Last starlight for ground-breaking Gaia

The European Space Agency’s Milky Way-mapper Gaia has completed the sky-scanning phase of its mission, racking up more than three trillion observations of about two billion stars and other objects over the last decade to revolutionise the view of our home galaxy and cosmic neighbourhood.

Launched on 19 December 2013, Gaia’s fuel tank is now approaching empty – it uses about a dozen grams of cold gas per day to keep it spinning with pinpoint precision. But this is far from the end of the mission. Technology tests are scheduled for the weeks ahead before Gaia is moved to its ‘retirement’ orbit, and two massive data releases are tabled for around 2026 and the end of this decade, respectively.

“Today marks the end of science observations and we are celebrating this incredible mission that has exceeded all our expectations, lasting for almost twice its originally foreseen lifetime,” says ESA Director of Science Carole Mundell.

“The treasure trove of data collected by Gaia has given us unique insights into the origin and evolution of our Milky Way galaxy, and has also transformed astrophysics and Solar System science in ways that we are yet to fully appreciate. Gaia built on unique European excellence in astrometry and will leave a long-lasting legacy for future generations."

“After 11 years in space and surviving micrometeorite impacts and solar storms along the way, Gaia has finished collecting science data. Now all eyes turn towards the preparation of the next data releases,” says Gaia Project Scientist Johannes Sahlmann.

“I am thrilled with the performance of this incredible mission, and excited about the discoveries that await us.”

Researchers from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) have played a crucial role in the Gaia mission since the very beginning. 

"The Gaia team at the University of Barcelona has been working on the mission since its inception around 1997." says Xavier Luri, director of the ICCUB and member of the Gaia UB team. "Since then, they have participated in all its phases, from defining the scientific case and industrial design to data processing and scientific exploitation. Now, although Gaia is ending its observations, several years of work remain to fully process all the data collected over these years and publish two additional data releases (DR4 and DR5)."

Gaia delivers best Milky Way map

Gaia has been charting the positions, distances, movements, brightness changes, composition and numerous other characteristics of stars by monitoring them with its three instruments many times over the course of the mission.

This has enabled Gaia to deliver on its primary goal of building the largest, most precise map of the Milky Way, showing us our home galaxy like no other mission has done before.

As such, we now also have the best reconstructed view of how our galaxy might look to an outside observer. This new artist impression of the Milky Way incorporates Gaia data from a multitude of papers over the past decade.

“It contains major changes from previous models, because Gaia has changed our impression of the Milky Way. Even basic ideas have been revised, such as the rotation of our galaxy’s central bar, the warp of the disc, the detailed structure of spiral arms, and interstellar dust near the Sun,” says Stefan Payne-Wardenaar, scientific visualiser at the Max Planck Institute for Astronomy, Germany.

“Still, the distant parts of the Milky Way remain educated guesses based on incomplete data. With further Gaia data releases our view of the Milky Way will become even more accurate.”

Discovery machine of the decade

Gaia’s repeated measurements of stellar distances, motions and characteristics are key to performing ‘galactic archeology’ on our Milky Way, revealing missing links in our galaxy’s complex history to help us learn more about our origins. From detecting ‘ghosts’ of other galaxies and multiple streams of ancient stars that merged with the Milky Way in its early history, to finding evidence for an ongoing collision with the Sagittarius dwarf galaxy today, Gaia is rewriting the Milky Way’s history and making predictions about its future.

In the process of scanning the stars in our own galaxy, Gaia has also spotted other objects, from asteroids in our Solar System backyard to galaxies and quasars – the bright and active centres of galaxies powered by supermassive black holes – outside our Milky Way.

For example, Gaia has provided pinpoint precision orbits of more than 150 000 asteroids, and has such high-quality measurements as to uncover possible moons around hundreds of them. It has also created the largest three-dimensional map of about 1.3 million quasars, with the furthest shining bright when the Universe was only 1.5 billion years old.

Gaia has also discovered a new breed of black hole, including one with a mass of nearly 33 times the mass of the Sun, hiding in the constellation Aquila, less than 2000 light-years from Earth – the first time a black hole of stellar origin this big has been spotted within the Milky Way.

“It is impressive that these discoveries are based only on the first few years of Gaia data, and many were made in the last year alone. Gaia has been the discovery machine of the decade, a trend that is set to continue,” says Anthony Brown, Chair of the Gaia Data Processing and Analysis Consortium (DPAC) and based at Leiden University in the Netherlands.

Warning! More ground-breaking science ahead

The Gaia scientific and engineering teams are already working full steam on the preparations for Gaia Data Release 4 (DR4), expected in 2026. The data volume and quality improves with every release and Gaia DR4, with an expected 500 TB of data products, is no exception. Furthermore, it will cover the mission’s first 5.5 years, corresponding to the length of the originally foreseen duration of the mission.

