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Alfred Nobel : the man behind the Peace Prize
Alfred Nobel was the man who founded the Nobel Prizes. Nobel also invented dynamite, becoming very wealthy from his invention. Saddened by its use for harmful destruction, Nobel left his fortune to create yearly prizes for those who have rendered the greatest services to mankind.
BOOK
Searching for Additional Planets in TESS Multiplanet Systems: Testing Empirical Models Based on Kepler Data
Multiplanet system architectures are frequently used to constrain possible formation and evolutionary pathways of observed exoplanets. Therefore, understanding the predictive and descriptive power of empirical exoplanetary system models is critical to understanding their formation histories. We analyze 52 TESS multiplanet systems previously studied using Dynamite, which used TESS data alongside empirical models based on Kepler planets to predict additional planets in each system. We analyze additional TESS data to search for these predicted planets. We thereby evaluate the degree to which these models can be used to predict planets in TESS multiplanet systems. Specifically, we study whether the period ratio method or clustered period model is more predictive. We find that the period ratio model predictions are most consistent with the planets discovered since 2020, accounting for detection sensitivity. However, neither model is highly predictive, highlighting the need for additional data and more nuanced models to describe the full population. Improved eccentricity and dynamical stability prescriptions incorporated into Dynamite provide a modest improvement in the prediction accuracy. We also find that the current sample of 183 TESS multiplanet systems are highly dynamically packed, and appear truncated relative to detection biases. These attributes are consistent with the Kepler sample, and suggest an efficient formation process.
Journal Article
Assessing Exoplanetary System Architectures with DYNAMITE Including Observational Upper Limits
The information gathered from observing planetary systems is not limited to the discovery of planets, but also includes the observational upper limits constraining the presence of any additional planets. Incorporating these upper limits into statistical analyses of individual systems can significantly improve our ability to find hidden planets in these systems by narrowing the parameter space in which to search. Here, I include radial velocity (RV), transit, and transit timing variation (TTV) upper limits on additional planets in known multiplanet systems into the Dynamite software package and test their impact on the predicted planets for these systems. The tests are run on systems with previous Dynamite analysis and with updated known planet parameters in the 2–3 yr since the original predictions. I find that the RV limits provide the strongest constraints on additional planets, lowering the likelihood of finding them within orbital periods of ∼10–100 days in the inner planetary systems, as well as truncating the likely planet size (radius and/or mass) distributions toward planets smaller than those currently observed. Transit and TTV limits also provide information on the size and inclination distributions of both the known and predicted planets in the system. Utilizing these limits on a wider range of systems in the near future will help determine which systems might be able to host temperate terrestrial planets and contribute to the search for extraterrestrial biosignatures.
Journal Article
An Integrative Analysis of the Rich Planetary System of the Nearby Star e Eridani: Ideal Targets for Exoplanet Imaging and Biosignature Searches
e Eridani, the fifth-closest Sun-like star, hosts at least three planets and could possibly harbor more. However, the veracity of the planet candidates in the system and its full planetary architecture remain unknown. Here we analyze the planetary architecture of e Eridani via DYNAMITE, a method providing an integrative assessment of the system architecture (and possibly yet-undetected planets) by combining statistical, exoplanet-population-level knowledge with incomplete but specific information available on the system. DYNAMITE predicts the most likely location of an additional planet in the system based on the Kepler population demographic information from more than 2000 planets. Additionally, we analyze the dynamical stability of e Eridani system via N-body simulations. Our DYNAMITE and dynamical stability analyses provide support for planet candidates g, c, and f, and also predict one additional planet candidate with an orbital period between 549–733 days, in the habitable zone of the system. We find that planet candidate f, if it exists, would also lie in the habitable zone. Our dynamical stability analysis also shows that the e Eridani planetary eccentricities, as reported, do not allow for a stable system, suggesting that they are lower. We introduce a new statistical approach for estimating the equilibrium and surface temperatures of exoplanets, based on a prior from the planetary albedo distribution. e Eridani is a rich planetary system with a possibility of containing two potentially habitable planets, and its vicinity to our solar system makes it an important target for future imaging studies and biosignature searches.
