Extrasolar Planets


On Signatures of Clouds in Exoplanetary Transit Spectra

On Signatures of Clouds in Exoplanetary Transit Spectra

Transmission spectra of exoplanetary atmospheres have been used to infer the presence of clouds/hazes. Such inferences are typically based on spectral slopes in the optical deviant from gaseous Rayleigh scattering or low-amplitude spectral features in the infrared.


Formation of Solar System Analogs

Formation of Solar System Analogs

Population synthesis models of planetary systems developed during the last ∼15 years could reproduce several of the observables of the exoplanet population, and also allowed to constrain planetary formation models. We present our planet formation model, which calculates the evolution of a planetary system during the gaseous phase.


Exoplanet Biosignatures: Future Directions

Exoplanet Biosignatures: Future Directions

Exoplanet science promises a continued rapid accumulation of rocky planet observations in the near future, energizing a drive to understand and interpret an unprecedented wealth of data to search for signs of life. The large statistics of exoplanet samples, combined with the ambiguity of our understanding of universal properties of life and its signatures, necessitate a quantitative framework for biosignature assessment.


Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its Environment

Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its Environment

Here we review how environmental context can be used to interpret whether O2 is a biosignature in extrasolar planetary observations. This paper builds on the overview of current biosignature research discussed in Schwieterman et al. (2017), and provides an in-depth, interdisciplinary example of biosignature identification and observation that serves as a basis for the development of the general framework for biosignature assessment described in Catling et al., (2017).


Neutron Star Planets: Atmospheric Processes and Habitability

Neutron Star Planets: Atmospheric Processes and Habitability

Of the roughly 3000 neutron stars known, only a handful have sub-stellar companions. The most famous of these are the low-mass planets around the millisecond pulsar B1257+12. New evidence indicates that observational biases could still hide a wide variety of planetary systems around most neutron stars.


Exoplanet Biosignatures: Observational Prospects

Exoplanet Biosignatures: Observational Prospects

We provide an overview of the prospects for biosignature detection and general characterization of temperate Earth-sized planets. We review planned space-based missions and ground-based projects as well as the basic methods they will employ, and summarize which exoplanet properties will become observable as these new facilities come on line.


Exoplanet Biosignatures: A Framework for Their Assessment

Exoplanet Biosignatures: A Framework for Their Assessment

Finding life on exoplanets from telescopic observations is the ultimate goal of exoplanet science. Life produces gases and other substances, such as pigments, which can have distinct spectral or photometric signatures. Whether or not life is found in future data must be expressed with probabilities, requiring a framework for biosignature assessment.


A Super-Earth on the Inner Edge of the Habitable Zone of the Nearby M-dwarf GJ 625

A Super-Earth on the Inner Edge of the Habitable Zone of the Nearby M-dwarf GJ 625

We report the discovery of a super-Earth orbiting at the inner edge of the habitable zone of the star GJ 625 based on the analysis of the radial-velocity (RV) time series from the HARPS-N spectrograph, consisting in 151 HARPS-N measurements taken over 3.5 yr. GJ 625 b is a planet with a minimum mass M sin i of 2.82 ± 0.51 M⊕ with an orbital period of 14.628 ± 0.013 days at a distance of 0.078 AU of its parent star.


A Statistical Comparative Planetology Approach to the Hunt for Habitable Exoplanets and Life Beyond the Solar System

A Statistical Comparative Planetology Approach to the Hunt for Habitable Exoplanets and Life Beyond the Solar System

The search for habitable exoplanets and life beyond the Solar System is one of the most compelling scientific opportunities of our time.


A Complete ALMA Map of the Fomalhaut Debris Disk

A Complete ALMA Map of the Fomalhaut Debris Disk

We present ALMA mosaic observations at 1.3 mm (223 GHz) of the Fomalhaut system with a sensitivity of 14 μJy/beam. These observations provide the first millimeter map of the continuum dust emission from the complete outer debris disk with uniform sensitivity, enabling the first conclusive detection of apocenter glow.