“This is the Gaia release the community has been waiting for, and it’s exciting to think this only covers half of the collected data,” says Antonella Vallenari, Deputy Chair of DPAC based at the Istituto Nazionale di Astrofisica (INAF), Astronomical Observatory of Padua, Italy.

“Even though the mission has now stopped collecting data, it will be business as usual for us for many years to come as we make these incredible datasets ready for use.”

 Gaia DR4 is set to expand its binary star catalogue, the largest such catalogue to date. Gaia has a unique ability to tease out the tiny motions of pairs of celestial objects orbiting close to each other, and has already spotted previously hidden companions around bright stars.

Incidentally, Gaia’s last targeted observation, on 10 January, was of binary pair 61 Cygni. This iconic star attracted the attention of 19th-century astronomers to yield some of the first proper motion and parallax measurements, techniques used by Gaia on some two billion stars.

Gaia’s exoplanet discoveries are also set to increase with the forthcoming datasets thanks to the longer timeframe of observations making it much easier to spot ‘wobbling’ stars gently tugged by orbiting planets.

“Over the next months we will continue to downlink every last drop of data from Gaia, and at the same time the processing teams will ramp up their preparations for the fifth and final major data release at the end of this decade, covering the full 10.5 years of mission data,” says Rocio Guerra, Gaia Science Operations Team Leader based at ESA’s European Space Astronomy Centre (ESAC) near Madrid in Spain.

“This will conclude an incredible coordinated effort between hundreds of experts across the science operations centre here at ESAC, the mission operations team flying Gaia from ESA’s European Space Operations Centre in Germany, and the huge consortium of data processing specialists, who have together ensured the smooth running of this beautiful mission for so long.”

Gaia’s retirement plan

While today marks the end of science observations, a short period of technology testing now begins. The tests have the potential to further improve the Gaia calibrations, learn more about the behaviour of certain technology after ten years in space, and even aid the design of future space missions.

After several weeks of testing, Gaia will leave its current orbit around Lagrange point 2, 1.5 million km from the Earth in the direction away from the Sun, to be put into its final heliocentric orbit, far away from Earth’s sphere of influence. The spacecraft will be passivated on 27 March 2025, to avoid any harm or interference with other spacecraft.

Wave farewell to Gaia

During the technology tests Gaia’s orientation will be changed, meaning it will temporarily become several magnitudes brighter, making observations through small telescopes a lot easier (it won’t be visible to the naked eye). A guide to locating Gaia has been set up here, and amateur astronomers are invited to share their observations.

“Gaia will treat us with this final gift as we bid farewell, shining among the stars ahead of its well-earned retirement,” concludes Uwe Lammers, Gaia Mission Manager.

“It’s a moment to celebrate this transformative mission and thank all of the teams for more than a decade of hard work operating Gaia, planning its observations, and ensuring its precious data are returned smoothly to Earth.”

The SKA Observatory (Square Kilometre Array, SKAO) has entrusted Compoxi (a Girona-based company specialising in the design and production of composite materials) and EOSOL (an international company based in Navarra specialising in engineering services) to build a large number of sub-reflectors for the mid-frequency telescope ‘SKA-Mid’, currently under construction in South Africa.

SKAO is considered one of the largest scientific engineering projects of the 21st century. Countries from five continents are collaborating in the construction of the two largest radio telescope arrays on Earth: on the one hand, in Australia, the low frequency array, known as ‘SKA-Low’, will have 131,072 antennas spread over 74 km; on the other hand, in South Africa, ‘SKA-Mid’ will have 197 parabolic antennas (incorporating the 64 of the ‘MeerKAT’ radio telescope) spread over 150 km. Because of the size and number of antennas, SKA will represent a significant leap in resolution, sensitivity and observing speed over other radio telescopes, allowing more parts of the universe to be seen in greater detail than ever before. The array design and processing power will also allow radio astronomers around the world to study different parts of the cosmos simultaneously.

The Institute of Space Studies of Catalonia (IEEC — Institut d’Estudis Espacials de Catalunya) collaborates with the SKA Observatory with researchers at the Institute of Space Sciences (ICE-CSIC) and the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), who participate in different science working groups. Some of the topics covered include the study of the cradle of life (the formation of planets, etc.), our galaxy, cosmic magnetism, pulsars or transient events.

Compoxi is part of the NewSpace Lab, the reference point for NewSpace sector facilities in Catalonia, an initiative of the Government of Catalonia and the IEEC to facilitate the use of the various infrastructures. With the participation of Compoxi in the construction of the sub-reflectors, the Catalan contribution to the observatory extends to the technical part from the private sector, which shows the great potential of the space sector in the region.

The sub-reflector is one of the critical parts of the satellite dish, which serves to concentrate the signals collected by the main reflector. Each sub-reflector is a 4.5-metre structure made of composite material and metallised to achieve the electromagnetic and mechanical properties required for the project.

