ESA - Gaia updates

[jacqmans]

[jacqmans]

Wobbling stars reveal hidden companions in Gaia data
04/02/2025


In brief

Using data from the European Space Agency’s Gaia mission, scientists have found a huge exoplanet and a brown dwarf. This is the first time a planet has been uniquely discovered by Gaia’s ability to sense the gravitational tug or ‘wobble’ the planet induces on a star. Both the planet and brown dwarf are orbiting low-mass stars, a scenario thought to be extremely rare.

In-depth

Gaia reveals two new mysterious celestial objects
New research, published today, uses data collected by ESA’s Gaia spacecraft to confirm the existence of two mysterious celestial objects. Gaia-4b is a ‘Super-Jupiter’ exoplanet, and Gaia-5b a brown dwarf. These massive objects are unexpectedly orbiting low-mass stars.

Gaia-4b is a planet orbiting the previously unremarkable star Gaia-4 around 244 light-years away. Gaia-5b orbits the Gaia-5 star, around 134 light-years away from Earth. These two newly discovered objects are nearby, in our own galactic neighbourhood. Their existence challenges current theories of planet formation, and Gaia's ongoing mission will provide valuable data to help us understand these intriguing objects.

“Gaia-4b is about twelve times more massive than Jupiter. With an orbital period of 570 days, it is a relatively cold gas giant planet,” explains first author Guðmundur Stefánsson of the University of Amsterdam, the Netherlands, and first author of the new study.

“With a mass of around 21 Jupiters, Gaia-5b is a brown dwarf, more massive than a planet but too light to sustain nuclear fusion to be a star,” Guðmundur adds.

From wobbles to new worlds

Since its launch in 2013, ESA’s Gaia spacecraft has been building the largest, most precise three-dimensional map of our galaxy. Spinning slowly, it scanned the sky with two optical telescopes, repeatedly pinpointing the positions of two billion objects with unprecedented precision, until its end of science observations on 15 January 2025. Because Gaia precisely tracked the motion of stars – a technique known as astrometry – thousands of new objects are expected to be discovered in its data.

A planet in orbit around a star creates a tiny gravitational ‘tug’ that makes the star ‘wobble’ around its centre of mass and travel in a corkscrew-like motion across the sky. The easiest objects to discover using astrometry are massive and in distant orbits around their parent star. Previously, a few massive brown dwarfs were confirmed to exist by other telescopes who observed their faint glow next to bright stars for which Gaia had detected such a wobble.

That’s in contrast to the transit method, which detects planets as they pass in front of their star and is most likely to find planets in a close orbit. And although detecting a wobble suggests a star might have a planet, there are other potential causes (such as binary star systems), so astrometric discoveries must be confirmed using other methods.

“Gaia was repeatedly scanning these stars, building up an increasingly detailed picture over time,” Guðmundur says. “In 2022, Gaia Data Release 3 included a list of stars that appear to be moving as though pulled by an exoplanet. Using ground-based spectroscopic data and the radial velocity technique to investigate these stars, we confirmed our first planet and our first brown dwarf.”

Combining astrometric and radial velocity data allows astronomers to find all the orbital details and the mass of the orbiting object, offering a unique opportunity to create three-dimensional visualisations.

https://www.esa.int/Science_Exploration/Space_Science/Gaia/Wobbling_stars_reveal_hidden_companions_in_Gaia_data#msdynmkt_trackingcontext=29060da5-fbe5-49ef-864c-4040514ed204

[JulesVerneATV]

Shockingly Large Black Hole Lurks In Nearby Large Magellanic Cloud, Say Astronomers

https://www.forbes.com/sites/brucedorminey/2025/03/08/shockingly-large-black-hole-lurks-in-nearby-large-magellanic-cloud-say-astronomers/

[hoku]

"The final commands have been sent to Gaia. This is the last time that the spacecraft will ever hear from its team on Earth. The final commands include those to shut down the spacecraft's communication systems and central computer."

https://bsky.app/profile/operations.esa.int/post/3lldwldh54c2n

[jacqmans]

Farewell, Gaia! Spacecraft operations come to an end
27/03/2025

The European Space Agency (ESA) has powered down its Gaia spacecraft after more than a decade spent gathering data that are now being used to unravel the secrets of our home galaxy.

On 27 March 2025, Gaia’s control team at ESA’s European Space Operations Centre carefully switched off the spacecraft’s subsystems and sent it into a ‘retirement orbit’ around the Sun.

