Maximum Brightness Research Articles

Low-dimensional phase optimization and defect passivation of quasi-2D perovskite to enhance electroluminescence by introducing b-NA

The energy funnel effect holds significant potential for enhancing light-emitting diode (LED) performance in the Quasi-two-dimensional (Quasi-2D) perovskite, which feature a unique multi-quantum well structure. However, random phase distribution and defects within Quasi-2D films pose challenges, leading to inefficient energy transfer and nonradiative recombination, thereby limiting device performance. Here, sodium 2-naphthalene sulfonate (b-NA) is introduced into the Quasi-2D perovskite film to enhance its the optical and electrical properties. The strong interaction between the S = O group and Na+ in b-NA with the perovskite matrix leads to reduced grain size, facilitating agglomeration and densification. This modification decreases the proportion of the low-n phase, enhances thermal stability, and passivates surface defects. Therefore, compared to the control device, the maximum brightness and external quantum efficiency of Quasi-2D perovskite LEDs with the optimal concentration (8b-NA) more than double, and the operational lifetime (T50) of the unpackaged device extends from 70.1 min to 168.5 min.

A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour

Blazars are beamed active galactic nuclei (AGNs) known for their strong multi-wavelength variability on timescales ranging from years down to minutes. Many different models have been proposed to explain this variability. We aim to investigate the suitability of the twisting jet model presented in previous works to explain the multi-wavelength behaviour of BL Lacertae, the prototype of one of the blazar classes. According to this model, the jet is inhomogeneous, curved, and twisting, and the long-term variability is due to changes in the Doppler factor due to variations in the orientation of the jet-emitting regions. We analysed optical data of the source obtained during monitoring campaigns organised by the Whole Earth Blazar Telescope (WEBT) in 2019--2022, together with radio data from the WEBT and other teams, and gamma -ray data from the Fermi satellite. In this period, BL Lacertae underwent an extraordinary activity phase, reaching its historical optical and gamma -ray brightness maxima. The application of the twisting jet model to the source light curves allows us to infer the wiggling motion of the optical, radio, and gamma -ray jet-emitting regions. The optical-radio correlation shows that the changes in the radio viewing angle follow those in the optical viewing angle by about 120 days, and it suggests that the jet is composed of plasma filaments, which is in agreement with some radio high-resolution observations of other sources. The gamma -ray emitting region is found to be co-spatial with the optical one, and the analysis of the gamma -optical correlation is consistent with both the geometric interpretation and a synchrotron self-Compton (SSC) origin of the high-energy photons. We propose a geometric scenario where the jet is made up of a pair of emitting plasma filaments in a sort of double-helix curved rotating structure, whose wiggling motion produces changes in the Doppler beaming and can thus explain the observed multi-wavelength long-term variability.

Bottom Electrode Modification Enables Efficient and Bright Silicon-Based Top-Emission Perovskite Light-Emitting Diodes.

The integration of perovskites with mature silicon platform has emerged as a promising approach in the development of efficient on-chip light sources and high-brightness displays. However, the performance of Si-based green perovskite light-emitting diodes (PeLEDs) still falls significantly short compared to their red and near-infrared counterparts. In this study, it is revealed that the high work function Au, widely employed in Si-based top-emission PeLEDs as the reflective bottom electrode, exhibits considerably lower reflectivity in the green spectrum than in the longer wavelengths. Consequently, Ag electrode is introduced to replace Au to enhance the green light reflectivity, and the ultrathin MoO3 and self-assembled monolayers (SAMs) are sequentially deposited for surface modification. These results indicate that the MoO3 layer removes the energy barrier at Ag/polymer hole transport layer interface, enhancing the hole injection efficiency; while the SAMs firmly anchor onto the MoO3 layer, effectively preventing interfacial defect formation. Benefited from this organic/inorganic dual-layer modification strategy, Si-based green PeLEDs with an impressive peak external quantum efficiency of 18.2% and a maximum brightness of 81931 cd m-2 are successfully fabricated, on par with those of the red and near-infrared counterparts. This achievement marks an advancement in developing high-performance Si-based PeLEDs with full-spectrum output.