“The ‘SKA-Mid’ subreflector is a technically challenging design; the surface requires high levels of precision and is a critical optical component to accurately reflect the faint astronomical signal received,” says SKAO Dish project manager Mark Harman. “It also has to be very rigid to withstand the environmental conditions. We are very impressed with the capabilities of EOSOL and COMPOXI and are excited to be working on this project as we start to prepare for construction activities next year.”

SKAO is part of a new era in the history of the exploration of the Universe. It will aim to answer fundamental questions in astrophysics, while bringing benefits to society through technological innovations and collaborations between continents and scientific communities. As for the IEEC, the following ICE-CSIC researchers participate in a working group of the project: Josep Miquel Girart, Ciska Kemper, Álvaro Sánchez Monge, Daniele Viganò, Francesco Coti Zelati, Nanda Rea, Laura Tolós, Diego Torres, Mar Mezcua and Josep Maria Trigo. From the ICCUB, the researcher Gemma Busquet is participating.

The radio telescopes are currently in the construction phase; the first scientific verifications are expected to begin with partial arrays at the end of 2026, and the scientific capabilities will increase as construction continues over the next six years.

Links

• IEEC
• ICE-CSIC
• ICCUB
• Compoxi
• EOSOL
• SKAO

Using the set of first-light observations from the new William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE) wide-field spectrograph, a team of more than 50 astronomers, led by Dr Marina Arnaudova at the University of Hertfordshire, has presented the first WEAVE scientific results on Stephan’s Quintet.
This state-of-the-art wide-field spectrograph is a 20-million Euro project that brings together leading experts from around the world. WEAVE is set to revolutionise our understanding of the Universe, offering unprecedented detail, as demonstrated in this new study of Stephan’s Quintet.

Stephan's Quintet, also known as the Hickson Compact Group 92, is a nearby galaxy group that consists of five galaxies (NGC 7317, NGC 7318a, NGC 7318b, NGC 7319 and NGC 7320c). Ever since its discovery in 1877, it has captivated astronomers, particularly because it represents a galactic crossroad where past collisions between galaxies have left behind a complex field of debris.

“Dynamical activity in this galaxy group has now been reawakened by NGC 7318b, a galaxy smashing through it at an incredible speed of over 2 million miles per hour (3.2 million kilometres per hour), leading to an immensely powerful shock, much like a sonic boom from a jet fighter”, says Dr Arnaudova. This system thus presents an ideal laboratory to understand the chaotic and often violent relationship between galaxies, and as such was the focus of the first-light observations by the WEAVE Large Integral Field Unit (LIFU).

Published in the Monthly Notices of the Royal Astronomical Society (MNRAS), Dr Arnaudova and her team provide a new insight into the large-scale shock front. By combining data from WEAVE's LIFU with other cutting-edge instruments such as the Low Frequency Array (LOFAR), the Very Large Array (VLA), and the James Webb Space Telescope (JWST), they have found a previously undiscovered dual nature of the shock.

As the shock moves through pockets of cold gas, it travels at hypersonic speeds—several times the speed of sound—powerful enough to rip apart electrons from atoms, leaving behind a glowing trail of charged gas, as seen with WEAVE. However, when the shock passes through the surrounding hot gas, it becomes much weaker. Instead of causing significant disruption, the weak shock compresses the hot gas, resulting in radio waves that are picked up by radio telescopes like LOFAR.

The WEAVE, a new generation spectrograph

The WEAVE spectrograph uses optical fibres to collect light from celestial objects and transmits it to a spectrograph that separates the light according to its different wavelengths. It can work at two different spectral resolutions, which are used to measure the speeds of objects in the line of sight (using the Doppler effect) and to determine their chemical composition. The versatility of WEAVE is one of its main strengths. While the LIFU mode contains hundreds of fibres in a compact distribution, essential for imaging extended areas of the sky, in the MOS mode about a thousand individual fibres can be placed (by two robots) to simultaneously collect light from stars, galaxies or quasars. During the first five years of operation, spectra of millions of individual stars and galaxies are expected, a goal that can be achieved thanks to the WEAVE spectrograph's ability to observe so many bodies at once.