Though the spacecraft’s operations are now over, the scientific exploitation of Gaia’s data has just begun.

Gaia’s stellar contributions

Launched in 2013, Gaia has transformed our understanding of the cosmos by precisely mapping the positions, distances, motions, and properties of nearly two billion stars and other celestial objects. It has provided the largest, most precise multi-dimensional map of our galaxy ever created, revealing its structure and evolution in unprecedented detail.


The mission uncovered evidence of past galactic mergers, identified new star clusters, contributed to the discovery of exoplanets and black holes, mapped millions of quasars and galaxies, and tracked hundreds of thousands of asteroids and comets. It also enabled the creation of the best visualisation of how our galaxy might look to an outside observer.

“Gaia’s extensive data releases are a unique treasure trove for astrophysical research, and influence almost all disciplines in astronomy,” says Gaia Project Scientist Johannes Sahlmann.

“Data release 4, planned for 2026, and the final Gaia legacy catalogues, planned for release no earlier than the end of 2030, will continue shaping our scientific understanding of the cosmos for decades to come.”

Saying goodbye is never easy

Gaia far exceeded its planned lifetime of five years, and its fuel reserves are dwindling. The Gaia team carefully considered how best to dispose of the spacecraft in line with ESA’s efforts to responsibly dispose of its missions.

They wanted to find a way to prevent Gaia from drifting back towards its former home near the scientifically valuable second Lagrange point (L2) of the Sun-Earth system and minimise any potential interference with other missions in the region.

“Switching off a spacecraft at the end of its mission sounds like a simple enough job,” says Gaia Spacecraft Operator Tiago Nogueira. “But spacecraft really don’t want to be switched off.”

“Gaia was designed to withstand failures such as radiation storms, micrometeorite impacts or a loss of communication with Earth. It has multiple redundant systems that ensured it could always reboot and resume operations in the event of disruption.”

“We had to design a decommissioning strategy that involved systematically picking apart and disabling the layers of redundancy that have safeguarded Gaia for so long, because we don’t want it to reactivate in the future and begin transmitting again if its solar panels find sunlight.”


On 27 March 2025, the Gaia control team ran through this series of passivation activities. One final use of Gaia’s thrusters moved the spacecraft away from L2 and into a stable retirement orbit around the Sun that will minimise the chance that it comes within 10 million km Earth for at least the next century.

The team then safely deactivated and switched off the spacecraft’s instruments and subsystems one by one, before deliberately corrupting its onboard software. The communication subsystem and the central computer were the last to be deactivated.

“Today, I was in charge of corrupting Gaia’s processor modules to make sure that the onboard software will never restart again once we have switched off the spacecraft,” says Spacecraft Operations Engineer, Julia Fortuno.

“I have mixed feelings between the excitement for these important end-of-life operations and the sadness of saying goodbye to a spacecraft I have worked on for more than five years. I am very happy to have been part of this incredible mission.”

Gaia’s final transmission to ESOC mission control marked the conclusion of an intentional and carefully orchestrated farewell to a spacecraft that has tirelessly mapped the sky for over a decade.

https://www.esa.int/Enabling_Support/Operations/Farewell_Gaia!_Spacecraft_operations_come_to_an_end#msdynmkt_trackingcontext=c96ce472-ff3b-45cb-8d38-3fd787db0300

[jacqmans]

Gaia spots odd family of stars desperate to leave home
29/04/2025


In brief

The European Space Agency’s Gaia mission has spotted an unusual family of stars all strangely eager to leave home – a family we couldn’t have discovered without the star-surveying spacecraft, and one unlike all others we have spotted to date.

In-depth

Stars in the Milky Way tend to form in families, with similar stars springing to life in roughly the same place at roughly the same time. These stars later head out into the wider galaxy when they’re ready to fly the nest. While smaller groups can completely dissipate, siblings from sizeable families usually move similarly and largely travel together.

We have seen many star families with Gaia. We’ve spotted strings of stars stretching out across the Milky Way and remaining intact for billions of years, mapped the ancient star streams that wound together to form the earliest structure of our galaxy, and put together a stellar ‘family portrait’ of our cosmic home.By studying star families we can piece together not only the characteristics and behaviour of the stars themselves, but also learn about how our galaxy is evolving as a whole.

A family like no other

Using Gaia data, scientists have now spotted a star family unlike any other: a massive family of over 1000 young stars behaving oddly. Despite its size, the family – dubbed Ophion – will soon have completely dispersed in record time, leaving just an empty nest behind.

