Hubble Observes Stars Flaring to Life in Orion - UNIVERSE

Just-forming stars, called protostars, dazzle a cloudy landscape in the Orion Molecular Cloud complex (OMC). These three new images from NASA’s Hubble Space Telescope were taken as part of an effort to learn more about the envelopes of gas and dust surrounding the protostars, as well as the outflow cavities where stellar winds and jets from the developing stars have carved away at the surrounding gas and dust.

Scientists used these Hubble observations as part of a broader survey to study protostellar envelopes, or the gas and dust around the developing star. Researchers found no evidence that the outflow cavities were growing as the protostar moved through the later stages of star formation. They also found that the decreasing accretion of mass onto the protostars over time and the low rate of star formation in the cool, molecular clouds cannot be explained by the progressive clearing out of the envelopes.

The OMC lies within the “sword” of the constellation Orion, roughly 1,300 light-years away.

Protostar HOPS 181 is buried in layers of dusty gas clouds, but its energy shapes the material that surrounds it.

NASA, ESA, and T. Megeath (University of Toledo); Processing: Gladys Kober (NASA/Catholic University of America)

This Hubble image shows a small group of young stars amidst molecular clouds of gas and dust. Near the center of the image, concealed behind the dusty clouds, lies the protostar HOPS 181. The long, curved arc in the top left of the image is shaped by the outflow of material coming from the protostar, likely from the jets of particles shot out at high speeds from the protostar’s magnetic poles. The light of nearby stars reflects off and is scattered by dust grains that fill the image, giving the region its soft glow.

A protostar wrapped in obscuring dust creates a cavity with glowing walls while its jet streams into space.

NASA, ESA, and T. Megeath (University of Toledo); Processing: Gladys Kober (NASA/Catholic University of America)

The bright star in the lower right quadrant called CVSO 188 might seem like the diva in this image, but HOPS 310, located just to the left of center behind the dust, is the true hidden star. This protostar is responsible for the large cavity with bright walls that has been carved into the surrounding cloud of gas and dust by its jets and stellar winds. Running diagonally to the top right is one of the bipolar jets of the protostar. These jets consist of particles launched at high speeds from the protostar’s magnetic poles. Some background galaxies are visible in the upper right of the image.

A curving cavity in a cloud of gas has been hollowed out by a protostar in this Hubble image.

NASA, ESA, and T. Megeath (University of Toledo); Processing: Gladys Kober (NASA/Catholic University of America)

The bright protostar to the left in this Hubble image is located within the Orion Molecular Clouds. Its stellar winds — ejected, fast-flowing particles that are spurred by the star’s magnetic field — have carved a large cavity in the surrounding cloud. In the top right, background stars speckle the image.

Source: Hubble Observes Stars Flaring to Life in Orion - NASA Science

Sub-zero green freezer achieves zero emissions - Engineering - Energy & Green Tech

Real-world application of the sub-zero Celsius elastocaloric cooling device. Credit: Nature (2026). DOI: 10.1038/s41586-025-09946-4

Researchers at the School of Engineering of The Hong Kong University of Science and Technology (HKUST) have developed the world's first sub-zero Celsius elastocaloric freezing device, capable of reaching temperatures as low as -12℃. This represents a significant milestone in expanding green solid-state elastocaloric refrigeration technology into the global freezing industry, offering a promising solution to combat climate change and accelerate low-carbon transformation of the global freezing market.

The findings have recently been published in Nature, under the title "Sub-zero Celsius Elastocaloric Cooling via Low-transition-temperature Alloys."

As global warming intensifies, the demand for freezing has been growing rapidly and accounts for a significant portion of global electricity consumption. Mainstream freezing based on vapor compression cooling technology relies on refrigerants with high global warming potential (GWP).

As an eco-friendly alternative, solid-state cooling technology based on the elastocaloric effect of shape memory alloys (SMAs) has drawn substantial attention from both academia and industry due to its zero greenhouse gas emissions and high energy efficiency potential. The technology harnesses the latent heat from cyclic phase transition of shape memory alloys to provide cooling without greenhouse gas refrigerants, offering a promising path to decarbonize the freezing sector of the cooling industry and to mitigate global emissions and climate change.

Illustration of the sub-zero Celsius elastocaloric cooling device and performance comparison. Credit: Nature (2026). DOI: 10.1038/s41586-025-09946-4

Challenges and recent breakthrough in elastocaloric cooling

However, the existing elastocaloric devices have been limited to air conditioning scenarios for room temperature applications. It is important to expand the technology into the freezing sector, which has the same market size as the air-conditioning sector.