The Catalan contribution to the WEAVE spectrograph

This project involves scientists from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and the Technical University of Catalonia (UPC). The Institute for Space Studies of Catalonia (IEEC) is taking part with researchers from the ICCUB and UPC units. The Catalan institutions have worked, from the beginning of the project, on the definition of the scientific objectives and the selection of the objects to be observed —from stars in various evolutionary phases to star clusters— as well as in the sampling of quasars, extremely bright and very distant active nuclei galaxies. Specifically, one ICCUB-IEEC member, Mercè Romero-Gómez, and one from the UPC, Roberto Raddi, are members of the international working groups on young stars, galactic archaeology and white dwarfs that make up the team of scientists responsible for planning the observations. Teresa Antoja (ICCUB) and Ignasi Pérez-Ràfols (UPC) co-lead the research teams responsible for galactic disc dynamics and quasars, respectively.
Mercè Romero-Gómez, from the Institute of Cosmos Sciences (ICCUB-IEEC), says: "After years of preparation, we have been able to obtain the first spectra with the Large Integral Field Unit of WEAVE from the Stephan’s quintet group of galaxies. The quality of the spectra has allowed to reassess the dynamical processes happening in this well-known set of galaxies”. In the following year, data coming from the Multi-Object Spectrograph will allow to assess the dynamics of our own Galaxy, together with the astrometric and spectroscopic data from Gaia (ESA).

Roberto Raddi and Ignasi Pérez-Ràfols, commenting on the contribution of the Polytechnic University of Catalonia, say: "Our teams will contribute to the study of some 100,000 white dwarfs previously identified by Gaia, and discover the secrets behind the last evolutionary phases of Sun-like stars, and with the identification of 450,000 quasars, the most distant and bright active galactic nuclei in the universe".

Research paper

M. I. Arnaudova et al., 2024, "WEAVE First Light observations: Origin and Dynamics of the Shock Front in Stephan's Quintet", MNRAS.

More information

"Inauguration of WEAVE", ING Press Release, 31 October 2023.

"WEAVE First Light", ING Press Release, 12 December 2022.

"WEAVE spectrograph begins study of galaxy formation and evolution", ICCUB Press Release, 12 December 2022.

Jin S., et al., 2024, "The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation", MNRAS, 530, 2688. Paper.

Gravity has shaped our cosmos. Its attractive influence turned tiny differences in the amount of matter present in the early universe into the sprawling strands of galaxies we see today. A new study using data from the Dark Energy Spectroscopic Instrument (DESI) has traced how this cosmic structure grew over the past 11 billion years, providing the most precise test to date of gravity at very large scales. 

DESI is an international collaboration of more than 900 researchers from over 70 institutions around the world and is managed by the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). In their new study, DESI researchers found that gravity behaves as predicted by Einstein’s theory of general relativity. The result validates our leading model of the universe and limits possible theories of modified gravity, which have been proposed as alternative ways to explain unexpected observations – including the accelerating expansion of our universe that is typically attributed to dark energy.

"These data allow us to study how fast the largest structures of the universe have formed, and thus set limits in the Einstein General Relativity theory at cosmological scales, much larger than the solar system scales" explains Héctor Gil Marín from the Institute of Cosmos Sciences of the University of Barcelona and member of the Institute of Space Studies of Catalonia who has co-lead this new analysis. "So far the results perfectly fit the predictions by the Einstein General Relativity Theory".

This simulation shows how more or less gravity affects the positions of galaxies that we observe, changing how they are clustered in a galaxy map. Because different models of gravity predict different clustering of galaxies, DESI researchers can compare observations with simulations to test gravity at cosmic scales.
Credit: Claire Lamman and Michael Rashkovetskyi / DESI collaboration

The study also provided new upper limits on the mass of neutrinos, the only fundamental particles whose masses have not yet been precisely measured. Previous neutrino experiments found that the sum of the masses of the three types of neutrinos should be at least 0.059 eV/c². (For comparison, an electron has a mass of about 511,000 eV/c².) DESI’s results indicate that the sum should be less than 0.071 eV/c², leaving a narrow window for neutrino masses.

The DESI collaboration shared their results in several papers posted to the online repository arXiv today. The complex analysis used nearly 6 million galaxies and quasars and lets researchers see up to 11 billion years into the past. With just one year of data, DESI has made the most precise overall measurement of the growth of structure, surpassing previous efforts that took decades to make. 

In this 360-degree video, take an interactive flight through millions of galaxies mapped using coordinate data from DESI. 
Credit: Fiske Planetarium, CU Boulder and DESI collaboration
 

Today’s results provide an extended analysis of DESI’s first year of data, which in April made the largest 3D map of our universe to date and revealed hints that dark energy might be evolving over time. The April results looked at a particular feature of how galaxies cluster known as baryon acoustic oscillations (BAO). The new analysis, called a “full-shape analysis,” broadens the scope to extract more information from the data, measuring how galaxies and matter are distributed on different scales throughout space. The study required months of additional work and cross-checks. Like the previous study, it used a technique to hide the result from the scientists until the end, mitigating any unconscious bias. 

«The results of the first year of DESI data are stunning», says Eusebio Sánchez, a researcher at CIEMAT who has contributed to the data analysis. «And this is only the beginning, the project is taking more data that will allow us to improve a lot the current understanding of gravity and dark energy».

