Stephen Kane

Venus might be habitable today, if not for Jupiter

Anonymous — Fri, 09 Oct 2020 20:58:54 +0000

Venus might be habitable today, if not for Jupiter Anonymous (not verified) Fri, 10/09/2020 - 13:58 More News Jules Bernstein | UCR News September 30, 2020

Venus might not be a sweltering, waterless hellscape today if Jupiter hadn’t altered its orbit around the sun, according to new UC Riverside research.

Animation depicts eccentricities of the inner planet orbits, and illustrates how circular the orbit of Venus is. (ChongChong He)

Jupiter has a mass that is two-and-a-half times that of all other planets in our solar system — combined. Because it is comparatively gigantic, it has the ability to disturb other planets’ orbits.

Early in Jupiter’s formation as a planet, it moved closer to and then away from the sun due to interactions with the disc from which planets form as well as the other giant planets. This movement in turn affected Venus.

Observations of other planetary systems have shown that similar giant planet migrations soon after formation may be a relatively common occurrence. These are among the findings of a new study published in the Planetary Science Journal.

Scientists consider planets lacking liquid water to be incapable of hosting life as we know it. Though Venus may have lost some water early on for other reasons, and may have continued to do so anyway, UCR astrobiologist Stephen Kane said that Jupiter’s movement likely triggered Venus onto a path toward its current, inhospitable state.

“One of the interesting things about the Venus of today is that its orbit is almost perfectly circular,” said Kane, who led the study. “With this project, I wanted to explore whether the orbit has always been circular and if not, what are the implications of that?”

To answer these questions, Kane created a model that simulated the solar system, calculating the location of all the planets at any one time and how they pull one another in different directions.

Scientists measure how noncircular a planet’s orbit is between 0, which is completely circular, and 1, which is not circular at all. The number between 0 and 1 is called the eccentricity of the orbit. An orbit with an eccentricity of 1 would not even complete an orbit around a star; it would simply launch into space, Kane said.

Currently, the orbit of Venus is measured at 0.006, which is the most circular of any planet in our solar system. However, Kane’s model shows that when Jupiter was likely closer to the sun about a billion years ago, Venus likely had an eccentricity of 0.3, and there is a much higher probability that it was habitable then.

“As Jupiter migrated, Venus would have gone through dramatic changes in climate, heating up then cooling off and increasingly losing its water into the atmosphere,” Kane said.

Recently, scientists generated much excitement by discovering a gas in the clouds above Venus that may indicate the presence of life. The gas, phosphine, is typically produced by microbes, and Kane says it is possible that the gas represents “the last surviving species on a planet that went through a dramatic change in its environment.”

For that to be the case, however, Kane notes the microbes would have had to sustain their presence in the sulfuric acid clouds above Venus for roughly a billion years since Venus last had surface liquid water — a difficult to imagine though not impossible scenario.

“There are probably a lot of other processes that could produce the gas that haven’t yet been explored,” Kane said.

Ultimately, Kane says it is important to understand what happened to Venus, a planet that was once likely habitable and now has surface temperatures of up to 800 degrees Fahrenheit.

“I focus on the differences between Venus and Earth, and what went wrong for Venus, so we can gain insight into how the Earth is habitable, and what we can do to shepherd this planet as best we can,” Kane said.

Read the original article here:

view article

Tags

Stephen Kane

Astrobiology

Atmospheric seasons could signal alien life

Anonymous — Thu, 03 Sep 2020 22:43:50 +0000

Atmospheric seasons could signal alien life Anonymous (not verified) Thu, 09/03/2020 - 15:43 More News Sarah Nightingale | UCR News May 09, 2018

Dozens of potentially habitable planets have been discovered outside our solar system, and many more are awaiting detection.

Is anybody — or anything — there?

Satellites monitor how ‘greenness’ changes with Earth’s seasons. (NASA)

The hunt for life in these places, which are impossible to visit in person, will begin with a search for biological products in their atmospheres. These atmospheric fingerprints of life, called biosignatures, will be detected using next-generation telescopes that measure the composition of gases surrounding planets that are light years away.

