arXiv subjects

Marcell Tessenyi

Publications and source records attributed to Marcell Tessenyi.

13 recordsLinked to original sources

arXiv2026

Atmospheric Characterisation with the Twinkle Space Telescope Following Advances from JWST Observations

The Twinkle Space Telescope is a satellite designed for spectroscopic observations of a wide range of extrasolar and solar system objects. Equipped with a 0.45 m diameter telescope and a spectrometer covering from 0.5 to 4.5 μm simultaneously, Twinkle will be launched in a sun-synchronous, low-Earth orbit, and it is expected to operate for seven years. Twinkle is developed, managed and operated by Blue Skies Space (BSSL), a space science data company whose vision is to accelerate and expand the availability of new, high-quality datasets to researchers worldwide, complementing the space-observatories delivered by government space agencies. Over its life-time, Twinkle will conduct large-scale survey programs. The scientific objectives and observational strategy of these surveys are defined by researchers who join the Science Team. Leveraging advances made possible by recent observations with the James Webb Space Telescope, we present here updated simulations evaluating Twinkle's observational capabilities in the context of exoplanet atmospheres. Through retrieval analyses of HD 209458 b, WASP-107 b, GJ 3470 b, and 55 Cnc e, we demonstrate how increasing observational investment enhances the retrieval of atmospheric parameters and molecular abundances. Our sensitivity study highlights Twinkle's capability to detect less abundant/detectable molecules depending on the observing strategies adopted. This work provides practical guidance for developing targeted observational strategies to maximize Twinkle's scientific return.

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arXiv2026

The Preliminary Mauve Science Programme: Science themes identified for the first year of operations

Mauve is a low-cost small satellite developed and operated by Blue Skies Space Ltd. The payload features a 13 cm telescope connected with a fibre that feeds into a UV-Vis spectrometer. The detector covers the 200-700 nm range in a single shot, obtaining low resolution spectra at R~20-65. Mauve has launched on 28th November 2025, reaching a 510 km Low-Earth Sun-synchronous orbit. The satellite will enable UV and visible observations of a variety of stellar objects in our Galaxy, filling the gaps in the ultraviolet space-based data. The researchers that have already joined the mission have defined the science themes, observational strategy and targets that Mauve will observe in the first year of operations. To date 10 science themes have been developed by the Mauve science collaboration for year 1, with observational strategies that include both long duration monitoring and short cadence snapshots. Here, we describe these themes and the science that Mauve will undertake in its first year of operations.

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arXiv2025

MauveSim: the instrument simulator software for the Blue Skies Space Mauve satellite

We present MauveSim, the instrument simulator software for Mauve, the latest mission from Blue Skies Space dedicated to time-domain stellar astronomy. MauveSim functions as an end-to-end simulator, employing the most up-to-date knowledge of the instrument's performance and characteristics that will be reviewed and updated after commissioning. The software accepts a stellar spectrum - either observed or synthetic - as input and produces a simulated observation. The tool thus enables the assessment of various scientific objectives, as well as determining limiting magnitudes and conducting signal-to-noise (S/N) analyses. The results of MauveSim have been validated against instrument performance data from extensive ground testing campaigns, ensuring that the software reflects the most up-to-date understanding of the payload performance. Accessible to all scientists involved in the mission, MauveSim serves as a crucial tool for target selection and observation planning.

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arXiv2022

Twinkle -- a small satellite spectroscopy mission for the next phase of exoplanet science

With a focus on off-the-shelf components, Twinkle is the first in a series of cost competitive small satellites managed and financed by Blue Skies Space Ltd. The satellite is based on a high-heritage Airbus platform that will carry a 0.45 m telescope and a spectrometer which will provide simultaneous wavelength coverage from 0.5-4.5 $\rm{μm}$. The spacecraft prime is Airbus Stevenage while the telescope is being developed by Airbus Toulouse and the spectrometer by ABB Canada. Scheduled to begin scientific operations in 2025, Twinkle will sit in a thermally-stable, sun-synchronous, low-Earth orbit. The mission has a designed operation lifetime of at least seven years and, during the first three years of operation, will conduct two large-scale survey programmes: one focused on Solar System objects and the other dedicated to extrasolar targets. Here we present an overview of the architecture of the mission, refinements in the design approach, and some of the key science themes of the extrasolar survey.

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arXiv2022

Original Research By Young Twinkle Students (ORBYTS): Ephemeris Refinement of Transiting Exoplanets III

We report photometric follow-up observations of thirteen exoplanets (HATS-1 b, HATS2 b, HATS-3 b, HAT-P-18 b, HAT-P-27 b, HAT-P-30 b, HAT-P-55 b, KELT-4A b, WASP-25 b, WASP-42 b, WASP-57 b, WASP-61 b and WASP-123 b), as part of the Original Research By Young Twinkle Students (ORBYTS) programme. All these planets are potentially viable targets for atmospheric characterisation and our data, which were taken using the LCOGT network of ground-based telescopes, will be combined with observations from other users of ExoClock to ensure that the transit times of these planets continue to be well-known, far into the future.

