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Results for “exoplanet characterization”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

The Maturing of High Contrast Imaging and Starlight Suppression Techniques for Future NASA Exoplanet Characterization Missions

Over 3000 exoplanets and hundreds of exoplanetary systems have been detected to date and we are now rapidly moving toward an era where the focus is shifting from detection to direct imaging and spectroscopic characterization of these new worlds and their atmospheres. NASA is currently studying several exoplanet characterization mission concepts for the 2020 Decadal Survey ranging from probe class to flagships. Detailed and comprehensive exoplanet characterization, particularly of exo-Earths, leading to assessment of habitability, or indeed detection of life, will require significant advances beyond the current state-of-the-art in high contrast imaging and starlight suppression techniques which utilize specially shaped precision optical elements to block the light from the parent star while controlling scattering and diffraction thus revealing and enabling spectroscopic study of the orbiting exoplanets in reflected light. In this paper we describe the two primary high contrast starlight suppression techniques currently being pursued by NASA: 1) coronagraphs (including several design variations) and 2) free-flying starshades. These techniques are rapidly moving from the technology development phase to the design and engineering phase and we discuss the prospects and projected performance for future exoplanet characterization missions utilizing these techniques coupled with large aperture telescopes in space.

high contrast↗
NASA NTRS2016

Combining Photometry from Kepler and TESS to Improve Short-Period Exoplanet Characterization

Planets emit thermal radiation and reflect incident light that they receive from their host stars. As a planet orbits its host star the photometric variations associated with these two effects produce very similar phase curves. If observed through only a single bandpass, this leads to a degeneracy between certain planetary parameters that hinder the precise characterization of such planets. However, observing the same planet through two different bandpasses gives much more information about the planet. Here we develop a Bayesian methodology for combining photometry from both Kepler and the Transiting Exoplanet Survey Satellite. In addition, we demonstrate via simulations that one can disentangle the reflected and thermally emitted light from the atmosphere of a hot-Jupiter as well as more precisely constrain both the geometric albedo and day-side temperature of the planet. This methodology can further be employed using various combinations of photometry from the James Webb Space Telescope, the Characterizing ExOplanet Satellite, or the PLATO mission.

photometric variations↗
NASA NTRS2016

Advances in Starshade Technology Readiness for an Exoplanet Characterizing Science Mission in the 2020's

The discovery of thousands of exoplanets is generating increasing interest in the direct imaging and characterization of these planets. Starshade, and eternal occulter, could fly in formation between a telescope and distant star, blocking out the light from the star, and enabling us to focus on the light of any orbiting planets. Recent technology developments in coordination with system design, has added much needed detail to define the technology requirements for a science mission that could launch in the 2020's. This paper address the mechanical architecture, the successful efforts to date, the current state of design for the mechanical system, and upcoming technology efforts.

occulter↗
NASA NTRS2017

Characterizing Exoplanet Atmospheres with the James Webb Space Telescope

The James Webb Space Telescope (JWST) will have numerous modes for acquiring photometry and spectra of stars, planets, galaxies, and other astronomical objects over wavelengths of 0.6 - 28 microns. Several of these modes are well-suited for observing atomic and molecular features in the atmospheres of transiting or spatially resolved exoplanets. I will present basic information on JWST capabilities, highlight modes that are well-suited for observing exoplanets, and give examples of what may be learned from JWST observations. This will include simulated spectra and expected retrieved chemical abundance, composition, equilibrium, and thermal information and uncertainties. JWST Cycle 1 general observer proposals are expected to be due in March 2018 with launch in October 2018, and the greater scientific community is encouraged to propose investigations to study exoplanet atmospheres and other topics.

space telescopes↗
NASA NTRS2010

Infrared Imaging and Characterization of Exoplanets: Can we Detect Earth-Twins on a Budget?

During the past decade considerable progress has been made developing techniques that can be used to detect and characterize Earth twins in the mid- infrared (7-20 microns). The principal technique is called nulling interferometry, and it was invented by Bracewell in the late 1970's. The nulling technique is an interferometric equivalent of an optical coronagraph. At the present time most of the technological hurdles have been overcome for a space mission to be able to begin Phase A early in the next decade, and it is possible to detect and characterize Earth-twins on a mid- sized strategic mission budget ($600-800 million). I will review progress on this exciting method of planet detection in the context of recent work on the Exoplanet Community Forum and the US Decadal Survey (Astro2010), including biomarkers, technological progress, mission concepts, the theory of these instruments, and a.comparison of the discovery space of this technique with others also under consideration.

