Search

In this poster we show the potential of a mid-infrared interferometer like LIFE (Large Interferometer for Exoplanets) to characterize Earth analogs. These results were obtained through atmospheric retrieval studies and are currently being used to determine the scientific and technical requirements for the mission.

Context. An important future goal in exoplanetology is to detect and characterize potentially habitable planets. Concepts for future space missions have already been proposed: from a large UV-optical-infrared space mission for studies in reflected light, to the Large Interferometer for Exoplanets (LIFE) for analyzing the thermal portion of the planetary spectrum. Using nulling interferometry, LIFE will allow us to constrain the radius and effective temperature of (terrestrial) exoplanets, as well as provide unique information about their atmospheric structure and composition. Aims. We explore the potential of LIFE for characterizing emission spectra of Earth at various stages of its evolution. This allows us (1) to test the robustness of Bayesian atmospheric retrieval frameworks when branching out from a modern Earth scenario while still remaining in the realm of habitable (and inhabited) exoplanets, and (2) to refine the science requirements for LIFE for the detection and characterization of habitable, terrestrial exoplanets. Methods. We performed Bayesian retrievals on simulated spectra of eight different scenarios, which correspond to cloud-free and cloudy spectra of four different epochs of the evolution of the Earth. Assuming a distance of 10 pc and a Sun-like host star, we simulated observations obtained with LIFE using its simulator LIFESIM, considering all major astrophysical noise sources. Results. With the nominal spectral resolution (R = 50) and signal-to-noise ratio (assumed to be S/N = 10 at 11.2 μm), we can identify the main spectral features of all the analyzed scenarios (most notably CO2, H2O, O3, and CH4). This allows us to distinguish between inhabited and lifeless scenarios. Results suggest that O3 and CH4 in particular yield an improved abundance estimate by doubling the S/N from 10 to 20. Neglecting clouds in the retrieval still allows for a correct characterization of the atmospheric composition. However, correct cloud modeling is necessary to avoid biases in the retrieval of the correct thermal structure. Conclusions. From this analysis, we conclude that the baseline requirements for R and S/N are sufficient for LIFE to detect O3 and CH4 in the atmosphere of an Earth-like planet with an O2 abundance of around 2% in volume mixing ratio. Doubling the S/N would allow a clearer detection of these species at lower abundances. This information is relevant in terms of the LIFE mission planning. We also conclude that cloud-free retrievals of cloudy planets can be used to characterize the atmospheric composition of terrestrial habitable planets, but not the thermal structure of the atmosphere. From the inter-model comparison performed, we deduce that differences in the opacity tables (caused by, e.g., a different line wing treatment) may be an important source of systematic errors., Astronomy & Astrophysics, 665, ISSN:0004-6361, ISSN:1432-0746

Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152−0.070+0.073 to 2.87−0.13+0.14 Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02−0.23+0.28 to 0.177−0.061+0.055 times the Earth’s density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes., Astronomy & Astrophysics, 649, ISSN:0004-6361, ISSN:1432-0746

One of the long-term goals of exoplanet science is the atmospheric characterization of dozens of small exoplanets in order to understand their diversity and search for habitable worlds and potential biosignatures. Achieving this goal requires a space mission of sufficient scale. We seek to quantify the exoplanet detection performance of a space-based mid-infrared nulling interferometer that measures the thermal emission of exoplanets. For this, we have developed an instrument simulator that considers all major astrophysical noise sources and coupled it with Monte Carlo simulations of a synthetic exoplanet population around main-sequence stars within 20 pc. This allows us to quantify the number (and types) of exoplanets that our mission concept could detect over a certain time period. Two different scenarios to distribute the observing time among the stellar targets are discussed and different apertures sizes and wavelength ranges are considered. Within a 2.5-year initial search phase, an interferometer consisting of four 2 m apertures covering a wavelength range between 4 and 18.5 μm could detect up to ~550 exoplanets with radii between 0.5 and 6 R⊕ with an integrated SNR≥7. At least ~160 of the detected exoplanets have radii ≤1.5 R⊕. Depending on the observing scenario, ~25-45 rocky exoplanets (objects with radii between 0.5 and 1.5 ⊕) orbiting within the empirical habitable zone (eHZ) of their host stars are among the detections. With four times 3.5 m aperture size, the total number of detections can increase to up to ~770, including ~60-80 rocky, eHZ planets. With four times 1 m aperture size, the maximum detection yield is ~315 exoplanets, including ≤20 rocky, eHZ planets. In terms of predicted detection yield, such a mission can compete with large single-aperture reflected light missions.

