Photo of orbits of the G objects at the center of our galaxy

Astronomers discover class of strange objects near our galaxy’s enormous black hole

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Photo of orbits of the G objects at the center of our galaxy

Orbits of the G objects at the center of our galaxy, with the supermassive black hole indicated with a white cross. Stars, gas and dust are in the background. Photo: Anna Ciurlo, Tuan Do/UCLA Galactic Center Group

Astronomers from UCLA’s Galactic Center Orbits Initiative have discovered a new class of bizarre objects at the center of our galaxy, not far from the supermassive black hole called Sagittarius A*. They published their research in the Jan. 16 issue of the journal Nature.

“These objects look like gas and behave like stars,” said co-author Andrea Ghez, UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics and director of the UCLA Galactic Center Group.

The new objects look compact most of the time and stretch out when their orbits bring them closest to the black hole. Their orbits range from about 100 to 1,000 years, said lead author Anna Ciurlo, a UCLA postdoctoral researcher.

Ghez’s research group identified an unusual object at the center of our galaxy in 2005, which was later named G1. In 2012, astronomers in Germany made a puzzling discovery of a bizarre object named G2 in the center of the Milky Way that made a close approach to the supermassive black hole in 2014. Ghez and her research team believe that G2 is most likely two stars that had been orbiting the black hole in tandem and merged into an extremely large star, cloaked in unusually thick gas and dust.

“At the time of closest approach, G2 had a really strange signature,” Ghez said. “We had seen it before, but it didn’t look too peculiar until it got close to the black hole and became elongated, and much of its gas was torn apart. It went from being a pretty innocuous object when it was far from the black hole to one that was really stretched out and distorted at its closest approach and lost its outer shell, and now it’s getting more compact again.”

“One of the things that has gotten everyone excited about the G objects is that the stuff that gets pulled off of them by tidal forces as they sweep by the central black hole must inevitably fall into the black hole,” said co-author Mark Morris, UCLA professor of physics and astronomy. “When that happens, it might be able to produce an impressive fireworks show since the material eaten by the black hole will heat up and emit copious radiation before it disappears across the event horizon.”

But are G2 and G1 outliers, or are they part of a larger class of objects? In answer to that question, Ghez’s research group reports the existence of four more objects they are calling G3, G4, G5 and G6. The researchers have determined each of their orbits. While G1 and G2 have similar orbits, the four new objects have very different orbits.

Ghez believes all six objects were binary stars — a system of two stars orbiting each other — that merged because of the strong gravitational force of the supermassive black hole. The merging of two stars takes more than 1 million years to complete, Ghez said.

“Mergers of stars may be happening in the universe more often than we thought, and likely are quite common,” Ghez said. “Black holes may be driving binary stars to merge. It’s possible that many of the stars we’ve been watching and not understanding may be the end product of mergers that are calm now. We are learning how galaxies and black holes evolve. The way binary stars interact with each other and with the black hole is very different from how single stars interact with other single stars and with the black hole.”

Ciurlo noted that while the gas from G2’s outer shell got stretched dramatically, its dust inside the gas did not get stretched much. “Something must have kept it compact and enabled it to survive its encounter with the black hole,” Ciurlo said. “This is evidence for a stellar object inside G2.”

“The unique dataset that Professor Ghez’s group has gathered during more than 20 years is what allowed us to make this discovery,” Ciurlo said. “We now have a population of ‘G’ objects, so it is not a matter of explaining a ‘one-time event’ like G2.”

The researchers made observations from the W.M. Keck Observatory in Hawaii and used a powerful technology that Ghez helped pioneer, called adaptive optics, which corrects the distorting effects of the Earth’s atmosphere in real time. They conducted a new analysis of 13 years of their UCLA Galactic Center Orbits Initiative data.

In September 2019, Ghez’s team reported that the black hole is getting hungrier and it is unclear why. The stretching of G2 in 2014 appeared to pull off gas that may recently have been swallowed by the black hole, said co-author Tuan Do, a UCLA research scientist and deputy director of the Galactic Center Group. The mergers of stars could feed the black hole.

The team has already identified a few other candidates that may be part of this new class of objects, and are continuing to analyze them.

Ghez noted the center of the Milky Way galaxy is an extreme environment, unlike our less hectic corner of the universe.

“The Earth is in the suburbs compared to the center of the galaxy, which is some 26,000 light-years away,” Ghez said. “The center of our galaxy has a density of stars 1 billion times higher than our part of the galaxy. The gravitational pull is so much stronger. The magnetic fields are more extreme. The center of the galaxy is where extreme astrophysics occurs — the X-sports of astrophysics.”

