The TESS-SPOC FFI target sample explored with gaia

The Transiting Exoplanet Survey Satellite (TESS) mission has provided the community with high-precision times-series photometry for ∼2.8 million stars across the entire sky via the full frame image (FFI) light curves produced by the TESS Science Processing Operations Center (SPOC). This set of light curves is an extremely valuable resource for the discovery of transiting exoplanets and other stellar science. However, due to the sample selection, this set of light curves does not constitute a magnitude-limited sample. In order to understand the effects of this sample selection, we use Gaia Data Release 2 (DR2) and Data Release 3 (DR3) to study the properties of the stars in the TESS-SPOC FFI light-curve set, with the aim of providing vital context for further research using the sample. We report on the properties of the TESS-SPOC FFI targets in Sectors 1–55 (covering Cycles 1–4). We cross-match the TESS-SPOC FFI targets with the Gaia DR2 and DR3 catalogues of all targets brighter than Gaia magnitude 14 to understand the effects of sample selection on the overall stellar properties. This includes Gaia magnitude, parallax, radius, temperature, non-single star flags, luminosity, radial velocity, and stellar surface gravity. In total, there are ∼16.7 million Gaia targets brighter than G = 14, which when cross-matched with the TESS-SPOC FFI targets leaves ∼2.75 million. We investigate the binarity of each TESS-SPOC FFI target and calculate the radius detection limit from two detected TESS transits that could be detected around each target. Finally, we create a comprehensive main-sequence TESS-SPOC FFI target sample that can be utilized in future studies

TESS Duotransit Candidates from the Southern Ecliptic Hemisphere

Discovering transiting exoplanets with long orbital periods allows us to study warm and cool planetary systems with temperatures similar to the planets in our own Solar system. The TESS mission has photometrically surveyed the entire Southern Ecliptic Hemisphere in Cycle 1 (August 2018 - July 2019), Cycle 3 (July 2020 - June 2021) and Cycle 5 (September 2022 - September 2023). We use the observations from Cycle 1 and Cycle 3 to search for exoplanet systems that show a single transit event in each year - which we call duotransits. The periods of these planet candidates are typically in excess of 20 days, with the lower limit determined by the duration of individual TESS observations. We find 85 duotransit candidates, which span a range of host star brightnesses between 8 < $T_{mag}$ < 14, transit depths between 0.1 per cent and 1.8 per cent, and transit durations between 2 and 10 hours with the upper limit determined by our normalisation function. Of these candidates, 25 are already known, and 60 are new. We present these candidates along with the status of photometric and spectroscopic follow-up.Comment: 25 pages, 16 figures, submitted to Monthly Notices of the Royal Astronomical Societ

Bismuth ferrite-based lead free ceramics and multilayers with high recoverable energy density

Lead-free ceramics with high recoverable energy density (Wrec) and energy storage efficiency (η) are attractive for advanced pulsed power capacitors to enable greater miniaturization and integration. In this work, dense bismuth ferrite (BF)-based, lead-free 0.75(Bi1-xNdx)FeO3-0.25BaTiO3 (BNxF-BT) ceramics and multilayers were fabricated. A transition from a mixed pseudocubic and R3c to a purely pseudocubic structure was observed as x increased with optimum properties obtained for mixed compositions. Highest energy densities, W ~ 4.1 J/cm3 and Wrec ~ 1.82 J/cm3 were achieved for BN15F-BT, due to the enhanced breakdown field strength (BDS ~ 180 kV/cm) and large maximum polarization (Pmax ~ 40 μC/cm2). Multilayers of this composition possessed both high Wrec of 6.74 J/cm3 and η of 77% and were stable up to 125 °C. Nd doped BF-based ceramics with enhanced BDS and large Wrec are therefore considered promising candidates for lead-free energy storage applications

TESS duotransit candidates from the Southern Ecliptic Hemisphere

Discovering transiting exoplanets with long orbital periods allows us to study warm and cool planetary systems with temperatures similar to the planets in our own Solar system. The Transiting Exoplanet Survey Satellite (TESS) mission has photometrically surveyed the entire Southern Ecliptic Hemisphere in Cycle 1 (2018 August–2019 July), Cycle 3 (2020 July–2021 June), and Cycle 5 (2022 September–2023 September). We use the observations from Cycle 1 and Cycle 3 to search for exoplanet systems that show a single transit event in each year, which we call duotransits. The periods of these planet candidates are typically in excess of 20 d, with the lower limit determined by the duration of individual TESS observations. We find 85 duotransit candidates, which span a range of host star brightnesses: 8 < Tmag < 14, transit depths between 0.1 per cent and 1.8 per cent, and transit durations between 2 and 10 h with the upper limit determined by our normalization function. Of these candidates, 25 are already known, and 60 are new. We present these candidates along with the status of photometric and spectroscopic follow-up

TIARA TESS 1: estimating exoplanet yields from Years 1 and 3 SPOC light curves

We present a study of the detection efficiency for the TESS mission, focusing on the yield of longer period transiting exoplanets (P &amp;gt; 25 d). We created the Transit Investigation and Recoverability Application (TIaRA) pipeline to use real TESS data with injected transits to create sensitivity maps which we combine with occurrence rates derived from Kepler. This allows us to predict longer period exoplanet yields, which will help design follow-up photometric and spectroscopic programs, such as the NGTS (Next Generation Transit Survey) Monotransit Program. For the TESS Years 1 and 3 SPOC (Science Processing Operations Centre) FFI (Full Frame Image) light curves, we find $2271^{+241}_{-138}$ exoplanets should be detectable around AFGKM dwarf host stars. We find $215^{+37}_{-23}$ exoplanets should be detected from single-transit events or ‘monotransits’. An additional $113^{+22}_{-13}$ detections should result from ‘biennial duotransit’ events with one transit in Year 1 and a second in Year 3. We also find that K dwarf stars yield the most detections by TESS per star observed. When comparing our results to the TOI (TESS objects of interest) catalogue, we find our predictions agree within 1σ of the number of discovered systems with periods between 0.78 and 6.25 d and agree to 2σ for periods between 6.25 and 25 d. Beyond periods of 25 d, we predict $403^{+64}_{-38}$ detections, which is three times as many detections as there are in the TOI catalogue with &amp;gt;3σ confidence. This indicates a significant number of long-period planets yet to be discovered from TESS data as monotransits or biennial duotransits

Chemical control of octahedral tilting and off-axis A cation displacement allows ferroelectric switching in a bismuth-based perovskite

Bi(Fe Mg Ti )O (BFTM) is a member of a small class of pure Bi A site perovskites which are stable without recourse to high pressure synthesis. BFTM is polar in the R3c space group, but ferroelectric switching of the polarisation is not attainable in bulk ceramics. Formation of solid solutions with BaTiO produces enhanced functional behaviour. The composition 0.75Bi(Fe Mg Ti )O -0.25BaTiO displays ferroelectric hysteresis loops and piezoelectric response (high field d of 85 pC N at 0.1 Hz and low field d of 16 pC N ). This change in functional behaviour is associated with significant changes in the average structure, where the rhombohedral distortion is reduced and transformed to a pseudo-cubic R3m space group, as substitution of the larger Ba cation suppresses tilting of the BO octahedra. Polar Bi displacements are refined solely along the pseudocubic direction of the perovskite subcell, with the off-axis displacements characteristic of BFTM being suppressed. The local structure deviates from the average structure in a similar way to PZT as shown by diffuse scattering in selected area electron diffraction, suggesting correlated displacements along directions other than the average rhombohedral unique axis. The switchable polarisation measured by PUND measurements is considerably smaller than the remanence measured in P(E) loops