Hetero-Nucleation Induced [111]-Oriented Mixed Halide Perovskite for Stable Pure Red Light-Emitting Diodes.

Mixed halide 3D perovskites are promising for bright, efficient, and wide-color gamut light-emitting diodes (LEDs) due to their excellent carrier transport, high luminescence, and easily tunable bandgaps. However, serious halide ion migration inside mixed halide 3D perovskite results in poor operational and spectral stability of the as-fabricated LEDs. Here, a hetero-nucleation crystallization strategy is reported to grow [111]-orientationpreferred mixed halide 3D perovskite CsPbI3-xBrx thin films for stable pure red LEDs. This hetero-nucleation crystallization is enabled by the addition of phosphoric acid (H3PO4) complexation, which promotes the growth of small perovskite grains into large grains with uniform [111]-orientation. The obtained [111]-orientation preferred film exhibits excellent stability under light or electric field stimulus as revealed by model analysis and experimental results compared to that of [001]-orientation preferred film. Thus, based on the [111]-orientationpreferred film, the fabricated LED exhibits an external quantum efficiency of 22.8%, a maximum brightness of 12000cdm-2, and a half-life time of 4080min under 1.5mA cm-2. More importantly, the electroluminescence spectrum of the device remains stable during the continuous operation of 4080min, showcasing the significant spectral stability improvement enabled by the hetero-nucleation induced [111]-orientation strategy.

Original Blue Light-Emitting Diphenyl Sulfone Derivatives as Potential TADF Emitters for OLEDs

Organic light-emitting diodes (OLEDs) have emerged as one of the dominant technologies in displays due to their high emission efficiency and low power consumption. However, the development of blue color emitters has fallen behind that of red and green emitters, posing challenges in achieving optimal efficiency, stability, and accessibility. In this context, thermally activated delayed fluorescence (TADF) emitters hold promise as a potential solution for cost-effective, exceptionally efficient, and stable blue OLEDs due to their potential high efficiency and stability. TADF is a principle where certain organic materials can efficiently convert both singlet and triplet excitons, theoretically achieving up to 100% internal quantum efficiency. This research focused on diphenyl sulfone derivatives with carbazole groups as TADF compounds. Quantum chemical calculations and photoluminescence properties show the potential TADF properties of the molecules. New materials exhibit glass transition temperatures that would classify them as molecular glasses. Depending on the structure of the molecule, the photoluminescence emission is in the blue or green spectral region. Organic light-emitting diodes were fabricated from neat thin films of emitters by the wet casting method. The best performance in the deep blue emission region was achieved by a device with a turn-on voltage of 4 V and a maximum brightness of 178 cd/m2. In the blue-green emission region, the best performance was observed by an OLED with a turn-on voltage of 3.5 V, reaching a maximum brightness of 660 cd/m2.

Isomerization enhanced fluorescence brightness of benzobisthiadiazole-based NIR-II fluorophores for highly efficient fluorescence imaging: A theoretical perspective

As a cutting-edge technique, fluorescence imaging in the second near-infrared window (NIR-II) is vital for both biomedical research and clinical applications. However, its intravital imaging capacity has been restricted by the extremely limited brightness of NIR-II fluorophores. To address this challenge, we elucidated the inner mechanism of constructing high-performance NIR-II chromophores based on molecular isomer engineering from detailed computational investigations. Herein, three pairs of cis–trans isomers (cis-1, 2, 3 and trans-1, 2, 3) are designed by attaching amino, methoxyl and nitro moieties to different positions on the donor–acceptor-donor molecular skeleton with benzobisthiadiazole as the acceptor and triphenylamine as the donor. All the compounds feature efficient NIR-II emission ranging in 1000–1164 nm, and the photophysical characterizations are regulated by molecular isomer manipulation. Interestingly, fluorescence quantum yields of cis-isomers are higher than those of their trans-counterparts. These enhancements can be attributed to the significant reduction in non-radiative transition, as evidenced by the non-adiabatic excitation energy, non-adiabatic electron coupling and electron-vibration coupling. Meanwhile, fluorophores with nitro terminal group exhibit superior performance facilitated by the prominently intramolecular charge transfer. As a result, cis-3 achieves an optimal brightness maxima of 196.36 M−1 cm−1 at 632 nm. Notably, the energy gap and the hole-electron related H index are respectively identified as strongly relevant to the emission wavelength and brightness, making them capable of evaluating the feasibility of fluorophores as effective NIR-II candidates. These findings highlight the correlations between molecular geometry and luminescent properties, which will inspire more insights into the development of highly efficient NIR-II fluorophores through rational isomer engineering for biomedical applications.

