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The unusual architecture of the υ Andromedae planetary system
The star υ Andromedae has 3 known planets orbiting it, all three close to or greater than the size of Jupiter. Surprisingly, observations show that the orbits of the outer two planets are tilted relative to each other by about 30 degrees, which is very unusual in comparison with the solar system. A study led by VPL graduate student Russell Deitrick together with VPL members Rory Barnes, Tom Quinn, and Rodrigo Luger used computer models to learn more about this interesting planetary system. The researchers were able to place constraints on the inner-most planet's mass and orbital tilt, which were previously unknown. They found that the inner-most planet is likely to be several Jupiter masses, and its orbital plane is probably aligned about halfway between the planes of the outer two planets. MORE>
Abiotic oxygen on exoplanets spells trouble for life-detection
Life has produced significant impacts on our own planet, including the oxygen we breathe, which makes up 21% of Earth's atmosphere. But what would happen if an early, lifeless Earth had been orbiting a different star? VPL Researchers Sonny Harman, Edward Schwieterman, and James Kasting examined what would happen if the early Earth was orbiting around different stars, ranging from a star slightly more massive than the Sun (an F type star) to a star less than half the mass of the Sun (an M type star). For the Earths orbiting smaller stars, the interaction between the atmosphere of the planet and the radiation from the star meant that some abiotic oxygen was produced. This could mean that when we look at distant planets around some types of stars, the presence of oxygen alone may not be a sure sign of life. MORE>
Is the pale blue dot unique?
Voyager 1's iconic image of the Pale Blue Dot shows hints of Earth's uniqueness are visible from great distances; the pale blue color of Earth sets it apart from other objects in our Solar System. But could planet color be used to easily identify Earth-like exoplanets? VPL graduate students Joshua Krissansen-Totton, Edward Schwieterman, Giada Arney, and VPL researchers Tyler Robinson, Benjamin Charnay, Victoria Meadows, and David Catling have authored a paper on whether color can be used to distinguish Earth-like exoplanets from uninhabitable worlds. This paper shows that numerous uninhabitable planets - particularly icy worlds with thick atmospheres - could mimic the Earth's pale blue color. It is possible to distinguish these icy worlds from Earth-like planets with extremely precise color observations, but this level precision demands a lot of telescope time. This suggests that spectral observations may be preferable to color observations for identifying Earth-like exoplanets. MORE>
Simulations of Exotic Clouds on Exoplanet GJ 1214b
What are clouds like on an exoplanet? In the case of GJ 1214b, they are unlike anything we have on Earth! For the first time, 3-D clouds on GJ 1214b have been simulated by VPL postdoc Benjamin Charnay, VPL PI Victoria Meadows, former VPL graduate student Amit Misra, current VPL graduate student Giada Arney, and University of Toronto researcher Jérémy Leconte. GJ 1214b is a "mini-Neptune" planet orbiting its star 42 light years away. The temperature of this planet's atmosphere is hotter than the boiling point of water, and clouds in it are likely to be composed of exotic salts such as zinc sulfide or potassium chloride. MORE>
Where to look for life?
