Astrobiology

Broccoli gas: a better way to find life in space

Mayra Gandarilla — Fri, 21 Oct 2022 18:34:35 +0000

Broccoli gas: a better way to find life in space Mayra Gandarilla Fri, 10/21/2022 - 11:34 More News Jules Bernstein October 10, 2022

"Broccoli, along with other plants and microorganisms, emit gases to help them expel toxins. Scientists believe these gases could provide compelling evidence of life on other planets.

These types of gases are made when organisms add a carbon and three hydrogen atoms to an undesirable chemical element. This process, called methylation, can turn potential toxins into gases that float safely away into the atmosphere. If these gases were to be detected in the atmosphere of another planet using telescopes, they would be suggestive of life somewhere on that planet."

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Astrobiology

Edward Schwieterman

Laughing gas in space could mean life

Mayra Gandarilla — Fri, 21 Oct 2022 18:18:45 +0000

Laughing gas in space could mean life Mayra Gandarilla Fri, 10/21/2022 - 11:18 More News Jules Bernstein October 04, 2022

"Scientists at UC Riverside are suggesting something is missing from the typical roster of chemicals that astrobiologists use to search for life on planets around other stars — laughing gas.

Chemical compounds in a planet’s atmosphere that could indicate life, called biosignatures, typically include gases found in abundance in Earth’s atmosphere today."

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Edward Schwieterman

Astrobiology

Newly discovered planet zips around baby star in a week

Anonymous — Mon, 03 Aug 2020 01:46:08 +0000

Newly discovered planet zips around baby star in a week Anonymous (not verified) Sun, 08/02/2020 - 18:46 More News Holly Ober | UCR News June 24, 2020

Understanding how planets form is one of the main challenges scientists face when placing our own and other planetary systems in context. Planets are thought to form from the disk-shaped clouds of gas and dust that surround newborn stars, but this process has never been observed. Astronomers normally only observe planets after they have already formed and have to deduce the pathways that led to their final states.

An artist's rendering of the AU Mic star system. (NASA’s Goddard Space Flight Center)

For more than a decade, astronomers have searched for planets orbiting AU Microscopii, a nearby star still surrounded by a disk of debris left over from its formation. Now scientists using data from NASA’s Transiting Exoplanet Survey Satellite, or TESS, and now-retired Spitzer Space Telescope report the discovery of a planet about as large as Neptune that circles the young star in just over a week.

The new planet, AU Mic b, is located 31.9 light-years away in the southern constellation Microscopium and described in a paper published in Nature. The system, known as AU Mic for short, provides a one-of-a-kind laboratory for studying how planets and their atmospheres form, evolve, and interact with their stars.

“AU Mic is a young, nearby M dwarf star. It’s surrounded by a vast debris disk in which moving clumps of dust have been tracked, and now, thanks to TESS and Spitzer, it has a planet with a direct size measurement,” said co-author Bryson Cale, a doctoral student at George Mason University in Fairfax, Virginia. “There is no other known system that checks all of these important boxes.”

“Finding a ‘missing link,’ such as the planet orbiting AU Mic, essentially caught in the act of forming, is extremely rare,” said co-author Stephen Kane, an associate professor in the Department of Earth and Planetary Sciences at the University of California, Riverside. “What makes this especially rare is that it also transits its star, so we can measure the radius as well as the mass, leading to an estimate of the bulk density of the planet and its likely composition.

An artist's rendering of the planet AU Mic b. (NASA’s Goddard Space Flight Center)

“This discovery will form the foundation for many years of observational and theoretical studies into the very earliest stages for planet formation,” added Kane, who helped develop the instrument that measured the planet mass and was part of the TESS team that discovered the transit of the planet.

AU Mic is a cool red dwarf star with an age estimated at 20 million to 30 million years, making it a stellar infant compared to our sun, which is at least 150 times older. The planet AU Mic b almost hugs its star, completing an orbit every eight-and-a-half days. It weighs less than 58 times Earth’s mass, placing it in the category of Neptune-like worlds.

“We think AU Mic b formed far from the star and migrated inward to its current orbit, something that can happen as planets interact gravitationally with a gas disk or with other planets,” said co-author Thomas Barclay, an associate research scientist at the University of Maryland, Baltimore County, and an associate project scientist for TESS at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

An artist's rendering of how scientists discovered AU Mic b. (NASA’s Goddard Space Flight Center)

When a planet crosses in front of its star from our perspective — an event called a transit — its passage causes a distinct dip in the star’s brightness. TESS monitors large swaths of the sky, called sectors, for 27 days at a time. During this long stare, the mission’s cameras regularly capture snapshots that allow scientists to track changes in stellar brightness.

