“What we found is that right around the size of Neptune, planets go from being almost always on circular orbits to very often having elliptical orbits,” said UCLA postdoctoral researcher Gregory Gilbert, the lead author of a paper describing the findings published in Proceedings of the National Academy of Sciences.

The researchers used data collected by NASA’s Kepler telescope, which monitored 150,000 stars and measured dips in their brightness caused by transiting planets to discover thousands of exoplanets. The measurements of stellar brightness over time are called light curves. The researchers performed a detailed analysis of the light curve dips to extract information about the shape of the planets’ orbits.

One of the most challenging aspects of this project was ensuring every single one of the 1,600 light curves was modeled with care.

“If stars behaved like boring light bulbs, this project would have been 10 times easier,” said co-author Erik Petigura, a UCLA physics and astronomy professor. “But the fact is that each star and its collection of planets has its own individual quirks, and it was only after we got eyes on each one of these light curves that we trusted our results.”

This is where UCLA undergraduate Paige Entrican came in. Entrican built a custom visualization tool kit and manually inspected each light curve.

“Reviewing the data was a meticulous process that required careful inspection of all data products to ensure the validity of our results. Several times during this project, I identified failure modes that only affected 1% of all our stars. But we needed to update our analysis to be robust to these issues and go back and reprocess the entire data set,” Entrican said.

The eccentricity split coincides with several other iconic features in the exoplanet population, such as the high abundance of small planets over large planets and a tendency for giant planets to form only around stars enriched in heavy elements such as oxygen, carbon and iron. Astronomers call these heavy elements metals.

“Small planets are common; large planets are rare. Large planets need metal-rich stars in order to form; small planets do not. Small planets have low eccentricities, and large planets have large eccentricities,” Gilbert explained.

The coincidence of trends in abundance, metallicity and eccentricity points to two distinct pathways for forming small and large planets.

“To see a transition in the eccentricities of the orbits at this same point tells us there really is something very different about how these giant planets form versus how small planets like Earth form. That’s really the major discovery to come out of this paper,” Gilbert said.

Scientists think that planets form when small space rocks fuse to form bigger rocks until eventually they form a planet that can be about the size of Earth or, if the planetary core is very large, up to 10 times bigger than Earth. At this point, the planet is large enough to hold onto large amounts of hydrogen and helium and becomes a gas giant like Jupiter and Saturn in our solar system. Planets larger than Neptune are somewhat rare because they must undergo runaway accretion, a feedback loop of accumulating hydrogen and helium gas. But this can usually only happen if they also are orbiting a star that contains large quantities of elements heavier than helium.

Larger planets with eccentric orbits also point to a more chaotic period of formation, during which planets interact via gravitational forces to produce noncircular orbits. For example, eccentric giant planets probably stir up their neighbors more frequently, causing giant impacts such as the one that produced Earth’s moon. In exoplanetary systems, these collisions can be much more violent, involving the mergers of two planets much larger than the Earth.

“It’s remarkable what we’ve been able to learn about the orbits of planets around other stars using the Kepler Space Telescope,” Petigura said. “The telescope was named after Johannes Kepler, who, four centuries ago, was the first scientist to appreciate that the planets in our solar system move on slightly elliptical rather than circular orbits. His discovery was an important moment in human history because it showed that the sun, rather than the Earth, was at the center of the solar system. I’m sure Kepler, the man, would be delighted to learn that a telescope named in his honor measured the subtle shapes of orbits of Earth-size planets around other stars.”

Jeffrey Pittman II, instructional assistant professor in nutrition and hospitality management, is researching the potential benefits — and numerous doubts — that surround robots invading the kitchen.

“We have to look at this from the standpoint of, ‘What benefits can these robots offer if they are implemented?'” he said. “What benefit can they have not just to the restaurant owner, but to the other employees and even to the customer?”

Restaurants across the globe have embraced automated cooks, and multiple restaurants in Mississippi have integrated robotic servers. That’s because the benefits are clear, Pittman said.

Robotic chefs and servers are never late, adhere to food safety protocols and rarely require maintenance. For the hospitality industry — which the Bureau of Labor Statistics reports has an annual turnover rate of more than 70% — robot chefs could be an answer to the labor shortage problem, Pittman said.

“The restaurant industry has had labor issues for about a decade,” said James Taylor, associate professor of nutrition and hospitality management. “With COVID, things got worse, and since COVID, things have not recovered.

“We’re seeing automation in the industry already. You see kiosks at fast-food restaurants where you can order, drive-thru windows have systems that can take your order. To move it into the kitchen is the next logical step.”

Despite the potential benefits, however, many people do not trust a robot to do the work of a chef.

“The current perception of robot chefs is that they’re never going to provide the human touch, they’re never going to be able to cook better than a human, and that they are nothing but a scheme by restaurant managers to get rid of jobs that good, hard-earned people need to save money,” he said.

“My research is really aimed at showing that robot chefs aren’t necessarily designed to work by themselves in a kitchen environment. They’re supposed to serve as a supportive mechanism.”