“Ophion is filled with stars that are set to rush out across the galaxy in a totally haphazard, uncoordinated way, which is far from what we’d expect for a family so big,” says Dylan Huson of Western Washington University (WWU), USA, and lead author of the discovery paper. “What’s more, this will happen in a fraction of the time it’d usually take for such a large family to scatter. It’s like no other star family we’ve seen before.”

A new model

To find Ophion, Dylan and colleagues developed a new model to explore Gaia’s vast, unrivalled trove of spectroscopic data and learn more about young, low-mass stars lying reasonably near to the Sun. They applied this model, named Gaia Net, to the hundreds of millions of stellar spectra released as part of Gaia’s data release 3. They then narrowed 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. This kind of bulk observing is one of Gaia’s truly unprecedented achievements.”

“Another is how the Gaia mission is creating opportunities for new collaborative and interdisciplinary science through its open data policy. Several members of the Ophion discovery team are undergraduate and postgraduate students in computer science, who used Gaia data to innovate and develop new methods that are now offering new insights into the stars of the Milky Way.”

Solving the mystery

The question remains: why is Ophion behaving so unusually?

The scientists discuss several options. The star family resides around 650 light-years away near to some other massive gatherings of young stars; energetic events within and interactions between these colossal neighbours may have influenced Ophion through the years.

There are also signs that stars have exploded here in the past. These supernova bursts 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. This marks the end of the spacecraft’s operations – 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. (Data Release 4 is planned towards the end of 2026, and the Gaia legacy data release is planned for publication not before the end of 2030).

Notes for editors

“Gaia Net: Towards robust spectroscopic parameters of stars of all evolutionary stages” by Dylan Huson et al. is published in The Astrophysical Journal. https://iopscience.iop.org/article/10.3847/1538-4357/adc2fa

For more information, please contact:
ESA Media relations
[email protected]

https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_spots_odd_family_of_stars_desperate_to_leave_home#msdynmkt_trackingcontext=ced6ac75-a101-4466-9ef6-0da4b9e60100

[jacqmans]

Gaia proves our skies are filled with chains of starry gatherings
26/08/2025

In the past decade, the European Space Agency’s Gaia mission has revealed the nature, history, and behaviour of billions of stars. Our pioneering stargazer has reshaped our view of the skies around us like no other, revealing that star clusters are more connected than expected over vast distances.

Understanding the Milky Way and its stars is what Gaia was built for – and the telescope was certainly fit for the job.

After more than a decade spent observing our skies, Gaia is now enjoying a quiet retirement, with most of its data is yet to be released. However, the mission’s first data releases have already nailed down the locations, motions, and brightnesses of stars in our galaxy with truly unprecedented precision, allowing us to understand these Milky Way residents like never before.

Since it opened its eyes in 2014, Gaia has mapped how different stars zip through space and pinpointed their whereabouts more precisely than ever. The telescope has watched whether they shrink and swell, spotted surprising ‘starquakes’, monitored how stars grow, evolve, and crystallise as they die, and discovered stellar travellers seeking solace in our galaxy after being kicked out of their own. It has created the largest and most precise multi-dimensional map of our galaxy ever.

Crucially, Gaia has meticulously scanned the contents of our galaxy to understand star clusters.

There are two types of cluster. The first are open clusters: small gatherings of hundreds or thousands of stars typically found closer to the main disc of a galaxy. The second are globular clusters, which lurk at a galaxy’s outer edges or central regions and can contain millions of starry residents.

While most stars are born and grow up together in clusters, star families don’t stick together forever; over time, stars disperse into the broader population of stars in the Milky Way. In this way, star clusters define the nature and composition of our galaxy’s disc and hold clues to what happened in its past. If we’re to understand the history and evolution of the Milky Way, we need to understand star clusters.

https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_proves_our_skies_are_filled_with_chains_of_starry_gatherings#msdynmkt_trackingcontext=e37eca73-9c56-46d2-b921-89e68aed0000

[jacqmans]

Gaia discovers our galaxy’s great wave
30/09/2025

Our Milky Way galaxy never sits still: it rotates and wobbles. And now, data from the European Space Agency’s Gaia space telescope reveal that our galaxy also has a giant wave rippling outwards from its centre.

We’ve known for about a hundred years that the galaxy’s stars rotate around its centre, and Gaia has measured their speeds and motions. Since the 1950s, we've known that the Milky Way's disc is warped. Then in 2020 Gaia discovered that this disc wobbles over time, similarly to the motion of a spinning top. 

