SN 2024ggi was first noticed on the night of 10 April 2024 local time. At that moment, Yi Yang, an assistant professor at Tsinghua University in Beijing, China, and lead author of the study, had just arrived in San Francisco after a long flight. Realizing the urgency, he moved quickly. Twelve hours later, he submitted an observation request to ESO, which approved it soon after. By April 11, only 26 hours after the discovery, the VLT in Chile was already observing the event.

A Rare Nearby Explosion

The supernova is located in the galaxy NGC 3621, in the direction of the constellation Hydra, approximately 22 million light-years away. For astronomers, this distance is close enough to investigate the blast in fine detail. Using the VLT and specialized instruments, the international team captured the early behavior of the explosion. “The first VLT observations captured the phase during which matter accelerated by the explosion near the centre of the star shot through the star’s surface. For a few hours, the geometry of the star and its explosion could be, and were, observed together,” says Dietrich Baade, an ESO astronomer in Germany and co-author of the study, published on November 12 in Science Advances.

“The geometry of a supernova explosion provides fundamental information on stellar evolution and the physical processes leading to these cosmic fireworks,” Yang explains. Scientists are still investigating the exact steps that trigger the explosions of massive stars, which are defined as stars more than eight times the mass of the Sun. SN 2024ggi began as a red supergiant with a mass between 12 and 15 times that of the Sun and a radius 500 times larger. This makes it a textbook example of a massive star approaching the end of its life.

What Happens When a Massive Star Runs Out of Fuel

Throughout its life, a star keeps a stable spherical shape because gravity pulls inward while pressure from nuclear fusion pushes outward. When the star exhausts its fuel, this balance collapses. The core gives way, the surrounding layers fall inward, and then bounce off the dense center. This rebound launches a shock wave that travels outward, ultimately tearing the star apart.

Once the shock reaches the surface, energy is released in enormous amounts and the supernova becomes visible. During the short window before the explosion interacts with surrounding material, astronomers can study the initial breakout shape.

Revealing Hidden Geometry with Spectropolarimetry

To capture this early structure, astronomers used a technique called ‘spectropolarimetry’. “Spectropolarimetry delivers information about the geometry of the explosion that other types of observation cannot provide because the angular scales are too tiny,” says Lifan Wang, co-author and professor at the Texas A&M University in the US, who began his career as a student at ESO. Although the exploding star appears as a single point of light, the polarization of that light contains subtle signals about the explosion’s shape, which the team successfully decoded.^[1]

The VLT’s FORS2 instrument, the only facility in the southern hemisphere able to make this type of measurement, revealed that the first burst of material resembled the shape of an olive. As the blast expanded and encountered material surrounding the star, the shape grew flatter, although the axis of symmetry stayed consistent. Yang notes that “these findings suggest a common physical mechanism that drives the explosion of many massive stars, which manifests a well-defined axial symmetry and acts on large scales.”

Advancing Supernova Science Through Global Collaboration

These observations allow scientists to eliminate some existing models and refine others, improving our understanding of massive star deaths. “This discovery not only reshapes our understanding of stellar explosions, but also demonstrates what can be achieved when science transcends borders,” says co-author and ESO astronomer Ferdinando Patat. “It’s a powerful reminder that curiosity, collaboration, and swift action can unlock profound insights into the physics shaping our Universe.”

Notes

1. Light particles (photons) have a property called polarization. In a sphere, the shape of most stars, the polarization of the individual photons cancels out so that the net polarization of the object is zero. When astronomers measure a non-zero net polarization, they can use that measurement to infer the shape of the object — a star or a supernova — emitting the observed light.

This research was presented in a paper published in Science Advances.

