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This stunning image of a star cluster in the Small Magellanic Cloud (SMC) is more than just a pretty picture. It’s part of a scientific effort to understand star formation in an environment different from ours. The young star cluster is called NGC 602, and it’s very young, only about 2 or 3 million years old.

This image lives up to the standard the JWST has set. NGC 602 is inside a nebula of multi-coloured gas and dust. The many energetic stars in the cluster light the nebula up from within, while its outer edges are dark. The cluster is rich in ionized gas, which indicates that star formation is still taking place.

The cluster is different from our region of space. It’s a low-density environment and has lower metallicity than our region. Metallicity affects the heating and cooling of gas, and in general, the more metals there are, the more they absorb heat, keeping the star-forming gas cooler. Since stars form from cooler gas, metallicity is expected to enhance star formation.

But there are many questions, including how brown dwarfs fit into this scenario. Do they form like other stars do, from the collapse of giant molecular clouds? Or do they form like planets from the fragmentation of circumstellar disks?

New research in The Astrophysical Journal examined NGC 602 with the JWST and reported the first detection of a brown dwarf population outside the Milky Way. It’s titled “Discovering Subsolar Metallicity Brown Dwarf Candidates in the Small Magellanic Cloud.” The lead author is Peter Zeidler of AURA/STScI for the European Space Agency.

Brown dwarfs are sometimes called planetars or hyperjovians because they’re more massive than planets but not massive enough to be stars. They’re also often called sub-stellar mass objects. For some reason, during formation, they fail to attract enough mass to trigger fusion and become full-blown stars. Identifying them in a low-metallicity environment is a chance to understand brown dwarfs and star formation in general in a different environment.

An artist’s conception of a brown dwarf. Brown dwarfs are more massive than Jupiter but less massive than the smallest main-sequence stars. Their dimness and low mass make them difficult to detect. Image: By NASA/JPL-Caltech (http://planetquest.jpl.nasa.gov/image/114) [Public domain], via Wikimedia Commons

“Only thanks to the incredible sensitivity and resolution in the right wavelength range we are able to detect these objects at such great distances,” shared lead author Zeidler. “This has never been possible before and also will remain impossible with telescopes on the ground for the foreseeable future.”

“Until now, we’ve known of about 3000 brown dwarfs, but they all live inside our own galaxy,” added team member Elena Manjavacas of AURA/STScI for the European Space Agency.

The Hubble space telescope played a role in this work, and it’s not the first time the pair of space telescopes have created valuable scientific synergy by working together.

“This discovery highlights the power of using both Hubble and Webb to study young stellar clusters,” explained team member Antonella Nota, executive director of the International Space Science Institute in Switzerland and the previous Webb Project Scientist for ESA. “Hubble showed that NGC602 harbours very young low-mass stars, but only with Webb can we finally see the extent and the significance of the substellar mass formation in this cluster. Hubble and Webb are an amazingly powerful telescope duo!”

The researchers found 64 brown dwarf candidates in the cluster. They ranged from 0.05 to 0.08 solar masses (50-84 Jupiter masses) and are co-located with main sequence stars. The low stellar density in the cluster helped the JWST resolve individual objects. The observations are important for studying the sub-solar mass function at low metallicities.

These figures from the research illustrate some of the observations. The black circles show the region of the NGC 602 cluster, while the blue circles show the control field. The top panel shows pre-Main Sequence (PMS) stars in red circles, while the candidate brown dwarfs (cBD) are shown in yellow diamonds. The bottom panel candidate young stellar objects (cYSO) in green. PMS stars and cBDs have the same distribution, while the cYSOs are mainly located on the gas and dust ridges. Image Credit: Zeidler et al. 2024.

The concept of the Initial Mass Function (IMF) is central to star formation theory. It’s like a recipe that tells us how many stars of different masses will form in a star-forming region. The IMF usually follows a power law, meaning that more low-mass stars will form than higher-mass stars. It generally features a broad peak centred at the mass of the mean mass star.

Usually, stars lower than one stellar mass make up about 70% of the initial mass budget in a region. But even small deviations in the mean mass can have large effects on the evolution of a star cluster. Stellar radiation from young stars can affect the mean mass by raising the temperature of the star-form gas. There’s some evidence that the mean mass shifts to higher masses when the initial temperature is higher.

