arXiv subjects

Ben Sutlieff

Publications and source records attributed to Ben Sutlieff.

3 recordsLinked to original sources

arXiv2023

The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems V: Do Self-Consistent Atmospheric Models Represent JWST Spectra? A Showcase With VHS 1256 b

The unprecedented medium-resolution (R~1500-3500) near- and mid-infrared (1-18um) spectrum provided by JWST for the young (140+/-20Myr) low-mass (12-20MJup) L-T transition (L7) companion VHS1256b gives access to a catalogue of molecular absorptions. In this study, we present a comprehensive analysis of this dataset utilizing a forward modelling approach, applying our Bayesian framework, ForMoSA. We explore five distinct atmospheric models to assess their performance in estimating key atmospheric parameters: Teff, log(g), [M/H], C/O, gamma, fsed, and R. Our findings reveal that each parameter's estimate is significantly influenced by factors such as the wavelength range considered and the model chosen for the fit. This is attributed to systematic errors in the models and their challenges in accurately replicating the complex atmospheric structure of VHS1256b, notably the complexity of its clouds and dust distribution. To propagate the impact of these systematic uncertainties on our atmospheric property estimates, we introduce innovative fitting methodologies based on independent fits performed on different spectral windows. We finally derived a Teff consistent with the spectral type of the target, considering its young age, which is confirmed by our estimate of log(g). Despite the exceptional data quality, attaining robust estimates for chemical abundances [M/H] and C/O, often employed as indicators of formation history, remains challenging. Nevertheless, the pioneering case of JWST's data for VHS1256b has paved the way for future acquisitions of substellar spectra that will be systematically analyzed to directly compare the properties of these objects and correct the systematics in the models.

astro-ph.EP↗

arXiv2020

Assessing the Impact of Space School UK

Space School UK (SSUK) is a series of summer residential programmes for secondary school aged students, held at the University of Leicester over 3 weeks each year. Each programme involves space-related activities run by a team of mentors - currently including university students, graduates, teachers and young professionals associated with the space sector - all of whom attended SSUK as students themselves. It includes the 6-day Space School UK and the 8-day Senior Space School UK (collectively SSUK) which are for 13-15 and 16-18 year olds respectively. This paper seeks to evaluate and present the benefits of SSUK to individuals who participate in the programme, organisations involved in the running of SSUK, and to highlight and promote these benefits to the wider UK and global space community. We also address which facets of SSUK make for such an engaging and encouraging experience for the students, that are missing from students' traditional education. We seek to show how SSUK acts as an excellent example of how to bridge the gap between secondary and tertiary space education. Through an analysis of our alumni survey results, we show that attending SSUK has a significant impact on career choices and prepares students for Higher Education, regardless of background. Some groups, such as women, and those from non-selective schools, reported a higher impact in some of these areas than others. Metrics such as skills learned, goals achieved, alongside knowledge of careers and Higher Education possibilities are discussed for various demographics.

physics.ed-ph↗

arXiv2018

Constraining the presence of giant planets in two-belt debris disk systems with VLT/SPHERE direct imaging and dynamical arguments

Giant, wide-separation planets often lie in the gap between multiple, distinct rings of circumstellar debris: this is the case for the HR\,8799 and HD\,95086 systems, and even the solar system where the Asteroid and Kuiper belts enclose the four gas and ice giants. In the case that a debris disk, inferred from an infrared excess in the SED, is best modelled as two distinct temperatures, we infer the presence of two spatially separated rings of debris. Giant planets may well exist between these two belts of debris, and indeed could be responsible for the formation of the gap between these belts. We observe 24 such two-belt systems using the VLT/SPHERE high contrast imager, and interpret our results under the assumption that the gap is indeed formed by one or more giant planets. A theoretical minimum mass for each planet can then be calculated, based on the predicted dynamical timescales to clear debris. The typical dynamical lower limit is $\sim$0.2$M_J$ in this work, and in some cases exceeds 1$M_J$. Direct imaging data, meanwhile, is typically sensitive to planets down to $\sim$3.6$M_J$ at 1'', and 1.7$M_J$ in the best case. Together, these two limits tightly constrain the possible planetary systems present around each target, many of which will be detectable with the next generation of high-contrast imagers.

astro-ph.EP↗