A new class of exoplanet very different to our own, but which could support life, has been identified by astronomers, which could greatly accelerate the search for life outside our Solar System.
In the search for life elsewhere, astronomers have mostly looked for planets of a similar size, mass, temperature and atmospheric composition to Earth. However, astronomers from the University of Cambridge believe there are more promising possibilities out there.
The researchers have identified a new class of habitable planets, dubbed ‘Hycean’ planets—hot, ocean-covered planets with hydrogen-rich atmospheres—which are more numerous and observable than Earth-like planets.
The researchers say the results, reported in The Astrophysical Journal, could mean that finding biosignatures of life outside our Solar System within the next two or three years is a real possibility.
“Hycean planets open a whole new avenue in our search for life elsewhere,” said Dr. Nikku Madhusudhan from Cambridge’s Institute of Astronomy, who led the research.
Many of the prime Hycean candidates identified by the researchers are bigger and hotter than Earth, but still have the characteristics to host large oceans that could support microbial life similar to that found in some of Earth’s most extreme aquatic environments.
These planets also allow for a far wider habitable zone, or ‘Goldilocks zone’, compared to Earth-like planets. This means that they could still support life even though they lie outside the range where a planet similar to Earth would need to be in order to be habitable.
Thousands of planets outside our Solar System have been discovered since the first exoplanet was identified nearly 30 years ago. The vast majority are planets between the sizes of Earth and Neptune and are often referred to as ‘super-Earths’ or ‘mini-Neptunes’: they can be predominantly rocky or ice giants with hydrogen-rich atmospheres, or something in between.
Most mini-Neptunes are over 1.6 times the size of Earth: smaller than Neptune but too big to have rocky interiors like Earth. Earlier studies of such planets have found that the pressure and temperature beneath their hydrogen-rich atmospheres would be too high to support life.
However, a recent study on the mini-Neptune K2-18b by Madhusudhan’s team found that in certain conditions these planets could support life. The result led to a detailed investigation into the full range of planetary and stellar properties for which these conditions are possible, which known exoplanets may satisfy those conditions, and whether their biosignatures may be observable.
The investigation led the researchers to identify a new class of planets, Hycean planets, with massive planet-wide oceans beneath hydrogen-rich atmospheres. Hycean planets can be up to 2.6 times larger than Earth and have atmospheric temperatures up to nearly 200 degrees Celsius, but their oceanic conditions could be similar to those conducive for microbial life in Earth’s oceans. Such planets also include tidally locked ‘dark’ Hycean worlds that may have habitable conditions only on their permanent night sides, and ‘cold’ Hycean worlds that receive little radiation from their stars.
Planets of this size dominate the known exoplanet population, although they have not been studied in nearly as much detail as super-Earths. Hycean worlds are likely quite common, meaning that the most promising places to look for life elsewhere in the Galaxy may have been hiding in plain sight.
However, size alone is not enough to confirm whether a planet is Hycean: other aspects such as mass, temperature and atmospheric properties are required for confirmation.
When trying to determine what the conditions are like on a planet many light years away, astronomers first need to determine whether the planet lies in the habitable zone of its star, and then look for molecular signatures to infer the planet’s atmospheric and internal structure, which govern the surface conditions, presence of oceans and potential for life.
Astronomers also look for certain biosignatures which could indicate the possibility of life. Most often, these are oxygen, ozone, methane and nitrous oxide, which are all present on Earth. There are also a number of other biomarkers, such as methyl chloride and dimethyl sulphide, that are less abundant on Earth but can be promising indicators of life on planets with hydrogen-rich atmospheres where oxygen or ozone may not be as abundant.
“Essentially, when we’ve been looking for these various molecular signatures, we have been focusing on planets similar to Earth, which is a reasonable place to start,” said Madhusudhan. “But we think Hycean planets offer a better chance of finding several trace biosignatures.”