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arXiv2020

Original Research By Young Twinkle Students (ORBYTS): Ephemeris Refinement of Transiting Exoplanets

We report follow-up observations of transiting exoplanets that have either large uncertainties (>10 minutes) in their transit times or have not been observed for over three years. A fully robotic ground-based telescope network, observations from citizen astronomers and data from TESS have been used to study eight planets, refining their ephemeris and orbital data. Such follow-up observations are key for ensuring accurate transit times for upcoming ground and space-based telescopes which may seek to characterise the atmospheres of these planets. We find deviations from the expected transit time for all planets, with transits occurring outside the 1 sigma uncertainties for seven planets. Using the newly acquired observations, we subsequently refine their periods and reduce the current predicted ephemeris uncertainties to 0.28 - 4.01 minutes. A significant portion of this work has been completed by students at two high schools in London as part of the Original Research By Young Twinkle Students (ORBYTS) programme.

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arXiv2019

Small Bodies Science with Twinkle

Twinkle is an upcoming 0.45m space-based telescope equipped with a visible and two near-infrared spectrometers covering the spectral range 0.4 to 4.5μm with a resolving power R~250 (λ<2.42μm) and R~60 (λ>2.42μm). We explore Twinkle's capabilities for small bodies science and find that, given Twinkle's sensitivity, pointing stability, and spectral range, the mission can observe a large number of small bodies. The sensitivity of Twinkle is calculated and compared to the flux from an object of a given visible magnitude. The number, and brightness, of asteroids and comets that enter Twinkle's field of regard is studied over three time periods of up to a decade. We find that, over a decade, several thousand asteroids enter Twinkle's field of regard with a brightness and non-sidereal rate that will allow Twinkle to characterise them at the instrumentation's native resolution with SNR > 100. Hundreds of comets can also be observed. Therefore, Twinkle offers researchers the opportunity to contribute significantly to the field of Solar System small bodies research.

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arXiv2019

Remote-sensing Characterisation of Major Solar System Bodies with the Twinkle Space Telescope

Remote-sensing observations of Solar System objects with a space telescope offer a key method of understanding celestial bodies and contributing to planetary formation and evolution theories. The capabilities of Twinkle, a space telescope in a low Earth orbit with a 0.45m mirror, to acquire spectroscopic data of Solar System targets in the visible and infrared are assessed. Twinkle is a general observatory that provides on demand observations of a wide variety of targets within wavelength ranges that are currently not accessible using other space telescopes or that are accessible only to oversubscribed observatories in the short-term future. We determine the periods for which numerous Solar System objects could be observed and find that Solar System objects are regularly observable. The photon flux of major bodies is determined for comparison to the sensitivity and saturation limits of Twinkle's instrumentation and we find that the satellite's capability varies across the three spectral bands (0.4-1, 1.3-2.42, and 2.42-4.5μm). We find that for a number of targets, including the outer planets, their large moons, and bright asteroids, the model created predicts that with short exposure times, high-resolution spectra (R~250, λ < 2.42μm; R~60, λ > 2.42μm) could be obtained with signal-to-noise ratio (SNR) of >100 with exposure times of <300s.

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arXiv2018

Exoplanet Spectroscopy and Photometry with the Twinkle Space Telescope

The Twinkle space telescope has been designed for the characterisation of exoplanets and Solar System objects. Operating in a low Earth, Sun-synchronous orbit, Twinkle is equipped with a 45 cm telescope and visible (0.4 - 1um) and infrared (1.3 - 4.5um) spectrometers which can be operated simultaneously. Twinkle is a general observatory which will provide on-demand observations of a wide variety of targets within wavelength ranges that are currently not accessible using other space telescopes or accessible only to oversubscribed observatories in the short-term future. Here we explore the ability of Twinkle's spectrometers to characterise the currently-known exoplanets. We study the spectral resolution achievable by combining multiple observations for various planetary and stellar types. We also simulate spectral retrievals for some well-known planets (HD 209458 b, GJ 3470 b and 55 Cnc e). From the exoplanets known today, we find that with a single transit or eclipse, Twinkle could probe 89 planets at low spectral resolution (R < 20) as well as 12 planets at higher resolution (R > 20) in channel 1 (1.3 - 4.5um). With 10 observations, the atmospheres of 144 planets could be characterised with R < 20 and 81 at higher resolutions. Upcoming surveys will reveal thousands of new exoplanets, many of which will be located within Twinkle's field of regard. TESS in particular is predicted to discover many targets around bright stars which will be suitable for follow-up observations. We include these anticipated planets and find that the number of planets Twinkle could observe in the near infrared in a single transit or eclipse increases to 558 for R > 20 and 41 at lower resolutions. By stacking 10 transits or eclipses, there are 1185 potential targets for study at R < 20 as well as 388 planets at higher resolutions.