DESI is a state-of-the-art instrument that can capture light from 5,000 galaxies simultaneously. It was constructed and is operated with funding from the DOE Office of Science. DESI is mounted on the U.S. National Science Foundation’s Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory (a program of NSF NOIRLab). The experiment is now in its fourth of five years surveying the sky and plans to collect roughly 40 million galaxies and quasars by the time the project ends.

The collaboration is currently analyzing the first three years of collected data and expects to present updated measurements of dark energy and the expansion history of our universe in spring 2025. DESI’s expanded results released today are consistent with the experiment’s earlier preference for an evolving dark energy, adding to the anticipation of the upcoming analysis. 

«The distribution of galaxies suggests the presence of dark matter and dark energy, both of which remain largely mysterious to us», says Hui Kong, a postdoctoral researcher at IFAE who worked on the curation of the galaxy catalogs. «However, the precise measurements provided by DESI offer promising insights into these fundamental questions about the universe».

DESI is supported by the DOE Office of Science and by the National Energy Research Scientific Computing Center, a DOE Office of Science user facility. Additional support for DESI is provided by the U.S. National Science Foundation; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Humanities, Sciences, and Technologies of Mexico; the Ministry of Science and Innovation of Spain; and by the DESI member institutions.

The DESI collaboration is honored to be permitted to conduct scientific research on I’oligam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation.

The institutions participating in DESI include the Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), the Instituto de Ciencias del Espacio (ICE-CSIC/IEEC), the Institut de Ciències del Cosmos at the Universitat de Barcelona (ICCUB), the Institut de Física d'Altes Energies (IFAE), the Instituto de Física Teórica (IFT-UAM/CSIC), the Instituto de Astrofísica de Andalucía (IAA) and the Instituto de Astrofísica de Canarias (IAC).
The full list of participating institutions and more information about DESI is available at: [https://www.desi.lbl.gov](https://www.desi.lbl.gov).

A group of scientists led by the Leibniz Institute for Astrophysics Potsdam (AIP) and the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) have used novel machine learning tecniques to process data for 217 million stars observed by the Gaia mission in an extremely efficient way, which opens up exciting opportunities to map characteristics like interstellar extinction and metallicity across the Milky Way, aiding in the understanding of stellar populations and the structure of our galaxy. They published their results in Astronomy and Astrophysics.

With the third data release of the European Space Agency’s Gaia space mission, astronomers gained access to improved measurements for 1.8 billion stars, which provides a vast amount of data for researching the Milky Way. However, analysing such a large dataset efficiently presents challenges. In the now published study, researchers explored the use of machine learning to estimate key stellar properties using Gaia's spectrophotometric data. The model was trained on high-quality data from 8 million stars and achieved reliable predictions with small uncertainties. 
“The underlying technique, called extreme gradient-boosted trees allows to estimate precise stellar properties, such as temperature, chemical composition, and interstellar dust obscuration, with unprecedented efficiency. The developed machine learning model, SHBoost, completes its tasks, including model training and prediction, within four hours on a single GPU - a process that previously required two weeks and 3000 high-performance processors,” says Arman Khalatyan from AIP and first author of the study. “The machine-learning method is thus significantly reducing computational time, energy consumption, and CO2 emission.” This is the first time such a technique was successfully applied to stars of all types at once.
The model trains on high-quality spectroscopic data from smaller stellar surveys and then applies this learning to Gaia’s large third data release (DR3), extracting key stellar parameters using only photometric and astrometric data, as well as the Gaia low-resolution XP spectra. “The high quality of the results reduces the need for additional resource-intensive spectroscopic observations when looking for good candidates to be picked-up for further studies, such as rare metal-poor or super-metal rich stars, crucial for understanding the earliest phases of the Milky Way formation”, says Cristina Chiappini from AIP. This technique turns out to be crucial for the preparation of future observations with multi-object spectroscopy, such as 4MIDABLE-LR, a large survey of the Galactic Disc and Bulge that will be part of the 4MOST project at the European Southern Observatory (ESO) in Chile.
“The new model approach provides extensive maps of the Milky Way’s overall chemical composition, corroborating the distribution of young and old stars. The data shows the concentration of metal-rich stars in the Galaxy’s inner regions, including the bar and bulge, with an enormous statistical power.“ adds Friedrich Anders from ICCUB.
The team also used the model to map young, massive hot stars throughout the Galaxy, highlighting distant poorly studied regions in which stars are forming. The data also reveal that there exist a number of “stellar voids” in our Milky Way, i.e. areas that host very few young stars. Furthermore, the data demonstrate where the three-dimensional distribution of interstellar dust is still poorly resolved. 

As Gaia continues to collect data, the ability of machine-learning models to handle the vast datasets quickly and sustainably makes them an essential tool for future astronomical research. The success of the approach demonstrates the potential for machine learning to revolutionise big data analysis in astronomy and other scientific fields while promoting more sustainable research practices.

