Most planets, including Earth, travel around their stars in relatively stable orbits. But these peaceful arrangements can sometimes end violently. If a planet ventures too close to its host star, the star’s gravity can drag it inward and eventually engulf it.

Scientists have observed many planetary systems with stable orbits, along with a small number of stars caught rapidly swallowing their planetary companions. Now, researchers have identified something that falls between those two extremes.

In a study published October 5 in Nature Astronomy, an international team led by scientists at MIT describes a star that is slowly feeding on a brown dwarf, an object more massive than a typical planet but not massive enough to sustain the hydrogen fusion that powers ordinary stars.

The system, designated ZTF J0440+2325, lies within our Milky Way galaxy approximately 300 light-years away. It is the first observed example of a low-mass star steadily drawing material from another low-mass object.

Even more remarkably, the transfer of material appears to be happening so slowly that the star could continue feeding on its companion for hundreds of thousands of years, potentially even billions.

“When we think of stars interacting with planets or brown dwarfs, the picture is always that the star eventually swallows the other thing,” says Kevin Burdge, assistant professor of physics at MIT. “This is what will happen to the Earth when the sun becomes a red giant. But here, we’ve found an alternative: Instead of swallowing the thing up, the star can gradually eat it, for billions of years.”

The MIT research team also includes Aaron Householder, Kaitlyn Shin, Saul Rappaport, Joheen Chakraborty, and Emma Chickles. Additional collaborators contributed from Caltech, the University of Hawaii, the Instituto de Astrofísica de Canarias and Universidad de La Laguna in Spain, and the Harvard-Smithsonian Center for Astrophysics.

A Mysterious Signal That Puzzled Astronomers for Years

The first clue to this unusual stellar relationship came from the Zwicky Transient Facility (ZTF), an astronomical survey that searches for objects whose brightness changes over time.

Operating with a telescope at Palomar Observatory in California, ZTF repeatedly photographs large sections of the night sky. Its sensitive camera can detect sudden or unusual changes in light that may indicate powerful cosmic events, including exploding stars called supernovae, gamma-ray bursts, and collisions between neutron stars.

Several years ago, while examining observations collected by ZTF, Burdge noticed a particularly strange pattern.

Astronomers study changes in an object’s brightness using a graph called a light curve. For some supernovae, these graphs form a rounded, bell-like shape as the exploding star grows brighter and then gradually fades.

The signal Burdge encountered looked completely different. Instead of a smooth rise and fall, the brightness repeatedly traced something resembling a triangle.

“I remember first looking at this and thinking, stars don’t make triangular waveforms like this,” he recalls.

At the time, Burdge and his colleagues were investigating another unusual signal that turned out to originate from a system known as a “black widow binary.”

These systems contain a neutron star, the extraordinarily dense remnant of a massive star, that spins rapidly while stripping material from a much smaller companion. They are named after black widow spiders because of the way the neutron star gradually destroys its partner.

Burdge initially considered whether the repeating triangular signal might come from another black widow system. However, the observations did not match what astronomers normally expect.

In a typical black widow binary, the strong contrast between the masses of the two objects produces a distinctive motion. The smaller companion moves rapidly around the much heavier neutron star, creating detectable changes in the light reaching Earth.

But the mysterious triangular signal showed no evidence of the same pronounced motion.

“We weren’t seeing that whipping back and forth here,” Burdge says. “It didn’t make any sense. We couldn’t explain what this was.”

That discrepancy led the researchers to consider another possibility. Perhaps the system did not contain one extremely massive object paired with a much lighter companion. Instead, both objects might have relatively small masses, allowing them to orbit each other with much less dramatic motion.

“If you have less mass in the system overall, things can gently orbit each other without whipping back and forth,” Burdge says. “That was the idea. But we never had any proof. And this weird triangle just sat for years.”

A Brown Dwarf That Orbits Its Star Every 87 Minutes

Eventually, Burdge and Aaron Householder, a graduate student in MIT’s Department of Earth, Atmospheric, and Planetary Sciences, returned to the unexplained signal.

Using the original ZTF observations, they identified its source as an object roughly 300 light-years away in the Milky Way. They then directed several telescopes toward the system, ZTF J0440+2325, to investigate its properties in greater detail.

A key measurement involved determining how much the system’s objects move in response to their mutual gravitational attraction. Although the researchers detected some wobbling, it was far smaller than the motion typically associated with black widow binaries.

