Can life survive a star’s death? Webb telescope can reveal the answer

When stars like our sun die, all that remains is an exposed core — a white dwarf. A planet orbiting a white dwarf presents a promising opportunity to determine if life can survive the death of its star, according to Cornell University researchers.

In a study published in the Astrophysical Journal Letters, they show how NASA’s upcoming James Webb Space Telescope could find signatures of life on Earth-like planets orbiting white dwarfs.

A planet orbiting a small star produces strong atmospheric signals when it passes in front, or “transits,” its host star. White dwarfs push this to the extreme: They are 100 times smaller than our sun, almost as small as Earth, affording astronomers a rare opportunity to characterize rocky planets.

“If rocky planets exist around white dwarfs, we could spot signs of life on them in the next few years,” said corresponding author Lisa Kaltenegger, associate professor of astronomy in the College of Arts and Sciences and director of the Carl Sagan Institute.

Co-lead author Ryan MacDonald, a research associate at the institute, said the James Webb Space Telescope, scheduled to launch in October 2021, is uniquely placed to find signatures of life on rocky exoplanets.

“When observing Earth-like planets orbiting white dwarfs, the James Webb Space Telescope can detect water and carbon dioxide within a matter of hours,” MacDonald said. “Two days of observing time with this powerful telescope would allow the discovery of biosignature gases, such as ozone and methane.”

The discovery of the first transiting giant planet orbiting a white dwarf (WD 1856+534b), announced in a separate paper — led by co-author Andrew Vanderburg, assistant professor at the University of Wisconsin, Madison — proves the existence of planets around white dwarfs. Kaltenegger is a co-author on this paper, as well.

This planet is a gas giant and therefore not able to sustain life. But its existence suggests that smaller rocky planets, which could sustain life, could also exist in the habitable zones of white dwarfs.

“We know now that giant planets can exist around white dwarfs, and evidence stretches back over 100 years showing rocky material polluting light from white dwarfs. There are certainly small rocks in white dwarf systems,” MacDonald said. “It’s a logical leap to imagine a rocky planet like the Earth orbiting a white dwarf.”

The researchers combined state-of-the-art analysis techniques routinely used to detect gases in giant exoplanet atmospheres with the Hubble Space Telescope with model atmospheres of white dwarf planets from previous Cornell research.

NASA’s Transiting Exoplanet Survey Satellite is now looking for such rocky planets around white dwarfs. If and when one of these worlds is found, Kaltenegger and her team have developed the models and tools to identify signs of life in the planet’s atmosphere. The Webb telescope could soon begin this search.

The implications of finding signatures of life on a planet orbiting a white dwarf are profound, Kaltenegger said. Most stars, including our sun, will one day end up as white dwarfs.

“What if the death of the star is not the end for life?” she said. “Could life go on, even once our sun has died? Signs of life on planets orbiting white dwarfs would not only show the incredible tenacity of life, but perhaps also a glimpse into our future.”

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Materials provided by Cornell University. Original written by Kate Blackwood. Note: Content may be edited for style and length.

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Surface deep: Light-responsive top layer of plastic film induces movement

Azobenzene-containing plastic film is a peculiar material; its surface can change shape when exposed to light, making it a valuable component in modern technologies/devices like TV screens and solar cells. Scientists now show that only a thin, topmost layer of the light-dependent azobenzene-containing plastic film needs to be light-sensitive, rather than the entire film, opening up new ways to potentially reduce production costs and revolutionize its use.

So far, it had been widely accepted that the light-sensitive nature of this material extends throughout the whole film, but scientists did not understand what was causing the shape-shifting movement. A group of scientists led by Dr Takahiro Seki of Nagoya University, Japan, set out to figure out exactly how this happens; they have published their findings in the journal Scientific Reports.

They cite a well-studied phenomenon called Marangoni flow as their inspiration: owing to this phenomenon, differences in “surface tension” (the property by which the particles in the outermost layer of liquids are always attracted inwards, creating a boundary for the liquid) cause many soft, plastic films to move in a peculiar pattern. The most famous example of this phenomenon is the formation of “wine legs” or droplets of liquid evaporating and streaking down the surfaces of wine glasses.

