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Ji-Wei Xie, Subo Dong, Zhaohuan Zhu, Daniel Huber, Zheng Zheng, Peter De Cat, Jianning Fu, Hui-Gen Liu, Ali Luo, Yue Wu, Haotong Zhang, Hui Zhang, Ji-Lin Zhou, Zihuang Cao, Yonghui Hou, Yuefei Wang, Yong Zhang
The nearly circular (mean eccentricity [Formula: see text]) and coplanar (mean mutual inclination [Formula: see text]) orbits of the solar system planets motivated Kant and Laplace to hypothesize that planets are formed in disks, which has developed into the widely accepted theory of planet formation. The first several hundred extrasolar planets (mostly Jovian) discovered using the radial velocity (RV) technique are commonly on eccentric orbits ([Formula: see text]). This raises a fundamental question: Are the solar system and its formation special? The Kepler mission has found thousands of transiting planets dominated by sub-Neptunes, but most of their orbital eccentricities remain unknown...
October 11, 2016: Proceedings of the National Academy of Sciences of the United States of America
H J Hoeijmakers, M L J Arts, F Snik, C U Keller, J M Kuiper
We provide a proof of the technical feasibility of LOUPE, the first integral-field snapshot spectropolarimeter, designed to monitor the reflected flux and polarization spectrum of Earth. These are to be used as benchmark data for the retrieval of biomarkers and atmospheric and surface characteristics from future direct observations of exoplanets. We perform a design trade-off for an implementation in which LOUPE performs snapshot integral-field spectropolarimetry at visible wavelengths. We used off-the-shelf optics to construct a polarization modulator, in which polarization information is encoded into the spectrum as a wavelength-dependent modulation, while spatial resolution is maintained using a micro-lens array...
September 19, 2016: Optics Express
Amaury Triaud
No abstract text is available yet for this article.
August 31, 2016: Nature
Daniel Clery
No abstract text is available yet for this article.
August 26, 2016: Science
Rebecca Oppenheimer
No abstract text is available yet for this article.
August 12, 2016: Science
Julien de Wit, Hannah R Wakeford, Michaël Gillon, Nikole K Lewis, Jeff A Valenti, Brice-Olivier Demory, Adam J Burgasser, Artem Burdanov, Laetitia Delrez, Emmanuël Jehin, Susan M Lederer, Didier Queloz, Amaury H M J Triaud, Valérie Van Grootel
Three Earth-sized exoplanets were recently discovered close to the habitable zone of the nearby ultracool dwarf star TRAPPIST-1 (ref. 3). The nature of these planets has yet to be determined, as their masses remain unmeasured and no observational constraint is available for the planetary population surrounding ultracool dwarfs, of which the TRAPPIST-1 planets are the first transiting example. Theoretical predictions span the entire atmospheric range, from depleted to extended hydrogen-dominated atmospheres...
July 20, 2016: Nature
Raymond T Pierrehumbert, Feng Ding
The diversity of characteristics for the host of recently discovered exoplanets opens up a great deal of fertile new territory for geophysical fluid dynamics, particularly when the fluid flow is coupled to novel thermodynamics, radiative transfer or chemistry. In this paper, we survey one of these new areas-the climate dynamics of atmospheres with a non-dilute condensible component, defined as the situation in which a condensible component of the atmosphere makes up a substantial fraction of the atmospheric mass within some layer...
June 2016: Proceedings. Mathematical, Physical, and Engineering Sciences
Kevin Wagner, Dániel Apai, Markus Kasper, Kaitlin Kratter, Melissa McClure, Massimo Robberto, Jean-Luc Beuzit
Direct imaging allows for the detection and characterization of exoplanets via their thermal emission. We report the discovery via imaging of a young Jovian planet in a triple-star system and characterize its atmospheric properties through near-infrared spectroscopy. The semimajor axis of the planet is closer relative to that of its hierarchical triple-star system than for any known exoplanet within a stellar binary or triple, making HD 131399 dynamically unlike any other known system. The location of HD 131399Ab on a wide orbit in a triple system demonstrates that massive planets may be found on long and possibly unstable orbits in multistar systems...
August 12, 2016: Science
J F Donati, C Moutou, L Malo, C Baruteau, L Yu, E Hébrard, G Hussain, S Alencar, F Ménard, J Bouvier, P Petit, M Takami, R Doyon, A Collier Cameron
Hot Jupiters are giant Jupiter-like exoplanets that orbit their host stars 100 times more closely than Jupiter orbits the Sun. These planets presumably form in the outer part of the primordial disk from which both the central star and surrounding planets are born, then migrate inwards and yet avoid falling into their host star. It is, however, unclear whether this occurs early in the lives of hot Jupiters, when they are still embedded within protoplanetary disks, or later, once multiple planets are formed and interact...
June 30, 2016: Nature
Manasvi Lingam
UNLABELLED: In this paper, percolation theory is employed to place tentative bounds on the probability p of interstellar travel and the emergence of a civilization (or panspermia) that colonizes the entire Galaxy. The ensuing ramifications with regard to the Fermi paradox are also explored. In particular, it is suggested that the correlation function of inhabited exoplanets can be used to observationally constrain p in the near future. It is shown, by using a mathematical evolution model known as the Yule process, that the probability distribution for civilizations with a given number of colonized worlds is likely to exhibit a power-law tail...
June 2016: Astrobiology
Richard A Frazin
A new generation of telescopes with mirror diameters of 20 m or more, called extremely large telescopes (ELTs), has the potential to provide unprecedented imaging and spectroscopy of exoplanetary systems, if the difficulties in achieving the extremely high dynamic range required to differentiate the planetary signal from the star can be overcome to a sufficient degree. Fully utilizing the potential of ELTs for exoplanet imaging will likely require simultaneous and self-consistent determination of both the planetary image and the unknown aberrations in multiple planes of the optical system, using statistical inference based on the wavefront sensor and science camera data streams...