The data from this work shows that the low-mass objects in NGC 602 are well below the characteristic mass. The brown dwarfs have masses between 0.048 and 0.08 solar masses or 50 and 84 Jupiter masses. Since these brown dwarfs are co-located with the cluster’s young pre-Main Sequence Stars, it suggests they formed synchronously. This indicates that the stellar mass function continues into the substellar mass regime.

This image shows roughly where the studied region is in NGC 602. Image Credit: ESA/Webb, NASA & CSA, P. Zeidler, E. Sabbi, A. Nota, M. Zamani (ESA/Webb)

Unlike other similar research, the team was able to accurately measure the ages of the brown dwarfs. Typically, it’s difficult to study the IMF below the hydrogen-burning limit because objects without fusion are constantly cooling down. That makes it difficult for astronomers to estimate an object’s mass because the effective temperature keeps changing.

But by finding these brown dwarfs co-located with hydrogen-burning stars, Zeidler and his co-researchers found a way around the problem. It shows that the brown dwarfs are roughly the same age as the stars. That means the brown dwarfs and the main sequence stars all provide insight into the IMF and the sub-stellar IMF.

This figure from the research shows the radial distribution of the PMS stars (red), candidate Young Stellar Objects (green), and cBDs (yellow) within the inner 60” from the cluster center. The main sequence stars and brown dwarfs are co-located and similarly distributed, while the YSOs are less concentrated in the center of the cluster. Image Credit: Zeidler et al. 2024.

This first study is just their first step, and they intend on digging deeper.

“The accurate selection of ages, together with the superb sensitivity and calibration of JWST, will allow us, in a forthcoming paper, to reliably study the substellar mass function, well below the turnover of the IMF,” the authors write.

It’s all aimed at understanding how brown dwarfs form. If they can study the sub-stellar IMF in detail, they can determine whether it’s a continuation of the stellar IMF. Then, the researchers can answer an important unanswered question: do these objects form from the fragmentation and collapse of giant molecular clouds like stars do? Or do they form from the fragmentation of circumstellar disks like planets do?

As of now, they have only a partial answer.

“From this work, the colocation with the PMS suggests that the formation channel of the cBDs is the same as the one for their more massive stellar counterparts, as expected from solar neighbourhood studies: the fragmentation and collapse of the GMC,” the authors conclude.

The post The Webb Discovers a Rich Population of Brown Dwarfs Outside the Milky Way appeared first on Universe Today.

U.S. Naval Research Laboratory (NRL) imaging instruments on three sun-orbiting observatories have captured sequences of comet C/2023 A3, known as Tsuchinshan-ATLAS, as it passed between the Earth and the Sun during the beginning of October 2024.

Since the 1960s, astronomers have theorized that the Universe may be filled with a mysterious mass that only interacts with “normal matter” via gravity. This mass, nicknamed Dark Matter (DM), is essential to resolving issues between astronomical observations and General Relativity. In recent years, scientists have considered that DM may be composed of axions, a class of hypothetical elementary particles with low mass within a specific range. First proposed in the 1970s to resolve problems in the Standard Model of particle physics, these particles have emerged as a leading candidate for DM.

In addition to growing evidence that this could be the case, researchers at CERN are developing a new telescope that could help the scientific community look for axions – the CERN Axion Solar Telescope (CAST). According to new research conducted by an international team of physicists, these hypothetical particles may occur in large clouds around neutron stars. These axions could be the long-awaited explanation for Dark Matter that cosmologists have spent decades searching for. What’s more, their research indicates that these axions may not be very difficult to observe from Earth.

The team was led by Dion Noordhuis, a Ph.D. student with the GRavitational AstroParticle Physics Amsterdam (GRAPPA) Institute, the Institute for Theoretical Physics (ITP), and the Delta Institute for Theoretical Physics at the University of Amsterdam (UvA). He was joined by researchers from Princeton University’s Center for Theoretical Science (PCTS), the University of Barcelona, and the Rudolf Peierls Centre for Theoretical Physics at the University of Oxford. The paper that describes their findings was published on October 17th, 2024, in the journal Physical Review X.

Like DM, the existence of axions was postulated to address gaps in our understanding of the behavior of another elementary particle—the neutron. However, also like DM, these hypothetical particles have not yet been detected after decades of investigation. This is understandable since, if such particles exist, they would be extremely light, making them very hard to detect through experiments or astronomical observations. This is why axions are considered a promising candidate to explain DM, which theoretically accounts for 85% of matter in our Universe.