It’s a tricky business, since biosignatures based on single measurements of atmospheric gases could be misleading. To complement these markers, and thanks to funding from the NASA Astrobiology Institute, scientists at the University of California, Riverside’s Alternative Earths Astrobiology Center are developing the first quantitative framework for dynamic biosignatures based on seasonal changes in the Earth’s atmosphere.

Titled “Atmospheric Seasonality As An Exoplanet Biosignature,” a paper describing the research was published today in The Astrophysical Journal Letters. The lead author is Stephanie Olson, a graduate student in UCR’s Department of Earth Sciences.

As Earth orbits the sun, its tilted axis means different regions receive more rays at different times of the year. The most visible signs of this phenomenon are changes in the weather and length of the days, but atmospheric composition is also impacted. For example, in the Northern Hemisphere, which contains most of the world’s vegetation, plant growth in summer results in noticeably lower levels of carbon dioxide in the atmosphere. The reverse is true for oxygen.

“Atmospheric seasonality is a promising biosignature because it is biologically modulated on Earth and is likely to occur on other inhabited worlds,” Olson said. “Inferring life based on seasonality wouldn’t require a detailed understanding of alien biochemistry because it arises as a biological response to seasonal changes in the environment, rather than as a consequence of a specific biological activity that might be unique to the Earth.” Further, extremely elliptical orbits rather than axis tilt could yield seasonality on extrasolar planets, or exoplanets, expanding the range of possible targets.

In the paper, the researchers identify the opportunities and pitfalls associated with characterizing the seasonal formation and destruction of oxygen, carbon dioxide, methane, and their detection using an imaging technique called spectroscopy. They also modeled fluctuations of atmospheric oxygen on a life-bearing planet with low oxygen content, like that of Earth billions of years ago. They found that ozone (O₃), which is produced in the atmosphere through reactions involving oxygen gas (O₂) produced by life, would be a more easily measurable marker for the seasonal variability in oxygen than O₂itself on weakly oxygenated planets.

“It’s really important that we accurately model these kinds of scenarios now, so the space and ground-based telescopes of the future can be designed to identify the most promising biosignatures,” said Edward Schwieterman, a NASA Postdoctoral Program fellow at UCR. “In the case of ozone, we would need telescopes to include ultraviolet capabilities to easily detect it.”

Schwieterman said the challenge in searching for life is the ambiguity of data collected from so far away. False positives — nonbiological processes that masquerade as life — and false negatives — life on a planet that produces few or no biosignatures — are both major concerns.

“Both oxygen and methane are promising biosignatures, but there are ways they can be produced without life,” Schwieterman said.

Olson said observing seasonal changes in oxygen or methane would be more informative.

“A potentially powerful way to assess exoplanets for inhabitation would be to observe their atmospheres throughout their orbits to see if we can detect changes in these biosignature gases over the course of a year,” she said. “In some circumstances, such changes would be difficult to explain without life and may even allow us to make progress towards characterizing, rather than simply recognizing, life on an exoplanet.”

Timothy Lyons, a professor of biogeochemistry in UCR’s Department of Earth Science and director of the Alternative Earths Astrobiology Center, said this work advances the fundamental approach to searching for life on very distant planets.

“We are particularly excited about the prospect of characterizing oxygen fluctuations at the low levels we would expect to find on an early version of Earth,” Lyons said. “Seasonal variations as revealed by ozone would be most readily detectable on a planet like Earth was billions of years ago, when most life was still microscopic and ocean dwelling.”

In addition to Olson, Schwieterman, and Lyons, the paper’s authors are Andy Ridgwell and Stephen Kane from UC Riverside, Christopher Reinhard from the Georgia Institute of Technology, and Victoria Meadows from the University of Washington. The work is funded by the NASA Astrobiology Institute and the National Science Foundation (NSF) Frontiers in Earth System Dynamics (FESD).

Read the original article online

Tags

Campus to celebrate 50th anniversary of historic Moon landing

Anonymous — Thu, 03 Sep 2020 22:32:22 +0000

Campus to celebrate 50th anniversary of historic Moon landing Anonymous (not verified) Thu, 09/03/2020 - 15:32 More News Iqbal Pittalwala | UCR News July 08, 2019

This year marks the 50th anniversary of the historic Apollo 11 Moon mission. To celebrate, the University of California, Riverside, is hosting a free public event on Thursday, July 11, from 6:30-9:30 p.m.