“It’s exciting that habitable conditions could exist on planets so different from Earth,” said co-author Anjali Piette, also from Cambridge.
Madhusudhan and his team found that a number of trace terrestrial biomarkers expected to be present in Hycean atmospheres would be readily detectable with spectroscopic observations in the near future. The larger sizes, higher temperatures and hydrogen-rich atmospheres of Hycean planets make their atmospheric signatures much more detectable than Earth-like planets.
The Cambridge team identified a sizeable sample of potential Hycean worlds which are prime candidates for detailed study with next-generation telescopes, such as the James Webb Space Telescope (JWST), which is due to be launched later this year. These planets all orbit red dwarf stars between 35-150 light years away: close by astronomical standards. Planned JWST observations of the most promising candidate, K2-18b, could lead to the detection of one or more biosignature molecules.
“A biosignature detection would transform our understanding of life in the universe,” said Madhusudhan. “We need to be open about where we expect to find life and what form that life could take, as nature continues to surprise us in often unimaginable ways.”
Habitability and Biosignatures of Hycean Worlds, Astrophysical Journal (2021). doi.org/10.3847/1538-4357/abfd9c
University of Cambridge
New class of habitable exoplanets represent a big step forward in the search for life (2021, August 25)
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Strontium isotopes can map monarch butterfly migrations and help conservation efforts – Yahoo News Canada
The eastern North American population of monarch butterflies are famous for their annual, multi-generational, round-trip migration from the oyamel fir forests of Central Mexico through the United States to Canada and back. Sadly, the population of monarch butterflies is declining, and the future of the monarch migratory phenomenon is uncertain.
Scientists can study migrations by looking at the chemicals stored within the teeth, bones, tusks and wings of animals. In the case of monarch butterflies, the signature contained in its wings reveals where it was a caterpillar, allowing researchers to trace its natal origin, or birthplace.
Isotopes are atoms of the same element that have different masses because they have a different number of neutrons. For some elements, such as hydrogen and strontium, the proportion of heavy versus light isotopes in the environment changes predictably between locations, giving locations unique isotopic signatures. A map of these local isotopic signatures is called an isoscape.
Read more: Explainer: what is an isotope?
Isotopes have informed conservation efforts for decades because they are helpful for identifying where an animal has migrated from.
Strontium (Sr) is an alkaline earth metal with four stable isotopes: 84Sr, 86Sr, 87Sr and 88Sr. Strontium isotopes ratios (the ratio of 87Sr to 86Sr) are a new addition to the ecologist’s isotopic toolbox. Strontium isotopes will help ecologists pinpoint the origins of migrating animals more precisely and solve longstanding questions related to the migratory connectivity and migratory patterns of monarch butterflies.
What bodies can reveal
As animals (including humans) feed and drink, they incorporate the local isotopic signature into their bodies. The isotopic signature of animal tissue can then be compared to an isoscape map to find out where the tissue was formed.
For example, the strontium isotope ratio of human teeth can tell you where a person spent their childhood because teeth are formed early in life. Human bones, however, will tell you where they spent the last decade of their life because bone tissue replaces itself every 10 years or so.
Why do we need isotope geolocation?
Ideally, we would study animal migration by putting tiny radio transmitters on many individuals and tracking them for a long period of time. However, this approach isn’t practical in many situations.
For example, we cannot use a radio transmitter to find the origin of poached elephant ivory or the home range size of extinct lemur specimens from a museum. But we can use isotopes to learn something about the lives of these deceased animals.
Some animals, like insects, are too small and numerous to be effectively tracked using tagging methods. Although significant advances have been made in recent years, insects are still too small to be tracked with radio transmitters on a large scale. Therefore, isotopes are one of our best tools for answering questions about insect migratory patterns and connectivity. Given the current context of global climate change and population declines, we urgently need to know more about animal migration so that we can conserve migrations for future generations.