Journal Article
An Integrative Analysis of the HD 219134 Planetary System and the Inner solar system: Extending DYNAMITE with Enhanced Orbital Dynamical Stability Criteria
Planetary architectures remain unexplored for the vast majority of exoplanetary systems, even among the closest ones, with potentially hundreds of planets still “hidden” from our knowledge. Dynamite is a powerful software package that can predict the presence and properties of these yet-undiscovered planets. We have significantly expanded the integrative capabilities of Dynamite, which now allows for (i) planets of unknown inclinations alongside planets of known inclinations, (ii) population statistics and model distributions for the eccentricity of planetary orbits, and (iii) three different dynamical stability criteria. We demonstrate the new capabilities with a study of the HD 219134 exoplanet system consisting of four confirmed planets and two likely candidates, where five of the likely planets and candiates are Neptune-sized or below with orbital periods less than 100 days. By integrating the known data for the HD 219134 planetary system with contextual and statistical exoplanet population information, we tested different system architecture hypotheses to determine their likely dynamical stability. Our results provide support for the planet candidates, and we predict at least two additional planets in this system. We also deploy Dynamite on analogs of the inner solar system by excluding Venus or Earth from the input parameters to test Dynamite's predictive power. Our analysis finds that the system remains stable while also recovering the excluded planets, demonstrating the increasing capability of Dynamite to accurately and precisely model the parameters of additional planets in multiplanet systems.
Journal Article
Why the Western Pacific Subtropical High Has Extended Westward since the Late 1970s
The western Pacific subtropical high (WPSH) is closely related to Asian climate. Previous examination of changes in the WPSH found a westward extension since the late 1970s, which has contributed to the interdecadal transition of East Asian climate. The reason for the westward extension is unknown, however. The present study suggests that this significant change of WPSH is partly due to the atmosphere’s response to the observed Indian Ocean–western Pacific (IWP) warming. Coordinated by a European Union’s Sixth Framework Programme, Understanding the Dynamics of the Coupled Climate System (DYNAMITE), five AGCMs were forced by identical idealized sea surface temperature patterns representative of the IWP warming and cooling. The results of these numerical experiments suggest that the negative heating in the central and eastern tropical Pacific and increased convective heating in the equatorial Indian Ocean/Maritime Continent associated with IWP warming are in favor of the westward extension of WPSH. The SST changes in IWP influences the Walker circulation, with a subsequent reduction of convections in the tropical central and eastern Pacific, which then forces an ENSO/Gill-type response that modulates the WPSH. The monsoon diabatic heating mechanism proposed by Rodwell and Hoskins plays a secondary reinforcing role in the westward extension of WPSH. The low-level equatorial flank of WPSH is interpreted as a Kelvin response to monsoon condensational heating, while the intensified poleward flow along the western flank of WPSH is in accord with Sverdrup vorticity balance. The IWP warming has led to an expansion of the South Asian high in the upper troposphere, as seen in the reanalysis.
Journal Article
The Modeling and Simulation of Chaff Release at High Speed
Commonly, chaff cartridge release the chaff based on detonating the dynamite or blasting form projectile. In order to improve the scatter effect of chaff, a novel technique of chaff release is proposed, which is be carried by a given carrier revolving around an axis at high speed. And the model of chaff motion in the phase of dispersing rapidly is established on the basis of the analysing the influence of resistance, gravity and viscous force. Simulation instance show that the method based on revolving carrier is efficacious, and some useful revelation can be elicited from the simulation. The research in this paper has great significance for the research and engineering implementation of gun launched chaff jamming projectile.
Journal Article
Dynamical modelling of galaxies with DYNAMITE
The combination of kinematic and chemical information from Galactic stars has revealed in great detail the structure, dynamics and history of our own Galaxy. In external galaxies, it is impossible to map the distribution of individual stars, but high signal-to-noise integral field unit (IFU) spectroscopy data at various wavelengths, together with sophisticated dynamical models, give us the opportunity to gather information on the structure, dynamics and formation history of these systems. The Schwarzschild method models galaxies through the superposition of stellar orbits, and is equipped to deal with very detailed kinematic measurements, allowing us to take full advantage of high-quality IFU datasets of nearby galaxies. Here we present an implementation of this method called DYNAMITE. We provide an overview of the modelling technique, introduce applications to observations and simulations, and anticipate our future plans for DYNAMITE.
Journal Article