SPACE/COSMOS
Supergiant star’s gigantic bubble surprises scientists
image:
Red supergiant DFK 52 and its surroundings as seen by ALMA. The vast, complex bubble blown by this extreme star is about 1.4 light years across, thousands of times wider than our Solar System. ALMA measures light invisible to our eyes, with wavelength around 1.3 millimetres, emitted by molecules of carbon monoxide and silicon monoxide. Thanks to the Doppler effect, the team has measured how fast the gas is moving along our sightline towards the star. In this image, parts of the bubble moving away from us relative to the star are shown in red, and material moving towards us in blue.
view moreCredit: ALMA (ESO/NAOJ/NRAO)/M. Siebert et al
Astronomers from Chalmers University of Technology, Sweden, have discovered a vast and expanding bubble of gas and dust surrounding a red supergiant star – the largest structure of its kind ever seen in the Milky Way. The bubble, which contains as much mass as the Sun, was blown out in a mysterious stellar eruption around 4000 years ago. Why the star survived such a powerful event is a puzzle, the scientists say.
The new results are published in the scientific journal Astronomy and Astrophysics, and the team was led by Mark Siebert, Chalmers, Sweden. Using the ALMA radio telescope in Chile, the researchers observed the star DFK 52 – a red supergiant similar to the well-known star Betelgeuse.
“We got a big surprise when we saw what ALMA was showing us. The star is more or less a twin of Betelgeuse, but it’s surrounded by a vast, messy bubble of material,” says Mark Siebert at Chalmers.
The bubble, a complex of clouds of gas and dust, weighs as much as the Sun, and extends out 1.4 light years from the star. That’s thousands of times wider than our own solar system.
If the star was as close to us as Betelgeuse is, the bubble would appear to span a third of the full Moon’s width in the sky.
ALMA’s radio observations let astronomers measure the motion of molecules in the cloud, revealing that the bubble is expanding. They believe it was formed when the star suddenly ejected part of its outer layers in a powerful explosion just a few thousand years ago.
“The bubble is made of material that used to be part of the star. It must have been ejected in a dramatic event, an explosion, that happened about four thousand years ago. In cosmic terms, that’s just a moment ago,” says Elvire De Beck, astronomer at Chalmers.
The galaxy's next supernova?
Why DFK 52 shed so much mass without exploding as a supernova is still unclear. One possibility is that the star has a hidden companion that helped it cast off its outer layers.
“To us, it’s a mystery as to how the star managed to expel so much material in such a short timeframe. Maybe, like Betelgeuse seems to, it has a companion star that’s still to be discovered,” says Mark Siebert.
Red supergiants like DFK 52 are nearing the ends of their lives and are expected to eventually explode as supernovae. Could this star be next?
“We’re planning more observations to understand what’s happening – and to find out whether this might be the Milky Way’s next supernova. If this is a typical red supergiant, it could explode sometime in the next million years,” says Elvire De Beck.
More about the research:
The research is presented in the paper "Stephenson 2 DFK 52: Discovery of an exotic red supergiant in the massive stellar cluster RSGC2", published in the journal Astronomy and Astrophysics. The image has been featured as ESO’s Picture of the Week.
The researchers involved in the study are Mark Siebert, Elvire De Beck and Wouter Vlemmings from Chalmers University of Technology, Sweden, and Guillermo Quintana Lacaci from Instituto de Fisica Fundamental, Spain.
Red supergiants are some of the rarest, brightest stars in the sky. They are the final stage of evolution of stars born much more massive than the Sun (more than eight times the Sun’s mass). For astronomers, they are keys to understanding the life stories of all stars and planets. The most massive stars create and spread newly-formed elements throughout interstellar space, energising gas and dust, and helping new generations of stars to form.
The closest red supergiants in our galaxy, the Milky Way, are easily visible for anyone with a clear view of a dark night sky. Betelgeuse, in the constellation Orion, and Antares, in Scorpius, are both well-known examples of red supergiant stars.
More about the ALMA telescope:
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility in Chile, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile.
In Sweden, Onsala Space Observatory at Chalmers University of Technology, has been involved in ALMA since its inception; receivers for the telescope are one of many contributions. Onsala Space Observatory is host to the Nordic ALMA Regional Centre, which provides technical expertise to the ALMA project and supports astronomers in the Nordic countries in using ALMA.
Red supergiant star DFK 52 is a member of the star cluster Stephenson 2. In this image, the brightest stars are all supergiants, and all members of the cluster. This image is made from data taken with the Spitzer Space Telescope in light much redder than our eyes can see (wavelengths 3.6, 4.5, 5.8 and 8 micrometres). Despite its remarkable bubble, too small to see in this image, DFK 52 is not unusually bright. The bright star in the lower left is another red supergiant, known as DFK 1 or Stephenson 2-18. It may be one of the largest stars known.