The case of monarch butterflies
Hydrogen and carbon isotopes have been used for decades to trace the natal origins of monarch butterflies. These studies have helped guide conservation efforts and inform listing decisions.
For example, isotopes have helped researchers figure out which regions of the United States contribute the most monarchs to the overwintering population. Other studies have shown that some monarchs are opting for a non-migratory lifestyle and have shown that an extreme northwestern migration into Canada came from the Midwest.
Strontium isotope ratios and monarch butterflies
My collaborators and I recently demonstrated how strontium isotopes can be used to study animal migration. We found that strontium isotopes, especially when combined with hydrogen isotopes, can estimate the natal origin of a monarch butterfly to a more precise geographic location — about four times better — than using hydrogen alone.
In our study, we created a strontium isoscape map for the breeding range of the monarch butterfly. This means we now have a ready-to-use tool for estimating the natal origin of monarch butterflies using strontium.
We hope that applying strontium isotopes to both new and archived monarch specimens will advance our understanding of how monarch migration patterns and connectivity have changed over time, and ultimately help guide conservation actions to protect this migratory phenomenon.
Megan Reich receives funding from the Ontario Government (OGS and QEII-GSST), the University of Utah SPATIAL group (ORIGIN Graduate Fellowship), and the Entomological Society of Canada.
World's most dangerous bird raised by humans 18000 years ago, study suggests – CTV News
The earliest bird reared by humans may have been a cassowary — often called the world’s most dangerous bird because of its long, dagger-like toe.
Territorial, aggressive and often compared to a dinosaur in looks, the bird is a surprising candidate for domestication.
However, a new study of more than 1,000 fossilized eggshell fragments, excavated from two rock shelters used by hunter-gatherers in New Guinea, has suggested early humans may have collected the eggs of the large flightless bird before they hatched and then raised the chicks to adulthood. New Guinea is a large island north of Australia. The eastern half of the island is Papua New Guinea, while the western half forms part of Indonesia.
“This behavior that we are seeing is coming thousands of years before domestication of the chicken,” said lead study author Kristina Douglass, an assistant professor of anthropology and African studies at Penn State University.
“And this is not some small fowl, it is a huge, ornery, flightless bird that can eviscerate you,” she said in a news statement.
The researchers said that while a cassowary can be aggressive (a man in Florida was killed by one in 2019), it “imprints” easily — it becomes attached to the first thing it sees after hatching. This means it’s easy to maintain and raise up to adult size.
Today, the cassowary is New Guinea’s largest vertebrate, and its feathers and bones are prized materials for making bodily adornments and ceremonial wear. The bird’s meat is considered a delicacy in New Guinea.
There are three species of cassowary, and they are native to parts of northern Queensland, Australia, and New Guinea. Douglass thought our ancient ancestors most likely reared the smallest species, the dwarf cassowary, that weighs around 20 kilograms (44 pounds).
The fossilized eggshells were carbon-dated as part of the study, and their ages ranged from 18,000 to 6,000 years old.
Humans are believed to have first domesticated chickens no earlier than 9,500 years ago.
NOT FOR SNACKING
To reach their conclusions, the researchers first studied the eggshells of living birds, including turkeys, emus and ostriches.
The insides of the eggshells change as the developing chicks get calcium from the eggshell. Using high-resolution 3D images and inspecting the inside of the eggs, the researchers were able to build a model of what the eggs looked like during different stages of incubation.
The scientists tested their model on modern emu and ostrich eggs before applying it to the fossilized eggshell fragments found in New Guinea. The team found that most of the eggshells found at the sites were all near maturity.
“What we found was that a large majority of the eggshells were harvested during late stages,” Douglass said. “The eggshells look very late; the pattern is not random.”
These late-stage eggshells indicate people living at these two rock shelter sites were harvesting eggs when the cassowary embryos had fully formed limbs, beaks, claws and feathers, the study said.
But were humans purposefully collecting these eggs to allow them to hatch or collecting the eggs to eat? It’s possible they were doing both, Douglass said.