“That was the real clincher for this system,” Householder says. “When we measured that wobble, we found we were not seeing a black widow. This was a low-mass star that’s orbited by a brown dwarf. The wobble was too small in amplitude to be anything else.”

The observations revealed two unusually compact objects orbiting at an extremely close distance.

The central star has approximately 85 times the mass of Jupiter, while the brown dwarf weighs about 25 Jupiter masses. For comparison, the Sun is more than 1,000 times as massive as Jupiter.

The brown dwarf completes a full revolution around its host star in just 87 minutes. Its entire orbit is so small that it would fit within the diameter of the Sun.

That extraordinarily close arrangement suggested that gravity might be doing more than simply keeping the objects in orbit. The researchers suspected that the star could be actively pulling matter away from the brown dwarf.

Scientists Discover a New Form of Stellar Cannibalism

When one astronomical object draws gas or other material from another, astronomers call the process accretion.

Accretion is especially familiar in systems involving black holes and neutron stars. Although these objects can be extremely massive, their physical dimensions are relatively small. Material falling toward a black hole, for example, often forms a swirling disk around it before moving inward.

But ZTF J0440+2325 appears to work differently.

Rather than a black hole or neutron star collecting matter, an ordinary low-mass star is receiving material from a nearby brown dwarf. Because the star has a much larger physical surface than a compact object such as a black hole, the incoming material can strike it directly.

“The difference here is, the thing absorbing matter is not a tiny black hole but a star, which is relatively big in size,” Burdge explains. “So matter just pummels directly onto the surface, at very high speeds, like an asteroid hitting the Moon.”

To investigate whether this was actually happening, the researchers created computer simulations of the system.

They modeled particles originating from the brown dwarf and calculated how those particles would move under the gravitational influence of both objects. The simulations incorporated the measured properties of the star and its companion, along with the physical equations governing orbital motion.

The results supported the team’s suspicion. Material leaving the brown dwarf followed trajectories that carried it directly into the star.

“When we track those test particles, we see they indeed fall right onto the surface of the star,” Householder says. “This is the first time we’ve caught a low-mass star actively accreting from another low-mass object.”

A Cosmic Feast That Could Continue for Billions of Years

The team also estimated how quickly the brown dwarf is losing material.

According to their calculations, the star is consuming approximately one hundred-thousandth of Earth’s mass every year.

That amount may sound insignificant, but it represents an enormous quantity of material. The researchers compare it to approximately 40 million dump trucks’ worth of matter, or about 1.3 trillion one-pound burritos every second.

Despite those staggering figures, the brown dwarf is so massive that this material loss represents only a tiny portion of its total mass.

In astronomical terms, the feeding process is remarkably gradual.

Based on the properties of the system and the estimated rate of mass transfer, researchers believe the star could continue drawing matter from its companion for billions of years.

Instead of a sudden, catastrophic collision that destroys the smaller object, the star appears to be sustaining a relatively steady flow of material from its neighbor.

That realization also helped explain the strange triangular light pattern that first attracted Burdge’s attention.

As matter streams from the brown dwarf toward the star, it strikes the stellar surface at high speeds, generating an intensely heated region.

This bright hotspot acts like a persistent fireball on the star.

As the brown dwarf moves through its 87-minute orbit, the hotspot repeatedly rotates into and out of the observer’s view. Those changes in visibility produce the distinctive pattern of brightening and dimming that the astronomers had struggled to understand.

“It’s like you’ve got this continuous fireball onto one of the objects, and as one orbits the other, that hotspot comes in and out of view, and the peak of the triangle signal is when you’re looking right at the fireball,” Burdge explains.

A Strange Star System Opens a New Window Into Planetary Evolution

With the triangular signal finally explained, the researchers are now interested in identifying other stellar systems that behave in similar ways.

Until now, observations of close interactions between stars and their planetary companions have largely emphasized either stable orbits or relatively rapid engulfment events.

ZTF J0440+2325 demonstrates that another possibility exists. Under the right conditions, a small star can steadily extract matter from a nearby brown dwarf without immediately destroying it.

Finding additional examples could help astronomers determine how common this process is, how long it can persist, and what ultimately happens to objects trapped in such extraordinarily close relationships.

The discovery may also provide new insights into the evolution of planets and brown dwarfs that orbit near their host stars.

“It’s inspiring a lot of new searches on our part,” Householder says. “I think we’re going to learn a lot about a different kind of way that planets and brown dwarfs interact with their host stars.”