Credit
NASA/JPL-Caltech/IPAC
Journal
Astronomy and Astrophysics
Method of Research
Observational study
Article Title
Stephenson 2 DFK 52: Discovery of an exotic red supergiant in the massive stellar cluster RSGC2
Article Publication Date
16-Aug-2025
SwRI-led work confirms decades-old theoretical models about solar reconnection
Research helps fill crucial observation gaps about process that drives solar flares, coronal mass ejections
Southwest Research Institute
image:
An SwRI-led study of the Sun confirms decades-old theoretical models about solar magnetic reconnection. Measurements from NASA’s Solar Parker Probe helped fill crucial gaps in the data about processes that drive solar flares, coronal mass ejections and other space weather phenomena. The measurements were taken from the region pictured in the white box, which was identified as the source of a coronal mass ejection. The figures shown here are taken from images captured by the ESA’s Solar Orbiter mission.
view moreCredit: ESA/NASA/Solar Orbiter
SAN ANTONIO — August 18, 2025 — New research led by Southwest Research Institute (SwRI) has confirmed decades-old theoretical models about magnetic reconnection, the process that releases stored magnetic energy to drive solar flares, coronal mass ejections and other space weather phenomena. The data was captured by NASA’s Parker Solar Probe (PSP), which is the only spacecraft to have flown through the Sun’s upper atmosphere.
Magnetic reconnection occurs when magnetic field lines in plasma sever and reconnect in a new configuration, releasing large amounts of stored energy. On the Sun, this energy release often results in solar activity that can affect technology on Earth, a phenomenon known as space weather. Modeling solar magnetic reconnection accurately may help predict coronal mass ejections, solar flares and other space weather events that can impact satellites, communication systems and even power grids on Earth.
“Reconnection operates at different spatial and temporal scales, in space plasmas ranging from the Sun to Earth’s magnetosphere to laboratory settings to cosmic scales,” said Dr. Ritesh Patel, a research scientist in SwRI’s Solar System Science and Exploration Division in Boulder, Colorado, and lead author of a new paper published in Nature Astronomy. “Since the late 1990s, we have been able to identify reconnection in the solar corona through imaging and spectroscopy. In-situ detection was possible in Earth's magnetosphere with the launch of missions like NASA’s Magnetospheric Multiscale (MMS) mission. Similar studies in the solar corona, however, only became possible when NASA’s Parker Solar Probe launched in 2018."
PSP’s record-breaking proximity to the Sun has enabled new opportunities for study. A Sept. 6, 2022, approach revealed a huge eruption, providing an opportunity to image and sample the plasma and magnetic field properties in detail for the first time. Using a combination of imaging and in-situ diagnostic techniques as well as complementary observations from the European Space Agency’s Solar Orbiter, the SwRI-led team confirmed that PSP had flown through a reconnection region in the solar atmosphere for the very first time.
“We’ve been developing the theory of magnetic reconnection for almost 70 years, so we had a basic idea of how different parameters would behave,” Patel said. “The measurements and observations received from the encounter have validated numerical simulation models that have existed for decades within some degree of uncertainty. The data will serve as strong constraints for future models and provide a path to understand PSP’s solar measurements from other timeframes and events.”
NASA’s MMS mission, led by SwRI, provided researchers with an idea of how reconnection occurs in the near-Earth environment on a smaller scale. The 2022 PSP observations now provide researchers with the missing piece connecting Earth scale to solar scale reconnection. SwRI will next work to identify whether reconnection mechanisms accompanied with turbulence or fluctuations and waves of the magnetic fields are present in the solar regions PSP identified as having active reconnection.
“Ongoing work provides discoveries at different scales, which allows us to see how energy is transferred and how particles are accelerated,” Patel said. “Understanding these processes at the Sun can help better predict solar activity and improve our understanding of the near-Earth environment.”
The Parker Solar Probe was developed as part of NASA’s Living with a Star program to explore aspects of the Sun-Earth system that directly affect life and society. The Living with a Star program is managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. Johns Hopkins University Applied Physics Laboratory designed, built and currently operates the spacecraft and manages the mission for NASA.
To read the Nature Astronomy paper online, visit: www.nature.com/articles/s41550-025-02623-6 or DOI: 10.1038/s41550-025-02623-6.
For more information, visit https://www.swri.org/markets/earth-space/space-research-technology/space-science/heliophysics.
