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Evidence of a Massive Stellar Storm on a Nearby Star

© Olena Shmahalo/Callingham et al.

Thrilled to announce our new paper in Springer Nature paper is now live. We’ve tuned into a massive stellar storm on the radio! 🌟📡

One of the big goals in astronomy over the coming decades is to find a truly habitable world around another star. We’ve already made incredible progress, discovering thousands of exoplanets. Many of these planets also orbit within the so-called “Habitable Zone” - the region where liquid water could exist on a planet’s surface.

But there’s still a huge unknown: how often do stars hurl super-heated plasma into space? Our own Sun does this through Coronal Mass Ejections (CMEs), which can trigger brilliant aurorae, but also knock out satellites and telecommunications here on Earth. Thankfully, Earth’s magnetic field shields us from the worst of it.

For other stars, though, we had no idea how frequent or powerful these eruptions could be. That’s where our study comes in. CMEs produce a unique radio fingerprint known as a Type II burst. Using the incredibly sensitive LOFAR radio telescope (operated by ASTRON) and advanced software developed by the brilliant team at Observatoire de Paris | PSL, we searched for these bursts from over 100,000 stars... and we got lucky! 🎯

The signal we detected was far more luminous and energetic than anything ever seen from our Sun - a truly colossal stellar storm. If a planet were sitting in that star’s habitable zone, its atmosphere would be in serious trouble.

This discovery adds a vital piece to the complex puzzle of finding potentially habitable worlds beyond our own. 🌍✨

I am incredibly fortunate to have a great team around me that made this work possible. In particular, the software developed by Cyril Tasse, Philippe Zarka, and team were fundamental in getting to this point.

DOI: 10.1038/s41586-025-09715-3

Colloquia

May 1, 2022

The Commensal Radio Astronomy FAST Survey (CRAFTS)

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) has released its first call for proposal and will be open to the international community next year. Based on a novel technique of high-cadence CAL injection, we have realized the world's first calibrated commensal survey mode, simultaneously taking data for pulsar search, HI galaxies, HI imaging, and FRBs. I introduce here one of the major survey plans, namely, the Commensal Radio Astronomy FAST Survey (CRAFTS, Li et al. 2018), which has discovered more than 100 new pulsars, including a few dozen MSPs, 5 new FRBs, including one new repeater. I will also briefly describe recent FAST results from CRAFTS and other dedicated programs, including new insights into the characteristic energy of FRBs, the formation process of neutron stars, the evolution of interstellar medium, etc.
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May 14, 2022

Extreme UV Emission: Bridging Galaxy Evolution Across Cosmic Time

In the last few years, our first glimpse of the spectral properties of z∼5−7 galaxies has emerged. Deep UV spectra have revealed prominent high-ionization nebular emission lines (i.e., C IV, He II, C III]) indicating that extreme radiation fields may be characteristic of reionization-era systems. While such strong high-ionization emission lines are atypical of the well-studied z∼0−3 galaxy samples, our recent UV spectral campaigns have revealed several galaxies with analogous emission-line features to reionization-era systems. I will discuss the recent detection of extremely strong UV emission in nearby galaxies and the potential sources of their very hard ionizing radiation fields. Such strong detections of high-ionization emission lines have been linked to the leakage of Lyman continuum (LyC) photons (necessary for reionization) both theoretically and observationally. These extreme UV emission-line dwarf galaxies provide a template for the extreme conditions that are important for reionization, however their features are still poorly understood. In preparation for the coming UV window onto the early universe with the advent of ELTs and JWST, I will introduce the COS Legacy Archival Spectroscopic SurveY - an upcoming large HST program designed to disentangle the stellar and nebular spectral signatures of 45 star-forming galaxies. This program will calibrate new UV diagnostics that will allow us to trace galaxy evolution to the distant universe, unveiling the properties of reionization-era galaxies.
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