Key Project Studies Massive Stars
Massive stars are larger than 8 times the size of our Sun. These stars are of great interest to astronomers, as they are the source of many astrophysical phenomena. The most massive stars explode as supernovae and collapse into black holes at the ends of their lives.
Scientists want to study massive stars to understand their inner structure, the material that they eject during their lives, and how much of the core material is mixed in this ejecta. Massive stars pulsate, changing their brightness at a rate of once every 4-8 hours, under the influence of their internal structure. These vibrations are called Asteroseismology. Studying Asteroseismology can help understand the inner structure of the star to measure its mass, age, composition, and internal rate of rotation.
Observations of massive stars that provide data for characterizing the pulsations require continuous observations from land-based optical telescopes and typically have taken many years to study a single star.
Prof Iair Arcavi of Tel Aviv University was a postdoctoral researcher at Las Cumbres Observatory when he devised a plan for studying massive stars with LCO’s telescope network. At LCO, Dr. Arcavi tested making 48 continuous hours of observations of a massive star and learned that the cameras were sensitive enough to pick up the subtle changes in brightness. These data shorten the study time of a single star to months rather than years. Since massive stars are very bright, Dr. Arcavi also discovered that these observations can be taken on the LCO network of smaller 40-cm aperture telescopes.
At Tel Aviv University, graduate student Noi Shitrit picked up the Asteroseismology project in 2019. Noi was excited to take on this unusual project and she won support from LCO for the Asteroseismology Key Project in 2023. Noi selected the stars for the study and compared the LCO data to data from the NASA TESS space telescope.
Ms. Shitrit and Dr. Arcavi formed a collaboration called the Global Asteroseismology Project, composed of worldwide experts who help with choosing the stars to study, planning the observations, and writing the analysis tools. Results of the study of massive stars by the Global Asteroseismology Project have been excellent and the proof of concept, for the use of LCO telescopes, was published in the Astronomical Journal in a paper this January. The authors believe that measuring the oscillations of massive stars brings researchers closer to solving some of the largest puzzles regarding massive-star structure and evolution. Using the LCO network will allow researchers to study three times as many massive stars as in the past.
Scheduling the LCO telescopes for this project is nontrivial and requires coordination between sites. A lot of the existing software tools at LCO are very helpful for automating this process. The Asteroseismology project will have broader impacts to assist other astronomers with continuous observations of exoplanets, binary stars, microlensing, and supernovae. This is just the beginning of learning to use the network to help anyone who wants to do science with continuous observations.
Dr. Arcavi comments on the unique aspects of LCO, “LCO is the only facility that can do this. The massive stars we have studied are the proof. This is now a project that one graduate student can do in 3 years, instead of the whole community for decades. That’s the difference LCO makes.”
Noi Shitrit is enjoying her work and is looking forward to studying a larger group of massive stars. Over the three years of the Key Project, she will perfect analysis tools that handle the data quickly and will develop evolution models for the lives of massive stars.
Ms. Shitrit says of her work, “Asteroseismology is changing the way we look at stars. It can really help us solve some of the anomalies and unknowns of massive stars.”
LCO congratulates Ms. Shitrit and Dr. Arcavi on their groundbreaking work.
Graduate student Noi Shitrit and Prof. Iair Arcavi examining the light curves of massive stars.