CsPb2Br5 Plates/Quasi-2D Perovskite Heterojunction for Efficient Sky-Blue Light-Emitting Diodes.

Perovskite light-emitting diodes (PeLEDs) have gained significant attention owing to their remarkable tunability and color stability, and substantial progress has been made with green and red PeLEDs. However, the advancement of blue PeLEDs still lags far behind their red and green counterparts. In this study, we report efficient sky-blue PeLEDs utilizing an in situ fabricated CsPb2Br5 plates/quasi-2D perovskite heterojunction using chelating molecules to modulate the crystallization process of perovskites. The wide bandgap of CsPb2Br5 facilitated the formation of a type-I band alignment at the heterojunction, allowing efficient carrier transfer from CsPb2Br5 to CsPbBr3. This heterojunction leads to a noteworthy enhancement of device efficiency. The PeLEDs exhibit a maximum brightness of 2311 cd m-2, accompanied by a maximum external quantum efficiency of 12.86% at 487 nm. Our tailored design of CsPb2Br5/perovskite heterojunction thin films offers a promising avenue for advancing PeLED performance. This work contributes valuable insights into the burgeoning field of perovskite electroluminescence, paving the way for further optimization of PeLED technologies.

The Black Hole Mass and Photometric Components of NGC 4826

We present infrared photometry and Hubble Space Telescope imaging and spectroscopy of the Sab galaxy NGC 4826. Schwarzschild dynamical modeling is used to measure its central black hole mass M. Photometric decomposition is used to enable a comparison of M to published scaling relations between black hole masses and properties of host bulges. This decomposition implies that NGC 4826 contains classical and pseudobulges of approximately equal mass. The classical bulge has best-fit Sérsic index n = 3.27. The pseudobulge is made up of three parts, an inner lens (n = 0.18 at r ≲ 4″), an outer lens (n = 0.17 at r ≲ 45″), and a n = 0.58 Sérsic component required to match the surface brightness between the lens components. The total V-band luminosity of the galaxy is M VT = −21.07, the ratio of classical bulge to total light is B/T ≃ 0.12, and the ratio of pseudobulge to total light is PB/T ≃ 0.13. The outer disk is exponential (n = 1.07) and makes up D/T = 0.75 of the light of the galaxy. Our best-fit Schwarzschild model has a black hole mass with 1σ uncertainties of M=8.4−0.6+1.7×106M⊙ and a stellar population with a K-band mass-to-light ratio of ϒK=0.46±0.03M⊙L⊙−1 at the assumed distance of 7.27 Mpc. Our modeling is marginally consistent with M = 0 at the 3σ limit. These best-fit parameters were calculated assuming the black hole is located where the velocity dispersion is largest; this is offset from the maximum surface brightness, probably because of dust absorption. The black hole mass—one of the smallest measured by modeling stellar dynamics—satisfies the well known correlations of M with the K-band luminosity, stellar mass, and velocity dispersion of the classical bulge only. In contrast, the black hole is undermassive with respect to the correlation of M with total (classical plus pseudo) bulge luminosity. Thus the composite (classical bulge plus pseudobulge) galaxy NGC 4826 is consistent with previous results on black hole scaling relations and helps to strengthen these results at low black hole masses.