And now it has become clear that a great wave stirs the motion of stars in our galaxy over distances of tens of thousands of light-years from the Sun. Like a rock thrown into a pond, making waves ripple outwards, this galactic wave of stars spans a large portion of the Milky Way’s outer disc.

The unexpected galactic ripple is illustrated in this figure above. Here the positions of thousands of bright stars are shown in red and blue, overlaid on Gaia’s maps of the Milky Way. 

In the left image, we look at our galaxy from ‘above’. On the right, we see across a vertical slice of the galaxy and look at the wave side-on. This perspective reveals that the ‘left’ side of the galaxy curves upward and the ‘right’ side curves downward (this is the warp of the disc). The newly discovered wave is indicated in red and blue: in red areas, the stars lie above, and in blue areas the stars lie below the warped disc of the galaxy.

Even if no spacecraft can travel beyond our galaxy, Gaia’s uniquely accurate vision – in all three spatial directions (3D) plus three velocities (moving towards and away from us, and across the sky) – is enabling scientists to make these top-down and edge-on maps.

From these, we can see that the wave stretches over a huge portion of the galactic disc, affecting stars around at least 30–65 thousand light-years away from the centre of the galaxy (for comparison, the Milky Way is around 100 thousand light-years across).

“What makes this even more compelling is our ability, thanks to Gaia, to also measure the motions of stars within the galactic disc,” says Eloisa Poggio who is an astronomer at the Istituto Nazionale di Astrofisica (INAF) in Italy, and led the team of scientists that discovered the wave.

“The intriguing part is not only the visual appearance of the wave structure in 3D space, but also its wave-like behaviour when we analyse the motions of the stars within it.”

https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_discovers_our_galaxy_s_great_wave#msdynmkt_trackingcontext=ff136ac8-d6c6-45d6-ad39-f53f7a6c0000

[JulesVerneATV]

Gaia data uncovers hidden link between asteroid collisions and chaotic spin states
https://www.spacedaily.com/reports/Gaia_data_uncovers_hidden_link_between_asteroid_collisions_and_chaotic_spin_states_999.html
Whether an asteroid spins smoothly or tumbles chaotically depends on how often it has collided with other objects, according to new findings presented at the EPSC-DPS2025 Joint Meeting in Helsinki. Using data from the European Space Agency's Gaia mission, researchers have discovered that these collision patterns reveal clues about asteroids' internal structure and evolution.

Dr Wen-Han Zhou of the University of Tokyo, who presented the results, said, "By leveraging Gaia's unique dataset, advanced modelling and A.I. tools, we've revealed the hidden physics shaping asteroid rotation, and opened a new window into the interiors of these ancient worlds."

Gaia's all-sky survey has captured vast amounts of light-curve data, showing how asteroid brightness changes as they spin. When plotted as rotation period versus diameter, the data reveals a distinct gap dividing two populations. Zhou's team, supported by work at the Observatoire de la Cote d'Azur, found that this division marks a balance between two competing processes: collisions that induce tumbling, and internal friction that stabilizes rotation.

Using machine learning to analyze Gaia's asteroid catalogue, the team confirmed that this dividing line matches their model's predictions. Below the gap lie slow, tumbling asteroids with rotational periods under 30 hours, while above it are faster, stable spinners. The study provides a physical explanation for why many smaller asteroids rotate irregularly rather than smoothly.

Collisions and solar radiation both play a role. Slowly spinning asteroids are more easily knocked into chaotic rotation, while the sunlight-driven YORP effect - small photon pushes from re-emitted heat - fails to stabilize them because their random tumbling cancels out the directional thrust. This dynamic traps such asteroids in the slow-rotation region seen in Gaia's data.

[JulesVerneATV]

Gaia BH2 (Gaia DR3 5870569352746779008) a binary system consisting of a red giant and a stellar-mass black hole.

Astronomers Found a Star That Makes No Sense
https://www.sciencealert.com/astronomers-found-a-star-that-makes-no-sense

Studying the light from stars tells us their temperature, composition, age, and evolutionary state.

But the red giant companion to Gaia BH2, a black hole system discovered in 2023, tells a contradictory story that doesn't make sense until you consider stellar violence!

The star is packed with heavy elements called alpha elements, chemical signatures typically found in ancient stars formed when the Universe was young. Based on this chemistry alone, it should be around ten billion years old.

Yet when astronomers from the University of Hawaii measured vibrations rippling through its interior using NASA's TESS satellite, they discovered the star is only about five billion years old.

