Kerry Vahala and collaborators from UC Santa Barbara have found a unique solution to an optics problem. When we last checked in with Caltech’s Kerry Vahala three years ago, his lab had recently reported the development of a new optical device called a turnkey frequency microcomb that has applications in digital communications, precision time keeping, spectroscopy, and even astronomy.

This device, fabricated on a silicon wafer, takes input laser light of one frequency and converts it into an evenly spaced set of many distinct frequencies that form a train of pulses whose length can be as short as 100 femtoseconds (quadrillionths of a second). (The comb in the name comes from the frequencies being spaced like the teeth of a hair comb.)

Now Vahala (BS ’80, MS ’81, PhD ’85), Caltech’s Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics and executive officer for applied physics and materials science, along with members of his research group and the group of John Bowers at UC Santa Barbara, have made a breakthrough in the way the short pulses form in an important new material called ultra-low-loss silicon nitride (ULL nitride), a compound formed of silicon and nitrogen.

“This was such a big, glaring hole,” said Dr. Maria Drout. “If it turned out that these stars are rare, then our whole theoretical framework for all these different phenomena is wrong, with implications for supernovae, gravitational waves, and the light from distant galaxies. This finding shows these stars really do exist.”

Can binary stars steal material from each other? This is what a recent study published in Science hopes to address as a team of international researchers examined how the interaction between binary stars can cause one star to strip material from its companion star over time, resulting in one massive star and one much smaller star. While this study could help astronomers better understand precursor signs to supernovae, scientists have only identified one candidate for being stripped of its hydrogen material, despite longstanding hypotheses that one in three binary stars are stripped of their hydrogen.

Our sun actively produces solar flares that can impact Earth, with the strongest flares having the capacity to cause blackouts and disrupt communications—potentially on a global scale. While solar flares can be powerful, they are insignificant compared to the thousands of “super flares” observed by NASA’s Kepler and TESS missions. “Super flares” are produced by stars that are 100–10,000 times brighter than those on the sun.

The physics are thought to be the same between solar flares and super flares: a sudden release of magnetic energy. Super-flaring stars have stronger magnetic fields and thus brighter flares but some show an unusual behavior—an initial, short-lived brightness enhancement, followed by a secondary, longer-duration but less intense flare.

A team led by University of Hawaiʻi Institute for Astronomy Postdoctoral Researcher Kai Yang and Associate Professor Xudong Sun developed a model to explain this phenomenon, which was published today in The Astrophysical Journal.