Ghez said this research will help to teach us what is happening in the majority of galaxies.

Other co-authors include Randall Campbell, an astronomer with the W.M. Keck Observatory in Hawaii; Aurelien Hees, a former UCLA postdoctoral scholar, now a researcher at the Paris Observatory in France; and Smadar Naoz, a UCLA assistant professor of physics and astronomy.

The research is funded by the National Science Foundation, W.M. Keck Foundation and Keck Visiting Scholars Program, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, Lauren Leichtman and Arthur Levine, Jim and Lori Keir, and Howard and Astrid Preston.

In July 2019, Ghez’s research team reported on the most comprehensive test of Einstein’s iconic general theory of relativity near the black hole. They concluded that Einstein’s theory passed the test and is correct, at least for now.

► Watch a four-minute film about Ghez’s research

►View an animation below of the orbits of the G objects, together with the orbits of stars near the supermassive black hole. Credit: Advanced Visualization Lab, National Center for Supercomputing Applications, University of Illinois

This article originally appeared in the UCLA Newsroom.

UCLA Opens World’s 1st Institute To Study Kindness

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UCLA receives $20 million to establish UCLA Bedari Kindness Institute

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Jennifer and Matthew C. Harris ‘84.

The Bedari Foundation, established by philanthropists Jennifer and Matthew C. Harris, has given $20 million to the UCLA College to establish the UCLA Bedari Kindness Institute.

The institute, which is housed in the division of social sciences, will support world-class research on kindness, create opportunities to translate that research into real-world practices, and serve as a global platform to educate and communicate its findings. Among its principal goals are to empower citizens and inspire leaders to build more humane societies.

“Universities should always be places where we teach students to reach across lines of difference and treat one another with empathy and respect — even when we deeply disagree,” UCLA Chancellor Gene Block said. “The UCLA Bedari Kindness Institute will bring the best thinking to this vital issue and, I think, will allow us to have a real social impact on future generations.”

The institute, which will begin operating immediately, will take an interdisciplinary approach to understanding kindness — through evolutionary, biological, psychological, economic, cultural and sociological perspectives. It will focus on research about the actions, thoughts, feelings and social institutions associated with kindness and will bring together researchers from across numerous disciplines at UCLA and at external organizations.

The inaugural director of the institute is Daniel Fessler, a UCLA anthropology professor whose research interests include exploring how witnessing acts of remarkable kindness can cause an uplifting emotional experience that in turn motivates the observer to be kind. Studies by Fessler and his colleagues have shed light on why some people are open to that type of “contagious kindness” experience.

The Bedari Foundation is a private family foundation whose aim is to enable significant cultural shifts in the fields of health and wellness, community displacement and environmental conservation.

“Our vision is that we will all live in a world where humanity discovers and practices the kindness that exists in all of us,” said Matthew Harris, the foundation’s co-founder and a 1984 UCLA graduate. “Much research is needed to understand why kindness can be so scarce in the modern world. As we seek at Bedari to bridge the divide between science and spirituality, through the establishment of the UCLA Bedari Kindness Institute we hope to educate and empower more and more people in the practice of kindness.”

Already, a range of researchers at UCLA are studying the types of questions that will be the basis of the institute’s work. For example, UCLA anthropologists are examining how kindness spreads from person to person and group to group. UCLA sociologists are analyzing how people who regularly act unkind might be encouraged to engage in kind acts instead, and UCLA psychologists are researching how kindness can improve people’s moods and reduce symptoms of depression. Others are pursuing research on changes in neurobiology and behaviors resulting from mindfulness, and how those changes can influence kindness and people’s mental, physical and social well-being.

“In the midst of current world politics, violence and strife, the UCLA Bedari Kindness Institute seeks to be an antidote,” said Darnell Hunt, dean of the UCLA division of social sciences. “Rooted in serious academic work, the institute will partner and share its research on kindness broadly in accessible formats. The Bedari Foundation’s extraordinary gift is truly visionary and we are grateful for its support and leadership.”

The Kindness Institute will provide seed funding for research projects that examine the social and physical mechanics of kindness and how kindness might be harnessed to create more humane societies. It also will provide mindfulness awareness training to students, faculty and staff and in underserved Los Angeles communities, and host an annual conference at which presenters will examine new discoveries in kindness research, among other activities.

“The mission of the Kindness Institute perfectly aligns with that of the division of social sciences, where engaging the amazing diversity and social challenges shaping Los Angeles routinely inspires research that has the potential to change the world,” Hunt said.