Transmission spectra probe the atmospheres of transiting exoplanets, but these observations are also subject to signals introduced by magnetic active regions on host stars. Here we outline scientific opportunities in the next decade for providing useful constraints on stellar photospheres and inform interpretations of transmission spectra of the smallest ($R, Science white paper submitted in response to the the U.S. National Academies of Science, Engineering, and Medicine's call for community input to the Astro2020 Decadal Survey; 9 pages, 3 figures

Over the past decade, the study of extrasolar planets has evolved rapidly from plain detection and identification to comprehensive categorization and characterization of exoplanet systems and their atmospheres. Atmospheric retrieval, the inverse modeling technique used to determine an exoplanetary atmosphere's temperature structure and composition from an observed spectrum, is both time-consuming and compute-intensive, requiring complex algorithms that compare thousands to millions of atmospheric models to the observational data to find the most probable values and associated uncertainties for each model parameter. For rocky, terrestrial planets, the retrieved atmospheric composition can give insight into the surface fluxes of gaseous species necessary to maintain the stability of that atmosphere, which may in turn provide insight into the geological and/or biological processes active on the planet. These atmospheres contain many molecules, some of them biosignatures, spectral fingerprints indicative of biological activity, which will become observable with the next generation of telescopes. Runtimes of traditional retrieval models scale with the number of model parameters, so as more molecular species are considered, runtimes can become prohibitively long. Recent advances in machine learning (ML) and computer vision offer new ways to reduce the time to perform a retrieval by orders of magnitude, given a sufficient data set to train with. Here we present an ML-based retrieval framework called Intelligent exoplaNet Atmospheric RetrievAl (INARA) that consists of a Bayesian deep learning model for retrieval and a data set of 3,000,000 synthetic rocky exoplanetary spectra generated using the NASA Planetary Spectrum Generator. Our work represents the first ML retrieval model for rocky, terrestrial exoplanets and the first synthetic data set of terrestrial spectra generated at this scale., Third workshop on Bayesian Deep Learning (NeurIPS 2018), Montreal, Canada

Transmission spectroscopy during planetary transits is expected to be a major source of information on the atmospheres of small (approximately Earth-sized) exoplanets in the next two decades. This technique, however, is intrinsically affected by stellar spectral contamination caused by the fact that stellar photo- and chromospheres are not perfectly homogeneous. Such stellar contamination will often reach or exceed the signal introduced by the planetary spectral features. Finding effective methods to correct stellar contamination -- or at least to quantify its possible range -- for the most important exoplanets is a necessary step for our understanding of exoplanet atmospheres. This will require significantly deepening our understanding of stellar heterogeneity, which is currently limited by the available data., White paper submitted to the NAS Committee on Exoplanet Science Strategy

