TrExoLiSTS: Transiting Exoplanets List of Space Telescope Spectroscopy
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Abstract We present the Space Telescope Science Institute Wide Field Camera 3 (WFC3) project webpage, Transiting Exoplanets List of Space Telescope Spectroscopy, TrExoLiSTS. It tabulates existing observations of transiting exoplanet atmospheres, available in the MAST archive made with Hubble Space Telescope (HST) WFC3 using the stare or spatial scan mode. A parallel page is available for all instruments aboard James Webb Space Telescope (JWST) using the spectral Time Series Observation mode. The webpages include observations obtained during primary transits, secondary eclipses and phase curves. TREXOLISTS facilitates proposal preparation for programs that are highly complementary to existing programs in terms of targets, wavelength coverage, as well as reduces duplication and redundant effort. Reference for the quality of the HST WFC3 visits taken more than 1.5 yr ago are made available via including diagrams of the direct image, white light curve and drift of the spectral time series across the detector. Future improvements to the webpage will include: Expanding program query to other HST instruments and reference for the quality of JWST visits.Keywords:
Spitzer Space Telescope
Abstract A number of transiting, potentially habitable Earth-sized exoplanets have recently been detected around several nearby M dwarf stars. These worlds represent important targets for atmospheric characterization for the upcoming NASA James Webb Space Telescope (JWST). Given that available time for exoplanet characterization will be limited, it is critically important to first understand the capabilities and limitations of JWST when attempting to detect atmospheric constituents for potentially Earth-like worlds orbiting cool stars. Here, we explore coupled climate-chemistry atmospheric models for Earth-like planets orbiting a grid of M dwarf hosts. Using a newly-developed and validated JWST instrument model—the JWST Exoplanet Transit Simulator—we investigate the detectability of key biosignature and habitability indicator gaseous species for a variety of relevant instruments and observing modes. Spectrally resolved detection scenarios as well as cases where the spectral impact of a given species is integrated across the entire range of an instrument/mode are considered and serve to highlight the importance of considering information gained over an entire observable spectral range. Our results indicate that detectability of gases at individual wavelengths is overly challenging for JWST but integrating the spectral impact of a species across the entire wavelength range of an instrument/mode significantly improves requisite detection times. When considering the entire spectral coverage of an instrument/mode, detections of methane, carbon dioxide, oxygen and water at signal-to-noise ratio 5 could be achieved with observations of several tens of transits (or less) for cloud-free Earth-like worlds orbiting mid- to late-type M dwarfs at system distances of up to 10–15 pc. When compared to previous results, requisite exposure times for gas species detection depend on approaches to quantifying the spectral impact of the species as well as underlying photochemical model assumptions. Thus, constraints on atmospheric abundances, even if just upper limits, by JWST have the potential to further our understanding of terrestrial atmospheric chemistry.
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The James Webb Space Telescope (JWST) will devote significant observing time to the study of exoplanets. It will not be serviceable as was the Hubble Space Telescope, and therefore the spacecraft/instruments will have a relatively limited life. It is important to get as much science as possible out of this limited observing time. We provide an analysis framework (including publicly released computational tools) that can be used to optimize lists of exoplanet targets for atmospheric characterization. Our tools take catalogs of planet detections, either simulated, or actual; categorize the targets by planet radius and equilibrium temperature; estimate planet masses; generate model spectra and simulated instrument spectra; perform a statistical analysis to determine if the instrument spectra can confirm an atmospheric detection; and finally, rank the targets within each category by observation time required. For a catalog of simulated Transiting Exoplanet Survey Satellite planet detections, we determine an optimal target ranking for the observing time available. Our results are generally consistent with other recent studies of JWST exoplanet target optimization. We show that assumptions about target planet atmospheric metallicity, instrument performance (especially the noise floor), and statistical detection threshold, can have a significant effect on target ranking. Over its full 10 yr (fuel-limited) mission, JWST has the potential to increase the number of atmospheres characterized by transmission spectroscopy by an order of magnitude (from about 50 currently to between 400 and 500).
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The James Webb Space Telescope (JWST) will likely revolutionize transiting exoplanet atmospheric science, due to a combination of 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) Cycle 1 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 transiting exoplanet characterization programs in later cycles. 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. The latter are a unique challenge compared to transit observations because of their significantly longer durations. Using only a single mode, we propose to observe a full-orbit phase curve of one of the previously characterized, short-orbital-period planets to evaluate the facility-level aspects of long, uninterrupted time-series observations.
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In this white paper, we assess the potential for JWST to characterize the atmospheres of super-Earth exoplanets, by simulating a range of transiting spectra with different masses and temperatures. Our results are based on a JWST simulator tuned to the expected performance of the workhorse spectroscopic instrument NIRSpec, and is based on the latest exoplanet transit models by Howe & Burrows (2012). This study is especially timely since the observing modes for the science instruments on JWST are finalized (Clampin 2010) and because NASA has selected the TESS mission as an upcoming Explorer. TESS is expected to identify more than 1000 transiting exoplanet candidates, including a sample of about 100 nearby (<50 pc) super- Earths (Ricker et al. 2010).