Danchi, William↗
NASA NTRS2012

Science with the James Webb Space Telescope

The science objectives of the James Webb Space Telescope fall into four themes. The End of the Dark Ages: First Light and Reionization theme seeks to identify the first luminous sources to form and to determine the ionization history of the universe. The Assembly of Galaxies theme seeks to determine how galaxies and the dark matter, gas, stars, metals, morphological structures, and black holes within them evolved from the epoch of reionization to the present. The Birth of Stars and Protoplanetary Systems theme seeks to unravel the birth and early evolution of stars, from infall onto dust-enshrouded protostars, to the genesis of planetary systems. The Planetary Systems and the Origins of Life theme seeks to determine the physical and chemical properties of planetary systems around nearby stars and of our own, and to investigate the potential for life in those systems. These four science themes were used to establish the design requirements for the observatory and instrumentation. Since Webb's capabilities are unique, those science themes will remain relevant through launch and operations and goals contained within these themes will continue to guide the design and implementation choices for the mission. More recently, it has also become clear that Webb will make major contributions to other areas of research, including dark energy, dark matter, active galactic nuclei, stellar populations, exoplanet characterization and Solar System objects. In this paper, we review the original four science themes and discuss how the scientific output of Webb will extend to these new areas of research. The James Webb Space Telescope was designed to meet science objectives in four themes: The End of the Dark Ages: First Light and Reionization, The Assembly of Galaxies, The Birth of Stars and Protoplanetary Systems, and Planetary Systems and the Origins of Life. More recently, it has become clear that Webb will also make major contributions to studies of dark energy, dark matter, active galactic nuclei, stellar populations, exoplanet characterization and Solar System objects. We review the original four science themes and discuss how the scientific output of Webb will extend to these new areas of research.

Gardner, Jonathan P.↗
DOE OSTI2022

Autodifferentiable Spectrum Model for High-dispersion Characterization of Exoplanets and Brown Dwarfs

We present an autodifferentiable spectral modeling of exoplanets and brown dwarfs. This model enables a fully Bayesian inference of the high-dispersion data to fit the ab initio line-by-line spectral computation to the observed spectrum by combining it with the Hamiltonian Monte Carlo in recent probabilistic programming languages. An open-source code, ExoJAX, developed in this study, was written in Python using the GPU/TPU compatible package for automatic differentiation and accelerated linear algebra, JAX. We validated the model by comparing it with existing opacity calculators and a radiative transfer code and found reasonable agreements for the output. As a demonstration, we analyzed the high-dispersion spectrum of a nearby brown dwarf, Luhman 16 A, and found that a model including water, carbon monoxide, and H 2 /He collision-induced absorption was well fitted to the observed spectrum (R = 10 5 and 2.28-2.30 μm). As a result, we found that T0 = 1295$^{-32}_{+35}$ K at 1 bar and C/O = 0.62 ± 0.03, which is slightly higher than the solar value. This work demonstrates the potential of a full Bayesian analysis of brown dwarfs and exoplanets as observed by high-dispersion spectrographs and also directly imaged exoplanets as observed by high-dispersion coronagraphy.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2010

Exploring a Nearby Habitable World...Orbiting an M-Dwarf Star

Topics include: the landscape of extrasolar planets and detection techniques, direct and indirect detection methods, summary of the known exoplanets, exploiting transits to characterize super earth atmospheres, how to characterize exoplanet atmospheres, and emitted or reflected spectra of hot Jupiters.

Deming, Drake↗
NASA NTRS2014

Compositional Constraints on the Best Characterized Rocky Exoplanet, Kepler-36 b

Kepler-36 is an extreme planetary system, consisting of two transiting sub-Neptune-size planets orbiting around a sub-giant star with periods of 13.84 and 16.24 days. Mutual gravitational interactions between the two planets perturb the planets' transit times, allowing the planets' masses to be measured. Despite the similarity of their masses and orbital radii, the planets show a stark contrast in their mean densities: the inner planet (Kepler-36 b) is more than eight times as dense as its outer companion planet (Kepler-36 c). We perform a photo-dynamical analysis of the Kepler-36 system based on more than three years of Kepler photometry. With N-body integrations of initial conditions sampled from the photo-dynamical fits, we further refine the properties of the system by ruling out solutions that show large scale instability within 5 billion days. Ultimately, we measure the planets' masses with 4.2% precision and the planets' radii with 1.8% precision. Kepler-36 b is the rocky exoplanet with the most precisely measured mass and radius. Kepler-36 b's mass and radius are consistent with an Earth-like composition, whereas an iron-enhanced Mercury-like composition is ruled out.

sub-Neptune-size planets↗
NASA NTRS2014

Brown Dwarf Variability: What's Varying and Why?

Surveys by ground based telescopes, HST, and Spitzer have revealed that brown dwarfs of most spectral classes exhibit variability. The spectral and temporal signatures of the variability are complex and apparently defy simplistic classification which complicates efforts to model the changes. Important questions include understanding if clearings are forming in an otherwise uniform cloud deck or if thermal perturbations, perhaps associated with breaking gravity waves, are responsible. If clouds are responsible how long does it take for the atmospheric thermal profile to relax from a hot cloudy to a cooler cloudless state? If thermal perturbations are responsible then what atmospheric layers are varying? How do the observed variability timescales compare to atmospheric radiative, chemical, and dynamical timescales? I will address such questions by presenting modeling results for time-varying partly cloudy atmospheres and explore the importance of various atmospheric processes over the relevant timescales for brown dwarfs of a range of effective temperatures. Regardless of the origin of the observed variability, the complexity seen in the atmospheres of the field dwarfs hints at the variability that we may encounter in the next few years in directly imaged young Jupiters. Thus understanding the nature of variability in the field dwarfs, including sensitivity to gravity and metallicity, is of particular importance for exoplanet characterization.