Attendees will have an opportunity to learn more about the Apollo 11 legacy, as well as current missions to our solar-system’s planets and moons. The event, which will take place in Pierce Lawn and the Life Sciences Building, will also feature telescope viewings of the moon, and multiple hands-on activities.

On July 16, 1969, astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins lifted off from Earth on a journey to the moon. Four days later, Armstrong and Aldrin became the first humans to set foot on the lunar surface.

“Landing on the moon was probably the single most important achievement of humankind since the beginning of civilization,” said Bahram Mobasher, a professor of physics and observational astronomy. He’s an expert on the formation and evolution of galaxies and the search for the most distant ones. “This honor belongs to all humanity regardless of race, religion, or the country of the origin. It shows the power of our will and the strength of our desires — a clear demonstration of what science can do.”

Stephen Kane, an associate professor of planetary astrophysics, agrees that the moon landing represents a significant milestone in our advancement of our civilization.

“For the first time in history, we were finally free from being restricted to only walking upon our planet,” said Kane, an expert on the detection, characterization, and habitability of exoplanets. “However, the famous quote of the landing being a ‘giant leap for mankind’ is more than just about scientific progress. It was an event that truly unified humanity and provided a key moment of reflection on how we are all custodians of our beautiful island oasis in a vast universe, and we should never lose sight of that big picture.”

Hands-on activities, such as touching a Martian meteorite, understanding the phases and eclipses of the moon, and cratering experiments, will take place from 6:30-7:30 p.m. in the Life Sciences courtyard, and will resume at 8:30 p.m. along with telescope viewings in Pierce Lawn.

Timothy Lyons, a distinguished professor of biogeochemistry in the Department of Earth and Planetary Sciences, will give a talk titled “Fifty Years of Discovery — From the Moon to Mars and Beyond” in Life Sciences 1500.

No RSVP is required to attend the event. Complimentary parking will be available for attendees in Lot 6.

“The moon landing was the first and one of the greatest attempts at space exploration in the entire human history,” said event organizer Xinnan Du, a postdoctoral scholar and director of education and public outreach in the Department of Physics and Astronomy. “As a millennial, I’ve always been awed by the fact that humankind had already walked on the surface of another celestial object when technology was still barely part of everyday life. This anniversary is an amazing opportunity to not only celebrate the achievement we made 50 years ago, but also learn about how far we’ve come in exploring space: from the moon, to Mars, to Pluto, and the outer edge of the solar system.”

Read the original article online

View article

Tags

Stephen Kane

Timothy Lyons

Star tours

Anonymous — Tue, 25 Aug 2020 04:27:38 +0000

Star tours Anonymous (not verified) Mon, 08/24/2020 - 21:27 More News Jules Bernstein | UCR News June 25, 2019

Astronomers have a new tool in their search for extraterrestrial life – a sophisticated bot that helps identify stars hosting planets similar to Jupiter and Saturn.

Artist’s impression of planets around stars in the Milky Way. (ESO/M. Kornmesser)

These giant planets’ faraway twins may protect life in other solar systems, but they aren’t bright enough to be viewed directly. Scientists find them based on properties they can observe in the stars they orbit. The challenge for planet hunters is that in our galaxy alone, there are roughly 200 billion stars.

“Searching for planets can be a long and tedious process given the sheer volume of stars we could search,” said Stephen Kane, UCR associate professor of planetary astrophysics. “Eliminating stars unlikely to have planets and pre-selecting those that might will save a ton of time,” he said.

The astronomy bot is a machine learning algorithm designed by Natalie Hinkel, a researcher formerly in Kane’s laboratory now with the Southwest Research Institute. Kane examined data produced by the bot and discovered three stars with strong evidence of harboring giant, Jupiter-like planets about 100 light years away.

A paper detailing the team’s work was published today in the Astrophysical Journal.

The algorithm uses information about the chemical composition of stars to predict whether it is surrounded by planets.

Scientists can use spectroscopy, or the way light interacts with atoms in a star’s upper layers, to measure the elements inside of it such as carbon, iron, and oxygen. These elements are key ingredients in making planets, since stars and planets are made at the same time and from the same materials.