The team is composed of Y. Yang (Department of Physics, Tsinghua University, China [Tsinghua University]), X. Wen (School of Physics and Astronomy, Beijing Normal University, China [Beijing Normal University] and Tsinghua University), L. Wang (Department of Physics and Astronomy, Texas A&M University, USA [Texas A&M University] and George P. and Cynthia Woods Mitchell Institute for Fundamental Physics & Astronomy Texas A&M University, USA [IFPA Texas A&M University]), D. Baade (European Organisation for Astronomical Research in the Southern Hemisphere, Germany [ESO]), J. C. Wheeler (University of Texas at Austin, USA), A. V. Filippenko (Department of Astronomy, University of California, Berkeley, USA [UC Berkeley] and Hagler Institute for Advanced Study, Texas A&M University, USA), A. Gal-Yam (Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Israel), J. Maund (Department of Physics, Royal Holloway, University of London, United Kingdom), S. Schulze (Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University, USA), X. Wang (Tsinghua University), C. Ashall (Department of Physics, Virginia Tech, USA and Institute for Astronomy, University of Hawai’i at Manoa, USA), M. Bulla (Department of Physics and Earth Science, University of Ferrara, Italy and INFN, Sezione di Ferrara, Italy and INAF, Osservatorio Astronomico d’Abruzzo, Italy), A. Cikota (Gemini Observatory/NSF NOIRLab, Chile), H. Gao (Beijing Normal University and Institute for Frontier in Astronomy and Astrophysics, Beijing Normal University, China), P. Hoeflich (Department of Physics, Florida State University, USA), G. Li (Tsinghua University), D. Mishra (Texas A&M University and IFPA Texas A&M University), Ferdinando Patat (ESO), K. C. Patra (California and Department of Astronomy & Astrophysics, University of California, Santa Cruz, USA), S. S. Vasylyev (UC Berkeley), S. Yan (Tsinghua University).

Most stars, including the Sun, form within groups. As they age, these groups gradually disperse, which makes it difficult to track which stars were born together. Astronomers can use stellar rotation as a “cosmic clock,” since young stars spin quickly and older stars slow down over time. The UNC-Chapel Hill team used this technique to locate many long-lost members of the Pleiades spread far beyond the central cluster. With rotation data from NASA’s TESS and precise measurements from ESA’s Gaia, they concluded that the Pleiades is not a compact grouping but the dense core of a much larger and slowly dispersing stellar association.

“This study changes how we see the Pleiades — not just seven bright stars, but thousands of long-lost siblings scattered across the whole sky,” said Andrew Boyle, lead author and graduate student in physics and astronomy at UNC-Chapel Hill.

Cultural Significance and Expanding Scientific Insight

The discovery reaches beyond astrophysics. The Pleiades has long served as a key reference point for understanding young stars and exoplanets, and it holds cultural meaning across many societies. It appears in the Old Testament and the Talmud, is honored as Matariki in New Zealand, and is depicted in the logo of Subaru in Japan. “We’re realizing that many stars near the Sun are part of massive extended stellar families with complex structures,” said Andrew Mann, co-author and professor of physics and astronomy at UNC-Chapel Hill. “Our work provides a new way to uncover these hidden relationships.”

Mapping Hidden Structures in the Milky Way

By studying how stars rotate, the researchers developed a new way to map our region of the Galaxy. Their findings suggest that many star clusters once thought to be isolated may actually belong to much larger stellar families. This method may eventually help scientists investigate the Sun’s own origins and determine whether it formed within a similarly extensive stellar group.

“By measuring how stars spin, we can identify stellar groups too scattered to detect with traditional methods — opening a new window into the hidden architecture of our Galaxy,” Boyle said.

Understanding How Solar Systems Form

The research contributes to ongoing efforts to reconstruct the environments in which stars and planets are born. These insights are essential for understanding how solar systems, including our own, take shape and evolve over time.

The research paper is available online in The Astrophysical Journal.

Researchers at the Penn State Cancer Institute reviewed cancer registry data collected from 2017 through 2021 and discovered that adults over age 50 living in a 15-county area of South Central Pennsylvania were 57% more likely to be diagnosed with melanoma, the deadliest form of skin cancer, compared to residents elsewhere in the state. The team reported these results on Nov. 14 in the journal JCO Clinical Cancer Informatics.

