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UCSB Professor Reveals New Findings on Universe Expansion



UCSB adjunct professor of physics Andy Howell published an article in the research journal Nature Communications last month detailing the scientific community’s knowledge of Type Ia supernovas.

People have observed the “zombie” stars — white dwarf stars in a binary system that reignite using matter from another star — since A.D. 1054 and have recently studied them to shed light on how the universe expanded millions to billions of years ago. Scientists also used the supernovas for studies indicating that dark matter makes up three-fourths of the universe.

According to Howell, a Las Cumbres Observatory Global Telescope Network staff member, the celestial phenomenon has revolutionized physicists’ understanding of several
properties of our universe.

“The universe is expanding, but instead of the expansion slowing down, as one would predict based on our current understanding, it’s accelerating,” Howell said. “This
means that something is working against gravity to keep the expansion from slowing down. This is what we call dark energy. Dark energy is something we don’t know much about. It seems to not dilute as space expands in the way we would expect.”

Howell said the supernovas create several heavy elements in the universe including iron, silicon, sulfur and oxygen.

“The iron in your blood cells has ultimately come from a supernova of this type,” Howell said. “Furthermore, these explosions are so bright that you can see them from across the universe. This is why we are able to use them as something of a standard candle to make a map of the universe’s expansion.”

Although studies of the entities have made significant developments, Howell said the available information is incomplete.

“We don’t know the second star in the binary systems,” Howell said. “We don’t understand exactly how the explosions work — this is extreme physics and it’s nearly impossible to recreate on Earth.”

The LCOGT is creating a system of observatories to provide new and more detailed information for the Type Ia’s, Howell said.

“The LCOGT is in the process of putting telescopes all over the world in order to get a better perspective on these phenomena and others,” Howell said. “It is the first network of its kind. We use one-meter telescopes to see into the supernovae. In many of these cases, we are seeing the remnants of an explosion that happened before life evolved on Earth. When you think about it that way, it really amazes you.”

According to Physics Dept. Chair Omar Blaes, Howell’s research reflects the university’s goal of challenging scientific boundaries.

“The Physics Department is engaged in research at the very frontiers of human understanding of the universe,” Blaes said in an e-mail. “Supernovae are exciting events in and of themselves — full of rich physics in extreme environments. But as the article points out, they are also useful probes of the dynamics of the entire universe on the largest scales.”

Blaes said the university and network’s collaborative effort will provide a better understanding of the supernovas and similar celestial bodies.

“The key to progress in this area is assembling large databases of supernovae so that we can improve our understanding of the diversity of the phenomenon,” Blaes said. “UCSB’s affiliation with the [LCOGT] Network — which will be dedicated to follow-up observations of transient events on the sky — will be key, as will its involvement with other transient surveys.”

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