Microwave diagnostics of flare plasma by the direct fitting method based on data from the Siberian Radioheliograph

In this paper, we analyze images and the frequency spectrum of microwave emission in the maximum of brightness distribution in the January 20, 2022 and July 16, 2023 flares recorded by the Siberian Radioheliograph in the 3–6 GHz and 6–12 GHz ranges. We use the obtained spectrum data for radio diagnostics of magnetic field strength and orientation, plasma density, and parameters of accelerated particles in a radio source. The radio diagnostics is carried out by a method based on minimizing the functional containing the intensities of theoretically calculated and observed frequency spectra of left-polarized and right-polarized emission. Since the form of such a multidimensional functional is quite complex, and it is not possible to minimize it by standard approaches, we employ a genetic minimization method. The radio diagnostics allows us to determine features of the dynamics of the magnetic field intensity and orientation, as well as the density and the energy spectral index of non-thermal electrons in the region of maximum brightness of the radio source. We have found that during the growth phase of the main radiation peaks the magnetic field decreases, whereas during the decay phase, on the contrary, it increases. The rate of these changes varies from a few G/s to 11 G/s for the January 20, 2022 flare and is about 1 G/s for the July 16, 2023 flare.

Микроволновая диагностика вспышечной плазмы методом фитирования по данным Cибирского радиогелиографа

In this paper, we analyze images and the frequency spectrum of microwave emission in the maximum of brightness distribution in the January 20, 2022 and July 16, 2023 flares recorded by the Siberian Radioheliograph in the 3–6 GHz and 6–12 GHz ranges. We use the obtained spectrum data for radio diagnostics of magnetic field strength and orientation, plasma density, and parameters of accelerated particles in a radio source. The radio diagnostics is carried out by a method based on minimizing the functional containing the intensities of theoretically calculated and observed frequency spectra of left-polarized and right-polarized emission. Since the form of such a multidimensional functional is quite complex, and it is not possible to minimize it by standard approaches, we employ a genetic minimization method. The radio diagnostics allows us to determine features of the dynamics of the magnetic field intensity and orientation, as well as the density and the energy spectral index of non-thermal electrons in the region of maximum brightness of the radio source. We have found that during the growth phase of the main radiation peaks the magnetic field decreases, whereas during the decay phase, on the contrary, it increases. The rate of these changes varies from a few G/s to 11 G/s for the January 20, 2022 flare and is about 1 G/s for the July 16, 2023 flare.

Comprehensive Analysis of Phycoerythrin 545 Stability and the Apoptotic Impact of Its Degradation Products on HT29 Cells.

This study investigates the properties and potential applications of phycoerythrin 545, a naturally occurring light-harvesting pigment protein from Rhodomonas salina. Phycoerythrin 545, characterized by its bright red color and maximum absorption wavelength at 545 nm, was extracted using freeze-thawing methods, further purified, and analyzed using chromatographic, spectroscopic techniques, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Phycoerythrin 545 consists of two subunits, primarily α and β, but lacks the γ subunit, and is stable at 4 °C within a pH range of 3-10. To further characterize it, its susceptibility to degradation by trypsin was assessed. The biological activity of phycoerythrin 545 and its degradation products were investigated in HT29 human colon cancer cells. The results showed that the degradation products, particularly those within 3-10 kDa, significantly decreased the viability of HT29 cells by inducing apoptosis. Mechanistic studies indicated these effects were mediated through the activation of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinases and MAPK/c-Jun N-terminal Kinase signaling pathways and involved the regulation of key apoptotic proteins such as p53, Bim, Bad, Bak, and Bax, leading to the activation of the Caspase-3 apoptotic pathway. These findings contribute to understanding the structural and functional properties of phycoerythrin 545, laying a foundation for its exploration in food industry applications and cancer therapy supplementation.