While DM is theorized to interact with visible matter via gravity, this does not necessarily mean that it has no other interactions that could be detectable. For example, axions are expected to convert into photons when exposed to electric and magnetic fields, which we can observe. However, the corresponding interaction strength and the amount of light produced should be very small. Therefore, they would likely go unnoticed unless there were an environment containing massive clouds of axions in a very strong electromagnetic field.

This led Noordhuis and his team to consider neutron stars since they are the densest class of stars in the Universe and generate very powerful electromagnetic fields. In fact, neutron stars generate magnetic fields that are billions of times stronger than Earth’s magnetosphere. What’s more, astronomers have used supernovae and cooling neutron stars for some time to constrain the properties of axons, including their mass and interactions with other particles. Recent research also supports the idea that their powerful magnetic fields allow neutron stars to produce huge amounts of axions near their surfaces.

In a previous study, Noordhuis and his colleagues investigated how axions could escape from a neutron star. This included computing the number of axions produced, which trajectories they would follow, and how their conversion into light could lead to an observable signal. In their latest work, the researchers focused on the axions theoretically captured by a neutron star’s gravity. Due to the very weak nature of their interactions, these particles will likely remain bound to their stars for millions of years.

Artist’s impression of an axion cloud around a neutron star. Credit: UvA

As they argue in their paper, they would gradually form a hazy cloud around the neutron star that could be visible to telescopes. The team also studied the formation, properties, and evolution of these axion clouds and found that (accounting for a wide range of axion properties) they would likely form around most, or even all, neutron stars. They also calculated that these clouds would be up to twenty orders of magnitude larger than local DM densities, producing powerful observational signatures.

These could come in the form of a continuous signal emitted during much of a neutron star’s life or as a one-time burst of light at the end of its life. These signatures would be detectable by current radio telescopes and could be used to probe the interaction between axions and photons. While no axion clouds have been observed yet, the team’s study offers astronomers parameters on what to look for. In addition to searching for axion clouds, this research presents additional opportunities for further theoretical research.

This includes follow-up work by one of the study’s co-authors on how the axion clouds can change the dynamics of neutron stars themselves. There’s also the possibility of exploring the numerical modeling of axion clouds to further constrain what and where astronomers should be looking. Finally, the present paper addresses single neutron stars, but there are also possibilities for binaries consisting of two neutron stars and a neutron star with a black hole companion. Taking advantage of next-generation instruments, in addition to current ones, these observations could be a step toward finding the elusive DM particle.

These studies could also have applications in other fields of research, such as particle physics, astrophysics, plasma physics, and radio astronomy. In short, this latest study presents opportunities for cross-disciplinary research that could resolve some of the greatest mysteries in astronomy and cosmology today.

Further Reading: University of Physics

The post White Dwarf Stars May be Shrouded in Extremely Light Particles Called Axions appeared first on Universe Today.

Some of the most cataclysmic and mysterious events in the cosmos only reveal themselves by their gravitational waves. We’ve detected some of them with our ground-based detectors, but the size of these detectors is limited. The next step forward in gravitational wave (GW) astronomy is a space-based detector: LISA, the Laser Interferometer Space Antenna.

When dense objects like black holes and neutron stars orbit each other and merge, they create gravitational waves. These ripples in space-time, which Einstein predicted in 1915, were observed for the first time in 2015 by LIGO (Laser Interferometer Gravitational-Wave Observatory). Now, we’ve observed dozens of them.

Ground-based detectors like LIGO have two long “arms” at right angles to each other. A powerful laser beam is split into two identical beams that travel down each arm, or tunnel, that are several kilometres apart. The beams are reflected back and forth by mirrors at the ends of the arms, and when they combine, they interfere with each other. Whenever a GW passes through Earth, it warps spacetime. That makes one arm longer than the other, which changes the interference pattern in the beams.

The Laser Interferometer Gravitational-Wave Observatory is made up of two detectors, this one in Livingston, La., and one near Hanford, Wash. The detectors use giant arms in the shape of an “L” to measure tiny ripples in the fabric of the universe. Credit: Caltech/MIT/LIGO Lab

The length of the arms limits the sizes of the GWs LIGO can detect and also limits the type of mergers it can detect. It can only detect higher-frequency GWs from 10 to 1,000 Hertz, which come from merging pairs of black holes (BH), merging pairs of neutron stars (NS) and merging mixed pairs of BHs and NSs.

LISA will be much different. It doesn’t have the same arm-length limitation. LISA will be the first dedicated space GW observatory, and it will consist of three separate spacecraft arranged in an equilateral triangle. Each spacecraft will be 2.5 million km apart, meaning LISA’s arms will be 2.5 million km long.