The gift is part of the Centennial Campaign for UCLA, which is scheduled to conclude in December.

Study shows how serotonin and a popular anti-depressant affect the gut’s microbiota

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Senior author Elaine Hsiao says researchers hope to build on their current study to learn whether microbial interactions with antidepressants have consequences for health and disease. Photo: Reed Hutchinson/UCLA

A new study in mice led by UCLA biologists strongly suggests that serotonin and drugs that target serotonin, such as anti-depressants, can have a major effect on the gut’s microbiota — the 100 trillion or so bacteria and other microbes that live in the human body’s intestines.

Serotonin — a neurotransmitter, or chemical messenger that sends messages among cells — serves many functions in the human body, including playing a role in emotions and happiness. An estimated 90% of the body’s serotonin is produced in the gut, where it influences gut immunity.

The team — led by senior author Elaine Hsiao and lead author Thomas Fung, a postdoctoral fellow — identified a specific gut bacterium that can detect and transport serotonin into bacterial cells. When mice were given the antidepressant fluoxetine, or Prozac, the biologists found this reduced the transport of serotonin into their cells. This bacterium, about which little is known, is called Turicibacter sanguinis. The study is published this week in the journal Nature Microbiology.

“Our previous work showed that particular gut bacteria help the gut produce serotonin. In this study, we were interested in finding out why they might do so,” said Hsiao, UCLA assistant professor of integrative biology and physiology, and of microbiology, immunology and molecular genetics in the UCLA College; and of digestive diseases in the David Geffen School of Medicine at UCLA.

Hsiao and her research group reported in the journal Cell in 2015 that in mice, a specific mixture of bacteria, consisting mainly of Turicibacter sanguinis and Clostridia, produces molecules that signal to gut cells to increase production of serotonin. When Hsiao’s team raised mice without the bacteria, more than 50% of their gut serotonin was missing. The researchers then added the bacteria mixture of mainly Turicibacter and Clostridia, and their serotonin increased to a normal level.

That study got the team wondering why bacteria signal to our gut cells to make serotonin. Do microbes use serotonin, and if so, for what?

In this new study, the researchers added serotonin to the drinking water of some mice and raised others with a mutation (created by altering a specific serotonin transporter gene) that increased the levels of serotonin in their guts. After studying the microbiota of the mice, the researchers discovered that the bacteria Turicibacter and Clostridia increased significantly when there was more serotonin in the gut.

If these bacteria increase in the presence of serotonin, perhaps they have some cellular machinery to detect serotonin, the researchers speculated. Together with study co-author Lucy Forrest and her team at the National Institutes of Health’s National Institute of Neurological Disorders and Stroke, the researchers found a protein in multiple species of Turicibacter that has some structural similarity to a protein that transports serotonin in mammals. When they grew Turicibacter sanguinis in the lab, they found that the bacterium imports serotonin into the cell.

In another experiment, the researchers added the antidepressant fluoxetine, which normally blocks the mammalian serotonin transporter, to a tube containing Turicibacter sanguinis. They found the bacterium transported significantly less serotonin.

The team found that exposing Turicibacter sanguinis to serotonin or fluoxetine influenced how well the bacterium could thrive in the gastrointestinal tract. In the presence of serotonin, the bacterium grew to high levels in mice, but when exposed to fluoxetine, the bacterium grew to only low levels in mice.

“Previous studies from our lab and others showed that specific bacteria promote serotonin levels in the gut,” Fung said. “Our new study tells us that certain gut bacteria can respond to serotonin and drugs that influence serotonin, like anti-depressants. This is a unique form of communication between bacteria and our own cells through molecules traditionally recognized as neurotransmitters.”

The team’s research on Turicibacter aligns with a growing number of studies reporting that anti-depressants can alter the gut microbiota. “For the future,” Hsiao said, “we want to learn whether microbial interactions with antidepressants have consequences for health and disease.” Hsiao wrote a blog post for the journal about the new research.

Other study co-authors are Helen Vuong, Geoffrey Pronovost, Cristopher Luna, Anastasia Vavilina, Julianne McGinn and Tomiko Rendon, all of UCLA; and Antoniya Aleksandrova and Noah Riley, members of Forrest’s team.

The research was supported by funding from the National Institutes of Health’s Director’s Early Independence Award, Klingenstein-Simons Fellowship Award, and David & Lucile Packard Foundation’s Packard Fellowship for Science and Engineering.

This article originally appeared in the UCLA Newsroom.