To train and test the algorithm, Hinkel fed it a publicly available database of stars that she developed. The database has allowed the algorithm to look at the elements that make up more than 4,200 stars and assess their likelihood of hosting planets.

In addition, Hinkel looked at different combinations of those ingredients to see how they influenced the algorithm. “We found that the most influential elements in predicting planet-hosting stars are carbon, oxygen, iron and sodium,” Hinkel said.

The team used the algorithm specifically to help them identify giant planets like Jupiter that are hard to find because they are farther from their host stars. Distant giant planets like these are likely to protect the Earth-like rocky planets near them, and any life they could be home to. Kane’s team at UCR has a long track record of discovering giant planets similar to Jupiter.

“Jupiter is very close to Earth at the moment, we can see how beautiful it is without a telescope, but many of us take for granted how it makes life on this planet possible,” Kane said.

Jupiter-like planets pull meteors, comets and other flying space objects out of their trajectories before they can smash into their smaller planet neighbors. Kane likens giant planets to his older brother, who kept him safe as a boy. “In school, it was very useful to have a big brother nearby who prevented bullies from beating me up on the playground,” Kane said. “That’s what Jupiter does for Earth.”

Read the original article online

View article

Tags

Stephen Kane

Meteor magnets in outer space

Anonymous — Tue, 25 Aug 2020 04:15:05 +0000

Meteor magnets in outer space Anonymous (not verified) Mon, 08/24/2020 - 21:15 More News Jules Bernstein | UCR News May 24, 2019

Astronomers believe planets like Jupiter shield us from space objects that would otherwise slam into Earth. Now they’re closer to learning whether giant planets act as guardians of solar systems elsewhere in the galaxy.

A UCR-led team has discovered two Jupiter-sized planets about 150 light years away from Earth that could reveal whether life is likely on the smaller planets in other solar systems.

“We believe planets like Jupiter have profoundly impacted the progression of life on Earth. Without them, humans might not be here to have this conversation,” said Stephen Kane, lead study author and UCR associate professor of planetary astrophysics. “Understanding how many other stars have planets like Jupiter could be very important for learning about the habitability of planets in those systems.”

Along with liquid water oceans, Kane said astronomers believe such planets have the ability to act as ‘slingshots,’ pulling objects like meteors, comets, and asteroids out of their trajectories en route to impact with small, rocky planets.

Many larger planets have been found close to their stars. However, those aren’t as useful for learning about the architecture of our own solar system, where the giant planets including Saturn, Uranus and Neptune are all farther from the sun. Big planets far from their stars have, until now, been harder to find.

A study recently published in the Astronomical Journal details how Kane’s team found success in a novel approach combining traditional detection methods with the latest technologies.

The “wobble” technique: blue wave shows movement toward Earth and the red occurs as the star heads away. (NASA/JPL-Caltech)

One popular method of searching for exoplanets — planets in other solar systems — involves monitoring stars for “wobble,” in which a star moves toward and away from Earth. The wobble is likely caused by the gravitational pull a nearby planet is exerting on it. When a star wobbles, it’s a clue there may be an exoplanet nearby.

When the planet is far from its star, the gravitational pull is weaker, making the wobble smaller and harder to detect. The other problem with using the wobble detection method, Kane said, is that it just takes a long time. Earth only takes a year to orbit the sun. Jupiter takes 12, Saturn takes 30, and Neptune takes an astonishing 164 years.

The larger exoplanets also take many years to circle their stars, which means observing a complete orbit could engulf an astronomer’s entire career. To accelerate the process, Kane and his team combined the wobble method with direct imaging. This way, if the team thought a planet might be causing wobble, they could confirm it by sight.

Obtaining a direct image of a planet quadrillions of miles away is no simple task. It requires the largest possible telescope, one that is at least 32 feet long and highly sensitive. Even from this distance, the light of the stars can overexpose the image, obscuring the target planets.

The team overcame this challenge by learning to recognize and eliminate the patterns in their images created by starlight. Removing the starlight allowed Kane’s team to see what remained.

