Astronomer Charles Telesco is primarily interested in the creation of planets and stars. So, when the University of Florida’s giant telescope was pointed at a star undergoing a magnificent and explosive death, Telesco, a UF professor, didn’t immediately appreciate what a rare and valuable find he had.

He soon learned. The event was about to reveal insights into some of the universe’s most tantalizing mysteries.

A super-bright exploding star is known as a supernova, which can come from the death of a single very massive star or the ignition of a white dwarf – the remains of a low-mass star – as matter overflows onto it from a dying companion. Telesco and his international team, which included UF researchers Dan Li, Peter Barnes, Naibí Mariñas, and Han Zhang, recorded the latter, less-common type on CanariCam, a sophisticated infrared camera developed at UF.

Attached to the largest optical-infrared telescope in the world, the Gran Telescopio Canarias in Spain’s Canary Islands, CanariCam is one of the few astronomical instruments that can record wavelengths in the spectral region 8 to 25 micrometers, well beyond the range of human vision. UF is the nation’s only institution with a stake in the GTC, which has been probing deep into the universe and producing new knowledge of exoplanets, planetary evolution, comets and galaxies for five years.

supernova
Supernovae such as 2014J, seen here from the Hubble Space Telescope, are among the most powerful events in the universe, revealing the structure of the universe as a bobbing cork reveals the contours of a lake’s surface.

Supernovae are among the most powerful events in the universe, revealing the structure of the universe as a bobbing cork reveals the contours of a lake’s surface. They are also an essential piece of the puzzle of stellar evolution, but many of their properties remain a mystery.

The observation of supernova 2014J is a first both for Telesco and CanariCam, and, as with many moments in scientific discovery, it wasn’t planned. When Florida State University physicist David Collins visited UF in early 2014, he asked Telesco if he was observing the brand-new supernova that had exploded in the nearby galaxy M82. Telesco jumped at the suggestion and worked with observatory staff in Spain to make it happen. First, they took images of the supernova at two different wavelengths to see if they could detect it.

“We weren’t even sure we would be able to see it at these wavelengths,” says Telesco. “We took pictures and got a weird ratio for the brightnesses of the supernova through the two filters. We thought we’d either screwed up or just made a very interesting finding.” To settle the issue, Telesco’s team took a detailed spectrum of the supernova and were blown away by what they saw.

When a type Ia supernova explodes, carbon and oxygen burn hot and fast, undergoing a series of chain reactions that convert them to a rich soup of other elements, the most prominent being radioactive nickel, which decays into cobalt and finally iron. This nuclear furnace burns at a temperature of hundreds of billions of degrees for just a second as the explosion is ignited. Witnessing this moment and its aftermath gives astronomers a rolling, action-packed picture of unfolding events that scientists use to create accurate models of supernovae and their elusive origins. To the delight and surprise of Telesco and his colleagues, CanariCam recorded a pristine spectral signature of cobalt, a key element in the rapid and powerful alchemy of a supernova.

The CanariCam team observed this elemental probe repeatedly between early and late spring, watching it change shape as the expanding supernova debris revealed more and more of its inner structure. That signature had been seen only once before, in a different, more distant supernova by a NASA space telescope in 2005, but it was only a one-time snapshot. Taking a “movie” of this evolution in 2014J was a big step forward.

“It was like seeing cells divide for the first time,” says Telesco. “Everyone knew that cell division occurred, but no one had actually seen it. Astrophysicists knew that cobalt would be produced, and they had ideas about how its appearance would change in the immediate aftermath of the explosion, but no one had actually seen it happen, which is critical to testing the models that the theorists come up with.”

The spectroscopy of the supernova was so valuable that Telesco and his team used precious telescope time to take a total of four spectra over a four-month period.

“We got to watch it every month in a spectral region no one has ever monitored a type Ia supernova in before,” says Telesco. “We were the only people capable of creating a temporal sequence of the closest type Ia supernova in 300 years.”

According to FSU astronomer Peter Höflich, a key collaborator on this project, these data will be the standard for the study of type Ia supernovae for at least a decade. To Telesco this is an example of a big payoff resulting from a colleague’s offhand comment.

“Sometimes it pays to listen,” he says.

The results of the CanariCam observations are published in the Dec. 20 issue of Astrophysical Journal.

UF geneticist contributes to groundbreaking study of bird evolution

Nature abhors a vacuum, which may explain the findings of a new study showing that bird evolution exploded 65 million years ago when nearly everything else on earth — dinosaurs included — died out.

The study is part of an ambitious project, published in the Dec. 12 issue of the journal Science, in which hundreds of scientists worldwide have decoded the avian genome.

Edward Braun, an evolutionary geneticist at the University of Florida and the UF Genetics Institute, is one of the key scientists who took part in this multi-year project that used nine supercomputers and 400 years of combined computing time to sequence 48 bird genomes representing the 10,500 living species of birds on the planet.

In 2008, Braun worked with scientists at UF and four other institutions to analyze 19 bird genes. This initial study suggested that the diversity of bird evolution occurred very quickly. Now Braun and scientists from Duke University, the Natural History Museum of Denmark, the Beijing Genomics Institute at Shenzhen, the University of Illinois, and many other institutions have built on that effort.

“Six years later, we have whole genomes,” he said. “That’s a major accomplishment. The ornithology books will change.”

The asteroid strike that triggered the Cretaceous–Paleogene extinction was bad news for dinosaurs, but may have created an opening for birds.

“The birds we see today probably diversified into that. That’s probably why it happened so fast,” said Braun. “Can we pick out what the very first split is? The answer is that for the first time, using whole genomes, it appears we can.”

From hummingbirds to herons, 95 percent of avians belong to an order called neoaves (nee-oh-AY-veez). Of this group, 90 percent belong to a group called Passerea and 5 percent called Columbea comprising doves, flamingos and grebes.

“Flamingos and grebes are enough of an odd couple,” said Braun. “Throw in a dove, and that’s a really odd collection.”

The genomic evidence belies common inference that birds of a feather flock together. The Columbea group shows a kinship between water birds and land birds. One might assume the duck to be closely related to other water birds, but it’s on a separate branch of the tree altogether. It was once assumed that grebes and loons belonged together because they’re both foot-propelled divers. Like the 2008 study, this study shows otherwise.

Braun, along with Eric Triplett from the UF Department of Microbiology and Cell Science, also were principal investigators comparing three species of crocodilians — the American alligator, saltwater crocodile and Indian gharial. The inclusion of the crocodilians not only provided a study in contrast but also provided researchers with the ability to reconstruct part of the genome of the common ancestor of archosaurs, the group that includes crocodilians, birds and extinct dinosaurs.

Whereas birds evolved rapidly, crocodilians evolved slowly. The DNA of slowly-evolving organisms is a gold mine for researchers as it allows them to find more things in the genetic structure. Braun looked for evidence of ancient viruses in the genomes in an effort led by Alex Suh from Uppsala University in Sweden.

“We were able to see evidence of viral infections that occurred during the age of the dinosaurs. The oldest we found is 200 million years old,” said Braun. “The fact that you can find ancient viruses in genomes is very cool.”