They decided to test whether ultraviolet light triggered changes in the surface tension of azobenzene plastic film, and whether those changes resulted in the film moving. They chose to first cover azobenzene film with a very thin top layer that was light-sensitive, then exposed this film to UV radiation. Next, they did the same with film that was covered in a top layer unresponsive to light. To their excitement, the scientists found surface structural changes in the film with a light-sensitive top layer, but not in the film with a “light-insensitive” top layer. “This is the first time anyone has demonstrated that only the light responsiveness of a very thin ‘nanometer’ level layer is needed for azobenzene-containing film to alter its surface morphology under UV,” said Dr Seki.

An important observation of this study is that the movement of the material isn’t dependent on “light polarization,” or the direction in which light waves travel. If it were, that would suggest that there is another force on the molecular level affecting the whole film. Instead, Dr Seki concludes that it is probably the changes in chemical structure at the surface induced by the UV radiation that changes surface tension, inducing movement to the top of the film.

Describing the wider ramifications of their results, Dr Seki states: “We are only at the cusp of developing this discovery onto an industrial scale, but you can imagine how needing only a very small amount of light-sensitive material can reduce costs. Many optical devices like photocopiers, printers, and monitors depend on the light-based surface change in azobenzene polymer film. Based on our findings, azobenzene film can also act as an “actuator” (that part in a device that moves other parts) in nanomachinery.”

These newly discovered properties have vast implications, from improving the economics of production and lowering material prices, to advancing the field of nanotechnology itself.

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Materials provided by Nagoya University. Note: Content may be edited for style and length.

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Simulations forecast US nationwide increase in human exposure to extreme climate events

By 2050, the United States will likely be exposed to a larger number of extreme climate events, including more frequent heat waves, longer droughts and more intense floods, which can lead to greater risks for human health, ecosystem stability and regional economies.

This potential future was the conclusion that a team of researchers from the Department of Energy’s Oak Ridge National Laboratory, Istanbul Technical University, Stanford University and the National Center for Atmospheric Research reached by using ORNL’s now-decommissioned Titan supercomputer to calculate the trajectories of nine types of extreme climate events. The team based these calculations on the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information Climate Extremes Index, or CEI.

Previous studies have demonstrated the impact that a single type of extreme, such as temperature or precipitation, could have on broad climate zones across the U.S. However, this team estimated the combined consequences of many different types of extremes simultaneously and conducted their analysis at the county level, a unique approach that provided unprecedented regional and national climate projections that identified the areas and population groups that are most likely to face such hardships. Results from this research are published in Earth’s Future.

“We calculated population exposure at a 1-kilometer scale, which had never been done before, to provide more precise estimates,” said Moetasim Ashfaq, a climate computational scientist at ORNL.

The team combined a high-resolution climate model ensemble, CEI estimates for various climate extreme categories, and future population projections in order to simulate multiple scenarios supplied by the Intergovernmental Panel on Climate Change, or IPCC. The team based one such simulation on a scenario called the Representation Concentration Pathway 8.5, which considers how climate conditions are likely to evolve if greenhouse gas emissions continue to rise without intervention.

According to the researchers’ estimates, on average, more than 47 million people throughout the country are exposed to extreme climate conditions annually, and this population exposure has been increasing in recent decades. They expect the prevailing trend to continue and anticipate that the number of people exposed could double by 2050, meaning one in every three people would be directly affected. Projected population growth could increase exposure even more.

Without adjusting for any change in population habits, this increased exposure could cause or exacerbate health problems. For example, high temperatures can worsen cardiovascular, respiratory and other medical conditions. Droughts can increase the risk of infectious disease outbreaks by reducing air quality and contaminating water and food sources.

Extreme heat can also reduce crop yields, disrupting economies reliant on agriculture. Additionally, costly and dangerous natural disasters such as wildfires and flash floods can leave trees defenseless against disease and insect infestations that can destroy entire ecosystems.

The researchers analyzed their results in comparison with a “reference period” containing historical simulation data from 1980 to 2005, and they designed their simulations to study human contributions to climate projections. As a result, the annual greenhouse gas concentrations were aligned in the historical simulations and in the observations but the occurrences of observed natural modes of climate variations were not.

The lack of alignment in natural modes of changes in climate, combined with the resemblance between simulated and observed trends in exposure to climate extremes, helped the team conclude that human behavior could be responsible for the observed increase in population exposure to climate extremes in the U.S. Additionally, these results improved confidence in the projected doubling of population exposure that the team anticipates will occur in the next 30 years unless greenhouse gas levels are reduced.

“Seeing the same upward trend in the number of climate extremes in our historical simulations and observations strongly suggests that these changes are driven by human activity,” Ashfaq said.