“Direct imaging has come a long way both in terms of understanding the patterns we find, and in terms of the instruments used to create the images, which are much higher resolution than they’ve ever been,” Kane said. “You see this every time a new smartphone is released — the camera detectors are always being improved and that’s true in astronomy as well.”

In this project, the team applied the combination of wobble and imaging method to 20 stars. In addition to the two being orbited by giant Jupiter-like planets that had not been previously discovered, the team also detected a third, previously observed star with a giant planet in its system.

Going forward, the team will continue to monitor 10 of the stars where planetary companions could not be ruled out. In addition, Kane is planning a new project to measure how long it takes these exoplanets to complete rotations toward and away from their stars, which cannot currently be measured.

Kane’s team is international, with members at the Australian Astronomical Observatory, University of Southern Queensland, University of New South Wales and Macquarie University in Australia, as well as at the University of Hertfordshire in the United Kingdom. They are also spread across the U.S. at the National Optical Astronomy Observatory in Tucson, AZ, Southern Connecticut State University, NASA Ames Research Center and Stanford University in California and the Carnegie Institution of Washington in D.C.

“This discovery is an important piece of the puzzle because it helps us understand the factors that make a planet habitable and whether that’s common or not,” said Kane. “We are converging rapidly on answers to this question that the past 3,000 recorded years of history could only wish they had available to them.”

Read the original article online

View article

Tags

Stephen Kane

The most spectacular celestial vision you’ll never see

Anonymous — Tue, 25 Aug 2020 01:35:40 +0000

The most spectacular celestial vision you’ll never see Anonymous (not verified) Mon, 08/24/2020 - 18:35 More News Jules Bernstein | UCR News November 04, 2019

Contrary to previous thought, a gigantic planet in wild orbit does not preclude the presence of an Earth-like planet in the same solar system – or life on that planet.

What’s more, the view from that Earth-like planet as its giant neighbor moves past would be unlike anything it is possible to view in our own night skies on Earth, according to new research led by Stephen Kane, associate professor of planetary astrophysics at UC Riverside.

The research was carried out in the backdrop of a planetary system called HR 5183, which is about 103 light years away in the constellation of Virgo. It was there that an eccentric giant planet was discovered earlier this year.

Comparison of HR 5183b's eccentric orbit to the more circular orbits of the planets in our own solar system. (W. M. Keck Observatory/Adam Makarenko)

Normally, planets orbit their stars on a trajectory that is more or less circular. Astronomers believe large planets in stable, circular orbits around our sun, like Jupiter, shield us from space objects that would otherwise slam into Earth.

Sometimes, planets pass too close to each other and knock one another off course. This can result in a planet with an elliptical or “eccentric” orbit. Conventional wisdom says that a giant planet in eccentric orbit is like a wrecking ball for its planetary neighbors, making them unstable, upsetting weather systems, and reducing or eliminating the likelihood of life existing on them.

Questioning this assumption, Kane and Caltech astronomer Sarah Blunt tested the stability of an Earth-like planet in the HR 5183 solar system. Their modeling work is documented in a paper newly published in the Astronomical Journal.

Kane and Blunt calculated the giant planet’s gravitational pull on an Earth analog as they both orbited their star. “In these simulations, the giant planet often had a catastrophic effect on the Earth twin, in many cases throwing it out of the solar system entirely,” Kane said.

“But in certain parts of the planetary system, the gravitational effect of the giant planet is remarkably small enough to allow the Earth-like planet to remain in a stable orbit.”

The team found that the smaller, terrestrial planet has the best chance of remaining stable within an area of the solar system called the habitable zone — which is the territory around a star that is warm enough to allow for liquid-water oceans on a planet.

These findings not only increase the number of places where life might exist in the solar system described in this study — they increase the number of places in the universe that could potentially host life as we know it.

This is also an exciting development for people who simply love stargazing. HR 5813b, the eccentric giant in Kane’s most recent study, takes nearly 75 years to orbit its star. But the moment this giant finally swings past its smaller neighbor would be a breathtaking, once-in-a-lifetime event.

“When the giant is at its closest approach to the Earth-like planet, it would be fifteen times brighter than Venus — one of the brightest objects visible with the naked eye,” said Kane. “It would dominate the night sky.”