For the first time in human history, we will soon be able to apply the scientific method to the question "Are We Alone?" The rapid advance of exoplanet discovery, planetary systems science, and telescope technology will soon allow scientists to search for life beyond our Solar System through direct observation of extrasolar planets. This endeavor will occur alongside searches for habitable environments and signs of life within our Solar System. While the searches are thematically related and will inform each other, they will require separate observational techniques. The search for life on exoplanets holds potential through the great diversity of worlds to be explored beyond our Solar System. However, there are also unique challenges related to the relatively limited data this search will obtain on any individual world. This white paper reviews the scientific community's ability to use data from future telescopes to search for life on exoplanets. This material summarizes products from the Exoplanet Biosignatures Workshop Without Walls (EBWWW). The EBWWW was constituted by a series of online and in person activities, with participation from the international exoplanet and astrobiology communities, to assess state of the science and future research needs for the remote detection of life on planets outside our Solar System., This is a white paper that was submitted to the National Academies of Sciences Study: Astrobiology Science Strategy for the Search for Life in the Universe

The James Webb Space Telescope (JWST) presents the opportunity to transform our understanding of planets and the origins of life by revealing the atmospheric compositions, structures, and dynamics of transiting exoplanets in unprecedented detail. However, the high-precision, timeseries observations required for such investigations have unique technical challenges, and prior experience with Hubble, Spitzer, and other facilities indicates that there will be a steep learning curve when JWST becomes operational. In this paper, we describe the science objectives and detailed plans of the Transiting Exoplanet Community Early Release Science (ERS) Program, which is a recently approved program for JWST observations early in Cycle 1. We also describe the simulations used to establish the program. The goal of this project, for which the obtained data will have no exclusive access period, is to accelerate the acquisition and diffusion of technical expertise for transiting exoplanet observations with JWST, while also providing a compelling set of representative data sets that will enable immediate scientific breakthroughs. The Transiting Exoplanet Community ERS Program will exercise the timeseries modes of all four JWST instruments that have been identified as the consensus highest priorities, observe the full suite of transiting planet characterization geometries (transits, eclipses, and phase curves), and target planets with host stars that span an illustrative range of brightnesses. The observations in this program were defined through an inclusive and transparent process that had participation from JWST instrument experts and international leaders in transiting exoplanet studies. The targets have been vetted with previous measurements, will be observable early in the mission, and have exceptional scientific merit. Community engagement in the project will be centered on a twophase Data Challenge that culminates with the delivery of planetary spectra, timeseries instrument performance reports, and open-source data analysis toolkits in time to inform the agenda for Cycle 2 of the JWST mission.

When the Stratospheric Observatory for Infrared Astronomy (SOFIA) was conceived and its first science cases defined, exoplanets had not been detected. Later studies, however, showed that optical and near-infrared photometric and spectrophotometric follow-up observations during planetary transits and eclipses are feasible with SOFIA's instrumentation, in particular with the HIPO-FLITECAM and FPI+ optical and near infrared (NIR) instruments. Additionally, the airborne-based platform SOFIA has a number of unique advantages when compared to other ground- and space-based observatories in this field of research. Here we will outline these theoretical advantages, present some sample science cases and the results of two observations from SOFIA's first five observation cycles -- an observation of the Hot Jupiter HD 189733b with HIPO and an observation of the Super-Earth GJ 1214b with FLIPO and FPI+. Based on these early products available to this science case, we evaluate SOFIA's potential and future perspectives in the field of optical and infrared exoplanet spectrophotometry in the stratosphere., Comment: Invited review chapter, accepted for publication in "Handbook of Exoplanets" edited by H.J. Deeg and J.A. Belmonte, Springer Reference Works

Here we report on the first successful exoplanet transit observation with the Stratospheric Observatory for Infrared Astronomy (SOFIA). We observed a single transit of the hot Jupiter HD 189733 b, obtaining two simultaneous primary transit lightcurves in the B and z' bands as a demonstration of SOFIA's capability to perform absolute transit photometry. We present a detailed description of our data reduction, in particular the correlation of photometric systematics with various in-flight parameters unique to the airborne observing environment. The derived transit depths at B and z' wavelengths confirm a previously reported slope in the optical transmission spectrum of HD 189733 b. Our results give new insights to the current discussion about the source of this Rayleigh scattering in the upper atmosphere and the question of fixed limb darkening coefficients in fitting routines., 40 pages, 7 figures, accepted for publication in JATIS

