Wenjie Zhang

Astronomers observed seven times how a black hole tears apart a passing star. They measured the flares with high precision in X-rays and noticed: the more energetic radiation always outpaced the soft by 500 seconds. It's like a sound echo in the mountains — first you hear the direct shout, then its reflection off a cliff.

The cosmic detective story began with a quiet flash in the optical band. AT2019wzc slowly brightened and faded like a smoldering ember. But hidden inside was something more energetic — repeating soft X-ray bursts that astronomers call quasi-periodic eruptions. These eruptions last minutes to hours and repeat every few hours or days.