Going forward, Kane and his colleagues will continue studying planetary systems like HR 5183. They’re currently using data from NASA's Transiting Exoplanet Survey Satellite and the Keck Observatories in Hawaii to discover new planets, and examine the diversity of conditions under which potentially habitable planets could exist and thrive.

Read the original article online

View article

Tags

Stephen Kane

UC Riverside astrophysicist part of TESS planet finder team

Anonymous — Tue, 25 Aug 2020 01:29:49 +0000

UC Riverside astrophysicist part of TESS planet finder team Anonymous (not verified) Mon, 08/24/2020 - 18:29 More News Sarah Nightingale | UCR News April 19, 2018

NASA’s Transiting Exoplanet Survey Satellite (TESS) launched on April 18 from Florida’s Cape Canaveral Air Force Station, rising off the pad aboard a SpaceX Falcon 9 rocket at 3:51 p.m. PDT and deploying into Earth’s orbit 49 minutes later.

Stephen Kane, an associate professor of planetary astrophysics at UC Riverside and a Guest Investigator on the TESS Mission, witnessed the takeoff from the launch viewing site in Cape Canaveral.

The telescope will search for exoplanets — planets outside our solar system — orbiting the brightest stars in the sky, including those that could support life. In a two-year survey of the solar neighborhood, TESS will monitor more than 200,000 stars for temporary drops in brightness caused by planetary transits. Those planets will then be studied in detail through follow-up observations by other ground- and space-based telescopes.

Wednesday’s launch was originally scheduled for Monday, but it was delayed to give SpaceX time to check a potential issue with the rocket’s guidance, navigation, and control systems.

“The spacecraft is reported to be in good health and both solar arrays have been deployed. TESS is now being deployed into its final orbit that will cross the orbit of the moon,” Kane said.

Kane said the TESS mission will pick up the search for exoplanets as the Kepler mission prepares to wind down. Launched in 2009, the Kepler Space Telescope has discovered more than 4,500 potential and confirmed exoplanets. The stars viewed by TESS will be 30-100 times brighter than those surveyed by the Kepler satellite, therefore TESS planets should be much easier to characterize with follow-up observations.

Kane, who led the Kepler Habitable Zone Working Group for the Kepler mission, is a key part of the TESS mission. He has been collaborating with other TESS scientists to create the list of stars that TESS will observe and prepare for observations that will characterize the atmospheres of detected planets.

His team at UCR will be measuring the masses of detected planets as well as studying their orbits and simulating potential habitable conditions. “There are many exciting exoplanet hunting days ahead for UCR and we expect that our astrobiology group will be extremely busy as we use the TESS data to better understand the prevalence of life in the universe,” Kane said.

Kane, a member of UCR’s NASA-funded Alternative Earths Astrobiology Center, is available for media interviews about the launch and his involvement in analyzing TESS data and observations.

Read the original article online

View article

Tags

Stephen Kane

Exoplanets

Distant moons may harbor life

Anonymous — Tue, 25 Aug 2020 01:23:43 +0000

Distant moons may harbor life Anonymous (not verified) Mon, 08/24/2020 - 18:23 More News Sarah Nightingale | UCR News May 30, 2018

We’ve all heard about the search for life on other planets, but what about looking on other moons?

In a paper forthcoming in The Astrophysical Journal, researchers at the University of California, Riverside and the University of Southern Queensland have identified more than 100 giant planets that potentially host moons capable of supporting life. Their work will guide the design of future telescopes that can detect these potential moons and look for tell-tale signs of life, called biosignatures, in their atmospheres.

Since the 2009 launch of NASA’s Kepler telescope, scientists have identified thousands of planets outside our solar system, which are called exoplanets. A primary goal of the Kepler mission is to identify planets that are in the habitable zones of their stars, meaning it’s neither too hot nor too cold for liquid water — and potentially life — to exist.

Terrestrial (rocky) planets are prime targets in the quest to find life because some of them might be geologically and atmospherically similar to Earth. Another place to look is the many gas giants identified during the Kepler mission. While not a candidate for life themselves, Jupiter-like planets in the habitable zone may harbor rocky moons, called exomoons, that could sustain life.

