Explosions Could Provide Clues About First Stars, Fellow Says

A set of explosions that happened thousands of years ago could provide clues about the formation of the earliest stars, according to Robert A. Simcoe, a research fellow at the Radcliffe Institute for Advanced Study and an associate professor of physics at MIT.

During a talk to about 90 people on Wednesday, Simcoe spoke about the emergence of the universe’s first stars and how to detect their traces as part of the 2016–2017 Fellows' Presentation Series hosted by the Radcliffe Institute.

Simcoe said the first generation of stars were “massive, hot, and short-lived,” and their explosions permanently changed the formation of future stars because they released new elements. Originally after the Big Bang, only a small number of elements including hydrogen and helium existed.

That change in the composition of the universe gives researchers like Simcoe clues about the formation of the earliest stars.

“Archaeologists talk about finding the first humans. There is no time when you can find the first human, but you can get a holistic sense of when they appeared. It’s the same thing for us,” Simcoe said. “We’re not finding the first star, we’re trying to find the first generation of when the elements formed.”

Astrophysicists use spectroscopy—the analysis of the interaction between objects and light—to look for indirect signs that they are looking at the first stars since it is impossible to look at them directly, Simcoe said.

“If a picture is worth a thousand words, a spectrum is worth a thousand pictures,” Simcoe said.

Simcoe is currently working on developing technology that will allow physicists to study the universe at the epoch when the first generation of stars began forming. His team at MIT is creating an on-ground infrared spectrometer for a space telescope that is set to be launched in 2018.

“I think the next couple of years are going to be really pivotal," he said. "There are a bunch of lines of reasoning that suggest that we’re kind of within striking distance of being able to study this epoch, and once we’ve done that, those are the earliest stars. We can’t go further than that. So it’s like reaching the end of a map.”

Simcoe said that he geared his talk to the audience, which included a significant number of fellows.

“The fellows are a group of highly intelligent individuals from every imaginable subject discipline, and so you can’t give a specialized talk to this group, but you have to assume that they will follow a lot of what you say. I geared this talk higher than I would for a normal public talk because this is not the general public,” Simcoe said.

Kelly N. Luce, another Radcliffe Fellow who attended the event, praised Simcoe as “a brilliant astronomer and scientist.”

“I would just love to be one of his students and have him explain this stuff to me because I know it’s really complicated, but he can always make whomever he’s talking to understand what he’s saying and make what he’s doing sound super interesting,” Luce said.