This research received partial support from the National Science Foundation.

Researchers at the University of Helsinki investigated this question and uncovered a striking finding: people with the same depression diagnosis can have dramatically different patterns of brain activity. In some cases, communication between brain regions was unusually strong, while in others, it was weaker than normal.

Depression is a major global health concern. According to the World Health Organization (WHO, 2025), approximately 332 million (5.2%) adults worldwide are affected. In Finland, depression is the leading individual cause of both extended sick leave and disability pensions.

Brain Study Reveals Five Distinct Depression Profiles

To investigate the biological differences associated with depression, researchers examined brain activity in 263 people diagnosed with major depressive disorder and 75 healthy participants who served as a comparison group.

The analysis revealed five distinct groups based on differences in functional connectivity, a measure of how closely activity in different brain regions is coordinated. When two regions show synchronized activity, it suggests they are working together as part of a larger brain network. However, stronger connectivity does not necessarily mean the brain is functioning better.

“What was particularly interesting was the contrasting patterns of brain activity found under the umbrella of the same depression diagnoses. In some individuals, the functional connectivity between brain regions was stronger than usual, while in others it was weaker,” says Director Satu Palva of the Neuroscience Center, University of Helsinki.

These differences were also associated with particular symptoms. Participants in one group showed especially strong connections between brain regions, along with more pronounced substance abuse problems. Another group displayed weaker connections and a greater prominence of post-traumatic stress disorder (PTSD) symptoms.

The contrasting results could help explain why earlier studies examining the brains of people with depression have sometimes reached conflicting conclusions. If researchers study different combinations of patients, they may observe very different patterns, even though everyone involved has received the same diagnosis.

The findings add to growing evidence that depression may not have a single, consistent biological signature. Instead, the condition could involve several distinct patterns of brain function.

The Five Brain Patterns Linked to Depression

The researchers classified participants with depression into five groups based on how strongly different brain areas communicated and the frequencies at which their activity was coordinated.

Each group had a characteristic pattern of brain connectivity and associated symptoms:

Group 1: Strong connectivity and severe symptoms

Participants generally showed relatively strong connections between brain regions. This profile was associated with more severe symptoms across several areas, including depression, anxiety, rumination, and reduced ability to function in daily life. Rumination refers to repeatedly dwelling on distressing thoughts, worries, or negative experiences.

Group 2: Weaker connectivity and milder depression

This group was characterized by relatively weak communication between brain regions. Compared with the other groups, participants generally experienced milder symptoms.

Group 3: Widespread weak connectivity and trauma symptoms

People in this group showed reduced connectivity across substantial portions of the brain. Symptoms associated with post-traumatic stress disorder (PTSD) were particularly prominent.

Group 4: Mixed connectivity and multiple challenges

This profile combined unusually strong connections in some brain regions with weaker connections in others. Participants tended to experience more severe depression, greater substance abuse problems, and lower overall well-being.

Group 5: The strongest connectivity and substance abuse symptoms

Participants in the fifth group had the strongest connections between brain regions of any group identified in the study. Substance abuse was a particularly prominent issue, while trauma related symptoms were less pronounced than in the other groups.

Importantly, all five groups also showed differences from the healthy participants. These distinctions extended beyond whether brain connections were strong or weak. The groups also differed in which brain regions were involved and the frequencies at which their activity was synchronized.

Together, the patterns suggest that people diagnosed with depression may experience substantially different changes in how their brain networks operate.

Measuring Brain Activity With Millisecond Precision

To capture these differences, the scientists used magnetoencephalography (MEG), a brain imaging technique that detects extremely faint magnetic fields produced by electrical activity in the brain.

Unlike methods that track slower changes associated with brain activity, MEG can follow electrical signals as they unfold over extremely short periods. This makes it particularly useful for investigating the timing and coordination of communication between brain regions.

Using MEG, the researchers recorded brain activity in all 263 participants with depression and the 75 healthy control subjects.

“MEG enabled us to monitor electrical brain activity with millisecond precision, helping us get closer to what actually happens in the brain at any given moment. Previously, depression phenotypes have been studied using methods with slower responses,” Palva notes.

This high level of temporal precision allowed the team to examine rapid changes in brain activity that might be difficult to distinguish using slower measurement techniques.

By studying these fast signals, the researchers were able to identify differences not only in the strength of connectivity but also in the frequencies at which brain regions appeared to work together.

