Archives

October 2020


We present occurrence rates for rocky planets in the habitable zones (HZ) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties.

tau Ceti is the closest single Sun-like star to the solar system and hosts a multi-planet system with four confirmed planets.

Membraneless compartments--models for a potential step in the early evolution of cells--have been shown to persist or form, disappear, and reform in predictable ways through multiple cycles of dehydration and rehydration.

Chemists studying how life started often focus on how modern biopolymers like peptides and nucleic acids contributed, but modern biopolymers don't form easily without help from living organisms.

The "Big Bang" may have started the universe but it's likely that littler bangs played a key role in life on Earth, say Albion College physics professor Nicolle Zellner and chemistry professor Vanessa McCaffrey.

The discovery of thousands of highly irradiated, low-mass, exoplanets has led to the idea that atmospheric escape is an important process that can drive their evolution.

Most of our current knowledge on planet formation is still based on the analysis of main-sequence, solar-type stars.

The detection of phosphine (PH3) has been recently reported in the atmosphere of Venus employing mm-wave radio observations (Greaves et at. 2020). We here demonstrate that the observed PH3 feature with JCMT can be fully explained employing plausible mesospheric SO2 abundances (~100 ppbv as per the SO2 profile given in their figure 9), while the identification of PH3 in the ALMA data should be considered invalid due to severe baseline calibration issues.

The photochemical haze produced in the upper atmosphere of Titan plays a key role in various atmospheric and surface processes on Titan.

Humankind's next giant step may be onto Mars. But before those missions can begin, scientists need to make scores of breakthrough advances, including learning how to grow crops on the red planet.

In the night of January 16, 2018, a fireball meteor streaked across the sky over the Midwest and Ontario before landing on a frozen lake in Michigan.

NASA scientists identified a molecule in Titan's atmosphere that has never been detected in any other atmosphere. In fact, many chemists have probably barely heard of it or know how to pronounce it: cyclopropenylidene, or C3H2.

TESS, the Transiting Exoplanet Survey Satellite, was launched in 2018 with the goal of discovering small planets around the Sun's nearest neighbors, stars bright enough to allow for follow-up characterizations of their planets' masses and atmospheres.

We report the first detection on Titan of the small cyclic molecule cyclopropenylidene (c-C3H2) from high sensitivity spectroscopic observations made with the Atacama Large Millimeter/sub-millimeter Array (ALMA).

We propose a classification of exoplanet atmospheres based on their H, C, O, N element abundances below about 600 K. Chemical equilibrium models were run for all combinations of H, C, N, O abundances, and three types of solutions were found, which are robust against variations of temperature, pressure and nitrogen abundance.

Australian scientists have developed a new type of sensor to measure and correct the distortion of starlight caused by viewing through the Earth's atmosphere, which should make it easier to study the possibility of life on distant planets.

A gas-phase formation route is proposed for the recently detected propargylimine molecule. In analogy to other imines, such as cyanomethanimine, the addition of a reactive radical (C2H in the present case) to methanimine (CH2NH}) leads to reaction channels open also in the harsh conditions of the interstellar medium.

Transit observations have found the majority of exoplanets to date. Spectroscopic observations of transits and eclipses are the most commonly used tool to characterize exoplanet atmospheres and will be used in the search for life.

Context: ALMA observations of Venus at 267 GHz have been presented in the literature that show the apparent presence of phosphine (PH3) in its atmosphere. Phosphine has currently no evident production routes on the planet's surface or in its atmosphere.

For the first time, researchers have mapped the biological diversity of marine sediment, one of Earth's largest global biomes. Although marine sediment covers 70% of the Earth's surface, little was known about its global patterns of microbial diversity.

Earth's history knows catastrophes which are unimaginable for humans. For example, around 66 million years ago an asteroid impact marked the end of the dinosaur era. Long before however, 252 million years ago at the boundary between the Permian and Triassic epochs, Earth witnessed a far more extreme mass extinction event that extinguished about three-quarters of all species on land and some 95 percent of all species in the ocean.

Titan harbors a dense, organic-rich atmosphere primarily composed of N2 and CH4 , with lesser amounts of hydrocarbons and nitrogen-bearing species.

Organic molecules formed the basis for the evolution of life. But how could inorganic precursors have given rise to them?

We design and train a neural network (NN) model to efficiently predict the infrared spectra of interstellar polycyclic aromatic hydrocarbons (PAHs) with a computational cost many orders of magnitude lower than what a first-principles calculation would demand.

We recommend that the planetary science and space exploration community engage in a robust reevaluation concerning the ethics of how future crewed and uncrewed missions to the Moon and Mars will interact with those planetary environments. This should occur through a process of community input, with emphasis on how such missions can resist colonial structures. Such discussions must be rooted in the historical context of the violent colonialism in the Americas and across the globe that has accompanied exploration of Earth.

Mammals and birds today are warm-blooded, and this is often taken as the reason for their great success.

Following the announcement of the detection of phosphine (PH3) in the cloud deck of Venus at millimeter wavelengths, we have searched for other possible signatures of this molecule in the infrared range.

Bacteria are a dominant form of life that inhabit every environment on Earth. This includes human bodies, where they outnumber our cells and genes and regulate our existence for good or bad.

We provide a new framework to model the day side and night side atmospheres of irradiated exoplanets using 1-D radiative transfer by incorporating a self-consistent heat flux carried by circulation currents (winds) between the two sides.

Amino acids are considered to be prime ingredients in chemistry, leading to life.