Evolution of pre-damaged ITER grade plasma facing components under WEST plasma exposure: smoothing and tungsten sources

The evaluation of the impact of plasma-facing units (PFUs) damage on subsequent plasma operation is an important issue for ITER. This is one of the topic addressed by the operation of dedicated PFUs in WEST. From the start of WEST in 2017, few ITER grade divertor PFUs were tested in the lower divertor for short plasma exposure (experimental campaigns C1–C5). A PFU is an assembly of tungsten blocks on CuCrZr tube via pure copper interlayer. Since 2022, WEST operates with a lower divertor fully equipped with ITER grade PFUs (experimental campaign C6–C7) with long duration plasma exposure capabilities. To test the ageing of the ITER-grade PFUs on an accelerated basis, well controlled damage was implemented on purpose with electron beam loading on the plasma facing surface of two different PFUs (pre-damage#1 and #2 featuring different level of damage). Damage tackled in this study is induced by the loading with numerous transient heat loading events to mimic the ELM impact on the ITER grade PFU. This paper presents the damage before and after WEST plasma exposure and shows the tungsten sources and temperature of the block measured during the operation. On damaged area, surface roughening is heterogeneous. With WEST campaigns (C3, C4 and C7) respectively ended in (2018, 2019 and 2023) a global smoothing of the pre-damaged surfaces, in particular those located in the high loaded erosion area, is observed. No evolution of the crack is observed in the electron beam loaded area, while new cracking are observed on non pre-damaged area on the tungsten top surfaces in highly loaded areas (outer strike point) after significant plasma duration and cumulated energy (first observation in C4 and tends to be confirmed with preliminary observations after the C7 campaign). Smoothing is less pronounced after the 2018 campaign, which may be due to the related short plasma duration. The surface smoothing of blocks also depends on their poloidal position. For PFU which has no shaping, toroidal positioning within a block has no influence on the surface smoothing. After 2019 and 2023 campaigns, equivalent relative smoothing is obtained (between 19 and 32%). For the explored plasma conditions, damage has no influence on the maximum brightness of W.

Designing the Second Target Station with a Coupled Neutronics-Mechanical Optimization Workflow

The Second Target Station (STS) at the Spallation Neutron Source of the U.S. Department of Energy’s Oak Ridge National Laboratory is being designed to become the world’s highest peak brightness source of cold neutrons. As the STS project evolves, neutronics and other engineering analyses will inform many design iterations. To facilitate this process, a fully automated optimization workflow was developed to convert a parameterized computer-aided-design model of the target into an unstructured mesh geometry model and then to run a neutronics calculation and (optionally) a mechanical analysis for each design iteration. This workflow enables efficient, high-fidelity modeling; simulation; and optimization of new designs, as has been demonstrated for the optimization of the STS neutron moderators. In this paper, we present the results of our first major effort to automate the design optimization process for a spallation target. In the first analysis, the goal is to find optimal dimensions of a monolithic tungsten target coupled with an optimal super-Gaussian proton beam profile to deliver maximum brightness of the resulting neutron beams while maintaining good mechanical properties of the target. In the second analysis, geometric and beam parameters are optimized for an alternative design with tungsten plates, which can reach superior mechanical performance without compromising the neutronics performance.

Compensating slice emittance growth in high brightness photoinjectors using sacrificial charge

Achieving maximum electron beam brightness in photoinjectors requires detailed control of the 3D bunch shape and precise tuning of the beam focusing. Even in state-of-the-art designs, slice emittance growth due to nonlinear space charge forces and partial nonlaminarity often remains non-negligible. In this work, we introduce a new means to linearize the transverse slice phase space: a sacrificial portion of the bunch’s own charge distribution, formed into a wavebroken shock front by highly nonlinear space charge forces within the gun, whose downstream purpose is to dynamically linearize the desired bunch core. We show that linearization of an appropriately prepared bunch can be achieved via strongly nonlaminar focusing of the sacrificial shock front, while the inner core focuses laminarly. This leads to a natural spatial separation of the two distributions: a dense core surrounded by a diffuse halo of sacrificial charge that can be collimated. Multiobjective genetic algorithm optimizations of the ultracompact x-ray free electron laser injector employ this concept, and we interpret it with an analytic model that agrees well with the simulations. In simulation, we demonstrate a final bunch charge of 100 pC, peak current ∼30 A, and a sacrificial charge of 150 pC (250 pC total emitted from cathode) with normalized emittance growth of <20 nm rad due to space charge. This implies a maximum achievable brightness approximately an order of magnitude greater than existing free electron laser injector designs. Published by the American Physical Society 2024

