The X-Ray Imaging and Spectroscopy Mission (XRISM) is a joint mission between the Japan Aerospace Exploration Agency (JAXA) and the National Aeronautics and Space Administration (NASA) in collaboration with the European Space Agency (ESA). In addition to the three space agencies, universities and research institutes from Japan, North America, and Europe have joined to contribute to developing satellite and onboard instruments, data-processing software, and the scientific observation program. XRISM is the successor to the ASTRO-H (Hitomi) mission, which ended prematurely in 2016. Its primary science goal is to examine astrophysical problems with precise, high-resolution X-ray spectroscopy. XRISM promises to discover new horizons in X-ray astronomy. It carries a 6 × 6 pixelized X-ray microcalorimeter on the focal plane of an X-ray mirror assembly (Resolve) and a co-aligned X-ray CCD camera (Xtend) that covers the same energy band over a large field of view. XRISM utilizes the Hitomi heritage, but all designs were reviewed. The attitude and orbit control system was improved in hardware and software. The spacecraft was launched from the JAXA Tanegashima Space Center on 2023 September 6 (UTC). During the in-orbit commissioning phase, the onboard components were activated. Although the gate valve protecting the Resolve sensor with a thin beryllium X-ray entrance window was not yet opened, scientific observation started in 2024 February with the planned performance verification observation program. The nominal observation program commenced with the following guest observation program beginning in 2024 September.
Terraforming Mars is an age old science fiction concept now worth revisiting through the lens of modern science and technology. This document serves as a summary of contemporary ideas about Mars terraforming, prepared for attendees of the 2025 Green Mars Workshop. It presents one illustrative story of how Mars might be transformed into a habitable world. The story is told in reverse, beginning with possible planetary endpoints and tracing backward to the steps required to reach them. Along the way, it highlights alternative approaches, critical unknowns and research priorities, and the near term applications and benefits of terraforming research for planetary science, climate engineering, and sustainable technologies on Earth.
Colin Snodgrass, Marina Galand, Arnaud Beth
et al.
We describe how the ESA Comet Interceptor mission, which is due to launch in 2028/29 to a yet-to-be-discovered target, can provide a conceptual basis for a future mission to visit an Interstellar Object. Comet Interceptor will wait in space until a suitable long period comet is discovered, allowing rapid response to perform a fast flyby of an object that will be in the inner Solar System for only a few years; an enhanced version of this concept could realistically provide the first in situ investigation of a visitor from another star system.
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.
CompOSE (CompStar Online Supernovae Equations of State) is an online repository of equations of state (EoS) for use in nuclear physics and astrophysics, e.g., in the description of compact stars or the simulation of core-collapse supernovae and neutron-star mergers, see https://compose.obspm.fr. The main services, offered via the website, are: a collection of data tables in a flexible and easily extendable data format for different EoS types and related physical quantities with extensive documentation and referencing; software for download to extract and to interpolate these data and to calculate additional quantities; webtools to generate EoS tables that are customized to the needs of the users and to illustrate dependencies of various EoS quantities in graphical form. This manual is an update of previous versions that are available on the CompOSE website, at arXiv:1307.5715 [astro-ph.SR], and that was originally published in the journal “Physics of Particles and Nuclei” with doi:10.1134/S1063779615040061. It contains a detailed description of the service, containing a general introduction as well as instructions for potential contributors and for users. Short versions of the manual for EoS users and providers will also be available as separate publications.
Luciene da Silva Coelho, Edgar Mendoza, Amancio Cesar dos Santos Friaça
This work presents the results of a theoretical study that analyzed the possibility of nucleobases to form in the interstellar medium, in the Horsehead nebula, which is a region considered an archetype of molecular cloud. Performing the Meudon PDR code, the reactions of the nitrogen bases formation from formamide, which is a precursor compound identified in several interstellar environment, where simulated. The model showed that at least cytosine and uracil presented significant abundances. Finally, from thermochemical and quantum calculations, a investigation was carried out on the formation reactions considered for the nucleobases and no insurmountable energy barrier which would prevent the reactions was found.
Rajib Kumbhakar, Soumen Mondal, Samrat Ghosh
et al.
We present a comprehensive analysis of a Transiting Exoplanet Survey Satellite (TESS) high-quality light curve for a young brown dwarf, MHO~4 having spectral type M7.0, in the Taurus star-forming region. We investigate the rotation periods and characterize the BD's dynamic atmosphere and surface features. We present light curve analysis of MHO~4, and estimate the rotation period to be around 2.224~d. Remarkably, MHO~4 exhibits two significant flaring events. Furthermore, we also estimated bolometric flare energies to be within the energy range of $10^{34}$ to $10^{35}$ erg, which sits in the superflare category.
Expansions in the oscillation modes of tidally perturbed bodies provide a useful framework for representing tidally induced flows. However, recent work has demonstrated that such expansions produce inaccurate predictions for secular orbital evolution when mode damping rates are computed independently. We explore the coupling of collectively driven modes by frictional and viscous dissipation, in tidally perturbed bodies that are both non-rotating and rigidly rotating. This exploration leads us to propose an alternative approach to treating the damping of tidally driven oscillations that accounts for dissipative mode coupling, but which does not require any information beyond the eigenfunctions and eigenfrequencies of adiabatic modes.