An artist’s concept of how LISA will work to detect gravitational waves from orbit in space. Courtesy ESA.

The ESA/NASA LISA mission is the next step in gravitational wave (GW) astronomy. With its much longer arms, LISA will detect low-frequency waves from 0.1 mHz to 1 Hz and expand our search for GWs and the events that create them. It’ll detect GWs from other sources, like supermassive black hole (SMBH) mergers, binary white dwarf systems, and Extreme Mass Ratio Inspirals (EMRIs). (EMRIs are systems where objects like a stellar-mass black hole or a white dwarf spiral into an SMBH.)

Like LIGO, LISA will also be a laser interferometer. Any change in its laser interference pattern can be attributed to a GW. However, LISA will do more than just detect GWs. It can determine other characteristics in the complex GW waveforms, like black hole spin.

NASA is busy working on the mission, which isn’t scheduled to launch until 2035. They’ve given us our first look at a full-scale prototype of the six cameras LISA will rely on.

“Twin telescopes aboard each spacecraft will both transmit and receive infrared laser beams to track their companions, and NASA is supplying all six of them to the LISA mission,” said Ryan DeRosa, a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The prototype, called the Engineering Development Unit Telescope, will guide us as we work toward building the flight hardware.”

On May 20, the full-scale Engineering Development Unit Telescope for the LISA (Laser Interferometer Space Antenna) mission, still in its shipping frame, was moved within a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. They’re made of an amber-coloured glass ceramic called Zerodur that resists changes over a wide range of temperatures. The telescopes also feature a thin layer of gold on their surface. Image Credit: NASA/Dennis Henry

The telescopes are made to be stable over a wide temperature range since precision is key to success. They need to detect changes as small as picometers, or trillionths of a meter, between each spacecraft. Unlike LIGO, the three spacecraft that make up the system cannot be kept at precise distances from one another. Over each year’s orbit, the distance between them changes significantly, and the system has to track the changes to guarantee precision.

The thin layer of gold is highly reflective in the infrared range that LISA’s lasers will use. It also minimizes thermal absorption and provides consistent reflectivity over long periods of time. Gold also resists corrosion, protects the underlying layer from degradation, and is thermally stable.

LISA has another trick up its sleeve: free-floating cubes or test masses. They reflect the lasers back and forth between the spacecraft and are a critical part of its detection system. They’re 46mm solid cubes made of gold-platinum alloy that weigh approximately 2 kg each. The cubes are extremely pure and will have a homogeneous material composition. They’ll float freely inside electrode housings within each spacecraft. The cubes serve as reference points for GW measurement.

The ESA and NASA have already tested some of LISA’s components in space. In 2015, the ESA launched the LISA Pathfinder mission. It tested a much smaller version of one of LISA’s arms and also tested the cubes. It placed two test masses in a near-perfect gravitational free-fall and controlled and measured their motion with unprecedented accuracy.

This image shows the interior layout of LISA Pathfinder’s science module. The test masses are visible in the centre of the image. Image Credit: ESA/ATG medialab. LICENCE: ESA Standard Licence

We’ve come a long way since Einstein predicted gravitational waves. When the first one was detected in 2015, it opened a new window into the cosmos.

LISA will throw that window wide open and reveal galaxy-defining events like supermassive black hole mergers.

The post NASA is Building Telescopes for the LISA Mission appeared first on Universe Today.

A team has developed a device that may rescue people from overdose without bystander help. In animal studies, the researchers found that the implantable device detects an overdose, rapidly delivers naloxone to prevent death and can alert emergency first responders.

Science laboratories across disciplines--chemistry, biochemistry and materials science--are on the verge of a sweeping transformation as robotic automation and AI lead to faster and more precise experiments that unlock breakthroughs in fields like health, energy and electronics.

Science laboratories across disciplines--chemistry, biochemistry and materials science--are on the verge of a sweeping transformation as robotic automation and AI lead to faster and more precise experiments that unlock breakthroughs in fields like health, energy and electronics.

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Researchers give robots a sense of touch by 'listening' to vibrations, allowing them to identify materials, understand shapes and recognize objects just like human hands. The ability to interpret the world through acoustic vibrations emanating from an object -- like shaking a cup to see how much soda is left or tapping on a desk to see if it's made out of real wood -- is something humans do without thinking. And it's an ability that researchers are on the cusp of bringing to robots to augment their rapidly growing set of sensing abilities.

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