Journal
Nature
Method of Research
Data/statistical analysis
Subject of Research
Not applicable
Article Title
Direct in situ observations of eruption-associated magnetic reconnection in the solar corona
Article Publication Date
18-Aug-2025
Supernovae: How to spot them at record speed
A new JCAP paper promises to reveal supernovae only hours after they explode
Sissa Medialab
image:
Example of observations used in the study
view moreCredit: Albany et al, JCAP, 2025
Supernovae appear to our eyes—and to astronomical instruments—as brilliant flashes that flare up in the sky without warning, in places where nothing was visible just moments before. The flash is caused by the colossal explosion of a star. Because supernovae are sudden and unpredictable, they have long been difficult to study, but today, thanks to extensive, continuous, high-cadence sky surveys, astronomers can discover new ones almost daily.
It is crucial, however, to develop protocols and methods that detect them promptly; only in that way can we understand the events and celestial bodies that triggered them. In a pilot study, LluÃs Galbany of the Institute of Space Sciences (ICE-CSIC) in Barcelona and his colleagues present a methodology that can obtain the earliest possible spectra of supernovae—ideally within 48 hours, or even 24 hours, of the “first light.” The results have just been published in the Journal of Cosmology and Astroparticle Physics (JCAP).
Supernovae are enormous explosions that mark the final stages of a star’s life. They fall into two broad categories, determined by the mass of the progenitor star. “Thermonuclear supernovae involve stars whose initial mass did not exceed eight solar masses,” explains Galbany, first author of the study. “The most advanced evolutionary stage of these stars before the supernova is the white dwarf—very old objects that no longer have an active core producing heat. White dwarfs can remain in equilibrium for a long time, supported by a quantum effect called electron-degeneracy pressure.”
If such a star is in a binary system, he continues, it can siphon matter from its companion. The extra mass raises the internal pressure until the white dwarf explodes as a supernova.
“The second major category involves very massive stars, above eight solar masses,” Galbany says. “They shine thanks to nuclear fusion in their cores, but once the star has burned through progressively heavier atoms—right up to the point where further fusion no longer yields energy—the core collapses. At that point the star collapses because gravity is no longer counterbalanced; the rapid contraction raises the internal pressure dramatically and triggers the explosion.”
The first hours and days after the blast preserve direct clues to the progenitor system—information that helps distinguish competing explosion models, estimate critical parameters, and study the local environment. “The sooner we see them, the better,” Galbany notes. Historically, obtaining such early data was difficult because most supernovae were discovered days or weeks after the explosion. Modern wide-field, high-cadence surveys—covering large swaths of sky and revisiting them frequently—are changing that picture and allowing discoveries within mere hours or days.
Protocols and criteria are still needed to exploit these surveys fully, and Galbany’s team tested such rules using observations from the Gran Telescopio de Canarias (GTC). Their study reports on ten supernovae: half thermonuclear, half core-collapse. Most were observed within six days of the estimated explosion, and in two cases within 48 hours.
The protocol begins with a rapid search for candidates based on two criteria: the light signal must have been absent in the previous night’s images, and the new source must lie within a galaxy. When both conditions are met, the team triggers the OSIRIS instrument on the GTC to obtain a spectrum.
“The supernova’s spectrum tells us, for instance, whether the star contained hydrogen—meaning we are looking at a core-collapse supernova,” Galbany explains. “Knowing about the supernova in its very earliest moments also lets us seek other kinds of data on the same object, such as photometry from the Zwicky Transient Facility (ZTF) and the Asteroid Terrestrial-impact Last Alert System (ATLAS) that we used in the study. Those light-curves show how brightness rises in the initial phase; if we see small bumps, it may mean another star in a binary system was swallowed by the explosion.” Additional checks cross-match data on the same patch of sky from other observatories.
Because this first study managed to gather data within 48 hours, the authors conclude that even faster observations are within reach. “What we have just published is a pilot study,” Galbany says. “We now know that a rapid-response spectroscopic program, well coordinated with deep photometric surveys, can realistically collect spectra within a day of the explosion, paving the way for systematic studies of the very earliest phases in forthcoming large surveys such as the La Silla Southern Supernova Survey (LS4) and the Legacy Survey of Space and Time (LSST), both in Chile.”
Journal
Journal of Cosmology and Astroparticle Physics
Method of Research
Data/statistical analysis
Article Title
Rapid follow-up of infant supernovae with the Gran Telescopio de Canarias
Article Publication Date
19-Aug-2025
Example of observations used in the study
Sissa Medialab
Artistic elaboration based on images from the original paper Galbany et al., JCAP, 2025
Credit
Galbany et al., JCAP, 2025
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