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The Mid-Infrared instrument (MIRI) on board the James Webb Space Telescope will perform the first ever characterization of young giant exoplanets observed by direct imaging in the 5-28 microns spectral range. This wavelength range is key for both determining the bolometric luminosity of the cool known exoplanets and for accessing the strongest ammonia bands. In conjunction with shorter wavelength observations, MIRI will enable a more accurate characterization of the exoplanetary atmospheric properties. Here we consider a subsample of the currently known exoplanets detected by direct imaging and we discuss their detectability with MIRI, either using the coronagraphic or the spectroscopic modes. By using the Exo-REM atmosphere model we calculate the mid-infrared emission spectra of fourteen exoplanets, and we simulate MIRI coronagraphic or spectroscopic observations. Specifically we analyze four coronagraphic observational setups, which depend on (i) the target-star and reference-star offset (0, 3, 14 mas), (ii) the wave-front-error (130, 204 nm rms), (iii) the telescope jitter amplitude (1.6, 7 mas). We then determine the signal-to-noise and integration time values for the coronagraphic targets whose planet-to-star contrasts range from 3.9 to 10.1 mag. We conclude that all the MIRI targets should be observable with different degrees of difficulty, which depends on the final in-flight instrument performances. Furthermore, we test for detection of ammonia in the atmosphere of the coolest targets. Finally, we present the case of HR 8799 b to discuss what MIRI observations can bring to the knowledge of a planetary atmosphere, either alone or in combination with shorter wavelength observations.
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This article summarizes a workshop held on March, 2014, on the potential of the James Webb Space Telescope (JWST) to revolutionize our knowledge of the physical properties of exoplanets through transit observations. JWST's unique combination of high sensitivity and broad wavelength coverage will enable the accurate measurement of transits with high signal-to-noise ratio (S/N). Most importantly, JWST spectroscopy will investigate planetary atmospheres to determine atomic and molecular compositions, to probe vertical and horizontal structure, and to follow dynamical evolution, i.e., exoplanet weather. JWST will sample a diverse population of planets of varying masses and densities in a wide variety of environments characterized by a range of host star masses and metallicities, orbital semi-major axes, and eccentricities. A broad program of exoplanet science could use a substantial fraction of the overall JWST mission.
Spitzer Space Telescope
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The James Webb Space Telescope (JWST), with its unprecedented sensitivity, will provide a unique set of tools for the study of transiting exoplanets and their atmospheres. The Near Infrared Spectrograph (NIRSpec) is one of four scientific instruments on JWST and offers a high-contrast aperture-spectroscopy mode developed specifically for exoplanet observations. Here we present the NIRSpec Exoplanet Exposure Time Calculator (NEETC) software, an exposure time calculator optimized to evaluate the signal-to-noise ratio and simulate spectra for observations of transiting exoplanets. The NEETC is being developed to help the NIRSpec instrument team, and ultimately future JWST users, to fully investigate NIRSpec's observation modes and the feasibility of exoplanet observations. We give examples of how the NEETC can be used to prepare observations, and present results highlighting the capabilities and limitations of NIRSpec.
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<p>In the last 15 years, significant progress has been made in the field of atmospheric characterisation of exoplanets, utilising the most advanced instruments both on the ground and in space. Today, we are entering an era of very exiting prospects for the field of exoplanet characterisation. The James Webb Space Telescope (JWST) has been successfully launched, deployed and aligned, while ESA&#8217;s M4 mission, Ariel, has been adopted and is planned to fly in 2029.</p> <p>This era will be characterised by the large volume of data that will be delivered from the new observatories. In my talk I will discuss the challenges we have to face in order to analyse the large data volume expected in the next decade. I will discuss the lessons learnt in the past years using the Wide Field Camera 3 on HST - the most successful instrument for exoplanet characterisation - and I will present a next-generation pipeline for the analysis of exoplanet spectroscopic observations, together with the first implementation on JWST data.</p>
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The James Webb Space Telescope (JWST) will revolutionize our understanding of exoplanets with transit spectroscopy of a wide range of mature planets close to their host stars ($$10 AU). The census of exoplanets has revealed an enormous variety of planets orbiting stars of all ages and spectral types. With TESS adding to this census with its all-sky survey of the closest, brightest stars, the challenge of the coming decade will be to move from demography to physical characterization. This white paper discusses the wide variety of exoplanet opportunities enabled by JWST's sensitivity and stability, its high angular resolution, and its suite of powerful instruments. JWST observations will advance our understanding of the atmospheres of young to mature planets and will provide new insights into planet formation.
White paper
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In this white paper, we assess the potential for JWST to characterize the atmospheres of super-Earth exoplanets, by simulating a range of transiting spectra with different masses and temperatures. Our results are based on a JWST simulator tuned to the expected performance of the workhorse spectroscopic instrument NIRSpec, and is based on the latest exoplanet transit models by Howe & Burrows (2012). This study is especially timely since the observing modes for the science instruments on JWST are finalized (Clampin 2010) and because NASA has selected the TESS mission as an upcoming Explorer. TESS is expected to identify more than 1000 transiting exoplanet candidates, including a sample of about 100 nearby (<50 pc) super- Earths (Ricker et al. 2010).
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