The digitization of historical astronomical plates is essential for preserving century-long observational data. This work presents the development and application of the specialized digitizers at the Shanghai Astronomical Observatory (SHAO), including technical details, international collaborations, and scientific applications on the plates.
Supernova 2018ibb of the PISN category related to the dynamical instability of oxygen core in a supermassive star induced by pair-creation shows at the nebular stage strong [\oiii] emission lines of an uncertain origin. I propose a simple model that demonstrates a possibility of [O III] lines emission from the supernova oxygen matter ionized and heated by the $^{56}$Co radioactive decay. The reason is pinpointed by which the [O III] line luminosity among supernovae of PISN category can vary in a broad range.
Lee D. Feinberg, John Ziemer, Megan Ansdell
et al.
NASA began the Great Observatory Maturation Program (GOMAP) with the goal of studying and advancing the Habitable Worlds Observatory (HWO), a large ultraviolet, optical, infrared space telescope recommended by the Astro 2020 Decadal Survey. Among its many goals, HWO will obtain spectra of at least 25 exo-Earth candidates to search for signs of life and conduct transformative astrophysics at ultraviolet, optical, and near-infrared wavelengths. The observatory, like HST and JWST, will be a powerful general class observatory. This past fall the GOMAP program stood up two study groups, the Science Technology Architecture Review Team (START) and the Technical Assessment Group (TAG) aimed at helping to study the science, technology and architecture options for this new flagship mission. This talk will discuss the engineering activities associated with these studies including the team and organization, the study plan and the use of the Concept Maturity Level (CML) approach. In addition, the talk will discuss the key initial engineering efforts, the key technology gaps, and overall engineering plans.
The Astro 2020 Decadal Survey"Pathways to Discovery in Astronomy and Astrophysics for the 2020s"has recommended that"after a successful mission and technology maturation program, NASA should embark on a program to realize a mission to search for biosignatures from a robust number of about ~25 habitable zone planets and to be a transformative facility for general astrophysics,"and prescribing that the high-contrast direct imaging mission would have"a target off-axis inscribed diameter of approximately 6 meters."The Decadal Survey assumed an exo-Earth frequency of ~25%, requiring that approximately 100 cumulative habitable zones of nearby stars should be surveyed. Surveying the nearby bright stars, and taking into account inputs from the LUVOIR and HabEx mission studies (but without being overly prescriptive in the required starlight suppression technology or requirements), we compile a list of 164 stars whose exo-Earths would be the most accessible for a systematic imaging survey of habitable zones with a 6-m-class space telescope in terms of angular separation, planet brightness in reflected light, and planet-star brightness ratio. We compile this star list to motivate observations and analysis to help inform observatory design (mission-enabling"precursor science") and enhance the science return of the Habitable Worlds Observatory (HWO) survey for exo-Earths (mission-enhancing"preparatory science"). It is anticipated that this list of target stars and their properties will be updated periodically by the NASA Exoplanet Exploration Program.
A key to understand exoplanets is characterisation of their host stars. One of the most powerful tools to characterise stellar properties like effective temperature, surface gravity and metallicity, is spectroscopy based on observations of stellar atmospheres. This chapter describes the stellar parameters that can be derived from a spectrum with examples of well established methods and theoretical model atmospheres. Combined with photometry and parallax measurements, the outcome of the spectroscopic modelling can be used to derive stellar radii and masses.
Gwenaëlle Dufour, Steven B. Charnley, Johan E. Lindberg
We have studied gas-grain chemical models of interstellar clouds to search for nonlinear dynamical evolution. A prescription is given for producing oscillatory solutions when a bistable solution exists in the gas-phase chemistry and we demonstrate the existence of limit cycle and relaxation oscillation solutions. As the autocatalytic chemical processes underlying these solutions are common to all models of interstellar chemistry, the occurrence of these solutions should be widespread. We briefly discuss the implications for interpreting molecular cloud composition with time-dependent models and some future directions for this approach.
Desde a descoberta dos primeiros planetas fora do Sistema Solar, os chamados exoplanetas, na década de 90, mais de 5000 exoplanetas já foram descobertos, além dos milhares de candidatos sendo analisados. A descoberta de que existem sistemas planetários ao redor de outras estrelas, suscita naturalmente o questionamento sobre a possibilidade de que esses exoplanetas possam hospedar vida. É nesse contexto que ganha cada vez mais destaque a astrobiologia, área de pesquisa multidisciplinar que consiste no estudo da origem e evolução da vida no Universo. Neste artigo apresentaremos uma breve revisão sobre a procura por exoplanetas e os principais resultados interessantes do ponto de vista da astrobiologia até o momento. Iniciaremos pela definição do conceito de zona habitável estelar, região em torno de uma estrela na qual é, em princípio, possível manter água no estado líquido na superfície de um planeta rochoso. Comentaremos sobre a procura por vida no Sistema Solar, descreveremos os principais métodos de detecção de exoplanetas e apresentaremos exemplos de exoplanetas com particular interesse astrobiológico. Finalizaremos comentando sobre a procura pelas chamadas bioassinaturas e tecnoassinaturas, indicadores da existência de vida fora da Terra, e as missões presentes e futuras com maior potencial para novas descobertas na área da astrobiologia.
This invited review for young researchers presents key ideas on cloud formation as key part for virtual laboratories for exoplanet atmospheres. The basic concepts are presented, followed by utilising a time-scale analysis to disentangle process hierarchies. The kinetic approach to cloud formation modelling is described in some detail to allow the discussion of cloud structures as prerequisite for future extrasolar weather forecasts.
