Archives

August 2016


Proxima Centauri b provides an unprecedented opportunity to understand the evolution and nature of terrestrial planets orbiting M dwarfs.

While we await with interest a formal write-up of the RATAN-600 result, the claim that the detection could be a signal from an extraterrestrial civilization has attracted much media interest.

We investigate retrieval of the stellar rotation signal for Proxima Centauri. We make use of high-resolution spectra taken with uves and harps of Proxima Centauri over a 13-year period as well as photometric observations of Proxima Centauri from asas and hst.

The world's attention is now on Proxima Centauri b, a possibly Earth-like planet orbiting the closest star, 4.22 light-years away. The planet's orbit is just right to allow liquid water on its surface, needed for life. But could it in fact be habitable?

We study the molecular abundance and spatial distribution of the simplest sugar alcohol, ethylene glycol (EG), the simplest sugar glycoladehyde (GA), and other chemically related complex organic species towards the massive star-forming region G31.41+0.31.

The newly detected Earth-mass planet in the habitable zone of Proxima Centauri could potentially host life - if it has an atmosphere that supports surface liquid water.

The NASA Kepler mission has discovered thousands of new planetary candidates, many of which have been confirmed through follow-up observations. A primary goal of the mission is to determine the occurrance rate of terrestrial-size planets within the Habitable Zone (HZ) of their host stars. Here we provide a list of HZ exoplanet candidates from the Kepler Data Release 24 Q1-Q17 data vetting process.

The abundance of key molecules determines the level of cooling that is necessary for the formation of stars and planetary systems. In this context, one needs to understand the details of the time dependent oxygen chemistry, leading to the formation of molecular oxygen and water.

To study the terrestrial-type planet formation during the post oligarchic growth, the initial distributions of planetary embryos and planetesimals used in N-body simulations play an important role. Most of these studies typically use ad hoc initial distributions based on theoretical and numerical studies.

Proxima Centauri b, an Earth-size planet in the habitable zone of our nearest stellar neighbour, has just been discovered. A theoretical framework of synchronously rotating planets, in which the risk of a runaway greenhouse on the sunlight side and atmospheric collapse on the reverse side are mutually ameliorated via heat transport is discussed.

Ultra high energy neutrinos may be observed in ice by the emission of acoustic signals. The SPATS detector has investigated the possibility of observing GZK-neutrinos in the clear ice near the South Pole at the IceCube detector site. To explore other potential detection sites glacial ice in the Alps and in Antarctica has been surveyed for its acoustical properties

Study of exoplanets is the holy grail of present research in planetary sciences and astrobiology. Analysis of huge planetary data from space missions such as CoRoT and Kepler is directed ultimately at finding a planet similar to Earth\-the Earth's twin, and answering the question of potential exo-habitability.

Habitability for planets orbiting active stars has been questioned. Especially, planets in the Habitable Zone (HZ) of M-stars, like our closest star Proxima Centauri, experience temporal high-ultraviolet (UV) radiation.

We analyze the evolution of the potentially habitable planet Proxima Centauri b to identify environmental factors that affect its long-term habitability. We consider physical processes acting on size scales ranging between the galactic scale, the scale of the stellar system, and the scale of the planet's core.

A new method for analyzing the chemical composition of stars may help scientists winnow the search for Earth 2.0.

An international team of astronomers including Carnegie's Paul Butler has found clear evidence of a planet orbiting Proxima Centauri, the closest star to our solar system.

Often described as the blueprint of life, DNA contains the instructions for making every living thing from a human to a house fly. But in recent decades, some researchers have been putting the letters of the genetic code to a different use: making tiny nanoscale computers.

Why are we now? We know that the universe is roughly 14 billion years old, and that someday it is likely to end -- perhaps because of a Big Freeze, Big Rip or Big Crunch.

A new generation of dedicated Doppler spectrographs will attempt to detect low-mass exoplanets around mid-late M stars at near infrared (NIR) wavelengths, where those stars are brightest and have the most Doppler information content.

A new study provides insight into base pair bonding in artificial DNA polymerase. Researchers focused on a previously unknown base pair: iso-guanine and methyl-pyrimidinone.

The long awaited second edition of the Astrobiology Primer is now published in the journal Astrobiology.

The search for habitable, alien worlds needs to make room for a second "Goldilocks," according to a Yale University researcher.

We reconsider the commonly held assumption that warm debris disks are tracers of terrestrial planet formation. The high occurrence rate inferred for Earth-mass planets around mature solar-type stars based on exoplanet surveys (roughly 20%) stands in stark contrast to the low incidence rate (less than 2-3%) of warm dusty debris around solar-type stars during the expected epoch of terrestrial planet assembly (roughly 10 Myr).

The habitability of planets in binary star systems depends not only on the radiation environment created by the two stars, but also on the perturbations to planetary orbits and rotation produced by the gravitational field of the binary and neighbouring planets.

Physicists from the Technical University of Munich (TUM) have succeeded in detecting a time-resolved supernova signal in the Earth's microfossil record.

Collisions of ice particles play an important role in the formation of planetesimals and comets. In recent work we showed, that CO2 ice behaves like silicates in collisions.

The distant planet GJ 1132b intrigued astronomers when it was discovered last year. Located just 39 light-years from Earth, it might have an atmosphere despite being baked to a temperature of around 450 degrees Fahrenheit. But would that atmosphere be thick and soupy or thin and wispy? New research suggests the latter is much more likely.

