For four decades, Astronomy Professor John Thorstensen has been captivated by the phenomena of cataclysmic variable stars (CVs)—binary star systems comprising a living star and a white dwarf.
Over the years, he has discovered and characterized hundreds of these fascinating star systems.
Recently, Thorstensen and his team of undergraduates ventured to South Africa to conduct research on cataclysmic variables, contributing valuable information to our understanding of these enigmatic celestial objects.
What are Cataclysmic Variables?
Cataclysmic variable stars consist of a white dwarf and a living star orbiting closely around each other.
Over time, the white dwarf siphons off hot gas from its companion star, creating a flare-up that can be observed from Earth. These systems provide a profound reminder that “not even the stars are eternal,” according to Thorstensen.
The Project’s Significance
Cataclysmic variables are important objects of study because they reveal critical insights into stellar evolution and lifecycle.
Despite more than 10,000 known CVs, only a fraction have been studied in detail. This particular research endeavor aimed to characterize seven previously little-known cataclysmic variables located 1,000 to 3,000 light-years from Earth.
Educational Impact and Student Experience
The project offered Dartmouth students a once-in-a-lifetime chance to immerse themselves in hands-on astronomical research and South African culture.
They operated telescopes, learned to use astronomy software like IRAF, PyRAF, and ds9, and even contributed to published research papers.
For Chase Alvarado-Anderson ’23, now headed to Stanford for a Ph.D. in planetary science, the experience reaffirmed his passion for space and astronomy.
The Role of Technology
The team used a telescope with a 1.9-meter mirror, equipped with a spectrograph to analyze the light emitted by the stars.
Through this, they were able to observe the Doppler effect in action, calculating the stars’ orbital periods and speeds.
All seven cataclysmic variables observed had typical orbital periods of a few hours and speeds exceeding 100 miles per second.
Changing Perceptions
Perhaps one of the most poignant aspects of the project was how it shifted the students’ perceptions of white dwarfs.
Rather than seeing them merely as dead stars, they came to see them as stars capable of a form of rebirth, siphoning off gas from their companions and flaring back to observable life.
Conclusion
The research expedition not only contributed valuable data to the field of astronomy but also served as a transformative educational experience for the students involved.
It highlighted the importance of fieldwork in the sciences and brought to life the fascinating, ever-changing world of cataclysmic variable stars.
The work of Thorstensen and his students reminds us that in the vast universe, even the stars are not constant but part of a grand, evolving cosmic ballet.
The research findings can be found in The Astronomical Journal.
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Source: Dartmouth College.