A research team led by Prof. Sun Qingping, Chair Professor from the Department of Mechanical and Aerospace Engineering at HKUST, has achieved a breakthrough in Sub-zero Celsius elastocaloric cooling. This advancement results from a synergistic combination of materials, heat transfer fluid and refrigeration structures. The features include:

1.   Super-elastic alloy: employing a binary low-transition-temperature nickel-titanium (NiTi) alloy with a high nickel content (51.2 at %) and lowering its austenite finish temperature (Af) to -20.8℃. This alloy maintains excellent super-elasticity and a substantial latent heat even at -20℃, with a peak adiabatic temperature change of 16.3℃ at 0℃ and a functional temperature window of 48.5℃.

2.   Freezing-resistant heat transfer fluid: using a 30wt% aqueous calcium chloride solution as the working fluid. Its low freezing point ensures that it remains fluid in sub-zero operation, while its good wettability on the NiTi surface enhances heat exchange efficiency.

3.   Cascaded tubular architecture: the regenerator operates on a compression-based active Brayton cycle and consists of eight cascaded units, each containing three thin-walled NiTi tubes. This design offers a high surface area-to-volume ratio (8.68 mm-1) and withstands a compressive stress of 900MPa without buckling, as verified by X-ray computed tomography.

Real-world freezing application of our elastocaloric device. Credit: Nature (2026). DOI: 10.1038/s41586-025-09946-4

Operating at 1Hz, the desktop-scale device achieved a cold-source temperature of -12 ℃ from a room-temperature heat sink (24℃), establishing a temperature lift of 36 ℃. This is the first reported sub-zero Celsius performance in elastocaloric cooling.

In a real-world demonstration, the system was integrated into a package measuring 1.0×0.5×0.5 m³ and tested outdoors at temperatures between 20 and 25℃. It successfully cooled an insulated chamber down to a stable -4℃ air temperature within 60 minutes and froze 20ml of distilled water into ice within 2 hours, validating its real-world freezing capability.

The device demonstrated a specific cooling power of up to 1.43W g-1 under zero-temperature-lift conditions. In addition, the system's coefficient of performance can reach 3.4 under the ideal work-recovery assumption, highlighting its potential energy efficiency.

Potential impact on global emissions

The work has a significant impact on global decarbonization to battle climate change. According to published data, global Hydrofluorocarbon (HFC) emissions are projected to exceed 1.2 gigatons of CO₂ equivalent annually by 2025, with roughly 27% originating from sub-zero freezing applications. This translates to approximately 330 million tons of CO₂ equivalent each year.

The successful demonstration of sub-zero elastocaloric cooling provides a viable, emission-free alternative for these applications. Widespread adoption of this technology could, therefore, potentially mitigate around 330 million tons of CO₂ equivalent emissions annually, contributing substantially to global climate goals.

Future directions and expert perspectives

The research team leader, Prof. Sun Qingping stated, "This achievement demonstrates the potential for large-scale application of elastocaloric freezing technology. We are collaborating with industry to drive its commercialization. As global regulations on HFCs tighten, this zero-emission, energy-efficient freezing technology is poised to reshape the freezing sector of the refrigeration industry and provide a key technical solution for carbon neutrality.

"Looking ahead, we will focus on optimizing system efficiency, power density, and cost-effectiveness through advances in shape memory alloy materials, manufacturing, heat exchange design, and system integration and optimization to achieve larger cooling power and high energy efficiency."

Prof. Lu Mengqian, Director of the HKUST Otto Poon Center for Climate Resilience and Sustainability, where Prof. Sun and Prof. Zhou are affiliated members, said, "This groundbreaking advancement in elastocaloric freezing technology by our center's members represents a significant step forward in our fight against climate change. By offering a zero-emission alternative for sub-zero applications, we are addressing the urgent need for sustainable freezing solutions. This achievement has been phenomenal since the center's establishment in July 2025. The work accelerates the center's mission to deliver impactful strategies for climate resilience and sustainable development worldwide." 

Provided by Hong Kong University of Science and Technology 

by Hong Kong University of Science and Technology

edited by Gaby Clark, reviewed by Robert Egan 

Source: Sub-zero green freezer achieves zero emissions