This study presents geodynamic experiments within the outer ice shell of Ganymede to investigate the effects of partial melting into the convective layer, and trying to infer any correlation between internal processes and strain deformations in surface regions such as cryovolcanism and polar deposits. The numerical models were conducted performing a sensitive analysis of the internal dynamic for compressible fluids by varying the viscosity, ice shell thickness, pressure at the melting point of ice, and applying the Anelastic Liquid Approximation (ALA). Results show molten material under restricted geophysical parameters that could allow for emerging material from the subsurface ocean to the surface. These findings will support the objectives of the RIME instrument on board of the JUICE mission, as they point out specific conditions that may, in the future, help to have a better understanding of the internal mechanisms that transfer heat on the surface and modify the geomorphology and atmospheric processes.

FU Ori stars (FUors) are undergoing powerful luminosity outbursts of ∼100 L⊙ in magnitude and of several decades in duration. Such outbursts inevitably affect physical and chemical structure of the surrounding protoplanetary disk. Using astrochemical and radiative transfer modelling, we study the lasting impact of the outburst on disks with and without an envelope and how it changes flux in chosen molecular lines. We formulate a number of criteria indicative of a recent outburst activity based on the molecular emission, analyze the chemistry behind the flux change and apply the criteria to available observations of quiescent protoplanetary disks. The latter revealed ten objects with possible outbursts in the past and four of them satisfy multiple proposed criteria.

We conducted the 31-night time-resolved simultaneous optical spectroscopic and pho-tometric observations of the mid M dwarf flare stars YZ CMi, EV Lac, and AD Leo, using APO 3.5m and SMARTS 1.5m telescopes. Among the 41 detected flares, 7 flares showed clear blue wing asymmetries in Balmer lines, with various correspondences in flare properties (e.g., flare durations are 20 min – 2.5 hours). The line-of-sight velocities of the blue-shifted components range from −73 to −122 km s−1. Assuming that the blue-shifts were caused by prominence eruptions, the mass of upward moving plasma was estimated to be 1015 − 1019 g, which are roughly on the relation between flare energy and erupting mass expected from solar coronal mass ejections (CMEs). Although further investigations are necessary for understanding the observed various properties, these possible prominence eruptions on M-dwarfs could evolve into CMEs, assuming the similar acceleration mechanism with solar eruptions.

With the combination of observations from in-situ and high-resolution remote sensing instruments, the Solar Orbiter (SolO) mission has become a particularly valuable mission for studying the inner heliosphere. With a field of view (FOV) of 4° to the east of the Sun, the Solar Orbiter Heliospheric Imager (SoloHI) is one of the six remote sensing instruments on board the Solar Orbiter (SolO) spacecraft. SoloHI’s high-resolution imaging observations of the heliosphere and its higher cadence than previous generations of heliospheric imagers make it a perfect candidate to perform and complement studies of CMEs evolution through the heliosphere. In this work, we present the first prominence material detected by SoloHI along with other remote sensing instruments. We report that as the CME propagates out in the heliosphere, the associated filament material reaches a heliocentric height of ∼122.5 R⊙ (∼0.57 au).

This paper studies instability of the in-plane equilibrium points (EPs) which lies on the line joining the main bodies in the frame of the restricted three-body problem with Poynting-Robertson (P-R) drag force and variable masses. The dynamical structures of the primaries and their mass variation are governed by the Gylden-Mestschersky problem (GMP) and the Mestschersky combined law (MCL), respectively, under the conditions that both primaries are radiation emitters with the Doppler shift and the absorption and subsequent re-emission of the incident radiation, considered. It is seen that there can be three, four and even up to six Collinear In-plane Equilibrium Points (CIEPs). Some are independent of the P-R drag while others depend on the mass parameter and P-R drag of the primaries. The stability of the CIEPs is investigated analytically and numerically for a dust grain particle in the gravitational field of all binary systems which covers most astronomical systems, and it is seen that all the CIEPs are unstable. Additionally, it is seen that the zero velocity curves (ZVC) around the CIEP L0, for all mass parameter do not exist as the P-R drag effects are annulled in the force function. Consequently, the resulting CIEP will be located on same point as the bigger primary, which in turns means that the force function will be undefined in this case. The stability of the CIEPs of the non-autonomous system which differ from those of the autonomized system by a function of time, are unstable as they do not converge as time tends to infinity. Our problem can be applied to the description of a dust grain in the gravitational field of stellar systems with radiation force and variable masses.