"Young, alpha-rich stars are quite rare and puzzling. The combination of youth and ancient chemistry suggests this star didn't evolve in isolation," says Daniel Hey, lead author of the study published in The Astrophysical Journal.

The technique, called asteroseismology, works like seismology on Earth.

Just as earthquake waves reveal our planet's internal structure, starquakes, oscillations that make a star's brightness flicker subtly, reveal what's happening beneath the surface.

These vibrations allowed the team to measure the star's core properties with remarkable precision.

The star's rotation adds another clue; ground-based telescopes show it spins once every 398 days, which is far faster than an isolated red giant of its age should rotate.




4th data release from Gaia isn’t until 2026, with the final data release around 2030.

Gaia Data Release 4 (Gaia DR4)
https://www.cosmos.esa.int/web/gaia/dr4

[Star One]

Gaia spacecraft passivation:

[jacqmans]

Gaia finds hints of planets in baby star systems
18/12/2025

Ever wondered how planetary systems like our own Solar System form? Thanks to the European Space Agency’s Gaia space telescope, we're getting a unique peek behind the cosmic curtain into these dusty environments.

In this collage, we see the images of 31 baby star systems. Click on the white dots next to each system to find out more about them. The bar on the top right shows the scale of the image in Astronomical Units (AU).

The collage also shows our own Solar System for reference on the bottom right, as it is predicted to have looked at an age of 1 million years, with the Sun at its centre (not visible).

All of the systems are centred around very young stars that have recently collapsed from vast clouds of gas and dust.

After the clouds collapsed under their own gravity, they spun faster and flattened into discs with hot, dense centres. These centres became the stars, sometimes multiple stars were formed. The discs around them are called protoplanetary discs.

The 31 baby systems are shown here in orange-purple, as seen by the Atacama Large Millimeter Array (ALMA) ground-based telescope.

Astronomers expect the remaining material in protoplanetary discs to clump together to form planets, but until now it’s been very difficult to spot them because of all the dust and gas present in discs. To date, very few planets have been detected around forming stars.

Enter Gaia.

In 31 out of 98 young star systems, Gaia has detected subtle motions that suggest the presence of unseen companions. For seven of these systems, the observed motions are consistent with objects of planetary mass. In eight systems, the data best match the presence of brown dwarfs – objects larger than planets but smaller than stars. The remaining sixteen systems likely have additional stars around.

Gaia’s predicted locations of these companions in the systems are shown in cyan. In the reference image of our baby Solar System, Jupiter’s orbit is also shown in cyan.

Gaia discovered the companions in the baby star systems thanks to its unique ability to sense the gravitational tug or ‘wobble’ a planet or companion induces on a star. This technique had already been used to find companions around older stars. But now, for the first time, a team of astronomers led by Miguel Vioque of the European Southern Observatory, Germany, has used this Gaia technique to find planets and companions around stars that are still forming.

The all-sky, large-scale nature of the Gaia survey enabled the team to study hundreds of forming stars and identify companions across large samples for the first time. This in contrast to costly ground-based searches that can only target a few stars at a time.

This ability of Gaia is revolutionising the field of star and planet formation. The companions that the telescope has already found, can now be followed up by telescopes like the NASA/ESA/CSA James Webb Space telescope that can study the inner discs of the baby systems in more detail.

With Gaia’s upcoming fourth data release, many more hidden planets are expected to be uncovered.

This new finding has been described in ‘Astrometric view of companions in the inner dust cavities of protoplanetary disks’ by M. Vioque et al., accepted for publication in Astronomy & Astrophysics.

Learn more

[Image description: A collage of 32 glowing discs on a black background. Each disc shows concentric rings in vivid colours: purple, orange, and yellow, with bright cyan centres. The discs vary in size and orientation, creating a striking pattern of circular and elliptical shapes.]

[AegeanBlue]

This is a lecture by a Gaia consortium member to a colloquium on October 30 2025. The lecturer, she mentions what is expected in DR4, whose release date has more firmly been place in December 2026 since that lecture. 2.5 billion objects, definitely becoming the largest astronomical catalog, thousands of exoplanets, 360,000 solar system objects, including shape models for 57,000 of them, 4,5 million quasars, and that is what is on top of my head. There was a brief mention of GaiaNir: IR sensors have improved enough to be as good as Gaia's visible sensor. Also they are investigating doubling the size of the mirrors, so as to reduce star crowding, which is going to be much worse in NIR where gas clouds are transparent, unlike visible light