Robots such as Flippy, a robot that flips burgers or works on frying stations, leave other kitchen workers in charge of plating and assembling the meal. By moving chefs into a supervisory role, restaurants could also work to solve a deeper problem, the Ole Miss professor said.

The restaurant industry’s struggle with hiring and sustaining long-time employees is tied to the low-pay and labor-intensive nature of the work, he said.

“There are a lot of restaurants that are understaffed, and the issue is not that managers don’t want to hire people,” Pittman said. “People aren’t applying for these jobs because nobody wants to work in a high-volume restaurant environment where you hardly have any days off, make minimum wage and don’t get to have a work-life balance, right?

“So, I’m asking, ‘How can a restaurant implement robot chefs to help provide that supportive labor while making sure that they remain profitable?'”

With the increased push to move from minimum wage to a living wage, fewer people are drawn to the low wages of restaurant labor, Taylor said.

“I don’t think that anybody who wants a job is not going to be able to get one because of automation,” he said. “They’re not applying for them now — that’s why we have that shortage. The restaurant used to be entry-level point for workers, but we’re really not seeing that anymore.”

If a robot reduces labor costs, however, restaurants could afford to pay their chefs more while increasing the quality of life for restaurant workers by removing some of the menial labor, Pittman said. With the rise of robot chefs, the industry would need also more robot technicians, opening the door for new jobs.

A restaurant owner can spend approximately $50,000 on a robot chef or rent one for $3,000 a month, which seems like a large investment, Pittman said. But owners must also account for the potential cost of employee turnover.

“On average, you’re going to be spending $5,000 to hire someone,” Pittman said. “That’s filing paperwork, paying for background checks, health insurance, drug tests and training. In addition to that, you have a salary.

“And if that person quits in four, five, even six months, that money is gone.”

Many kitchen robots don’t need maintenance for at least four years, Pittman said.

“That’s $50,000 for four years of work, and even when they need maintenance, the cost to repair them is relatively low,” he said.

The Ohio State University study’s results provide new information about the timing of accretion — the process of accumulating a large amount of gas as well as solid particles that are rich in carbon and oxygen to make large planets, like Jupiter.

Planets are formed from protoplanetary disks, spinning clouds of dust and gas that are the perfect ingredients for planet formation. This new study suggests the accretion takes place early, when disks are massive and much younger than researchers previously believed.

While the number of newly confirmed exoplanets has continued to grow, the origins of these worlds and the factors that impact their formation is a puzzle scientists are still aiming to solve. Jupiter-like exoplanets, for instance, were initially thought to take nearly 3 to 5 million years to fully form; recent observations now suggest that for a gas giant like Jupiter, this process is likely closer to about 1 to 2 million years.

This discovery challenges researchers’ existing theories regarding at what “age” of the protoplanetary disks these planets were formed, said Ji Wang, author of the study and an assistant professor in astronomy at Ohio State. The results could lead scientists to re-evaluate and revamp their theories of planet formation for the solar system and elsewhere.

“Everything we know about exoplanets can be put in the context of the solar system and vice versa,” said Wang. “Usually planet formation is a bottom-up scheme, meaning it starts with small objects that build up to form a bigger planet, but that way takes time.”

Though exoplanets refer to planetary objects that orbit far beyond the confines of our solar system, understanding more about how they form could help researchers gain more insight into the evolution of the solar system and early Earth, whose formation was much later than Jupiter’s, but was still greatly impacted by it.

The “‘bottom-up” interpretation of planetary formation is called the “core accretion theory,” but another possible formation mechanism is when planets are formed through gravitational instability — when the clumps in a disk around a star are too massive to support themselves and collapse to form planets. Because a planet’s accretion history could be closely linked to these two compelling yet complementary formation mechanisms of evolution, Wang said, it’s important to determine which process is more often the case.

The study was recently published in The Astrophysical Journal.

The study analyzed a sample of seven gas giant exoplanets whose stellar and planetary chemical properties had already been directly measured by previous studies and compared them to data on the gas giants in our solar system, Jupiter and Saturn.

Wang showed that the early formation of these exoplanets is consistent with recent evidence that Jupiter formed much earlier than previously thought. This finding is based on the surprisingly high amount of solids these exoplanets accreted.

All the materials accreted at the beginning of a planet’s formation increase the metallicity of its atmosphere, and by observing the traces they leave behind, researchers are able to measure the amount of solids the planet once gathered.

The higher the metallicity, the more solids and metals — anything on the periodic table more massive than hydrogen and helium — scientists can assume were accreted during the formation process, said Wang.

“We can infer that on average, every one of the five planets sampled accreted the equivalent of 50 Earth masses worth of solids,” he said. “Such a large amount of solids can only be found when a system is younger than 2 million years, but in our solar system, the total solids available is only on the order of 30 to 50 Earth masses worth.”

This new data implies that the building blocks used to form the exoplanets were available at an earlier stage of the protoplanetary disk’s evolution than once expected and their availability of these building blocks greatly decreased over a span of millions of years. Because scientists usually don’t expect to find proof that planets formed that early, it’s a finding that current theories will likely struggle to reconcile, Wang said.

