Bradley Schaefer, an astronomer at Louisiana State University, studies cataclysmic variable stars. These stars change brightness due to major events happening in their systems. His focus is on recurrent novas—two-star systems where a white dwarf pulls material from its partner. This process can lead to nuclear fusion, causing bright outbursts that occur at least twice a century. While there are other types of novas, theirs happen much less frequently due to smaller white dwarfs.
Schaefer believes there may be a link between recurrent novas and Type Ia supernovas, which play a critical role in understanding how fast the universe is expanding. He is currently testing whether these novas could eventually evolve into supernovas. By measuring their brightness over many years and multiple outbursts, he hopes to identify patterns that could inform future models of stellar evolution. So far, he’s studied the orbital periods of over a dozen systems, ruling some out as likely precursors to supernova explosions.
To succeed, Schaefer needs long-term data. “You need many decades’ worth of data,” he says. “Archival data is the only game in town.” This highlights a truth in astronomy: understanding present phenomena often requires a look back at historical data.
Research on active galactic nuclei (AGNs) reveals similar challenges. Jeff Graham, a co-leader of the Zwicky Transient Facility, studies these supermassive black holes and their accretion disks. Despite having 60 years of data and millions of time series images, scientists still struggle to fully grasp how their brightness changes. “We still really don’t understand the mechanisms by which they are variable,” Graham notes. His facility uses a telescope that bridges modern and historical observation methods, employing both advanced digital technology and data from the earlier days of glass photographic plates.
Recently, Graham digitized 20 terabytes of old photographic plates from the Palomar Observatory Sky Survey. These plates, created in the 1940s through the 1990s, provide invaluable historical context. By combining data from various telescopes over different time periods, astronomers can better interpret the brightness variations they observe today.
However, deciphering old plates isn’t without challenges. Factors like different optics and varying sensitivity of older photography can complicate comparisons with newer data. Some plates are in poor condition, with cracks or peeling emulsion, making their preservation crucial. “Surviving plate collections can be a constant source of discovery,” Griffin, another astronomer, says. Through careful scanning, they can reveal hidden insights about cosmic activity over the past century.
The effort to preserve these historical artifacts is essential. Many collections were lost or damaged due to neglect or improper storage, highlighting the need for continued attention to these valuable resources. As Schaefer emphasizes, understanding current astronomical phenomena often relies on insights gleaned from the past.
Understanding the cosmos requires more than just new data; it requires a commitment to preserving and utilizing historical information. In a field where every second counts, maintaining access to past observations could prove vital for future discoveries.