Polymerized Carbon Dots with Broad Emission and Suppressed Aggregation‐Caused Quenching Effect Toward Electroluminescent White Light‐Emitting Diodes

AbstractCarbon dots (CDs) possess intrinsically broad emission spectra, making them suitable for modulating high‐quality white light‐emitting diodes (WLEDs). However, the chief technical challenge in applying CDs to WLEDs is the aggregation‐caused quenching (ACQ) effect. A common solution is polymer post‐modification on the surface of CDs, which is a low‐yield, hard‐to‐purified, and complicated process. Herein, polymerized CDs with broad emission (full width at half maxima, FWHM = 187 nm) are synthesized via a one‐step solvothermal method. The obtained polymerized CDs display excellent solution‐processed and film‐forming capabilities, with absolute photoluminescence quantum yield as high as 4.7% in thin film state, creating a firm foundation for assembling solution‐processed WLEDs. Moreover, the polymerization steps of CDs are analyzed and described in detail. The polymer chains prevent ACQ and create new energy levels, resulting in the broad emission of CDs in an aggregated state. Subsequently, WLEDs are fabricated using polymerized CDs as the single active emitting material. The optimal device achieves the maximum brightness of 337.50 cd m−2 and FWHM of 242 nm, covering nearly the entire visible spectral window. The results present a new approach to obtaining polymerized CDs and further fabricating WLED with a straightforward, cost‐effective method.

Efficient deep-blue electroluminescence from Ce-based metal halide

Rare earth ions with d-f transitions (Ce3+, Eu2+) have emerged as promising candidates for electroluminescence applications due to their abundant emission spectra, high light conversion efficiency, and excellent stability. However, directly injecting charge into 4f orbitals remains a significant challenge, resulting in unsatisfied external quantum efficiency and high operating voltage in rare earth light-emitting diodes. Herein, we propose a scheme to solve the difficulty by utilizing the energy transfer process. X-ray photoelectron spectroscopy and transient absorption spectra suggest that the Cs3CeI6 luminescence process is primarily driven by the energy transfer from the I2-based self-trapped exciton to the Ce-based Frenkel exciton. Furthermore, energy transfer efficiency is largely improved by enhancing the spectra overlap between the self-trapped exciton emission and the Ce-based Frenkel exciton excitation. When implemented as an active layer in light-emitting diodes, they show the maximum brightness and external quantum efficiency of 1073 cd m−2 and 7.9%, respectively.

Excellent Electroluminescent Property of Eu3+-Induced Polystyrene-co-poly(acrylic acid) Aggregates (EIPAs) in Polymeric Light-Emitting Diodes.

Eu3+-induced polystyrene-co-poly(acrylic acid) aggregates (EIPAs) were synthesized using a self-assembly approach, and their structures and photophysical characteristics were examined to achieve effective monochromatic red emission in polymer light-emitting diodes (PLEDs). By adjusting the monomer ratio in RAFT polymerization, the size of Eu3+-induced block copolymer nanoaggregates can be regulated, thereby modulating the luminescence intensity. High-performance bilayer polymer light-emitting devices were fabricated using poly(9,9-dioctylfluorene) (PFO) and 2-(tert-butylphenyl)-5-biphenylyl-1,3,4-oxadiazole (PBD) as the host matrix, with EIPAs as the guest dopant. The devices exhibited narrow red emission at 615 nm with a full width at half-maximum (fwhm) of 15 nm across doping concentrations of 1, 3, 5, and 10 wt %. At a doping concentration of 3 wt %, the device achieved a maximum brightness of 1864.48 cd/m2 at 193.82 mA/cm2 and an external quantum efficiency of 3.20% at a current density of 3.5 mA/cm2. These results indicate that incorporating polystyrene-co-poly(acrylic acid) with Eu3+ complexes enhances the excitation and emission intensity, as well as the structural stability of the emitting layer in PLEDs, thereby improving the device performance.