“These exoplanets formed so early that there was still a large reservoir of metals available,” said Wang. “This is something that the scientific community was not fully prepared for so now they’ll have to scramble to come up with new theories to explain it.”

Because gas giants pull in huge amounts of matter during accretion, their formation and migration through space also affects the development of rocky planets elsewhere in a protoplanetary disk. In the solar system, this phenomenon is believed to have caused Jupiter and Saturn to push Mercury out of its original orbit, and caused Mars to become much smaller than the Earth or Venus.

That said, to aid astronomers looking to do similar planetary formation analyses in the future, the work also provides a statistical framework for inferring the total mass of solid accretion for any other exoplanet, which the study notes can be an ideal tool for investigating other kinds of complex elemental data as well.

And while this research relied purely on archival data, Wang expects his work to be further complemented with new high-resolution data collected by better instruments, such as more powerful ground-based astronomical observatories or next-generation technologies like the James Webb Space Telescope.

“By expanding this work with a larger sample of exoplanets, we hope to see the trend of evidence found in this paper continue to hold,” said Wang.

This work was supported by the National Science Foundation.

“We’re at the tipping point,” said electrical and computer engineering professor Daniel Blumenthal.

In an invited article that was also selected for the cover of Optica Quantum, Blumenthal, along with graduate student researcher Andrei Isichenko and postdoctoral researcher Nitesh Chauhan, lays out the latest developments and future directions for trapping and cooling the atoms that are fundamental to these experiments — and that will bring them to devices that fit in the palm of your hand.

Cold atoms are atoms that have been cooled to very low temperatures, below 1 mK, reducing their motion to a very low energy regime where quantum effects emerge. This makes them sensitive to some of the faintest electromagnetic signals and fundamental particles, as well as ideal timekeeping, navigation devices and quantum “qubits” for computing.

In order to capitalize on these properties, many researchers currently work with highly sensitive laboratory-scale atomic optical systems to confine, trap and cool the atoms. Conventionally, these systems use free-space lasers and optics, generating beams that are guided, directed and manipulated by lenses, mirrors and modulators. These optical systems are combined with magnetic coils and atoms in a vacuum to create cold atoms using the ubiquitous 3-dimensional magneto-optical trap (3D-MOT). The challenge that researchers face is how to replicate the laser and optics functions onto a small, durable device that could be deployed outside of the highly controlled environment of the lab, for applications such as gravitational sensing, precision timekeeping and metrology, and quantum computing

The Optica Quantum review article covers recent and rapid advancements in the realm of miniaturizing complex cold-atom experiments via applications of compact optics and integrated photonics. The authors reference photonics achievements across a variety of sub-fields, ranging from telecommunications to sensors, and map the technology development to cold atom science.

“There’s been a lot of really great work miniaturizing beam delivery,” said Isichenko, “but it’s been done with components that are still considered free-space optics — smaller mirrors or smaller gratings — but you still couldn’t integrate multiple functionalities onto a chip.”

Enter the researchers’ photonic integrated 3D-MOT, a miniaturized version of equipment used widely in experiments to deliver beams of light to laser cool the atoms. Embedded into a low-loss silicon nitride waveguide integration platform, it’s the part of a photonic system that generates, routes, expands and manipulates all the beams necessary to trap and cool the atoms. The review article highlights the photonic integrated 3D-MOT — or “PICMOT” demonstrated by the UC Santa Barbara team as a major milestone for the field.

“With photonics, we can make lasers on chip, modulators on chip and now large-area grating emitters, which is what we use to get light on and off the chip,” Isichenko added.

Of particular interest is the atomic cell, a vacuum chamber where the atoms are trapped and cooled. One feat the researchers accomplished was to route the input light from an optical fiber, which is less than the width of a hair, via waveguides to three grating emitters that generate three collimated free-space intersecting beams 3.5 mm wide. Each beam is reflected back on itself for a total of six intersecting beams that trap a million atoms from the vapor inside the cell and, in combination with magnetic fields, cool the atoms to a temperature of just 250 uK. The larger the beams the more atoms can be trapped into a cloud and interrogated, Blumenthal noted, and the more precise an instrument can be.

“We created cold atoms with integrated photonics for the first time,” said Blumenthal.

The implications of the researchers’ innovations are far-reaching. With planned improvements to durability and functionality, future chip-scale MOT designs can take advantage of a menu of photonic components, including recent results with chip-scale lasers. This can be used to optimize technology for applications as diverse as measuring volcanic activity to the effects of sea level rise and glacier movement by sensing the gradient of gravity on and around the Earth.

Integration of the 3D-MOT can give quantum scientists and time keepers new ways to send today’s earthbound instruments into space and conduct new fundamental science, and enable measurements not possible on Earth. Additionally, the devices could advance research projects by decreasing the time and effort spent establishing and fine tuning optical setups. They can also open the door to accessible quantum research projects for future physicists.