April 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Muriel Gargaud, Wolf Dietrich Geppert, Nigel J Mason
No abstract text is available yet for this article.
April 23, 2016: Origins of Life and Evolution of the Biosphere
A Frank, W T Sullivan
UNLABELLED: In this article, we address the cosmic frequency of technological species. Recent advances in exoplanet studies provide strong constraints on all astrophysical terms in the Drake equation. Using these and modifying the form and intent of the Drake equation, we set a firm lower bound on the probability that one or more technological species have evolved anywhere and at any time in the history of the observable Universe. We find that as long as the probability that a habitable zone planet develops a technological species is larger than ∼10(-24), humanity is not the only time technological intelligence has evolved...
May 2016: Astrobiology
Fernando J Ballesteros, B Luque
UNLABELLED: As the number of detected extrasolar planets increases, exoplanet databases become a valuable resource, confirming some details about planetary formation but also challenging our theories with new, unexpected properties. KEY WORDS: Exoplanets-Gravity-Planetary habitability and biosignatures. Astrobiology 16, 325-327.
May 2016: Astrobiology
S Seager, W Bains, J J Petkowski
UNLABELLED: Thousands of exoplanets are known to orbit nearby stars. Plans for the next generation of space-based and ground-based telescopes are fueling the anticipation that a precious few habitable planets can be identified in the coming decade. Even more highly anticipated is the chance to find signs of life on these habitable planets by way of biosignature gases. But which gases should we search for? Although a few biosignature gases are prominent in Earth's atmospheric spectrum (O2, CH4, N2O), others have been considered as being produced at or able to accumulate to higher levels on exo-Earths (e...
June 2016: Astrobiology
J Hrušák, I Paidarová
Methane conversion and in particular the formation of the C-O bond is one of fundamental entries to organic chemistry and it appears to be essential for understanding parts of atmospheric chemistry of Titan, but, in broader terms it might be also relevant for Earth-like exoplanets. Theoretical study of the reactions of methane with atomic oxygen ion in its excited electronic states requires treating simultaneously at least 19 electronic states. Development of a computational strategy that would allow chemically reasonable and computationally feasible treatment of the CH4 (X)/O(+) ((2)D, (2)P) system is by far not trivial and it requires careful examination of all the complex features of the corresponding 19 potential energy surfaces...
April 11, 2016: Origins of Life and Evolution of the Biosphere
M S Lundkvist, H Kjeldsen, S Albrecht, G R Davies, S Basu, D Huber, A B Justesen, C Karoff, V Silva Aguirre, V Van Eylen, C Vang, T Arentoft, T Barclay, T R Bedding, T L Campante, W J Chaplin, J Christensen-Dalsgaard, Y P Elsworth, R L Gilliland, R Handberg, S Hekker, S D Kawaler, M N Lund, T S Metcalfe, A Miglio, J F Rowe, D Stello, B Tingley, T R White
Simulations predict that hot super-Earth sized exoplanets can have their envelopes stripped by photoevaporation, which would present itself as a lack of these exoplanets. However, this absence in the exoplanet population has escaped a firm detection. Here we demonstrate, using asteroseismology on a sample of exoplanets and exoplanet candidates observed during the Kepler mission that, while there is an abundance of super-Earth sized exoplanets with low incident fluxes, none are found with high incident fluxes...
2016: Nature Communications
Florian Gallet, Corinne Charbonnel, Louis Amard
With about 2000 exoplanets discovered within a large range of different configurations of distance from the star, size, mass, and atmospheric conditions, the concept of habitability cannot rely only on the stellar effective temperature anymore. In addition to the natural evolution of habitability with the intrinsic stellar parameters, tidal, magnetic, and atmospheric interactions are believed to have strong impact on the relative position of the planets inside the so-called habitable zone. Moreover, the notion of habitability itself strongly depends on the definition we give to the term "habitable"...
April 6, 2016: Origins of Life and Evolution of the Biosphere
J H C Martins, N C Santos, P Figueira, C Melo
The direct detection of reflected light from exoplanets is an excellent probe for the characterization of their atmospheres. The greatest challenge for this task is the low planet-to-star flux ratio, which even in the most favourable case is of the order of 10(-4) in the optical. This ratio decreases even more for planets in their host's habitable zone, typically lower than 10(-7). To reach the signal-to-noise level required for such detections, we propose to unleash the power of the Cross Correlation Function in combination with the collecting power of next generation observing facilities...
March 31, 2016: Origins of Life and Evolution of the Biosphere
Brice-Olivier Demory, Michael Gillon, Julien de Wit, Nikku Madhusudhan, Emeline Bolmont, Kevin Heng, Tiffany Kataria, Nikole Lewis, Renyu Hu, Jessica Krick, Vlada Stamenković, Björn Benneke, Stephen Kane, Didier Queloz
Over the past decade, observations of giant exoplanets (Jupiter-size) have provided key insights into their atmospheres, but the properties of lower-mass exoplanets (sub-Neptune) remain largely unconstrained because of the challenges of observing small planets. Numerous efforts to observe the spectra of super-Earths--exoplanets with masses of one to ten times that of Earth--have so far revealed only featureless spectra. Here we report a longitudinal thermal brightness map of the nearby transiting super-Earth 55 Cancri e (refs 4, 5) revealing highly asymmetric dayside thermal emission and a strong day-night temperature contrast...
April 14, 2016: Nature
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