The Hubble Space Telescope has recently emerged as the first telescope to detect molecular signatures in an exoplanet via infrared spectroscopy. Molecular spectroscopy of exoplanets is demanding and requires an accurate determination and removal of the instrument systematics. Here we report on our effort to extract accurate exoplanet spectra from NICMOS spectrophotometry. We developed a standardized and highly automated pipeline to remove instrument systematics based on our previous results. We tested the pipeline and find excellent agreement with observation specific implementations. The process of decorrelating instrument parameters from the measured time series is well understood, stable and guarantees reproducible results.

This thesis deals with techniques and results of observations of exoplanets from several platforms. In this work I present and then attempt solutions to particular issues and problems connected to ground- and space-based approaches to spectroscopic characterization of extrasolar planets. Furthermore, I present the future prospects of the airborne observatory, SOFIA, in this field of astronomy. The first part of this thesis covers results of an exploratory study to use near-infrared integral-field-spectroscopy to observe transiting extrasolar planets. I demonstrate how adaptive-optics assisted integral field spectroscopy compares with other spectroscopic techniques currently applied, foremost being slit spectroscopy. An advanced reduction method using elements of a spectral-differential decorrelation and optimized observation strategies is discussed. This concept was tested with K-Band time series observations of secondary eclipses of HD 209458b and HD 189733b obtained with the SINFONI at the Very Large Telescope (VLT), at spectral resolution of R~3000. In ground-based near infrared (NIR) observations, there is considerable likelihood of confusion between telluric absorption features and spectral features in the targeted object. I describe a detailed method that can cope with such confusion by a forward modelling approach employing Earth transmission models. In space-based transit spectroscopy with Hubble's NICMOS instrument, the main source of systematic noise is the perturbation in the instrument's configuration due to the near Earth orbital motion of the spacecraft. I present an extension to a pre-existing data analysis sequence that has allowed me to extract a NIR transmission spectrum of the hot-Neptune class planet GJ 436b from a data set that was highly corrupted by the above mentioned effects. Satisfyingly, I was able to obtain statistical consistency in spectra (acquired over a broad wavelength grid) over two distinct observing visits by HST. Earlier reductions were unable to achieve this feat. This work shows that systematic effecting the spectrophotometric light-curves in HST can be removed to levels needed to observe features in the relatively small scale-height atmospheres of hot Neptune class planets orbiting nearby stars. In the third and final part of this thesis, I develop and discuss possible science cases for the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) in the field of detection and characterization of extrasolar planets. The principle advantages of SOFIA and its suite of instrumentation is illustrated and possible targets are introduced. Possible next generation instrumentation (dedicated to exoplanetary science) is discussed., In der hier vorgelegten Dissertation beschreibe ich zunächst die spezifischen Probleme und ihre möglichen Lösungen im Bereich der boden- und weltraum-gebundenen spektroskopischen Charakterisierung von extrasolaren Planeten. Weiterhin werden zukünftige Perspektiven mit dem Flugzeugteleskop SOFIA in diesem Feld präsentiert. Der boden-gebundene Teil dieser Dissertation beschreibt Ergebnisse einer Beispielstudie zur Anwendung abbildender Spektrographen in der Charakterisierung extrasolarer Planeten. Hier vergleiche ich die Kombination aus adaptiver Optik und abbildender Spektroskopie mit anderen spektroskopischen Methoden, insbesondere der Spalt-Spektroskopie. In diesem Teil diskutiere ich eine fortgeschrittene Methode der Datenreduktion, die Elemente einer spektral-differentiellen Dekorrelation enthält, und erarbeite eine optimale Beobachtungsstrategie. Das hier präsentierte Konzept wurde an K-Band Zeitserien-Beobachtungen eines sekund\ären Transits der Planeten HD 209458b und HD 189733b getestet. Diese Beobachtung wurden mit dem SINFONI Instrument am Very Large Telescope der ESO (VLT) bei einer spektralen Auflösung von R~3000 durchgeführt. Für boden-gebundene Nahinfrarot-Beobachtungen ist das zentrale Problem die Absorption tellurischer Spurengase wie Wasser oder Methan, die auch in den beobachteten Planeten vermutet werden. In dieser Dissertation beschreibe ich eine Methode zur Lösung dieses Problems, unter anderem durch die Anwendung von Transmissionsmodellen der Erdatmosphäre. Bei weltraum-gebundenen Beobachtungen der gleichen Art mit dem NICMOS-Instrument des Hubble Weltraumteleskopes ist die Hauptquelle systematischen Rauschens die Störungen in der Instrument-Konfiguration, die durch die Bewegung des Satelliten-Teleskopes durch den erdnahen Orbit hervorgerufen werden. Hier präsentiere ich eine Erweiterung der bestehenden Datenreduktions-Sequenz. Diese Methode konnte aus einem Datensatz, der hochgradig von diesen Effekten gestört ist, ein Nahinfrarot-Spektum des 'heissen Neptun' Planet GJ~436b extrahieren. Im Ergebnis war es mir möglich, ein statistisch konsistentes Spektrum für zwei unabhängig beobachtete Bedeckungen zu berechnen. Diese Arbeit zeigt, dass systematische Effekte in spektro-photometrischen Lichtkurven des Hubble Weltraumteleskops bis auf Niveaus korrigiert werden können, die es ermöglichen, selbst die Atmosphären heisser Neptun Planeten mit relativ kleinen Äquivalenthöhen zu charakterisieren. Im dritten und letzten Teil der Arbeit entwickle und diskutiere ich zukünftige Einsatzmöglichkeiten des Flugzeugteleskops SOFIA (Stratosphären Observatorium für Infrarot Astronomie) im Bereich der Detektion und Charakterisierung extrasolarer Planeten. Generelle Vorteile von SOFIA und ihrer Instrumentierung werden dargestellt und mögliche Beobachtungs-Projekte vorgestellt. Zuletzt werden mögliche, auf die Charakterisierung von Exoplaneten spezialisierte Instrumente der zweiten Generation diskutiert.