“There are currently 175 known moons orbiting the eight planets in our solar system. While most of these moons orbit Saturn and Jupiter, which are outside the Sun’s habitable zone, that may not be the case in other solar systems,” said Stephen Kane, an associate professor of planetary astrophysics and a member of the UCR’s Alternative Earths Astrobiology Center. “Including rocky exomoons in our search for life in space will greatly expand the places we can look.”

Exomoons might provide a favorable environment for life. (NASA GSFC/Jay Friedlander & Britt Griswold)

The researchers identified 121 giant planets that have orbits within the habitable zones of their stars. At more than three times the radii of the Earth, these gaseous planets are less common than terrestrial planets, but each is expected to host several large moons.

Scientists have speculated that exomoons might provide a favorable environment for life, perhaps even better than Earth. That’s because they receive energy not only from their star, but also from radiation reflected from their planet. Until now, no exomoons have been confirmed.

“Now that we have created a database of the known giant planets in the habitable zone of their star, observations of the best candidates for hosting potential exomoons will be made to help refine the expected exomoon properties. Our follow-up studies will help inform future telescope design so that we can detect these moons, study their properties, and look for signs of life,” said Michelle Hill, an undergraduate student at the University of Southern Queensland who is working with Kane and will join UCR’s graduate program in the fall.

The title of the paper is “Exploring Kepler Giant Planets in the Habitable Zone.” In addition to Hill, who is the is lead author, and Kane, other contributors are: Eduardo Seperuelo Duarte from Instituto Federal do Rio de Janeiro in Brazil; Ravi K. Kopparapu from the NASA Goddard Flight Center in Maryland; Dawn M. Gelino from the NASA Exoplanet Science Institute at Caltech; and Robert A. Wittenmyer from University of Southern Queensland.

Read the original article online

View article

Tags

Stephen Kane

Omega centauri unlikely to harbor life

Anonymous — Tue, 25 Aug 2020 01:07:17 +0000

Omega centauri unlikely to harbor life Anonymous (not verified) Mon, 08/24/2020 - 18:07 More News Sarah Nightingale | UCR News August 09, 2018

Searching for life in the vast universe is an overwhelming task, but scientists can cross one place off their list.

Omega Centauri — a densely packed cluster of stars in our galactic backyard — is unlikely to be home to habitable planets, according to a study by scientists at the University of California, Riverside, and San Francisco State University.

Forthcoming in The Astrophysical Journal, the study was led by Stephen Kane, an associate professor of planetary astrophysics in UCR’s Department of Earth Sciences and a pioneer in the search for habitable planets outside our solar system, known as exoplanets. Sarah Deveny, a graduate student at San Francisco State who is working with Kane, co-authored the paper.

Omega Centauri. NASA, ESA, AND THE HUBBLE ERO TEAM.

In the hunt for habitable exoplanets, Omega Centauri, the largest globular cluster in the Milky Way, seemed like a good place to look. Comprising an estimated 10 million stars, the cluster is nearly 16,000 light years from Earth, making it visible to the naked eye and a relatively close target for observations by the Hubble Space Telescope.

“Despite the large number of stars concentrated in Omega Centauri’s core, the prevalence of exoplanets remains somewhat unknown,” Kane said. “However, since this type of compact star cluster exists across the universe, it is an intriguing place to look for habitability.”

Starting with a rainbow-colored assortment of 470,000 stars in Omega Centauri’s core, the researchers homed in on 350,000 stars whose color — a gauge of their temperature and age — means they could potentially harbor life-bearing planets.

For each star, they then calculated the habitable zone — the orbital region around each star in which a rocky planet could have liquid water, which is a key ingredient for life as we know it. Since most of the stars in Omega Centauri’s core are red dwarfs, their habitable zones are much closer than the one surrounding our own larger sun.

“The core of Omega Centauri could potentially be populated with a plethora of compact planetary systems that harbor habitable-zone planets close to a host star,” Kane said. “An example of such a system is TRAPPIST-1, a miniature version of our own solar system that is 40 light years away and is currently viewed as one of the most promising places to look for alien life.”