Reference: https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202451427

A study published in the journal Nature has discovered 55 high-speed stars ejected from the young star cluster R136, located in the Large Magellanic Cloud — a satellite galaxy of the Milky Way — some 160,000 light-years away. This finding increases the number of known runaway stars in this region of the cosmos tenfold and is a new scientific contribution from the European Space Agency’s (ESA) Gaia telescope, which aims to identify the positions, distances and speed of more than a billion stars in our galaxy.

This is the first time that such a large number of high-speed stars have been detected coming from a single cluster. In particular, R136 is a cluster of particular characteristics, containing hundreds of thousands of stars, including the most massive stars known (up to three hundred times the mass of the Sun), and is part of the largest known star-forming region within five million light-years.

Runaway stars launched from the young cluster R136 — beyond the moon, at a distance of 1.5 million kilometres from Earth — have been identified at extremely far distances for the Gaia mission, ESA’s most ambitious project to detail the stellar mapping of our galaxy. Since its inception, astronomers from teams at the Department of Quantum Physics and Astrophysics of the University of Barcelona, the Institute of Cosmos Sciences of the UB (ICCUB) and the Institute of Space Studies of Catalonia (IEEC) have been participating in the Gaia project.

The new study, led by experts from the University of Amsterdam, Leiden University and Radboud University (the Netherlands), is co-authored by Dr. Mark Gieles, (ICREA, ICCUB, IEEC). Astronomers from the Royal Observatory of Belgium (Belgium), Tel Aviv University (Israel), the Netherlands National Institute for Space Research (The Netherlands) and the University of Geneva (Switzerland) have also signed the paper.

Runaway stars at high speeds in the Large Magellanic Cloud

When star clusters form, collisions between smaller star clusters can cause the ejection of stars from the young cluster. The science team led by Mitchel Stoop, a PhD student at the University of Amsterdam, has found that the young cluster R136 has ejected up to a third of its most massive stars outwards in the last few million years, at speeds of over 100, 000 km/h. These stars travel up to 1,000 light-years from their birthplace before exploding as supernovae at the end of their stellar life and giving rise to a neutron star or black hole.

Another surprising result of the study indicates that there was not a single period when stars were dynamically ejected, but two. According to Scoop, “the first episode was 1.8 million years ago, when the cluster formed, and fits with the ejection of stars during the formation of the cluster”. “The second episode was only 200,000 years ago and had very different characteristics. For example, the runaway stars of this second period moved more slowly and did not shoot off in random directions as in the first episode, but in a preferred one”, says the expert.

Gieles, from ICREA, ICCUB and IEEC and co-author of the research, says that “a lot happens in a short time during the formation of massive star clusters and the images only provide a snapshot”. He adds that “these new observations of the motion of escaping stars are like a ‘rearview mirror’, giving us an unprecedented view of what happened before”.

It is worth recalling that the Dutch astronomer Adriaan Blaauw (1914-2010) identified the first indications of the existence of runaway stars, i.e. stars moving at high speed through the Milky Way. With this discovery, Blaauw opened one of the most exciting and surprising chapters in astronomy and cosmology research, which has been unravelling its mysteries thanks to an initial ESA mission — called Hipparcos — and now with the Gaia telescope.

Reference article:

Stoop, Mitchell; de Koter, Alex. et al. «Two waves of massive stars running away from the young cluster R136». Nature, October 2024. DOI: 10.1038/s41586-024-08013-8
 

Licia Verde, ICREA researcher and Scientific Director of the Institute of Cosmos Sciences of the University of Barcelona, has been awarded the 2024 Medal by the Real Sociedad Española de Física (RSEF) and the BBVA Foundation. This prestigious prize celebrates Prof. Verde's significant contributions to cosmology, particularly in the study of the universe's expansion history, dark matter, and dark energy. Her research has been instrumental in shaping our understanding of the standard cosmological model. 

The RSEF-Fundación BBVA awards, presented annually, are among the most prestigious recognitions in Spain for contributions to physics. These awards honour groundbreaking work in various fields of physics, as well as outstanding educational and outreach efforts. The Medal is awarded to a physicist whose work has had an enduring and far-reaching impact on the field. Verde’s pioneering research has contributed significantly to our understanding of the fundamental properties of the cosmos, earning her global recognition. 

“My most sincere thanks to the committee,” says Prof. Verde, “And also, to my mentors and to everyone who has supported me and to all the researchers in training who passed through my group; In research, “it takes a whole village””. 

The ICCUB warmly congratulates Licia Verde for this remarkable achievement, which will be added to her extensive list of recognitions and marks the excellence of the research carried out at our institution. 

For more information on the RSEF-Fundación BBVA awards, visit the Fundación BBVA website. 

