Astronomers Capture Non-Spherical Geometry of Supernova SN 2024ggi Explosion

An international consortium of astronomers has achieved a groundbreaking observation, capturing the geometry of the supernova SN 2024ggi explosion during its most fleeting, initial phase. This success yielded crucial empirical data regarding the shape of the ejected material precisely as it breached the surface of the progenitor star. The stellar catastrophe unfolded within the spiral galaxy NGC 3621, situated approximately 22 million light-years distant within the constellation Hydra.

The rapid response of the research team proved critical. Supernova SN 2024ggi was initially detected on April 10, 2024. Demonstrating exceptional operational speed, researchers initiated observations using the European Southern Observatory’s (ESO) Very Large Telescope (VLT) just 26 hours later, on April 11, 2024. This brief “breakout phase” is typically over within a matter of hours, underscoring why the swift mobilization was essential for gathering information that would be lost in later stages. The methodological breakthrough involved employing spectropolarimetry via the FORS2 instrument on the VLT, enabling scientists to ascertain the geometry of the light source, even though it appears merely as a point object from Earth's vast distance.

The resulting data revealed a startling finding: the initial expulsion of stellar material was decidedly non-spherical. Instead, it possessed an elongated, olive-like shape, confirming pronounced axial symmetry right from the very first moments of the cataclysm. Although this form gradually flattened as the material expanded and interacted with the surrounding environment, the fundamental axis of symmetry remained fixed. This persistent orientation strongly suggests that the explosion’s directionality was predetermined by internal factors within the star, such as its rotation or magnetic field, at the moment of core collapse.

Astronomers successfully identified the progenitor star of SN 2024ggi as a red supergiant. Its estimated mass ranged from 12 to 15 times that of the Sun, with a radius approximately 500 times larger than the solar radius. Stars of this immense size conclude their lives through gravitational core collapse, culminating in a Type II supernova explosion. The detailed study of this early-stage geometry provides astrophysicists with critical constraints, allowing them to refine and improve the theoretical models that govern how these massive celestial bodies explode.

The success of this observation hinged on robust international coordination. Key specialists involved included Yi Yang of Tsinghua University, who initiated the observation request, alongside co-authors Dietrich Baade and Ferdinando Patat from the European Southern Observatory (ESO). Analysis of the early spectra also detected narrow emission lines, including H, He I, C III, and N III. Furthermore, historical data retrieved from the Hubble and Spitzer telescopes helped paint a complete picture of the progenitor, confirming its status as an isolated red supergiant years before its demise. This significant achievement, detailed in the journal Science Advances, not only showcases the efficacy of global scientific collaboration but also establishes a fundamental baseline for building statistical data regarding the geometry of stellar explosions.