Jorge Perez Gonzalez, Nicolas Carrizosa Arias, Andres Cadenas Blanco
VarStar Detect is a Python package available on PyPI optimized for the detection of variability inside photometric measurements. Based off of the Least Squares method of regression, VarStar Detect calculates the amplitude of a Fourier Polynomial fit of the data as a measure of variability to assess if the star is indeed variable. This work shows the mathematical background of the package and an analysis of the code's functionality on TESS Sector 1 Data.
Proton beam therapy (PBT) is a novel method for treating malignant disease with radiotherapy. The purpose of this work was to evaluate the state of the science of PBT and arrive at a recommendation for the use of PBT. The emerging technology committee of the American Society of Radiation Oncology (ASTRO) routinely evaluates new modalities in radiotherapy and assesses the published evidence to determine recommendations for the society as a whole. In 2007, a Proton Task Force was assembled to evaluate the state of the art of PBT. This report reflects evidence collected up to November 2009. Data was reviewed for PBT in central nervous system tumors, gastrointestinal malignancies, lung, head and neck, prostate, and pediatric tumors. Current data do not provide sufficient evidence to recommend PBT in lung cancer, head and neck cancer, GI malignancies, and pediatric non-CNS malignancies. In hepatocellular carcinoma and prostate cancer and there is evidence for the efficacy of PBT but no suggestion that it is superior to photon based approaches. In pediatric CNS malignancies PBT appears superior to photon approaches but more data is needed. In large ocular melanomas and chordomas, we believe that there is evidence for a benefit of PBT over photon approaches. PBT is an important new technology in radiotherapy. Current evidence provides a limited indication for PBT. More robust prospective clinical trials are needed to determine the appropriate clinical setting for PBT.
We present photometric transit observations of the exoplanet WASP-2b using the MTM-500 telescope of the Crimean Astrophysical Observatory of RAS. A brief history of the discovery of the exoplanet WASP-2b and its main characteristics are considered. Observations and the processing procedure are described. The analysis of the obtained results was carried out and compared with information from the ETD and NASA Exoplanet Archive databases. The photometry data of the star WASP-2 and the comparison star GSC 0052201406 are given in the supplementary table.
Here we present a "SCINDA-Iono" toolbox for the MATLAB. This is a software to analyze ionosphere scintillation indices provided by a SCINDA GNSS receiver. The toolbox is developed in the MATLAB R2018b. This software allows to preprocess the original data and analyze ionosphere scintillations on the 1-minute and 1-hour time scales both for averaged over all available satellites values and separately for each receiver-satellite pair.
À la charnière du xixe et du xxe siècle, des médiums spirites, en Europe et aux États-Unis, affirmèrent être en mesure de communiquer avec des Martiens. Les dialogues avaient lieu en langue martienne et les médiums enregistraient leur contenu au moyen d’écritures elles aussi martiennes. L’analyse de ces langues et écritures employées par Catherine Élise Müller (plus connue sous le nom d’Hélène Smith) et Ida Cleaveland (un peu plus connue sous le nom de Mrs Smead), considérées dans cet article comme des langues et des écritures inventées, apporte un éclairage original sur les facteurs linguistiques et cognitifs qui contraignirent ces inventions à adopter des logiques sémiotiques semblables.
The aim of this paper is to underline the most important aspects of advanced lung cancer therapy.The described trends and problems were presented during ASTRO 59 Conference in San Diego.
The rotation rate of a star has important implications for the detectability, characterisation and stability of any planets that may be orbiting it. This chapter gives a brief overview of stellar rotation before describing the methods used to measure the rotation periods of planet host stars, the factors affecting the evolution of a star's rotation rate, stellar age estimates based on rotation, and an overview of the observed trends in the rotation properties of stars with planets.
We develop a magnetic ribbon model for molecular cloud filaments. These result from turbulent compression in a molecular cloud in which the background magnetic field sets a preferred direction. We use our model to calculate a synthetic observed relation between apparent width in projection versus observed column density. The relationship is relatively flat, in rough agreement with the observations, and unlike the simple expectation based on a Jeans length argument.
There are two possible mechanisms to imprint planet signatures in the chemical composition of Sun-like stars: i) dust condensation at the early stages of planet formation, causing a depletion of refractory elements in the gas accreted by the star in the late stages of its formation; ii) planet engulfment, enriching the host star in lithium and refractory elements. We discuss both planet signatures, the influence of galactic chemical evolution, and the importance of binaries composed of stellar twins as laboratories to verify abundance anomalies imprinted by planets.
The presence of excesses of short-lived radionuclides in the early solar system evidenced in meteorites has been taken as testament to close encounters with exotic nucleosynthetic sources, including supernovae or AGB stars. An analysis of the likelihoods associated with different sources of these extinct nuclides in the early solar system indicates that rather than being exotic, their abundances were typical of star-forming regions like those observed today in the Galaxy. The radiochemistry of the early solar system is therefore unexceptional, being the consequence of extensive averaging of molecular cloud solids.
The correlation between the frequency and the absolute value of the frequency derivative of the kilohertz QPOs observed for the first time from 4U 1636-53 is a simple consequence and indicator of the existence of a non-Keplerian rotation rate in the accretion disk boundary layer. This paper interprets the observed correlation, showing that the observations provide strong evidence in support of the fundamental assumption of disk accretion models around slow rotators, that the boundary layer matches the Keplerian disk to the neutron star magnetosphere.