brown dwarfs↗
NASA NTRS2019

The Future of Exoplanet Direct Detection

Diffraction fundamentally limits our ability to image and characterize exoplanets. Currant and planned coronagraphic searches for exoplanets are making incredible strides but are fundamentally limited by the inner working angle of a few λ/D. Some crucial topics, such as demographics of exoplanets within the first 50 Myr and the infrared characterization of terrestrial planets, are beyond the reach of the single aperture angular resolution for the foreseeable future. Interferometry offers some advantages in exoplanet detection and characterization and we explore in this white paper some of the potential scientific breakthroughs possible. We demonstrate here that investments in "exoplanet interferometry" could open up new possibilities for speckle suppression through spatial coherence, a giant boost in astrometric precision for determining exoplanet orbits, ability to take a census of young giant exoplanets (clusters <50 Myr age), and an unrivaled potential for infrared nulling from space to detect terrestrial planets and search for atmospheric biomarkers. All signs point to an exciting future for exoplanets and interferometers, albeit a promise that will take decades to fulfill.

John Monnier↗
NASA NTRS2014

Deformable Mirrors Capture Exoplanet Data, Reflect Lasers

To image and characterize exoplanets, Goddard Space Flight Center turned to deformable mirrors (DMs). Berkeley, California-based Iris AO, Inc. worked with Goddard through the SBIR program to improve the company’s microelectromechanical DMs, which are now being evaluated and used for biological research, industrial applications, and could even be used by drug manufacturers.

Source record↗
NASA NTRS2012

Integrated Optics Achromatic Nuller for Stellar Interferometry

This innovation will replace a beam combiner, a phase shifter, and a mode conditioner, thus simplifying the system design and alignment, and saving weight and space in future missions. This nuller is a dielectric-waveguide-based, four-port asymmetric coupler. Its nulling performance is based on the mode-sorting property of adiabatic asymmetric couplers that are intrinsically achromatic. This nuller has been designed, and its performance modeled, in the 6.5-micrometer to 9.25-micrometer spectral interval (36% bandwidth). The calculated suppression of starlight for this 15-cm-long device is 10(exp -5) or better through the whole bandwidth. This is enough to satisfy requirements of a flagship exoplanet-characterization mission. Nulling interferometry is an approach to starlight suppression that will allow the detection and spectral characterization of Earth-like exoplanets. Nulling interferometers separate the light originating from a dim planet from the bright starlight by placing the star at the bottom of a deep, destructive interference fringe, where the starlight is effectively cancelled, or nulled, thus allowing the faint off-axis light to be much more easily seen. This process is referred to as nulling of the starlight. Achromatic nulling technology is a critical component that provides the starlight suppression in interferometer-based observatories. Previously considered space-based interferometers are aimed at approximately 6-to-20-micrometer spectral range. While containing the spectral features of many gases that are considered to be signatures of life, it also offers better planet-to-star brightness ratio than shorter wavelengths. In the Integrated Optics Achromatic Nuller (IOAN) device, the two beams from the interferometer's collecting telescopes pass through the same focusing optic and are incident on the input of the nuller.

Ksendzov, Alexander↗
NASA NTRS2018

HOMES: Holographic Method for Exoplanet Spectroscopy

The search for habitable exoplanets in the "neighborhood," that is within 10 parsecs (pc),invites new observational techniques, because telescopes available today have significant limitations. For example, gravitational micro-lensing is a deep field method that has little or no utility within 10 pc. Photometry of transits reduces the availability of exoplanets to a probability of approximately a 1%, and fewer than 1 out of 100 earth twins would ever be seen. For the 1% of exoplanets seen in transit, spectra of albedos cannot be taken.Even more limiting, Doppler shift studies are indirect and cannot characterize exoplanets other than by their orbits and masses through stellar radial velocity (RV). Moreover, RV by Doppler shift cannot detect planets in orbits on a plane perpendicular to our line of sight. Astrometry can be used to measure stellar orbital wobble for those exoplanetary systems in the plane perpendicular to our line of sight, as was contemplated for the cancelled NASA SIM mission 1 and rests now with ESA's GAIA2. In either case, the exoplanets detected by stellar RV or astrometry would not be directly observed, so the assumption that the three phases of water could exist does not answer a key question of habitability. Is there water on the exoplanet? Moreover, the discovery of water on an exoplanet in the habitable zone, exciting though it would be, is insufficient to determine just how habitable the exoplanet might possibly be. Like Goldilocks' porridge - there are many other ingredients beyond water alone in a life-sustaining soup.We propose a new species of optical telescope that has as one of its capabilities the high resolution spectrographic characterization of exoplanets on stars within 10 pc of the observatory. To achieve this performance specification, we propose to break with convention by taking advantage of an optical technology unknown until relatively recent times: the hologram. In this Report we show how holograms used in primary and secondary can extract spectrograms from exoplanets at distances reaching 33 light years from our solar system. We describe a notional space telescope using these novel optics that could make its observations in a space deployment scenario.

Ditto, Thomas↗