Consuming eggs with fully formed embryos is considered a delicacy in some parts of the world, but Douglass said the research team’s analysis suggested people were hatching the chicks.
“We also looked at burning on the eggshells,” Douglass said in the news release. “There are enough samples of late stage eggshells that do not show burning that we can say they were hatching and not eating them.”
BIG BIRD AS VALUABLE RESEARCH
Less mature eggshells showed more signs of burning — suggesting that when cassowary eggs were consumed they were cooked and eaten when their contents were primarily liquid.
“In the highlands today people raise cassowary chicks to adulthood, in order to collect feathers, and consume or trade the birds. It is possible cassowaries were also highly valued in the past, since they are among the largest vertebrate animals on New Guinea. Raising cassowaries from chicks would provide a readily available source of feathers and meat for an animal that is otherwise challenging to hunt in the wild as an adult,” she explained via email.
However, there is still much the researchers don’t know.
To successfully hatch and raise cassowary chicks, people would need to know where the nests were, know when the eggs were laid and remove them from the nest just before hatching. This is no easy feat as birds don’t nest at the same sites each year. Once a female lays the eggs, male birds take over nest duty and don’t leave for 50 days while incubating the eggs.
“People may have hunted the male and then collected the eggs. Because males don’t leave the nest unattended they also don’t feed much during the incubation period making them more vulnerable to predators,” she said.
The research was published in the peer-reviewed scientific journal PNAS on Monday.
Atlas V: Rocket launch creates strange lights in UK sky – BBC News
Amateur stargazers in the UK were sent rushing for their cameras by strange cone-shaped lights in the sky created by a US rocket.
Nasa launched the Atlas V, carrying the Landsat 9 satellite, at about 20:00 BST on Monday.
About two hours later it performed a reversing manoeuvre, releasing two glowing clouds of vapour.
Clear skies made for an out-of-this-world view of the stellar spectacle, visible above large parts of UK.
Photographer Simon Woodley “couldn’t believe his eyes” when he snapped the launch from South Shields.
Mr Woodley was out taking photos of the moonrise when he saw the unknown bright light for “three or four minutes”.
“I went through the possibilities of comet or aircraft or even a laser beam. It was only when I got home I found out what it was,” he said.
Education charity UK Astronomy said the light was the rocket’s deorbit burn, created as it fires its engines to commence its re-entry into Earth’s atmosphere before burning up.
Astronomer and science writer Will Gater said the glowing, tear drop-shaped clouds were a result of sunlight scattering off material released into space.
Elliott Stone, who snapped the rocket from his garden in Keighley, West Yorkshire, thought he was seeing a comet at first.
“I noticed it was travelling the wrong way, so I thought it must have been a plane with its light on,” Mr Stone said.
What is the Landsat 9 satellite?
- Landsat 9 is part of a satellite array photographing and measuring the Earth’s surface
- The first Landsat satellite launched in 1972
- Designed to measure changes on Earth such as deforestation
- Launched into orbit using an Atlas V rocket from Vandenberg Space Force Base in California
In Whitley Bay, Tyne and Wear, Ian Sproat was left “scrambling” to set up his camera when he saw the light above him.
“I was gobsmacked, I honestly thought it was a meteor or a comet, never did I expect to see the Landsat 9,” he said.
Mr Sproat only went to the spot near St Mary’s Lighthouse because he thought he might be able to see the northern lights.
“When I got there and was setting up, a ball of light appeared above me,” he said.
He felt “truly blessed to have witnessed this spectacular sight”, he added.
Fellow astronomy enthusiast Freddy Lees snapped a photo of the rocket from Nottingham as it climbed above the tree line shortly after 22:00.
The NASA Atlas V rocket was launched from California’s Vandenberg Space Force base 20:11 BST.
Visible rocket burns are rare in European skies and more often seen above Florida or California.
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