The Sun has been found to be depleted in refractory (rock-forming) elements relative to nearby solar analogs, suggesting a potential indicator of planet formation.

The nearby star ϵ Eridani has been a frequent target of radio surveys for stellar emission and extraterrestial intelligence. Using deep 2−4 GHz observations with the Very Large Array, we have uncovered a 29 μJy compact, steady continuum radio source coincident with ϵ Eridani to within 0.06 arcseconds (≲2σ; 0.2 au at the distance of the star).

Isolated dense molecular cores are investigated to study the onset of complex organic molecule formation in interstellar ice.

Recent advances in our understanding of the dynamical history of the Solar system have altered the inferred bombardment history of the Earth during accretion of the Late Veneer, after the Moon-forming impact.

Observations of exoplanets and protoplanetary disks show that binary stellar systems can host planets in stable orbits. Given the high binary fraction among stars, the contribution of binary systems to Galactic habitability should be quantified.

The detection of exoplanets in high-contrast imaging (HCI) data hinges on post-processing methods to remove spurious light from the host star.

From life on other planets to virtual classrooms this thesis spans a wide array of research topics all based on how we see other worlds. Our understanding of everything from moon phases, the planets in our Solar System, and exoplanet atmospheres come from our interpretation of light and one day, our knowledge of light will be used as evidence for the discovery of life on another planet.

The aim of this study is to investigate the chemical evolution from the prestellar phase to the formation of the disk, and to determine the impact that the chemical composition of the cold and dense core has on the final composition of the disk.

High above our heads, even beyond 120,000 feet up, scientists have found tiny organisms called microbes. These high-flyers were swept up from the ground by winds and storms, or spewed out through volcanic processes.

With the discovery of TRAPPIST-1 and its seven planets within 0.06 au, the correct treatment of tidal interactions is becoming necessary. The eccentricity, rotation, and obliquity of the planets of TRAPPIST-1 are indeed the result of tidal evolution over the lifetime of the system.

The agency's newest rover will use the first ground-penetrating radar instrument on the Martian surface to help search for signs of past microbial life.

Superflares may provide the dominant source of biologically relevant UV radiation to rocky habitable zone M-dwarf planets (M-Earths), altering planetary atmospheres and conditions for surface life.

As our ability to undertake more powerful Searches for Extraterrestrial Intelligence (SETI) grows, so does interest in the more controversial endeavour of Messaging Extraterrestrial Intelligence (METI).

NASA's telescope on an airplane, the Stratospheric Observatory for Infrared Astronomy, has provided a new glimpse of the chemistry in the inner region surrounding massive young stars where future planets could begin to form. It found massive quantities of water and organic molecules in these swirling, disk-shaped clouds, offering new insights into how some of the key ingredients of life get incorporated into planets during the earliest stages of formation.

Planets form and obtain their compositions in disks of gas and dust around young stars. The chemical compositions of these planet-forming disks regulate all aspects of planetary compositions from bulk elemental inventories to access to water and reactive organics, i.e. a planet's hospitality to life and its chemical origins.

Ultraviolet light from giant stellar flares can destroy a planet's habitability. New research from the University of North Carolina at Chapel Hill will help astrobiologists understand how much radiation planets experience during super flares and whether life could exist on worlds beyond our solar system.

For the time being, Earth remains the best and only example of a habitable (and inhabited) world.

Earth is not necessarily the best planet in the universe. Researchers have identified two dozen planets outside our solar system that may have conditions more suitable for life than our own. Some of these orbit stars that may be better than even our sun.

Photosynthesis is an ancient metabolic process that began on the early Earth, offering plentiful energy to organisms that utilize it, to the extent that they can achieve global significance. The potential exists for similar processes to operate on habitable exoplanets and result in observable biosignatures.

We examine the effect of varying background N2 surface pressure (labelled as pN2) on the inner edge of the habitable zone for 1:1 tidally locked planets around M dwarfs, using the three-dimensional (3D) atmospheric general circulation model (AGCM) ExoCAM. In our experiments, the rotation period is fixed when varying the stellar flux, in order to more clearly isolate the role of pN2.

In the past decade, the analysis of exoplanet atmospheric spectra has revealed the presence of water vapour in almost all the planets observed, with the exception of a fraction of overcast planets.

Non-linear behavior in interstellar chemical models has been recognized for 25 years now. Different mechanisms account for the possibility of multiple fixed-points at steady state, characterized by the ionization degree of the gas.

Data from Martian meteorites suggest the planet may have two hydrogen reservoirs beneath its surface, according to a recent study by NASA's Astromaterials Exploration Research and Science (ARES) Division and a team of planetary scientists. The study, published in the journal Nature Geoscience, could shed light on how Mars formed and evolved.

The detection of liquid water by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) at the base of the south polar layered deposits in Ultimi Scopuli has reinvigorated the debate about the origin and stability of liquid water under present-day Martian conditions.

We have collected transit times for the TRAPPIST-1 system with the Spitzer Space Telescope over four years.

Catherine Neish is counting the days until her space launch. While the Western planetary geologist isn't space-suiting up for her own interstellar voyage, she is playing a key role in an international mission - dispatching a robotic drone to Saturn's moon Titan - set to blast-off in 2027.

We announce the discovery of two planets orbiting the M dwarfs GJ 251 (0.360±0.015 M⊙) and HD 238090 (0.578±0.021 M⊙) based on CARMENES radial velocity (RV) data.