Could Brain Activity Lead to More Personalized Depression Treatments?

The discovery raises an important possibility for the future of mental health care: treatments might eventually be selected partly according to a person’s individual pattern of brain activity.

Today, finding an effective depression treatment can involve trying different medications or therapies and evaluating how well each works. Because patients can respond differently to the same treatment, identifying the most suitable approach is not always straightforward.

Brain activity measurements could eventually provide additional information to help guide these decisions. However, the researchers emphasize that their findings are not yet ready for clinical use.

“We’re not yet at the point where brain measurements can be used to choose the right treatment for patients, but the study does show one possible route,” Palva says.

A major long-term goal is to better understand how particular symptoms relate to the way brain networks function. Connecting these biological patterns with patients’ experiences could help researchers develop more precise ways to identify and characterize depression.

Eventually, such knowledge might allow doctors to determine which therapies are most likely to help individual patients, potentially reducing the amount of trial and error involved in treatment.

For now, the five brain profiles offer a different way to understand depression. Rather than assuming that one diagnosis corresponds to one underlying pattern of brain activity, the findings suggest that depression can involve markedly different biological changes, sometimes even in opposite directions.

The research was carried out in collaboration with Aalto University and Helsinki and Uusimaa Hospital District (HUS).

High-intensity interval training (HIIT), which involves alternating short bursts of demanding exercise with easier recovery periods, may be especially helpful for older adults who want to reduce fat without sacrificing lean muscle.

In a study published in Maturitas, researchers from the University of the Sunshine Coast compared three different exercise intensities. Although participants across the groups experienced modest fat loss, HIIT stood out for its ability to reduce fat while maintaining lean tissue.

“We found that high, medium and low intensity exercises all led to modest fat loss but only HIIT retained lean muscle,” said lead author and exercise physiologist Dr. Grace Rose of the University of the Sunshine Coast.

The results highlight an important distinction in healthy aging: losing weight is not necessarily the same as improving body composition.

Six Months of Exercise Revealed a Key Difference

The Australian research team investigated how workout intensity affects body composition, meaning the proportions of fat, muscle and other tissues that make up the body.

A total of 123 healthy older adults from the Greater Brisbane region participated in the trial. Their average age was 72, and their average body mass index was approximately 26kg/m², which the researchers described as normal for adults over 65.

Participants completed three supervised gym sessions each week for six months. Each session lasted 45 minutes, and participants were assigned to high-intensity intervals, moderate-intensity exercise, or a low-intensity comparison group.

To track changes, researchers measured body composition at the beginning of the study, after three months, and again at six months. They used a specialized scanning technique that estimates fat and lean tissue throughout the body.

The findings revealed that exercise intensity made a difference.

Both high- and moderate-intensity training significantly reduced fat mass, with larger improvements than those seen in the low-intensity group. However, the two more demanding approaches differed in their effects on lean tissue.

“While moderate training reduced fat mass, it also caused a small decline in lean muscle,” Rose said.

Participants performing HIIT, meanwhile, reduced fat without experiencing the same decline in lean mass.

This could be particularly valuable later in life, when maintaining muscle becomes increasingly important for physical independence. Strong muscles help people climb stairs, get out of chairs, maintain balance, and carry out everyday activities.

One important distinction is that the scans measured lean tissue rather than muscle strength directly. Lean mass includes muscle but also other tissues and water, so changes in these measurements do not necessarily translate into equivalent changes in strength.

High-Intensity Exercise Also Reduced Abdominal Fat

The researchers found another potentially important benefit involving fat stored around the middle of the body.

“Both high and moderate intensities improved the composition of weight carried around the middle. Further analysis is needed of the low intensity results.”

The original study found improvements in visceral adipose tissue among both the high and moderate intensity groups.

Visceral fat is different from the fat that sits directly beneath the skin. It accumulates deeper in the abdomen, surrounding internal organs such as the liver and intestines.

Excessive amounts of this fat have been linked to insulin resistance, cardiovascular disease, and other metabolic problems.

According to Rose, these findings matter because body composition can influence the development and progression of chronic diseases as people age.

While body weight and body mass index provide useful general information, they do not reveal how much fat or muscle a person carries, or where that fat is stored.

Someone who loses fat while maintaining muscle may experience a more favorable change in body composition than someone who loses a similar amount of weight along with valuable lean tissue.

Still, the original researchers emphasized that the improvements were relatively small. They cautioned that the differences were not clearly clinically meaningful when compared with lower intensity exercise, particularly after accounting for measurement uncertainty.