Mar Carretero-Castrillo, a predoctoral researcher of the Institute of Cosmos Sciences of the University of Barcelona and the Institute of Space Studies of Catalonia (ICCUB-IEEC), has been named a finalist for the 2024 La Vanguardia Science Award. This recognition follows her role as the first author of the groundbreaking discovery of numerous massive runaway stars in the Milky Way, alongside Drs. Marc Ribó and Josep M. Paredes, a finding that offers new insight into the stellar evolution of massive stars.

The discovery, made possible through data from the European Space Agency’s Gaia mission, identified a population of massive runaway stars that have been ejected from their birthplaces due to changes in gravitational forces, travelling at high velocities within the galaxy. These findings provide vital clues to understanding the critical processes in massive stellar evolution that lead to their ejection from stellar clusters or from binary systems after supernova explosions.

Mar Carretero-Castrillo, who leads the study, emphasised the importance of these discoveries: “the identification of so many massive runaway stars opens the door to discover new interesting astrophysical sources. We have released the catalogues of the runaway stars found in open format to the scientific community to maximise the exploitation of the potential discoveries”. 

This groundbreaking research not only expands our understanding of massive star dynamics but also sets the stage for further investigations into high-energy systems associated with runaway stars. 

In recognition of her pioneering research, Mar Carretero-Castrillo has been selected as a finalist for the La Vanguardia Science Award, which aims to honour women leading scientific contributions across Spain and help reduce the gender gap in science. The award celebrates research that drives innovation and enhances global understanding.

La Vanguardia and the Fundació Catalunya La Pedrera, which have jointly organized the award since 2011, invite readers to choose the winning research in a vote that will be open until Sunday, October 20.

The prize will be awarded to the three researchers that receive the most votes and will be presented at an event open to the public, which will be held on November 27, in La Pedrera.

For more information about Mar Carretero-Castrillo’s study, please visit the following website or the original article “Galactic runaway O and Be stars found using Gaia DR3⋆” .

Adriana Nadal, a predoctoral researcher at the Physical Cosmology group at the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and the Institute of Space Sciences of Catalonia (IEEC), has been awarded the Jordi Porta i Jué Award by the Catalan Society of Physics of the Institute of Catalan Studies (IEC). Nadal was honored for her master’s thesis titled "Testing the robustness of the BAO determination in the presence of massive neutrinos," completed as part of the Master's in Astrophysics, Particle Physics and Cosmology at the University of Barcelona.

The award ceremony took place on Tuesday, April 23rd, coinciding with Sant Jordi's Day, at the IEC social quarters and was presided over by IEC President Teresa Cabré. The Jordi Porta i Jué Award is a significant component of the IEC’s Sant Jordi Awards, which aim to promote scientific research and the dissemination of all elements of Catalan culture.

Nadal’s master thesis made significant contributions to the field of cosmology, focusing on the Baryon Acoustic Oscillation (BAO), one of the primary probes of cosmology today. Her research studied and quantified the impact of built-in assumptions of the data analysis pipeline on the measurement of the isotropic BAO peak, particularly in the context of massive neutrinos. This work was supervised by ICCUB researchers Héctor Gil Marin (ICCUB-IEEC) and Licia Verde (ICREA-ICCUB).

Now continuing her academic journey, Adriana Nadal is a predoctoral researcher at ICCUB, where she is working on her doctoral thesis titled "Developing tools for the analysis of DESI data employing higher-order statistics," under the guidance of Héctor Gil Marin and Licia Verde. Her ongoing research promises to further advance our understanding of the universe through innovative analytical techniques.

For more information about Adriana Nadal's research and the work of the Physical Cosmology group at ICCUB, please visit ICCUB’s website.

More than two hundred international experts will take part in the 10th International Conference on Quarks and Nuclear Physics (QNP2024), a scientific summit organized by the UB Institute of Cosmos Sciences (ICCUB), which will be held in the Aula Magna of the Faculty of Biology at the University of Barcelona from 8 to 12 July. This meeting, hosted by the UB for the first time, will bring together world experts in the fields of nuclear physics and hadronic physics to discuss the latest advances in theory, experimentation and technology and to address the scientific challenges of the 21st century regarding the nature and phenomena related to the essential components of matter in the universe.

In previous editions, this date with the world of nuclear physics was held in the cities of Adelaide (Australia), Jülich (Germany), Bloomington (United States), Madrid (Spain), Beijing (China), Palaiseau (France), Valparaíso (Chile), Tsukuba (Japan) and Tallahassee (United States).