Stellar outflows, in the form of winds and transient (bursty) mass ejections, drive the “exo-space weather” around exoplanets. The exo-space weather can be substantially dif-ferent from that of solar system planets. In particular, close-in exoplanets experience much harsher stellar wind conditions than any planet in the solar system. These exoplanets are con-veniently located in the region where the stellar wind is still accelerating, and they are thus nature’s own “Parker Solar Probe” or “Solar Orbiter”. Here, we present our recent efforts towards characterising the stellar wind properties of GJ 436. UV spectroscopic transits and optical spectropolarimetric observations of the host star, together with 3D MHD wind models, have allowed us to probe the wind of the planet hosting star GJ 436. This has implications for constraining exo-space weather and also for understanding the wind driving of cool dwarf stars.

Modelling is essential for studies that quantify the impact from satellite downlinks on radio astronomy sites. To estimate this impact it is necessary to know not only the position and velocity of satellites but also their behaviour in the radio spectrum domain. As many large satellite constellations are using steerable beam antennas, deterministically predicting the transmitted power towards a defined direction (in this case where a radio telescope points) becomes an almost impossible task and therefore another approach has to be used. This work presents a method to simulate and estimate the percentiles of the radiation pattern of satellites with steerable beam patterns based on simulations and a comparison with measurements of Starlink satellites using the Onsala Twin Telescopes in Sweden.

An overview is presented of the activities of the ALMA Spectrum Management Office and the synergies with other entities that engage in similar scientific research activities or that develop actions aimed at the control and regulation of radio frequency emissions.

This study focuses on the impact of satellite trails on spectroscopic observations in the visible and near-infrared, which represent a large fraction of the observing time on large professional telescopes. We simulate the number of observations affected using an hypothetical large set of low Earth orbit satellite constellations. We evaluate the effect of this contamination on various spectrographs. We also measure the contamination on actual data from the ESO archive for a set of representative objects, after adding a scaled solar analogue spectrum to represent the satellite.

Even with a satellite population much larger than today’s, the fraction of contaminated spectra will remain low, essentially thanks to the typically small field of view of these instruments. Furthermore, high-resolution spectrographs, and medium-resolution ones on smaller telescopes, are essentially blind to satellites. However, for a range of instruments the contamination will be at a level comparable to that of the science signal, making its identification difficult, and potentially affecting the astrophysical measurements derived from the data.

Coronal mass ejections (CMEs) have been suggested to be the source of high-energy protons producing sustained gamma-ray emission (SGRE) events at the Sun, where the >100 MeV gamma-ray emission observed by Fermi Large Area Telescope (LAT) lasts beyond the end of the associated X-ray flare. Large SEP events observed at 1 au are produced by shocks driven by fast and wide (FW) CMEs. However, there are more large SEP events than SGRE events and more FW CMEs than the large SEP events. Magnetic connectivity of the observer to the shock nose affects the detectability of SEP events at 1 au. [Makela et∼al., 2023] found that the SGRE-producing halo CMEs associated with type II radio bursts and/or a large SEP events have higher space speeds and initial accelerations than those without an SGRE event. In this paper, we consider characteristics of CME eruptions associated with co-occurring SEP and SGRE events.

We are in the age of the direct and indirect search for extraterrestrial life. The major question is: what are we looking for and to what extent can life on Earth provide an analogy for extraterrestrial life. We will address these questions by examining the emergence of life and its evolution through geological time, based on consideration of the Earth as an exoplanet. We conclude that, with the exception of a couple of hundred million years during the Great Oxydation Event 2.3-2.1 Ga, it would not have been possible for an extraterrestrial observer to detect traces of terrestrial life until the advent of planktonic eukaryotic algae after the Neoproterozoic Oxydation Event about 800 Ma. Thus, for most of the history of life on Earth, there would be no externally observable evidence of its existence. We address the implications of this for the search for extraterrestrial life.

The increasing amount of space debris and the number of mega-constellations are creating a serious problems for terrestrial astronomy. Light trails caused by these objects contaminate astronomical images, rendering them ultimately worthless. Knowing where in the sky these objects will be and how bright they will be are essential to optimising observation planning and avoiding such contamination. Photometric phase functions are a powerful tool for understanding asteroids and resident space objects (RSOs) such as satellites, upper stages, and space debris. However, they also provide a means of predicting how these objects will reflect sunlight toward the observer. We consider a model that assumes a spherical object with diffuse and specular components. We defined the phase functions of more than 600 rotating RSOs using more than one million photometric measurements of more than 10 000 objects from the Mini-MegaTORTORA (MMT) light curve catalogue. We discuss in detail the photometric properties of space debris and satellites extracted from the MMT photometric catalogue using the model. We introduce our freely available online service that predicts the brightness of RSOs, including space debris and mega-constellations, for the purpose of supporting astronomers’ decision-making.

