storyteller and create those Dana Scullys and Captain Janeways, as opposed to becoming one of those characters. And that’s OK. All of those steps along the way helped inform the work I do now.”

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The 2009 math and astrophysics double major has successfully transformed herself from a scientist to an educator to a storyteller sailing with the enterprise known as 'Star Trek.'

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CU Boulder, Fort Lewis College support Native American astrophysics students

Anonymous — Fri, 14 Jul 2023 02:01:59 +0000

CU Boulder, Fort Lewis College support Native American astrophysics students Anonymous (not verified) Thu, 07/13/2023 - 20:01

Doug McPherson

Julie Comerford, associate professor of astrophysics, initiated the NSF-funded research program opening pathways to students often underrepresented in physical sciences

A new program at the �Թ�� of Colorado Boulder is helping Native American undergraduate students delve into astrophysics and more fully participate in scientific research that frequently happens on Indigenous lands.

The National Science Foundation-supported program is a partnership between CU Boulder and Fort Lewis College in Durango, Colorado. Julie Comerford, associate professor of astrophysical and planetary sciences, who is leading the program, notes that Fort Lewis College does not have an astrophysics program, so students interested in the field lack opportunities.

“The intent is to open pathways to astrophysics for Native American students,” Comerford says.

Julie Comerford, associate professor of astrophysical and planetary sciences, initiated a summer research partnership between CU Boulder and Fort Lewis College to open pathways to astrophysics for Native American undergraduate students.

The American Institute of Physics reports that for every 1,000 Native American students who earn a bachelor’s degree, only four do so in physics or geosciences.

“In individual terms, an average of two Native American students earn a bachelor’s degree in astronomy each year, and fewer than one earns a Ph.D. in astronomy each year,” Comerford says. “These low numbers are especially stark for a field that builds many of its ground-based telescopes on land that’s sacred to Indigenous peoples. So even though our program is small–only three students per year–the potential impact could be massive in terms of opening pathways to astrophysics.”

Individualized research

Each student in the program is participating in a different research project with their advisor, who are CU Boulder or National Solar Observatory faculty members. The students’ projects include analyzing images from the Daniel K. Inouye Solar Telescope in Hawaii and using image data from Mars rovers and orbiters to study high-altitude noctilucent clouds—research inspired by the student’s experience during childhood of seeing a sunlit cloud in the sky at night. Program participants also are exploring qualities of planets beyond our solar system.

In addition, the students are taking part in professional development workshops hosted by the Boulder Solar Alliance Research Experience for Undergraduates, part of the CU Boulder Laboratory for Atmospheric and Space Physics. The workshops include how to give a brief description of their research projects, how to write scientific abstracts, how to make a research poster and how to apply to graduate school. The students also get mentoring from CU Boulder graduate students.

Astrophysics program interns and mentors—including (left to right around the table) intern Yoshi Levey, mentor and CU graduate student Charles (Charlie) Marrder, mentor and CU graduate student Anna Zuckerman and mentor and CU graduate student Marcel Corchado-Albelo—attend a professional development workshop at the Laboratory for Atmospheric and Space Physics/National Solar Observatory in Boulder.

The idea for the program came to Comerford when she saw an NSF solicitation for its Partnerships in Astronomy & Astrophysics Research and Education (PAARE) program, which works to improve astronomy and astrophysics research and education.

“I thought it sounded really interesting and worthwhile,” Comerford says.

Statewide partnership

As Comerford was thinking about what institution to partner with, her department chair, Nils Halverson, mentioned the CU Boulder-Fort Lewis partnership the CU@FLC Postdoctoral Teaching Fellowship Program, started by former Associate Dean for Research Theresa D. Hernández and James White, former acting dean for the CU Boulder College of Arts and Sciences.

“I reached out to Theresa to learn more and came out of that conversation thinking that Fort Lewis College would be an amazing partner.” Comerford says. “I owe a lot to Nils and Theresa for encouraging me and helping me get my PAARE proposal off the ground. I wrote the proposal in January 2022, so it's been 18 months to get from the proposal to this first cohort of students.”

Hernandez says Comerford's partnership with Fort Lewis College creates an amazing opportunity to engage undergraduates in astrophysics and to increase the recruitment, retention and successes of groups often underrepresented in that field.

“This program also rounds out CU’s and Fort Lewis College’s Post-Doctoral Teaching Fellowship Program,” Hernandez says. “Together, these create a strong foundation for regular interaction between both campuses and for students through their undergraduate, graduate and post-doctoral studies. We’re thrilled that the first group of students have started, and by Dr. Comerford’s strong commitment to this important work in her field.”

In summer 2025, alumni from the astrophysics program will gather at Chimney Rock National Monument in southwest Colorado for the lunar standstill, during which the full moon rises between two rock formations as viewed from an ancestral Puebloan ceremonial site.

Andy Cowell, faculty director of the Center for Native American and Indigenous Studies (CNAIS) at CU Boulder, says CNAIS is excited to support Comerford’s project. “We’ve been working recently to expand our cooperative work with natural sciences departments. We want to help promote not just Native and Indigenous Studies as an academic discipline, but also Native communities in all academic areas across the campus, and this project is a good example of how that can be done.”

Comerford says she has funds to run the program for three summers. After the third summer, she plans to gather all program alumni at Chimney Rock National Monument in southwest Colorado for the 2025 lunar standstill, during which the full moon rises between two rock formations as viewed from an ancestral Puebloan ceremonial site.

“I want to use these first three years to establish the program, and then grow it into a longstanding, established program with institutional support from CU Boulder,” Comerford says, adding that she thinks of the NSF funding as a seed grant. “The goal is for this to become an embedded program that continues decades from now.”

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Julie Comerford, associate professor of astrophysics, initiated the NSF-funded research program opening pathways to students often underrepresented in physical sciences.

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What are the little red dots deep in space?

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