Ultimately, though, the cozy nature of stars in Omega Centauri forced the researchers to conclude that such planetary systems, however compact, cannot exist in the cluster’s core. While our own sun is a comfortable 4.22 light years from its nearest neighbor, the average distance between stars in Omega Centauri’s core is 0.16 light years, meaning they would encounter neighboring stars about once every 1 million years.

“The rate at which stars gravitationally interact with each other would be too high to harbor stable habitable planets,” Deveny said. “Looking at clusters with similar or higher encounter rates to Omega Centauri’s could lead to the same conclusion. So, studying globular clusters with lower encounter rates might lead to a higher probability of finding stable habitable planets.”

The title of the paper is “Habitability in the Omega Centauri Cluster.”

Read the original article online

View article

Tags

Stephen Kane

Exoplanets

NASA’s TESS mission finds ‘missing link’ planets

Anonymous — Tue, 25 Aug 2020 00:48:19 +0000

NASA’s TESS mission finds ‘missing link’ planets Anonymous (not verified) Mon, 08/24/2020 - 17:48 More News Jules Bernstein | UCR News July 29, 2019

NASA’s newest planet-hunting satellite has discovered a type of planet missing from our own solar system.

Launched in 2018, the Transiting Exoplanet Survey Satellite, or TESS, has found three new worlds around a neighboring star. Stephen Kane, a UC Riverside associate professor of planetary astrophysics, says the new star system, called TESS Object of Interest, or TOI-270, is exactly what the satellite was designed to find.

A paper describing TOI-270 has been published in the journal Nature Astronomy and is now available online. Of the three new exoplanets, meaning they’re outside our solar system, one is rocky and slightly larger than Earth, while the two others are gaseous and roughly twice Earth’s size.

Compare and contrast worlds in the TOI 270 system. (NASA’s Goddard Space Flight Center)

Not only is the smaller planet in the habitable zone — the range of distances from a star that are warm enough to allow liquid-water oceans on a planet — but the TOI-270 star is nearby, making it brighter for viewing. It’s also “quiet,” meaning it has few flares and allows scientists to observe it and its orbiting planets more easily.

“We’ve found very few planets like this in the habitable zone, and many fewer around a quiet star, so this is rare,” said Kane. “We don’t have a planet quite like this in our solar system.”

In our own solar system, there are either small, rocky planets like Earth, Mercury, Venus, and Mars, or much larger planets like Saturn, Jupiter, Uranus, and Neptune that are dominated by gasses rather than land. We don’t have planets about half the size of Neptune, though these are common around other stars.

“TOI-270 will soon allow us to study this “missing link” between rocky Earth-like planets and gas-dominant mini-Neptunes, because here all of these types formed in the same system,” said lead researcher Maximilian Gunther, a Torres Postdoctoral Fellow at the Massachusetts Institute of Technology.

Follow-up observations on the system have been planned for 2021, when the James Webb Space Telescope launches. It will be able to measure the composition of the TOI-270 planets’ atmospheres for oxygen, hydrogen, and carbon monoxide.

Kane says these kinds of observations can help determine whether a planet has ever had a liquid water ocean, and whether any of the planets has conditions suitable for life as we know it.

While TOI-270 is far enough away that no one living will likely ever travel there, at 73 light-years away it is still considered close.

“The diameter of our galaxy is 100,000 light years, and our galaxy is just one of millions of galaxies,” Kane said. “So, 73 light years means it’s one of our neighboring stars.”

TESS is a NASA Astrophysics Explorer mission led and operated by MIT and managed by NASA’s Goddard Space Flight Center. Additional partners include Northrop Grumman, NASA’s Ames Research Center, the Harvard-Smithsonian Center for Astrophysics, MIT’s Lincoln Laboratory, and the Space Telescope Science Institute. More than a dozen universities, research institutes, and observatories worldwide are participants in the mission.

Kane, a member of UCR’s NASA-funded Alternative Earths Astrobiology Center, is available for media interviews about TESS and his involvement in analyzing its data and observations.

He and the team hope further research will reveal additional planets in the system beyond the three now known. The smaller planet is unlikely to host life because its surface could be too warm for the presence of liquid water. But additional planets at greater distances from the star might be cooler, allowing water to pool on their surfaces.

Read the original article online

View article

Tags

Stephen Kane

Exoplanets