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arXiv2015

Generation of an optimal target list for the Exoplanet Characterisation Observatory (EChO)

The Exoplanet Characterisation Observatory (EChO) has been studied as a space mission concept by the European Space Agency in the context of the M3 selection process. Through direct measurement of the atmospheric chemical composition of hundreds of exoplanets, EChO would address fundamental questions such as: What are exoplanets made of? How do planets form and evolve? What is the origin of exoplanet diversity? More specifically, EChO is a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planetary sample within its four to six year mission lifetime. In this paper we use the end-to-end instrument simulator EChOSim to model the currently discovered targets, to gauge which targets are observable and assess the EChO performances obtainable for each observing tier and time. We show that EChO would be capable of observing over 170 relativity diverse planets if it were launched today, and the wealth of optimal targets for EChO expected to be discovered in the next 10 years by space and ground-based facilities is simply overwhelming. In addition, we build on previous molecular detectability studies to show what molecules and abundances will be detectable by EChO for a selection of real targets with various molecular compositions and abundances. EChO's unique contribution to exoplanetary science will be in identifying the main constituents of hundreds of exoplanets in various mass/temperature regimes, meaning that we will be looking no longer at individual cases but at populations. Such a universal view is critical if we truly want to understand the processes of planet formation and evolution in various environments. In this paper we present a selection of key results. The full results are available online (http://www.ucl.ac.uk/exoplanets/echotargetlist/).

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arXiv2014

Influence of different parameters on the chemical composition of warm neptunes

We developed a 1D photo-thermochemical model to study the atmosphere of warm exoplanets. The chemical scheme used in this model is completely new in planetology and has been constructed in collaboration with specialists of combustion. It has been validated as a whole through experiments on a large range of temperature (300 - 2500 K) and pressure (1 mbar - 100 bar), allowing to study a wide variety of exoplanets. We have used this chemical model to study the atmosphere of two warm Neptunes, GJ3470b and GJ436b, and the influence of different parameters (vertical mixing, metallicity, temperature, . . . ) on their chemical composition. We present here the results obtained in these studies.

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arXiv2013

The atmospheric chemistry of the warm Neptune GJ 3470b: influence of metallicity and temperature on the CH4/CO ratio

Current observation techniques are able to probe the atmosphere of some giant exoplanets and get some clues about their atmospheric composition. However, the chemical compositions derived from observations are not fully understood, as for instance in the case of the CH4/CO abundance ratio, which is often inferred different from what has been predicted by chemical models. Recently, the warm Neptune GJ3470b has been discovered and because of its close distance from us and high transit depth, it is a very promising candidate for follow up characterisation of its atmosphere. We study the atmospheric composition of GJ3470b in order to compare with the current observations of this planet, to prepare the future ones, but also as a typical case study to understand the chemical composition of warm (sub-)Neptunes. The metallicity of such atmospheres is totally uncertain, and vary probably to values up to 100x solar. We explore the space of unknown parameters to predict the range of possible atmospheric compositions. Within the parameter space explored we find that in most cases methane is the major carbon-bearing species. We however find that in some cases, typically for high metallicities with a sufficiently high temperature the CH4/CO abundance ratio can become lower than unity, as suggested by some multiwavelength photometric observations of other warm (sub-)Neptunes, such as GJ1214b and GJ436b. As for the emission spectrum of GJ3470b, brightness temperatures at infrared wavelengths may vary between 400 and 800K depending on the thermal profile and metallicity. Combined with a hot temperature profile, a substantial enrichment in heavy elements by a factor of 100 with respect to the solar composition can shift the carbon balance in favour of carbon monoxide at the expense of CH4. Nevertheless, current observations of this planet do not allow yet to determine which model is more accurate.

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arXiv2013

Probing the extreme planetary atmosphere of WASP-12b

We report near-infrared measurements of the terminator region transmission spectrum and dayside emission spectrum of the exoplanet WASP-12b obtained using the HST WFC3 instrument. The disk-average dayside brightness temperature averages about 2900 K, peaking to 3200 K around 1.46 microns. We modeled a range of atmospheric cases for both the emission and transmission spectrum and confirm the recent finding by Crossfield et al. (2012b) that there is no evidence for C/O >1 in the atmosphere of WASP-12b. Assuming a physically plausible atmosphere, we find evidence that the presence of a number of molecules is consistent with the data, but the justification for inclusion of these opacity sources based on the Bayesian Information Criterion (BIC) is marginal. We also find the near-infrared primary eclipse light curve is consistent with small amounts of prolate distortion. As part of the calibration effort for these data, we conducted a detailed study of instrument systematics using 65 orbits of WFC3-IR grims observations. The instrument systematics are dominated by detector-related affects, which vary significantly depending on the detector readout mode. The 256x256 subarray observations of WASP 12 produced spectral measurements within 15% of the photon-noise limit using a simple calibration approach. Residual systematics are estimated to be less than 70 parts per million.

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