The European Space Agency’s Gaia mission has made another groundbreaking discovery – a star family unlike any other. Dubbed Ophion, this massive group of over 1,000 young stars is behaving oddly, with its members set to rush out across the galaxy in a totally haphazard and uncoordinated way. This is far from what we’d expect for a family so big, making it like no other star family seen before.

Gaia’s vast trove of spectroscopic data allowed scientists to develop a new model, Gaia Net, to explore this data and learn more about young, low-mass stars lying reasonably near to the Sun. The team applied this model to hundreds of millions of stellar spectra released as part of Gaia’s data release 3, narrowing their search to ‘young’ stars of under 20 million years in age – and out jumped Ophion.

“This is the first time that it’s been possible to use a model like this for young stars, due to the immense volume and high quality of spectroscopic observations needed to make it work,” adds ESA Gaia Project Scientist Johannes Sahlmann. “It’s still pretty new to be able to reliably measure the parameters of lots of young stars at once.”

The scientists discuss several options as to why Ophion is behaving so unusually, including energetic events within and interactions between other massive gatherings of young stars, and signs that stars have exploded here in the past, causing supernova bursts that could have swept material away from Ophion and caused its stars to move far more rapidly and erratically than before.

“We don’t know exactly what happened to this star family to make it behave this way, as we haven’t found anything quite like it before. It’s a mystery,” says co-author Marina Kounkel of the University of North Florida, USA.

Excitingly, it changes how we think about star groups and how to find them. Previous methods identified families by clustering similarly moving stars together, but Ophion would have slipped through this net. Without the huge, high-quality datasets from Gaia, and the new models we can now use to dig into these, we may have been missing a big piece of the stellar puzzle.

After more than a decade spent mapping our skies, Gaia stopped observing in March, but it’s just the beginning of the science. Many more discoveries are anticipated in the coming years, along with Gaia’s biggest data releases yet.

The NASA New Horizons spacecraft has achieved a major milestone in its journey to explore the outer reaches of our solar system by creating the first-ever map of Lyman-alpha emissions from the galaxy. This breakthrough was made possible by the spacecraft’s extensive observations using the Alice instrument, an ultraviolet spectrograph developed by the Southwest Research Institute (SwRI).

Lyman-alpha is a specific wavelength of ultraviolet light emitted and scattered by hydrogen atoms, which is crucial for astronomers studying distant stars, galaxies, and the interstellar medium. By mapping this emission, scientists can gain insights into the composition, temperature, and movement of these celestial objects.

According to Dr. Randy Gladstone, lead investigator on the study and first author of the publication, understanding the Lyman-alpha background helps shed light on nearby galactic structures and processes. The research suggests that hot interstellar gas bubbles, like the one our solar system is embedded within, may actually be regions of enhanced hydrogen gas emissions at a wavelength called Lyman alpha.

During its initial journey to Pluto, New Horizons collected baseline data about Lyman-alpha emissions using the Alice instrument. After completing its primary objectives at Pluto, scientists used Alice to make broader and more frequent surveys of Lyman-alpha emissions as the spacecraft traveled farther from the Sun. These surveys included an extensive set of scans in 2023 that mapped roughly 83% of the sky.

To isolate emissions from the galaxy, the New Horizons team modeled scattered solar Lyman-alpha emissions and subtracted them from the spectrograph’s data. The results indicate a roughly uniform background Lyman alpha sky brightness 10 times stronger than expected from previous estimates.

These findings point to the emission and scattering of Lyman-alpha photons by hydrogen atoms in the shell of a hot bubble, known to surround our solar system and nearby stars, that was formed by nearby supernova events a few million years ago. The study also found no evidence that a hydrogen wall, thought to surround the Sun’s heliosphere, substantially contributes to the observed Lyman-alpha signal.

“This is really landmark observations,” said co-author and New Horizons Principal Investigator Dr. Alan Stern, “in giving the first clear view of the sky surrounding the solar system at these wavelengths, both revealing new characteristics of that sky and refuting older ideas that the Alice New Horizons data just doesn’t support.” The Lyman-alpha map also provides a solid foundation for future investigations to learn even more about our galactic neighborhood.

The universe is home to an astonishing array of celestial bodies, but recent discoveries have shed new light on the prevalence of one type of planet: the super-Earth. Using the Korea Microlensing Telescope Network (KMTNet), an international team of researchers has found that these massive worlds are more common across the cosmos than previously thought.

By studying light anomalies caused by the newly found planet’s host star, combined with a larger sample from a KMTNet microlensing survey, the team was able to show that super-Earths can exist as far from their host star as our gas giants are from the sun. This is particularly interesting because it challenges previous theories about the formation and evolution of these planets.

One of the key findings of this study is that for every three stars, there should be at least one super-Earth present with a Jupiter-like orbital period. This suggests that these massive worlds are extremely prevalent across the universe. To make these discoveries, researchers used an observational effect called microlensing, which occurs when the presence of mass warps the fabric of space-time to a detectable degree.

The team was able to locate OGLE-2016-BLG-0007, a super-Earth with a mass ratio roughly double that of Earth’s and an orbit wider than Saturn’s. These observations allowed them to divide exoplanets into two groups: one consisting of super-Earths and Neptune-like planets, and the other comprising gas giants like Jupiter or Saturn.

This discovery opens new doors for planetary system science, as having a better understanding of exoplanet distribution can reveal new insights about the processes by which they form and evolve. The study also compared their findings to predictions made from theoretical simulations of planet formation, showing that while exoplanets can be separated into groups by mass and makeup, the mechanisms that may produce them can vary.

The researchers believe that greater swaths of long-term data from specialized systems like KMTNet and other microlensing instruments will be necessary to distinguish between different theories of gas-giant formation. This study was led by researchers in China, Korea, and at Harvard University and the Smithsonian Institution in the United States, and was recently published in the journal Science.

In conclusion, this discovery has significant implications for our understanding of the universe, revealing a cosmic abundance of super-Earths that challenges previous theories about their formation and evolution. Further research will be necessary to uncover more secrets about these enigmatic worlds.