This thesis deals with techniques and results of observations of exoplanets from several platforms. In this work I present and then attempt solutions to particular issues and problems connected to ground- and space-based approaches to spectroscopic characterization of extrasolar planets. Furthermore, I present the future prospects of the airborne observatory, SOFIA, in this field of astronomy. The first part of this thesis covers results of an exploratory study to use near-infrared integral-field-spectroscopy to observe transiting extrasolar planets. I demonstrate how adaptive-optics assisted integral field spectroscopy compares with other spectroscopic techniques currently applied, foremost being slit spectroscopy. An advanced reduction method using elements of a spectral-differential decorrelation and optimized observation strategies is discussed. This concept was tested with K-Band time series observations of secondary eclipses of HD 209458b and HD 189733b obtained with the SINFONI at the Very Large Telescope (VLT), at spectral resolution of R~3000. In ground-based near infrared (NIR) observations, there is considerable likelihood of confusion between telluric absorption features and spectral features in the targeted object. I describe a detailed method that can cope with such confusion by a forward modelling approach employing Earth transmission models. In space-based transit spectroscopy with Hubble's NICMOS instrument, the main source of systematic noise is the perturbation in the instrument's configuration due to the near Earth orbital motion of the spacecraft. I present an extension to a pre-existing data analysis sequence that has allowed me to extract a NIR transmission spectrum of the hot-Neptune class planet GJ 436b from a data set that was highly corrupted by the above mentioned effects. Satisfyingly, I was able to obtain statistical consistency in spectra (acquired over a broad wavelength grid) over two distinct observing visits by HST. Earlier reductions were unable to achieve this feat. This work shows that systematic effecting the spectrophotometric light-curves in HST can be removed to levels needed to observe features in the relatively small scale-height atmospheres of hot Neptune class planets orbiting nearby stars. In the third and final part of this thesis, I develop and discuss possible science cases for the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) in the field of detection and characterization of extrasolar planets. The principle advantages of SOFIA and its suite of instrumentation is illustrated and possible targets are introduced. Possible next generation instrumentation (dedicated to exoplanetary science) is discussed., In der hier vorgelegten Dissertation beschreibe ich zunächst die spezifischen Probleme und ihre möglichen Lösungen im Bereich der boden- und weltraum-gebundenen spektroskopischen Charakterisierung von extrasolaren Planeten. Weiterhin werden zukünftige Perspektiven mit dem Flugzeugteleskop SOFIA in diesem Feld präsentiert. Der boden-gebundene Teil dieser Dissertation beschreibt Ergebnisse einer Beispielstudie zur Anwendung abbildender Spektrographen in der Charakterisierung extrasolarer Planeten. Hier vergleiche ich die Kombination aus adaptiver Optik und abbildender Spektroskopie mit anderen spektroskopischen Methoden, insbesondere der Spalt-Spektroskopie. In diesem Teil diskutiere ich eine fortgeschrittene Methode der Datenreduktion, die Elemente einer spektral-differentiellen Dekorrelation enthält, und erarbeite eine optimale Beobachtungsstrategie. Das hier präsentierte Konzept wurde an K-Band Zeitserien-Beobachtungen eines sekund\ären Transits der Planeten HD 209458b und HD 189733b getestet. Diese Beobachtung wurden mit dem SINFONI Instrument am Very Large Telescope der ESO (VLT) bei einer spektralen Auflösung von R~3000 durchgeführt. Für boden-gebundene Nahinfrarot-Beobachtungen ist das zentrale Problem die Absorption tellurischer Spurengase wie Wasser oder Methan, die auch in den beobachteten Planeten vermutet werden. In dieser Dissertation beschreibe ich eine Methode zur Lösung dieses Problems, unter anderem durch die Anwendung von Transmissionsmodellen der Erdatmosphäre. Bei weltraum-gebundenen Beobachtungen der gleichen Art mit dem NICMOS-Instrument des Hubble Weltraumteleskopes ist die Hauptquelle systematischen Rauschens die Störungen in der Instrument-Konfiguration, die durch die Bewegung des Satelliten-Teleskopes durch den erdnahen Orbit hervorgerufen werden. Hier präsentiere ich eine Erweiterung der bestehenden Datenreduktions-Sequenz. Diese Methode konnte aus einem Datensatz, der hochgradig von diesen Effekten gestört ist, ein Nahinfrarot-Spektum des 'heissen Neptun' Planet GJ~436b extrahieren. Im Ergebnis war es mir möglich, ein statistisch konsistentes Spektrum für zwei unabhängig beobachtete Bedeckungen zu berechnen. Diese Arbeit zeigt, dass systematische Effekte in spektro-photometrischen Lichtkurven des Hubble Weltraumteleskops bis auf Niveaus korrigiert werden können, die es ermöglichen, selbst die Atmosphären heisser Neptun Planeten mit relativ kleinen Äquivalenthöhen zu charakterisieren. Im dritten und letzten Teil der Arbeit entwickle und diskutiere ich zukünftige Einsatzmöglichkeiten des Flugzeugteleskops SOFIA (Stratosphären Observatorium für Infrarot Astronomie) im Bereich der Detektion und Charakterisierung extrasolarer Planeten. Generelle Vorteile von SOFIA und ihrer Instrumentierung werden dargestellt und mögliche Beobachtungs-Projekte vorgestellt. Zuletzt werden mögliche, auf die Charakterisierung von Exoplaneten spezialisierte Instrumente der zweiten Generation diskutiert.