Esse artigo discute a questão temporal em cosmologia, em particular a crítica de Gödel ao uso de um tempo cósmico global. Examina também os sistemas de coordenadas que permitem a separação da variedade espaço-tempo em três dimensões de espaço e um tempo único comum. Descreve a possibilidade de usar um sistema gaussiano que permite tal separação, e examina ainda as condições em que um tempo cósmico não pode ser usado para cobrir toda a variedade, como no modelo de Gödel.
A pilot survey conducted at the Lookout Observatory has confirmed seven faint (V ~ 13 to 17) variables in the region of Kepler-76b that were recently discovered by the Asteroid Terrestrial-Impact Last Alert System (ATLAS). The ATLAS survey identified 315,000 probably variables within its wide-field survey in 2018. The faintness (down to r ~ 18) and small amplitudes (down to 0.02 mag) included in these candidates makes external validation difficult. Our confirmation of seven such variable stars gives credibility to the ATLAS list. Further, the agreement between various surveys and LO data validates the use of our new survey for variable star and exoplanet research.
Reliable spatial information can be difficult to obtain in planetary remote sensing applications because of errors present in the metadata of images taken with space probes. We have designed a pipeline to address this problem on disk-resolved images of Jupiter's moon Europa taken with New Horizons' LOng Range Reconnaissance Imager, Galileo's Solid State Imager and Voyager's Imaging Science Subsystem. We correct for errors in the spacecraft position, pointing and the target's attitude by comparing them to the same reference. We also address ways to correct for distortion prior to any metadata consideration. Finally, we propose a vectorized method to efficiently project images pixels onto an elliptic target and compute the coordinates and geometry of observation at each intercept point.
A commissioning survey of the Lookout Observatory has observed fourteen faint (V ~ 13 to 17) variables in the region of the exoplanet Kepler-8b. Three of these are variable star candidates discovered by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) and confirmed here. The ATLAS survey identified 315,000 probable variables within its wide-field survey in 2018. The faintness (down to r ~ 18) and small amplitudes (down to 0.02 mag) included in these candidates makes external validation difficult. The confirmation of this handful of variable stars lends credibility to the ATLAS catalog. Lastly, the agreement between various surveys and this new one validates the use of this instrument for variable star and exoplanet research.
A primeira formulação de uma física completa, do ponto de vista lógico, foi feita por Aristóteles no século IV a.c. A física aristotélica dominou o pensamento ocidental por quase dois mil anos. Tentarei mostrar neste texto que as teses aristotélicas contêm um primeiro protótipo de teoria gravitacional, inteiramente refutada a partir dos conhecimentos atuais, mas mesmo assim importante pelo contexto em que surge e por suas diversas implicações.
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.
Rotational scaling relationships are examined for the degree of equipartition between magnetic and kinetic energies in stellar convection zones. These scaling relationships are approached from two paradigms, with first a glance at scaling relationship built upon an energy-balance argument and second a look at a force-based scaling. The latter implies a transition between a nearly-constant inertial scaling when in the asymptotic limit of minimal diffusion and magnetostrophy, whereas the former implies a weaker scaling with convective Rossby number. Both scaling relationships are then compared to a suite of 3D convective dynamo simulations with a wide variety of domain geometries, stratifications, and range of convective Rossby numbers.
Krzysztof G. Hełminiak, Andrés Jordán, Nestor Espinoza
et al.
We present high-precision light curves of several M- and K-type, active detached eclipsing binaries (DEBs), recorded with 2-minute cadence by the Transiting Exoplanet Survey Satellite (TESS). Analysis of these curves, combined with new and literature radial velocity (RV) data, allows to vastly improve the accuracy and precision of stellar parameters with respect to previous studies of these systems. Results for one previously unpublished DEB are also presented.
HAT-P-11 is a planet-hosting K4V star in the Kepler field, with an activity cycle that bear similarities to the Sun's. The chromospheric activity of HAT-P-11 indicates that a new activity cycle is beginning. We report ground-based observations with holographic diffuser photometry to measure the starspots of HAT-P-11 in its second observed magnetic activity cycle (Cycle 1). We find the area coverage of starspots within the transit chord for UTC 2017-10-30 is 14% --- which makes this transit the most spotted HAT-P-11 transit observed to date. We suggest that we are likely observing occultations of large spot groups appearing at the beginning of Cycle 1.
Mark A. Hutchison, Daniel J. Price, Guillaume Laibe
We present a new algorithm, MULTIGRAIN, for modelling the dynamics of an entire population of small dust grains immersed in gas, typical of conditions that are found in molecular clouds and protoplanetary discs. The MULTIGRAIN method is more accurate than single-phase simulations because the gas experiences a backreaction from each dust phase and communicates this change to the other phases, thereby indirectly coupling the dust phases together. The MULTIGRAIN method is fast, explicit and low storage, requiring only an array of dust fractions and their derivatives defined for each resolution element.
The search for extraterrestrial communication has mainly focused on microwave photons since the 1950s. We compare other high speed information carriers to photons, such as electrons, protons, and neutrinos, gravitational waves, inscribed matter, and artificial megastructures such as occulters. The performance card includes the speed of exchange, information per energy and machine sizes, lensing performance, cost, and complexity. In fast point-to-point communications, photons are superior to other carriers by orders of magnitude. Sending probes with inscribed matter requires less energy, but has higher latency. For isotropic beacons with low data rates, our current technological level is insufficient to determine the best choice. We discuss cases where our initial assumptions do not apply, and describe the required properties of hypothetical particles to win over photons.