Charlene Lam, associate professor of dermatology at Penn State Health and co-author of the study, noted that the elevated cases appear in both rural and urban counties. She explained that the higher risk is not limited to isolated locations or people who spend much of their time outdoors.

Agricultural Environments Linked to Elevated Risk

“Melanoma is often associated with beaches and sunbathing, but our findings suggest that agricultural environments may also play a role,” she said. “And this isn’t just about farmers. Entire communities living near agriculture, people who never set foot in a field, may still be at risk.”

The usual suspect — sunlight — was included in the analysis. Yet even after adjusting for ultraviolet radiation levels in Pennsylvania and considering socioeconomic factors, two consistent associations emerged. Counties with more cultivated acreage and counties with greater herbicide use displayed significantly higher melanoma rates.

Herbicides, Biological Effects, and Melanoma Patterns

“Pesticides and herbicides are designed to alter biological systems,” said Eugene Lengerich, emeritus professor of public health sciences at Penn State and senior author on the paper. “Some of those same mechanisms, like increasing photosensitivity or causing oxidative stress, could theoretically contribute to melanoma development.”

According to the analysis, a 10% increase in cultivated land was linked to a 14% rise in melanoma cases across the region. Herbicide exposure showed a similar pattern: a 9% increase in herbicide-treated land corresponded to a 13% increase in melanoma incidence.

Lam emphasized that exposure is not restricted to those handling agricultural chemicals. She explained that these substances can drift on air currents, settle in household dust and enter water sources.

Chemical Drift and Community-Wide Exposure

“Our findings suggest that melanoma risk could extend beyond occupational settings to entire communities,” she said. “This is relevant for people living near farmland. You don’t have to be a farmer to face environmental exposure.”

The study also referenced earlier research showing links between pesticide and herbicide exposure and melanoma, citing evidence that these chemicals can heighten sensitivity to sunlight, interfere with immune responses and damage DNA in non-human animals and plants.

Study Shows Associations, Not Proof of Cause

Benjamin Marks, first author on the paper and a medical and public health student at the Penn State College of Medicine, cautioned that while higher melanoma rates appear in areas with more cropland and herbicide use, the findings do not prove that chemicals used on crops such as corn, soybeans and grains directly cause cancer. Instead, he said the patterns point to a connection that deserves further study.

He added that research of this kind is useful for spotting broad trends, even though it cannot identify individual risk.

“Think of this as a signal, not a verdict,” Marks said. “The data suggest that areas with more cultivated land and herbicide use tend to have higher melanoma rates, but many other factors could be at play like genetics, behavior or access to health care. Understanding these patterns helps us protect not just farmers, but entire communities living near farmland.”

Implications Beyond Pennsylvania

Lam said she hopes to better understand how agricultural practices relate to public health, especially since similar trends have been identified in farming regions of Utah, Poland and Italy. She encouraged anyone concerned about risk to perform routine skin checks and use sun-protective clothing and sunscreen. As part of the next phase of research, she is leading studies in rural communities within the affected area to learn more about farming practices and potential exposure pathways.

“Cancer prevention can’t happen in isolation,” Lengerich said. “This study demonstrates the importance of a ‘One Health’ approach, an understanding that human health is deeply connected to our environment and agricultural systems. If herbicides and farming practices are contributing to melanoma risk, then solutions must involve not just doctors, but farmers, environmental scientists, policymakers and communities working together.”

Other co-authors include Jiangang Liao, professor of public health sciences at Penn State College of Medicine, and Camille Moeckel, a fourth-year medical student and research associate at Penn State College of Medicine.

This work was supported by the MPH Capstone Program and the Medical Student Research Project at the Penn State College of Medicine, along with the University’s Algin B. Garrett Professorship.