The researchers are preparing to run another set of simulations based on new scenarios for the next IPCC report, and their existing data have already been incorporated into other studies.

“These collaborative efforts could uncover how various climate extremes affect certain areas and help determine the types of policies and mitigation strategies that may be required to prevent or reduce the damage,” Ashfaq said.

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Poorly Configured Server Exposes International Fitness Retailer’s API Data

The cybersecurity research team at vpnMentor has discovered a security issue that left exposed over 123 million records containing personal information belonging to the customers of an international fitness retailer. Decathlon, a sporting goods retailer based in France, operated the ElasticSearch server at the center of the debacle.

Noam Rotem and Ran Locar, lead researchers for vpnMentor, discovered the vulnerability earlier this month. Their published findings note that Decathlon’s servers lacked even the most basic security, allowing attackers to easily access employee usernames, unencrypted passwords, API logs, API usernames, and more. This exposure of API credentials is especially concerning, with vpnMentor noting that:

“The company is not one to shy away from making technological advances, introducing in-store mobile checkouts and inventory robots. However, these API-enabled tech systems are a soft spot for vulnerabilities, particularly when the correlating databases are not properly secured.”

vpnMentor states that they notified Dethalon of the issue on February 16th, 2020 and that the database was taken down the next day. As usual, it is impossible to know how much of the data was exposed to bad actors before it was taken down. 

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Author: <a href="">KevinSundstrom</a>


New commuter concern: Cancerous chemical in car seats

The longer your commute, the more you’re exposed to a chemical flame retardant that is a known carcinogen and was phased out of furniture use because it required a Proposition 65 warning label in California.

That is the conclusion of a new UC Riverside study published this month in the journal Environment International.

While much research on automobile pollution focuses on external air pollutants entering vehicle interiors, this study shows that chemicals emanating from inside your car could also be cause for concern.

Though there are other Proposition 65-list chemicals that are typically used in the manufacture of automobiles, this flame retardant is a new addition to the list. Known as the Safe Drinking Water and Toxic Enforcement Act, Proposition 65 requires the state to maintain and update a list of chemicals known to cause cancer or reproductive harm.

Some scientists assumed that humans stopped being exposed to the chemical, called TDCIPP or chlorinated tris, after it was placed on California’s Proposition 65 list in 2013. However, it is still widely used in automobile seat foam. The study shows that not only is your car a source of TDCIPP exposure, but that less than a week of commuting results in elevated exposure to it.

David Volz, associate professor of environmental toxicology at UCR, said the results were unexpected.

“I went into this rather skeptical because I didn’t think we’d pick up a significant concentration in that short a time frame, let alone pick up an association with commute time,” Volz said. “We did both, which was really surprising.”

Over the past decade, Volz has studied how various chemicals affect the trajectory of early development. Using zebrafish and human cells as models, the Volz laboratory has been studying the toxicity of a newer class of flame retardants called organophosphate esters since 2011.

Little is known about the toxicity of these organophosphate esters — TDCIPP is one of them — but they’ve replaced older flame-retardant chemicals that lasted longer in the environment and took longer to metabolize.

Using zebrafish as a model, Volz found TDCIPP prevents an embryo from developing normally. Other studies have reported a strong association between TDCIPP and infertility among women undergoing fertility treatments.

Knowing its use is still widespread in cars, Volz wondered whether a person’s exposure is elevated based on their commute. UC Riverside undergraduates made for excellent study subjects, as a majority of them have a daily commute.

The research team included collaborators at Duke University and was funded by the National Institutes of Health as well as the USDA National Institute of Food and Agriculture.

Participants included around 90 students, each of whom had commute times that varied from less than 15 minutes to more than two hours round trip. All of them were given silicone wristbands to wear continuously for five days.

The molecular structure of silicone makes it ideal for capturing airborne contaminants. Since TDCIPP isn’t chemically bound to the foam, Aalekyha Reddam, a graduate student in the Volz laboratory, said it gets forced out over time and ends up in dust that gets inhaled.

Multiple organophosphate esters were tested, but TDCIPP was the only one that showed a strong positive association with commute time.

“Your exposure to TDCIPP is higher the longer you spend in your vehicle,” Reddam said.

While Volz and his team did not collect urine samples to verify that the chemical migrated into the bodies of the participants, they believe that’s what happened.

“We presume it did because of how difficult it is to avoid the ingestion and inhalation of dust,” Volz said. Additionally, other studies have examined the accumulation of TDCIPP in urine, but not as a function of how long a person sits in a car.