An Observational Diagnostic for Distinguishing Between Clouds and Haze in Hot Exoplanet Atmospheres

An Observational Diagnostic for Distinguishing Between Clouds and Haze in Hot Exoplanet Atmospheres

The nature of aerosols in hot exoplanet atmospheres is one of the primary vexing questions facing the exoplanet field.


Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life

Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life

In the coming years and decades, advanced space- and ground-based observatories will allow an unprecedented opportunity to probe the atmospheres and surfaces of potentially habitable exoplanets for signatures of life.


The Surface UV Environment on Planets Orbiting M-Dwarfs: Implications for Prebiotic Chemistry & Need for Experimental Follow-Up

The Surface UV Environment on Planets Orbiting M-Dwarfs: Implications for Prebiotic Chemistry & Need for Experimental Follow-Up

Potentially-habitable planets orbiting M-dwarfs are of intense astrobiological interest because they are the only rocky worlds accessible to biosignature search over the next 10+ years due to a confluence of observational effects.


Most Habitable Planets May Lack Dry Land

Most Habitable Planets May Lack Dry Land

When it comes to exploring exoplanets, it may be wise to take a snorkel along. A new study, published in a paper in the journal Monthly Notices of the Royal Astronomical Society, has used a statistical model to predict that most habitable planets may be dominated by oceans spanning over 90% of their surface area.


The O2 A-band in Fluxes and Polarization of Starlight Reflected by Earth-like Exoplanets

The O2 A-band in Fluxes and Polarization of Starlight Reflected by Earth-like Exoplanets

Earth-like, potentially habitable exoplanets are prime targets in the search for extraterrestrial life. Information about their atmosphere and surface can be derived by analyzing light of the parent star reflected by the planet.


NIR-Driven Moist Upper Atmospheres of Synchronously Rotating Temperate Terrestrial Exoplanets

NIR-Driven Moist Upper Atmospheres of Synchronously Rotating Temperate Terrestrial Exoplanets

H2O is a key molecule in characterizing atmospheres of temperate terrestrial planets, and observations of transmission spectra are expected to play a primary role in detecting its signatures in the near future.


Making Terrestrial Planets: High Temperatures, FU Orionis Outbursts, Earth, and Planetary System Architectures

Making Terrestrial Planets: High Temperatures, FU Orionis Outbursts, Earth, and Planetary System Architectures

Current protoplanetary dust coagulation theory does not predict dry silicate planetesimals, in tension with the Earth. While remedies to this predicament have been proposed, they have generally failed numerical studies, or are in tension with the Earth's (low, volatility dependent) volatile and moderately volatile elemental abundances.


A Temperate Rocky Super-Earth Transiting a Nearby Cool Star

A Temperate Rocky Super-Earth Transiting a Nearby Cool Star

M dwarf stars, which have masses less than 60 per cent that of the Sun, make up 75 per cent of the population of the stars in the Galaxy [1]. The atmospheres of orbiting Earth-sized planets are observationally accessible via transmission spectroscopy when the planets pass in front of these stars [2,3].


Newly Discovered Exoplanet May be Best Candidate in Search for Signs of Life

Newly Discovered Exoplanet May be Best Candidate in Search for Signs of Life

An exoplanet orbiting a red dwarf star 40 light-years from Earth may be the new holder of the title "best place to look for signs of life beyond the Solar System". Using ESO's HARPS instrument at La Silla, and other telescopes around the world, an international team of astronomers discovered a "super-Earth" orbiting in the habitable zone around the faint star LHS 1140.


Updated Masses for the TRAPPIST-1 Planets

Updated Masses for the TRAPPIST-1 Planets

The newly detected TRAPPIST-1 system, with seven low-mass, roughly Earth-sized planets transiting a nearby ultra-cool dwarf, is one of the most important exoplanet discoveries to date.



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