Plants, bacteria and fungi react to light with light-sensitive proteins. Scientists from the University of Gothenburg and their Finnish colleagues from University of Jyväskylä have now determined the inner workings of one of these proteins. The results have been published in the most recent issue of Science Advances.

The number of microbes in, on, and around the planet - on the order of a nonillion, or 10^30 - is estimated to outnumber the stars in the Milky Way.

In 2020, NASA plans to launch a new Mars rover that will be tasked with probing a region of the planet scientists believe could hold remnants of ancient microbial life.

We develop a simple model to predict the radial distribution of planetesimal formation. The model is based on the observed growth of dust to mm-sized particles, which drift radially, pile-up, and form planetesimals where the stopping time and dust-to-gas ratio intersect the allowed region for streaming instability-induced gravitational collapse.

Short-period Earth to Neptune size exoplanets (super-Earths) with voluminous gas envelopes seem to be very common. These gas atmospheres are thought to have originated from the protoplanetary disk in which the planets were embedded during their first few Myr.

Scientists at The Scripps Research Institute (TSRI) have taken a big step toward the laboratory re-creation of the "RNA world," which is generally believed to have preceded modern life forms based on DNA and proteins.

I review some recent works on magnetism of cool, main-sequence stars, their winds and potential impact on surrounding exoplanets. The winds of these stars are very tenuous and persist during their lifetime.

The presence of the ancient valley networks on Mars indicates that the climate at 3.8 Ga was warm enough to allow substantial liquid water to flow on the martian surface for extended periods of time. However, the mechanism for producing this warming continues to be debated.

The relatively recent development of high-throughput sequencing (HTS) techniques has revealed a wealth of novel sequences found in very low abundance: the rare biosphere.

We classified the reddest (r-J> 2.2) stars observed by the NASA Kepler mission into main sequence dwarf or evolved giant stars and determined the properties of 4216 M dwarfs based on a comparison of available photometry with that of nearby calibrator stars, as well as available proper motions and spectra.

Over the past five decades, radio astronomy has shown that molecular complexity is a natural outcome of interstellar chemistry, in particular in star forming regions.

Condensible substances are nearly ubiquitous in planetary atmospheres. For the most familiar case-water vapor in Earth's present climate-the condensible gas is dilute, in the sense that its concentration is everywhere small relative to the noncondensible background gases.

Cold seeps are places where hydrocarbons, mostly methane, emanate from the sea floor. Unlike the hydrothermal vents, the fluids and bubbles are no hotter than the surrounding seawater, thus the name.

Physicists from the Technical University of Munich (TUM) have succeeded in detecting a time-resolved supernova signal in the Earth's microfossil record.

Multicellularity--the integration of previously autonomous cells into a new, more complex organism--is one of the major transitions in evolution.

O2 and O3 have been long considered the most robust individual biosignature gases in a planetary atmosphere, yet multiple mechanisms that may produce them in the absence of life have been described.

The determination of atmospheric structure and molecular abundances of planetary atmospheres via spectroscopy involves direct comparisons between models and data.

We investigate 3D atmosphere dynamics for tidally locked terrestrial planets with an Earth-like atmosphere and irradiation for different rotation periods (Prot=1100 days) and planet sizes (RP=12REarth) with unprecedented fine detail.

To better understand how microbes behave in extreme environments, one possible proxy, not often considered by astrobiologists, is the human body. Over billions of years of evolution, certain species of microbes inside humans have adapted to environments in the human body that would be extremely rough to many other organisms.

Binary systems with similar components are ideal laboratories which allow several physical processes to be tested, such as the possible chemical pattern imprinted by the planet formation process.

A spectral line image cube generated from 115 minutes of MWA data that covers a field of view of 400 sq. deg. around the Galactic Centre is used to perform the first Search for ExtraTerrestrial Intelligence (SETI) with the Murchison Widefield Array.

Scientists in their preliminary findings suggest signs of life from under Mars' surface may not survive in rocks excavated by some meteorite impacts.

We report radio SETI observations on a large number of known exoplanets and other nearby star systems using the Allen Telescope Array (ATA) for about 19000 hours from May 2009 to Dec 2015.

Present-day Venus is an inhospitable place with surface temperatures approaching 750K and an atmosphere over 90 times as thick as present day Earth's. Billions of years ago the picture may have been very different.

A new study could explain why DNA and not RNA, its older chemical cousin, is the main repository of genetic information.

The universe is 13.8 billion years old, while our planet formed just 4.5 billion years ago. Some scientists think this time gap means that life on other planets could be billions of years older than ours.

Looking for another Earth? An international team of researchers has pinpointed which of the more than 4,000 exoplanets discovered by NASA's Kepler mission are most likely to be similar to our rocky home.

Recently, a team of astrobiologists from the EU funded MASE (Mars Analogues for Space Exploration) project descended 1.1 kilometers below Earth's surface to the Mars-like environment of the Boulby Mine in the UK looking for answers about life on other planets.

Newly discovered fossil evidence from Namibia strengthens the proposition that the world's first mass extinction was caused by "ecosystem engineers" - newly evolved biological organisms that altered the environment so radically it drove older species to extinction.