Glimmer Synchronization Of Luciola Parvula Fireflies To External Stimulas

It is known that the Luciola parvula fireflies clearly emit the lights at regular time intervals and synchronization between multiple males are observed, but the details of synchronization have not yet been clarified. Presently, we took videos of the luminescence phenomenon of multiple male Luciola parvula fireflies and performed a correlation analysis on the details of the time change of the luminescence brightness of each male Luciola parvula fireflies. The 12 Luciola parvula fireflies are kept in glass wells so that each Luciola parvula fireflies can only moves in restricted areas and their luminescence is recorded by a digital movie camera at the video rate of 30 fps. According to the preliminary study, each glimmer lasts about 3 frames and thus the time series brightness is fitted by a parabolic function in order to give a precise timing of maximum brightness. First of all, time intervals between glimmers of each Luciola parvula fireflies are evaluated. Secondly, the glimmer correlation between different Luciola parvula fireflies are investigated. As a result, it was clarified that the light emission cycle of Luciola parvula fireflies is almost constant at 0.54 seconds, more than 70% of all light emissions are synchronized and the order of synchronization is almost fixed with very small delay. Consequently, it has been shown quantitatively that the glimmers of male Luciola parvula fireflies are well synchronized.

The Mira discovery problem—Observations by David Fabricius in 1596 and 1609 (and by others before?): Positional accuracy, brightness, color index, and period

AbstractThe pulsating variable star Mira (o Ceti) was observed by David Fabricius (Frisia) in 1596 and 1609. We review suggested previous detections (e.g., China, Hipparchos). We analyze all Mira records from Fabricius in their historical context. Fabricius measured the separation of Mira to other stars to ±1.6−1.7′. From his texts, we derive a brightness (slightly brighter than Hamal) of ca. 1.9±0.1 mag and a color index B‐V1.3−1.4 mag (‘like Mars’) for 1596 Aug 3 (Jul.). Mira started to fainten 19 days later and was observed until mid/late Oct. We show why such a red star cannot be followed by the naked eye until ca. 6 mag: For Mira's color at disappearance and altitude from Frisia, the limit is reduced by ca. 1.0 mag. Since Fabricius connected the Mira brightening with the close‐by prograde Jupiter, he re‐detected it only 12 years later, probably shortly before a relatively bright maximum—discoveries are strongly affected by biases. A Mira period of 330.2 days is consistent with both the oldest data (from Fabricius 1596 to Hevelius 1660) and the most current data (VSX 2004–2023), so that we see no evidence for secular period or phase shifts. (We also present Fabricius' observations of P Cygni in 1602.)

Latitudinal Asymmetry in the Dayside Atmosphere of WASP-43b

We present two-dimensional near-infrared temperature maps of the canonical hot Jupiter WASP-43b using a phase-curve observation with JWST NIRSpec/G395H. From the white-light planetary transit, we improve constraints on the planet’s orbital parameters and measure a planet-to-star radius ratio of 0.15883−0.00053+0.00056 . Using the white-light phase curve, we measure a longitude of maximum brightness of 6.9−0.°5+0.°5 east of the substellar point and a phase-curve offset of 10.0−0.°8+0.°8 . We also find a ≈4σ detection of a latitudinal hotspot offset of −13.4−1.°7+3.°2 , the first significant detection of a nonequatorial hotspot in an exoplanet atmosphere. We show that this detection is robust to variations within planetary parameter uncertainties, but only if the transit is used to improve constraints, showing the importance of transit observations to eclipse mapping. Maps retrieved from the NRS1 and NRS2 detectors are similar, with hotspot locations consistent between the two detectors at the 1σ level. Our JWST data show brighter (hotter) nightsides and a dimmer (colder) dayside at the shorter wavelengths relative to fits to Spitzer 3.6 and 4.5 μm phase curves. Through comparison between our phase curves and a set of general circulation models, we find evidence for clouds on the nightside and atmospheric drag or high metallicity reducing the eastward hotspot offset.