Regular dips in a star’s brightness signal the possibility of a transiting planet. Usually, it takes at least two observed transits to recognize a planet’s presence.

“As luck would have it, the second of three TESS transits occurred when the spacecraft was near its closest point to Earth. At such times, TESS is not observing because it is busy downlinking all of the stored data,” said co-author Diana Dragomir, a research assistant professor at the University of New Mexico in Albuquerque. “To fill the gap, our team was granted observing time on Spitzer, which caught two additional transits in 2019 and enabled us to confirm the orbital period of AU Mic b.”

Because the amount of light blocked by a transit depends on the planet’s size and orbital distance, the TESS and Spitzer transits provide a direct measure of AU Mic b’s size. Analysis of these measurements shows the planet is about 8% larger than Neptune.

AU Mic b might not be the only planet orbiting its star.

“There is an additional candidate transit event seen in the TESS data, and TESS will hopefully revisit AU Mic later this year in its extended mission,” said lead author Peter Plavchan, an assistant professor of physics and astronomy at George Mason. “We are continuing to monitor the star with precise radial velocity measurements, so stay tuned.”

The paper, “A planet within the debris disk around the pre-main-sequence star AU Microscopii,” was published June 24.

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Exoplanets and Planetary Science

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Surprising number of exoplanets could host life

Anonymous — Sun, 02 Aug 2020 23:10:42 +0000

Surprising number of exoplanets could host life Anonymous (not verified) Sun, 08/02/2020 - 16:10 More News Jules Bernstein | UCR News July 31, 2020

Our solar system has one habitable planet — Earth. A new study shows other stars could have as many as seven Earth-like planets in the absence of a gas giant like Jupiter.

Image from NASA's Juno spacecraft of Jupiter, the largest planet in our solar system. (NASA/JPL-Caltech/SwRI/MSSS)

This is the conclusion of a study led by UC Riverside astrobiologist Stephen Kane published this week in the Astronomical Journal.

The search for life in outer space is typically focused on what scientists call the “habitable zone,” which is the area around a star in which an orbiting planet could have liquid water oceans — a condition for life as we know it.

Kane had been studying a nearby solar system called Trappist-1, which has three Earth-like planets in its habitable zone.

“This made me wonder about the maximum number of habitable planets it’s possible for a star to have, and why our star only has one,” Kane said. “It didn’t seem fair!”

His team created a model system in which they simulated planets of various sizes orbiting their stars. An algorithm accounted for gravitational forces and helped test how the planets interacted with each other over millions of years.

They found it is possible for some stars to support as many as seven, and that a star like our sun could potentially support six planets with liquid water.

“More than seven, and the planets become too close to each other and destabilize each other’s orbits,” Kane said.

Why then does our solar system only have one habitable planet if it is capable of supporting six? It helps if the planets’ movement is circular rather than oval or irregular, minimizing any close contact and maintain stable orbits.

The Trappist-1 planetary system has three planets in its habitable zone, compared to our solar system which has only one. (NASA/JPL/Caltech)

Kane also suspects Jupiter, which has a mass two-and-a-half times that of all the other planets in the solar system combined, limited our system’s habitability.

“It has a big effect on the habitability of our solar system because it’s massive and disturbs other orbits,” Kane said.

Only a handful of stars are known to have multiple planets in their habitable zones. Moving forward, Kane plans to search for additional stars surrounded entirely by smaller planets. These stars will be prime targets for direct imaging with NASA telescopes like the one at Jet Propulsion Laboratory’s Habitable Exoplanet Observatory.

Kane’s study identified one such star, Beta CVn, which is relatively close by at 27 light years away. Because it doesn’t have a Jupiter-like planet, it will be included as one of the stars checked for multiple habitable zone planets.

Future studies will also involve the creation of new models that examine the atmospheric chemistry of habitable zone planets in other star systems.

Projects like these offer more than new avenues in the search for life in outer space. They also offer scientists insight into forces that might change life on our own planet one day.

“Although we know Earth has been habitable for most of its history, many questions remain regarding how these favorable conditions evolved with time, and the specific drivers behind those changes,” Kane said. “By measuring the properties of exoplanets whose evolutionary pathways may be similar to our own, we gain a preview into the past and future of this planet — and what we must do to main its habitability.”

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Exoplanets and Planetary Science

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