The James Webb Space Telescope will revolutionize transiting exoplanet atmospheric science due to its capability for continuous, long-duration observations and its larger collecting area, spectral coverage, and spectral resolution compared to existing space-based facilities. However, it is unclear precisely how well JWST will perform and which of its myriad instruments and observing modes will be best suited for transiting exoplanet studies. In this article, we describe a prefatory JWST Early Release Science (ERS) program that focuses on testing specific observing modes to quickly give the community the data and experience it needs to plan more efficient and successful future transiting exoplanet characterization programs. We propose a multi-pronged approach wherein one aspect of the program focuses on observing transits of a single target with all of the recommended observing modes to identify and understand potential systematics, compare transmission spectra at overlapping and neighboring wavelength regions, confirm throughputs, and determine overall performances. In our search for transiting exoplanets that are well suited to achieving these goals, we identify 12 objects (dubbed "community targets") that meet our defined criteria. Currently, the most favorable target is WASP-62b because of its large predicted signal size, relatively bright host star, and location in JWST's continuous viewing zone. Since most of the community targets do not have well-characterized atmospheres, we recommend initiating preparatory observing programs to determine the presence of obscuring clouds/hazes within their atmospheres. Measurable spectroscopic features are needed to establish the optimal resolution and wavelength regions for exoplanet characterization. Other initiatives from our proposed ERS program include testing the instrument brightness limits and performing phase-curve observations.