Why HIIT May Help Aging Muscles Stay Strong

One possible explanation for HIIT’s advantage lies in the way it challenges the body.

Rather than exercising at the same pace throughout a workout, HIIT repeatedly pushes the cardiovascular system and working muscles through periods of intense effort, followed by easier activity.

University of the Sunshine Coast Associate Professor of Physiology and study co-author Mia Schaumberg explained how the training worked.

“High-intensity training in this study involved repeated short bursts, or intervals, of very hard exercise — where breathing is heavy and conversation is difficult — alternated with easier recovery periods.

“HIIT likely works better because it puts more stress on the muscles, giving the body a stronger signal to keep muscle tissue rather than lose it.”

This explanation is consistent with the idea that muscles adapt to the demands placed on them. When exercise provides a sufficiently challenging stimulus, the body has more reason to maintain the tissues needed to perform that activity.

Muscle preservation is especially important because aging is often accompanied by a gradual decline in muscle mass and strength. In more advanced cases, this can contribute to sarcopenia, a condition characterized by reduced muscle strength and quantity that can interfere with mobility and independence.

Schaumberg said the original research could help people make more informed decisions about exercise and healthy aging.

When the university publicized the findings in early 2026, she also highlighted their relevance to people setting fitness goals.

“With the festive season now behind most of us and New Year’s resolutions in full swing, this research can help inform people’s plans for healthy aging in 2026,” she said.

The research involved collaborators from UniSC’s Healthy Ageing Research Cluster and The University of Queensland.

More Recent Studies Reveal Additional Benefits of HIIT

Research published in 2026 has provided further insight into how HIIT affects older adults, although it also suggests that intense workouts are not necessarily superior in every situation.

One 2026 study, published in Medicine & Science in Sports & Exercise, investigated whether older adults could benefit from completing HIIT at home with remote supervision.

The study involved 20 adults aged 61 to 74 who exercised using a specialized machine that let them work their arms and legs without bearing their body weight.

After eight weeks of training, participants had lost an average of approximately 1.4 kilograms, or about 3 pounds, of fat mass. Their aerobic fitness also improved substantially.

Participants completed 96 percent of their scheduled workouts, and the researchers reported no exercise-related adverse events.

Although the trial was small, its findings suggest that appropriately supervised HIIT programs may offer benefits outside a conventional gym.

Another 2026 randomized trial, published in The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences, compared HIIT with continuous moderate-intensity exercise in older adults living with HIV.

In that study, participants completed 16 weeks of exercise, with both groups also performing resistance training.

Unlike the original Australian study, both exercise groups experienced reductions in fat and increases in lean mass. The researchers found no statistically significant difference between the two groups in those body composition changes.

These results suggest that workout intensity is not the only factor that matters. Resistance training, which challenges muscles through weights or other forms of resistance, may also help preserve or increase lean tissue.

The populations and training programs differed, so the findings should not be treated as a direct contradiction of the Australian results.

Is HIIT Really the Best Exercise for Older Adults?

A broader scientific review published in the Journal of Clinical Medicine in August 2026 offers additional perspective.

Researchers examined 25 reports involving approximately 2,818 participants to assess how HIIT and other forms of interval training affect older adults.

The most consistent benefits involved cardiovascular fitness, including improvements in the body’s ability to use oxygen during exercise.

Some studies also reported improvements in physical function and metabolic health. However, the review did not establish that HIIT was consistently better than moderate-intensity exercise.

The researchers noted that differences between exercise programs, participant characteristics, and study methods made it difficult to identify a single optimal training approach.

Taken together, the findings suggest that HIIT can be a useful tool for healthy aging, but it is not the only way to improve fitness or protect muscle.

For adults over 65, the Centers for Disease Control and Prevention recommends a combination of aerobic exercise, muscle strengthening activities, and exercises that improve balance.

Higher intensity workouts may be appropriate for some older adults, but people who are inactive or have medical conditions may benefit from gradually building up their fitness and seeking guidance before beginning a demanding program.

The central message from the Australian study remains compelling: what happens to muscle during fat loss may be just as important as the amount of weight someone loses.

HIIT showed promise because it helped participants reduce body fat while maintaining lean tissue. Combined with newer findings, the research reinforces the value of exercise programs that support not just a lower number on the scale, but also the strength, fitness, and physical function needed for healthy aging.