Astrobiology is generally considered to be a promising gateway into science, and storytelling techniques have been getting increasingly more traction lately in education and outreach because of their potential benefits for learning. At the European Astrobiology Institute, we combined these two pathways by creating two anthologies of astrobiology-inspired science fiction stories accompanied by science fact essays, Strangest of All and Life Beyond Us. Furthermore, we created educational materials that build on the anthology project and acquaint students with the issue of planetary protection. Here we introduce the project and planned future directions in story-driven astrobiology outreach and education.

In the recent past investigations of stellar Coronal Mass Ejections (CMEs) and flares/superflares gained special attention because of their relevance for planetary habitability and stellar evolution. With respect to that, we present an observing campaign at the ESO152 telescope on LaSilla operated by the PLATOSpec consortium of the late-K/early-M dwarf binary CC Eri. The ESO152 telescope is currently equipped with an Echelle spectrograph which enables the investigation of a broad spectral range, allowing the investigation of CMEs and flares/superflares in various spectral lines. Within the observing campaign CC Eri was not observed by TESS, but we have coordinated g’-band photometry to cross-check for white light flares. Preliminary results of the observing campaign are presented.

This paper presents an overview of the attitudes and awareness within the amateur astronomical community regarding modern satellite megaconstellation projects. A series of interviews and polls to assess the perspectives of this large community was conducted, aiming to uncover their concerns and issues. Additionally, the potential to involve respondents in community-driven projects focused on satellite data acquisition and processing was investigated. The objective is to enhance data quality for astronomical imagery protection and improve existing tools for scientific research, including satellite tracking, trajectory prediction, and the detection of space debris and orbital objects.

We examined the origin of 3He abundance enhancement in 23 high-energy (25–50 MeV) solar proton events that coincide with 3He-rich periods detected by ACE ULEIS in 1997–2021. In seven events, 3He enhancement was due to 3He leftover from preceding events or independent 3He events occurring during proton events. One event is the most likely impulsive (3He-rich), and another is unclear. Reaccelerated remnant flare material was the most probable cause of 3He enhancements in the remaining 14 proton events. Imaging observations showed coronal jets in the parent active regions in six of these 14 events. Remarkably, the highest 3He/4He occurred in events with jets, implying their contribution to 3He enhancement.

Traditionally the search for extraterrestrial intelligence (SETI) has been mostly a kind of engineering task, based on two assumptions: the existence of other technological culture somewhere in our Galaxy and that this culture is using radiotechnology that can be detected with our receivers. However, SETI endeavors could benefit more by expanding its scope into two-folded interdisciplinary research program, one exploring the nature of human, other animals, and artificial cognition, and the another exploring all possible and hypothetical ways and channels that potential ETI could use to manifest itself. This kind of new research program could be named cognitive astrobiology in order to better describe its research areas.

This paper provides an update on the coronal mass ejection (CME) catalog maintained at the CDAW Data Center, NASA Goddard Space Flight Center (http://cdaw.gsfc.nasa.gov/CME_list). This is version 2 (v2) of the Catalog that has been made as the default version as of May 1, 2024. The new features of the Catalog v2 are (i) online measurement tool, (ii) combination JavaScript movies from the STEREO and Solar Dynamics Observatory (SDO) missions, and (iii) insertion of newly identified CMEs for the period 1996 to 2004. The CME identification was revisited resulting in a set of ∼3000 new CMEs added to the Catalog. A vast majority of these CMEs are weak and narrow. The resulting statistical properties of CMEs are not significantly different from those reported using version 1.

The predicted impact of large satellite constellations on optical astronomy has been worked out, from the beginning, using Montecarlo methods: individual satellite orbits inside each shell are randomly initialised and satellite tracks are computed one by one to check whether or not they hit the field of view, and under what conditions. However, it is known that the density of satellites inside each shell follows the analytic double-sine probability density distribution, which offers new ways to get similar results at a much lower computational cost. We compare results obtained applying the two approaches and we derive some conclusions on the advantages and drawbacks of each method. The original FORTRAN code of the software is available at https://galadi.net/satsim/.

In the JCMT-Venus project, we conducted three multi-week disc-integrated observations of Venus’ atmosphere using the JCMT ‘Ū‘ū receiver. This paper focuses on the HDO 2(2,0)-3(1,3) transition line at 266.1611 GHz, employed as a proxy for water abundance under the assumption of a constant D/H ratio. Based on the HDO line depth, we observed significant and rapid short-term variations, and have tentatively identified potential long-term effects. Water vapor abundance values were retrieved daily, and their variations will be displayed and discussed in our forthcoming publications.