Swedish scientists engaged in finding record numbers of exploding stars
A small telescope on a mountain in California has enabled collecting over 10 000 supernovae over the past 7 years. A large team of international scientists – including astronomers in Stockholm– has made this possible.
The international supernova survey Zwicky Transient Facility (ZTF) and its Bright Transient Survey (BTS) has finally reached 10 000 supernovae.
A supernova is an exploding star, and the best way to find one is to monitor many, many distant galaxies and look for new bright objects. This is done routinely with the ZTF telescope on Palomar, California, in the BTS study led by Caltech staff-scientist Christoffer Fremling. This project has now reached a record-breaking number of 10 000 supernovae.
The most prolific supernova hunter in the team is Fremling's former PhD supervisor, Professor Jesper Sollerman at the Department of Astronomy at Stockholm University.
"I have taken advantage of being able to follow the Palomar night in day-time Stockholm. This has allowed us in Europe to react quickly to new events in the data stream. The nice animation here shows that the ZTF survey has contributed very significantly to this field."
Statistics from the Transient Name Server shows that ZTF has discovered half of the classified supernovae accumulated there, and have classified close to half as well, more than any of the other large surveys.
Sollerman's main job has been to decide which supernovae should be followed up for classification with a neighbor telescope on Palomar. This means confirming that the new object is indeed a supernova and deciding which type of explosion it is.
"With this job I also got to discover many new objects to keep the follow-up telescope busy, says Sollerman. I have in principle been hunting for supernovae every clear Palomar night for the past 6.5 years. Summing this up makes thousands of classified supernovae that I have found, and probably 10 000 we never managed to classify. I have to admit that I have become a bit addicted to supernova hunting. It sort of feels like I have accomplished something when I have discovered a new supernova even before biking to work."
Many scientists at the Oskar Klein centre have contributed to this large international effort. While the astronomers have been focusing on the exploding massive stars, the scientists at the Physics department like Joel Johansson have been instrumental in keeping track of their favorite white dwarf supernovae.
"At the end of the day, what counts it what science we make out of the many supernovae we now have gathered. We have already found many rare objects, and the full sample will allow for much more systematic investigations", ends Sollerman.
Last updated: December 5, 2024
Source: Department of Astronomy