The meeting will be inaugurated by the rector, Joan Guàrdia, on Monday, 8 July, in an event in which will participate the professors Xavier Luri and Àngels Ramos, from the Faculty of Physics and the ICC, and M. José García Borge, from the Institute of the Structure of Matter (IEM, CSIC). This will be followed by lectures by Juan M. Nieves, from the University of Valencia, entitled “Charge-conjugation asymmetry and molecular content: the Tcc(3875) and Ds(2317) in nuclear matter”, and Takashi Nakatsukasa, from the University of Tsukuba (Japan), with the paper “Energy density functional approaches to inhomogeneous superfluid neutron-star matter”.

Discovering yet unknown phenomena in nuclear physics

One of the most shocking discoveries in the world of physics was the Higgs boson, announced in July 2012 and postulated theoretically in 1964 by the scientist Peter Higgs to explain the essential building blocks of matter. The discovery is a major milestone at CERN’s Large Hadron Collider (LHC) in Geneva (Switzerland), one of the main scientific infrastructures that are shedding new light on the world of particle physics to understand its nature and the interaction mechanisms that are still unknown to the research community.

“Nuclear and hadronic physics in the 21st century present a number of fascinating scientific challenges, such as the fundamental understanding of strong interactions, the study of new exotic hadrons, the development of more precise nuclear models and the exploration of new states of matter”, says Xavier Luri, professor at the Department of Quantum Physics and Astrophysics and director of the ICCUB.
“It is worth noting that advances in nuclear and hadronic physics have a major impact on other areas of knowledge. In the field of astrophysics, for example, research to create new elements will help to understand the phenomenon of nucleosynthesis in the universe, and studies to characterize the behaviour of nuclear matter under extreme conditions will help to understand the properties and internal composition of neutron stars. In the field of particle physics, experiments on the double beta decay of nuclei, which seek to elucidate the nature of neutrons, will explore the limits of the standard model, while very precise measurements of nuclear and hadronic processes could lead to the detection of dark matter”, adds Luri.

Beyond the standard model of particle physics

The new edition of the international conference will address the limits of knowledge beyond the standard model that describes the most fundamental forces and particles in the universe. Theorists and experimentalists will discuss the progress of recent advances in hadronic and nuclear physics, and share the most revealing results on the structure of quarks and gluons in hadrons, decays and interactions between different particles, cold dark matter and large scientific-technical equipment, among others.

“Very precise measurements of the properties of nuclei and hadronic interactions are needed to discover ‘new physics’ phenomena, i.e. those that cannot be explained by the standard model of particle physics. Sophisticated theoretical studies of certain hadronic processes now show that the degree of precision needed to detect possible candidates for the elusive dark matter (which makes up 85% of the mass of our universe!) is beginning to be achievable in large experimental facilities, such as the Large Hadron Collider (LHC) at CERN”, says Professor Àngels Ramos, head of the UB’s Theoretical Nuclear Physics and Many Interacting Particles Group and coordinator of the conference.

“Another possible manifestation of ‘new physics’ could come from underground laboratories, such as the Canfranc laboratory (LSC), where the so-called double beta decay of nuclei without neutrino emission is being searched for, which will help to elucidate the nature of neutrinos and their mass hierarchy”, says Ramos.

To discuss new research horizons, the conference will feature internationally renowned experts such as Tomohiro Uesaka, head of the Nuclear Dynamics Research Group at the RIKEN centre in Japan, author of significant experimental contributions to the properties of exotic nuclei — rich in neutrons — that test modern theories of nuclear structure; Laura Fabbietti, from the Technical University of Munich (Germany) and the LHC ALICE collaboration, who has led the use of femtoscopy to characterize interactions between unstable hadrons; Yvonne Leifels, head of the Research Division of the Helmholtz Centre for Heavy Ion Research (GSI), who will present the scientific prospects of FAIR (Germany), the ion collider that will allow us to understand how elements are synthesized in the universe or the composition of matter under extreme conditions of density and temperature, and Eulogio Oset, theoretical physicist at the University of Valencia, internationally recognized for his outstanding contributions in the fields of hadronic physics and nuclear physics, and distinguished with the medal of the Royal Spanish Physics Society 2023.

Within the framework of the conference, and in collaboration with the Fundaciño Catalunya La Pedrera, Professor Freya Blekman, from the German Electron Synchrotron (DESY, University of Hamburg), will give the talk “Understanding the Large Hadron Collider: What, why and how?”, on Wednesday 10 July, at 6.30 p.m., in the auditorium of the Casa Milà (La Pedrera). The talk, open to the public, will focus on the research activity at the LHC in Geneva — the Swiss Army Knife of experiments, which investigates everything from new particles and forces to the birth of the universe — without neglecting the more fun and social aspects of this exceptional scientific facility.

The 10th International Conference on Quarks and Nuclear Physics is supported by the Barcelona City Council, the Fundació Catalunya La Pedrera, the International Union of Pure and Applied Physics (IUPAP) and the European Committee for Nuclear Physics Collaboration (NuPECC), which is one of the expert committees of the European Science Foundation (ISF).