UWAB astronomers Rory Barnes, Victoria Meadows, and research assistant Nicole Evans have co-authored a paper on how to prioritize targets in the search for life beyond our solar system. We know of over 3000 exoplanets now, and we'll discover many more in the coming years. To quote Rory: "Now it's as if Goldilocks has hundreds of bowls of porridge to choose from!" Which ones should we focus on precious telescope observing time on? A new metric called the "habitability index for transiting planets" ranks worlds according to a suite of properties that impact how life-friendly a planet is likely to be. MORE>
Sheltered by the magnetic cocoon
Habitable planets orbiting close to low mass M dwarf stars probably have magnetic fields to protect them according to VPL researchers Peter Driscoll and Rory Barnes. Planets orbiting near M dwarfs are likely to be tidally locked, meaning they rotate at the same rate they orbit the star just like the moon does around the Earth. It has been assumed that these planets would not have magnetic fields, which are important for protecting planets against events like stellar flares which are frequent and violent on M dwarfs. However, this assumption might not be true. Heat generated in the interior of these planets by tidal forces can create enough energy to generate a magnetic field, providing a protective magnetic cocoon to shield these worlds from stellar activity. The paper can be read here. MORE>
The Center of Light: Detecting Exomoons
VPL Researcher Eric Agol has led a study on detecting exomoons along with VPL PI Victoria Meadows and researcher Tyler Robinson. Planets have been found in abundance orbiting other stars, which brings up the question: do these planets have moons? This paper identifies a new method for detecting moons orbiting planets, orbiting other stars, using the fact that a moon can outshine a planet at wavelengths where the planet is dark. Future space-based telescopes will be able to suppress starlight, enabling the telescope to see the much fainter planet hiding in the wings. If the planet hosts a moon, then the center of light of the planet will appear to shift at certain wavelengths where the moon outshines the planet. As the moon orbits the planet, the position will vary with time, allowing a measurement of the mass of the planet and moon. Disentangling the planet and moon spectral signatures will enable determination of their atmospheric properties, including potential chemical signatures that might be signposts for life! MORE>
Yuk Yung wins Kuiper Prize!
VPL researcher Yuk Yung has been awarded the AAS Division of Planetary Sciences Gerard P. Kuiper prize! This award honors individuals who have made outstanding contributions to the field of planetary science. Dr. Yung's work has led to significant advances in atmospheric photochemistry, global habitability, climate change, radiative transfer, and atmospheric evolution. The models produced by Dr. Yung have been used widely in the planetary science community to interpret results from missions ranging from Voyager to New Horizons. Congratulations Yuk Yung! MORE>
Is that really alien life?
In an article at Space.com, VPL PI Victoria Meadows and VPL researcher Shawn Domagal-Goldman discuss how processes in a planetary environment might mimic the presence of photosynthesis and confuse future searches for life on exoplanets. Oxygen produced by bacteria and plants has long been regarded as a strong sign of life on our planet, but VPL research has uncovered four separate ways that a planet with no life could build up large quantities of oxygen in its atmosphere MORE>
Collisions could reveal “invisible gas” in exoplanets
VPL graduate student Edward Schwieterman, professor Victoria Meadows, and researchers Tyler Robinson, Amit Misra, and Shawn Domagal-Goldman have demonstrated that the collisional absorption signature of nitrogen gas can be detected in Earth’s disk-averaged spectrum and have modeled how it would appear on Earth-like exoplanets. Usually, nitrogen is considered an “invisible gas” because it lacks normal spectral features. Detection of nitrogen would provide a means to characterize the bulk atmosphere of potentially habitable exoplanets and constrain the likelihood of oxygen production by non-living processes. The paper has been published in The Astrophysical Journal here. MORE>
Atmospheric signs of volcanic activity could aid search for life
VPL graduate students Amit Misra, Josh Krissansen-Totton, Steve Sholes, and colleague have collaborated on an interdisciplinary paper on how to detect geological activity on extrasolar planets by looking for volcanically-induced transient sulfate aerosols in the planet's atmosphere. MORE>
Searching for Alien Biosignatures: Non-Photosynthetic Organisms May Produce Novel Signatures of Life on Exoplanets
VPL graduate student Edward Schwieterman, professor Victoria Meadows, and professor Charles Cockell at the UK Centre for Astrobiology present an interdisciplinary study of the possibility non-photosynthetic organisms may create signs of life on Earth-like exoplanets. These organisms contain pigments that reflect light differently than water, rocks, or photosynthetic organisms like land plants, producing spectral signatures that could indicate the presence of life. The paper was published in the May issue of Astrobiology. MORE>
Earliest evidence for microbial nitrogen fixation at 3.2 billion years ago
VPL Researchers, led by NAI NPP postdoc Eva Stueeken, with colleagues Matt Koehler and Roger Buick analyzed 3.2 billion year old rocks from Australia and found the oldest record of life using atmospheric nitrogen to make organic chemicals. This discovery implies that the size of the early biosphere was not limited by nitrogen availability - a critical bottleneck for life - and that microbial life may have been quite abundant on the early Earth. The paper was recently published in "Nature". MORE>