Free Astronomy Magazine November-December 2019

31 NOVEMBER-DECEMBER 2019 SPACE CHRONICLES searchers has now done, using data from the X-shooter instrument on ESO’s VLT. Following the GW170817 merger, ESO’s fleet of telescopes began monitoring the emerging kilonova explosion over a wide range of wavelengths. X-shooter in particu- lar took a series of spectra from the ultraviolet to the near infrared. Initial analysis of these spectra sug- gested the presence of heavy ele- ments in the kilonova, but astron- omers could not pinpoint individual elements until now. “By reanalysing the 2017 data from the merger, we have now identified the signature of one heavy element in this fireball, strontium, proving that the collision of neutron stars creates this element in the Uni- verse,” says the study’s lead author Darach Watson from the University of Copenhagen in Denmark. A team of European researchers, using data from the X-shooter instrument on ESO’s Very Large Tele- scope, has found signatures of strontium formed in a neutron-star merger. This artist’s impression shows two tiny but very dense neu- tron stars at the point at which they merge and explode as a kilonova. In the foreground, we see a represen- tation of freshly created strontium. [ESO/L. Calçada/M. Kornmesser]