We present near-infrared high-precision photometry for eight transiting hot Jupiters observed during their predicted secondary eclipses. Our observations were carried out using the staring mode of the WIRCam instrument on the Canada-France-Hawaii Telescope (CFHT). We present the observing strategies and data reduction methods which delivered time series photometry with statistical photometric precision as low as 0.11 per cent. We performed a Bayesian analysis to model the eclipse parameters and systematics simultaneously. The measured planet-to-star flux ratios allowed us to constrain the thermal emission from the day side of these hot Jupiters, as we derived the planet brightness temperatures. Our results combined with previously observed eclipses reveal an excess in the brightness temperatures relative to the blackbody prediction for the equilibrium temperatures of the planets for a wide range of heat redistribution factors. We find a trend that this excess appears to be larger for planets with lower equilibrium temperatures. This may imply some additional sources of radiation, such as reflected light from the host star and/or thermal emission from residual internal heat from the formation of the planet.

One of the long-term goals of exoplanet science is the atmospheric characterization of dozens of small exoplanets in order to understand their diversity and search for habitable worlds and potential biosignatures. Achieving this goal requires a space mission of sufficient scale. We seek to quantify the exoplanet detection performance of a space-based mid-infrared nulling interferometer that measures the thermal emission of exoplanets. For this, we have developed an instrument simulator that considers all major astrophysical noise sources and coupled it with Monte Carlo simulations of a synthetic exoplanet population around main-sequence stars within 20 pc. This allows us to quantify the number (and types) of exoplanets that our mission concept could detect over a certain time period. Two different scenarios to distribute the observing time among the stellar targets are discussed and different apertures sizes and wavelength ranges are considered. Within a 2.5-year initial search phase, an interferometer consisting of four 2 m apertures covering a wavelength range between 4 and 18.5 μm could detect up to ~550 exoplanets with radii between 0.5 and 6 R⊕ with an integrated SNR≥7. At least ~160 of the detected exoplanets have radii ≤1.5 R⊕. Depending on the observing scenario, ~25-45 rocky exoplanets (objects with radii between 0.5 and 1.5 ⊕) orbiting within the empirical habitable zone (eHZ) of their host stars are among the detections. With four times 3.5 m aperture size, the total number of detections can increase to up to ~770, including ~60-80 rocky, eHZ planets. With four times 1 m aperture size, the maximum detection yield is ~315 exoplanets, including ≤20 rocky, eHZ planets. In terms of predicted detection yield, such a mission can compete with large single-aperture reflected light missions., arXiv