Going forward, the research team would like to repeat the study with a larger group of people whose ages are more varied. They would also like to study ways to protect commuters from this and other toxic compounds.

Until more specific reduction methods can be identified, the team encourages frequently dusting the inside of vehicles, and following U.S. Environmental Protection Agency guidelines for reducing exposure to contaminants.

Until safer alternatives are identified, more research is needed to fully understand the effects of TDCIPP on commuters.

“If we picked up this relationship in five days, what does that mean for chronic, long-term exposure, for people who commute most weeks out of the year, year over year for decades?” Volz asked.

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Scientists observe how acoustic interactions change materials at the atomic level

When exposed to stress and strain, materials can display a wide range of different properties. By using sound waves, scientists have begun to explore fundamental stress behaviors in a crystalline material that could form the basis for quantum information technologies. These technologies involve materials that can encode information in a number of states simultaneously, allowing for more efficient computation.

In a new discovery by researchers at the U.S. Department of Energy’s Argonne National Laboratory and the Pritzker School of Molecular Engineering (PME) at the University of Chicago, scientists used X-rays to observe spatial changes in a silicon carbide crystal when using sound waves to strain buried defects inside it. The work follows on an earlier recent study in which the researchers observed changes in the spin state of the defect’s electrons when the material was similarly strained.

Because these defects are well isolated within the crystal, they can act as a single molecular state and as carriers of quantum information. When the electrons trapped near the defects change between spin states, they emit energy in the form of photons. Depending on which state the electrons are in, they emit either more or fewer photons in a technique known as spin-dependent readout.

In the experiment, the researchers sought to assess the relationship between the sound energy used to produce the strain on the defects in the crystal lattice and the spin transitions indicated by the emitted photons. While the defects in the crystal naturally fluoresce, the additional strain causes the ground spin of the electron to change state, resulting in a coherent manipulation of the spin state that can be measured optically.

“We wanted to see the coupling between the sound strain and the light response, but to see exactly what the coupling between them is, you need to know both how much strain you’re applying, and how much more optical response you’re getting out,” said Argonne nanoscientist Martin Holt, the lead author of the study.

The electrodes used to generate the sound waves are roughly five microns in width, far larger than the defects themselves, which consist of two missing atoms known as a divacancy complex. The sound wave strains the defects by alternately pushing and pulling on them, causing the electrons to change their spins.

To characterize the lattice and defects, Argonne researchers used the Hard X-ray Nanoprobe beamline operated jointly at the laboratory’s Center for Nanoscale Materials and Advanced Photon Source (APS), both DOE Office of Science User Facilities. Through a newly developed technique called stroboscopic Bragg diffraction microscopy, Holt and his colleagues were able to image the lattice around the defects at many different points throughout the strain cycle.

“We’re interested in how to manipulate the original spin state with acoustic waves, and how you can spatially map out the mechanics of the strain with X-rays,” said Argonne materials scientist and PME staff scientist Joseph Heremans, another author of the study.

“The X-rays measure exactly the lattice distortion,” Holt added.

Stroboscopic Bragg diffraction involves synchronizing the frequency of the acoustic wave to the frequency of the electron pulses in the APS’s storage ring. In this way, the researchers were essentially able to “freeze the wave in time,” according to Holt. This allowed them to create a series of images of the strain experienced by the lattice at each point on the wave.

“It’s like if you had ripples in a pond, and you could shine a light on one spot of the pond,” Holt said. “You’d see a movement of peak to trough, and trough to peak.”

“We’re directly imaging sound’s footprint going through this crystal,” Heremans added. “The sound waves cause the lattice to curve, and we can measure exactly how much the lattice curves by going through a specific point of the lattice at a specific point in time.”

The use of stroboscopic Bragg diffraction allows scientists to determine the direct correlation between the dynamic strain and the quantum behavior of the defect, Holt said. In silicon carbide, this relationship is fairly well understood, but in other materials the technique could reveal surprising relationships between strain and other properties.

“This technique opens a way for us to figure out the behaviors in a lot of systems in which we don’t have a good analytical prediction of what the relationship should be,” Holt said.

“This study combines expertise from a leading academic institution with state-of-the-art instrumentation of a national laboratory to develop a novel technique for probing matter at the atomic scale, revealing the ability of sound waves to control semiconductor quantum technologies,” added Argonne senior scientist and PME Liew Family Professor of Molecular Engineering David Awschalom, a collaborator on the research.

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