Tens of millions of years ago, a white dwarf star exploded in a corner of the universe. Between then and now, the light has been traveling toward Earth. Koichi Itagaki, an amateur astronomer curious about the universe, observed the darkened sky on a night in 2019 and noticed a new addition to the constellations. A sudden bright light mapped the history of the white dwarf star’s violent death, a supernova, its light finally reaching the telescope’s lens. Not 24 hours later and for the span of only a few weeks, scientists quickly worked to identify and analyze the event, as the luminosity of the destroyed celestial body would rapidly fade and eventually disappear.
The Las Cumbres Observatory (LCO), located in Goleta, California, is one of the many worldwide observatories where robotic telescopes are designed to collect astronomical data. There are many ongoing research projects at the facility, including the current study of supernovae. UC Santa Barbara graduate student researchers Jamison Burke, Estefania Padilla Gonzalez and Craig Pellegrino work with UCSB Department of Physics adjunct professor and LCO staff scientist Andy Howell to observe and understand the data collected from the telescopes, with the goal of improving their understanding of astronomical phenomena. The researchers give insight to the operations and processes that occur among a worldwide network of 10 robotic telescopes.
While a few supernovae have been discovered manually, such as Itagaki’s 2019 finding, much of the supernova identification is credited to sky surveys, in which a series of telescopes around the world are programmed to frequently capture images of portions of the night sky that, when pieced together, map nearly the entirety of it. According to Pellegrino, the variation in the sky’s patterns across different times indicates the presence of celestial phenomena. “[The telescopes] look at those images and see if anything is there that night that wasn’t there the night before. That’s the way that a lot of these supernovae are discovered … like blips, points of light and galaxies that pop up in these images.”
Through this process, around 100 supernovae are discovered every night. With the great diversity in the collected data, there is a sense of freedom in that researchers are able to study projects that interest them. “[Graduate] students, when they come here, have tons of different projects that they can choose to work on. So it’s really whatever interests them or excites them,” Pellegrino said.
Despite all the observations, there is still much that astronomers do not understand about the behaviors of different supernovae, like a class of supernovae called Type IC. “[Type ICs] are a little bit weird, just because … it’s a little bit hard to classify besides saying this type of explosion … doesn’t show hydrogen or helium [like other supernovae],” Padilla Gonzalez said. “The reason why I also found Type ICs to be interesting is because we don’t know much about them.”
Many times, there are anomalous events that deviate from the typical supernovae. Itagaki’s discovery of SN 2019yvq, for example, exhibited unexpected behavior. Burke stated that, generally, supernovae increase in intensity for a period of time, while the observed object did not.
“They get lighter over the course of a few weeks, and the supernova did not do that,” Burke said. “Instead, down in the redder wavelengths, it did brighten but the other wavelengths of light did not. So as you get into the UV, instead of brightening, it faded very quickly.” The findings revealed an increased amount of UV light, which is invisible to the human eye, that was not typical of most other supernovae. With less light from the visible spectrum, the lifetime of the explosion appeared to be shorter than expected. Burke’s responsibility at the LCO was to explain the cause of this abnormal behavior.
The data suggested that a white dwarf exploded in a binary system, where another star orbited in close proximity. When the star’s life ended with a supernova, the ejecta — which is the debris — likely collided with the other body, causing a buildup of heat in the UV spectrum, which is not visible to the human eye. “As it gets heated up, it’ll emit extra light, and because it’s so hot in the UV … that’s where we think this UV excess comes from,” Burke confirmed. The analysis of the SN 2019yvq supernova, similar to other studies, paved the path for an informative research paper that was published in The Astrophysical Journal in October of 2021.
There is always one of LCO’s worldwide network of telescopes observing the night sky. This allowed for a continuous observation of SN 2019yvq, so scientists like Burke could have more puzzle pieces to understand its odd behavior. “The sun never rises on the LCO empire,” Burke quipped. The research at the Los Cumbres Observatory allows for scientists to discover and describe the everlasting unknowns of the universe. The timeline of astronomical study spans beyond lifetimes, and while individuals may never witness the entire capability of the celestial realm, the observations made can aid in mapping the narrative of our vast surroundings, piece by piece.
“There’s just so much uncertainty about what we’re actually observing,” Burke said. “It’s so interesting to constantly be discovering new things that push the field in new directions and to have to live with the uncertainty you won’t ever know everything about what’s going on.”
A version of this article appeared on p. 15 of the April 14 issue of the Daily Nexus.