A comparative analysis of sub-THz emission of stellar flares from red dwarfs has been carried out. ALMA observations indicate that the sub-THz emission flux from stellar flares with a duration of 10 s is an order of magnitude greater than for solar flares. The sub-THz emission is linearly polarized and decreases with frequency. The degree of polarization can reach tens of percent. We show that these types of spectrum slopes and linear polarization can be caused by the synchrotron emission of ultrarelativistic electrons. The origin of the observed relationships between sub-THz, low frequency radio, and X-ray emissions of stellar flares are discussed.

Coronal rain is formed in the post-impulsive phase of solar flares due to the thermal instability of coronal plasma in EUV loops. As a result, the sub-terahertz (sub-THz) emission flux in the post-impulsive phase of solar flares can be increased due to the increasing of the optical thickness of the thermal source. This suggests that sub-THz observations can be used as a diagnostic tool for coronal rain.

This work is aimed to analyse the relationship between the sub-THz radiation and variations of the temperature and the emission measure of the EUV coronal plasma during the post-impulsive phase of the SOL2022-05-04T08:45 solar flare.

Based on the two-dimensional temperature and emission measure distributions obtained from the AIA/SDO EUV intensity data, it was found that the temperature decreases whereas the emission measure reaches the maximum near the sub-THz flare peak. This circumstance and peculiarities of the radiation time profiles in different wave ranges show evidence in favor of the significant contribution of the thermal coronal loop plasma to the flare sub-THz radiation at least for some flare events. The sub-THz emission may be associated with a coronal condensation, accompanied by the formation of coronal rain.

We present an analysis of high resolution spectra in the optical and near infrared wavelength region for cool protoplanetary nebulae with the goal to identify lines of carbon bearing molecules and some less studied neutron capture elements. The site of formation of CN and C2 lines in the spectra of IRAS 22272+5435 and IRAS Z02229+6208 appears to be an extended stellar atmosphere and inner/outer CSE. The abundance of thulium was estimated for the first time in the photosphere of IRAS22272+5435, log ε(Tm) ≃ 1.5.

I have performed numerical hydrodynamical calculations of outflows driven by the evaporation of a pseudo-barotropic ring around a luminous central star. The outflow shapes and internal structures resemble known cylindrical nebulae. Some of the corresponding synthetic spectra show ‘Hubble’ type outflow.

The origin of the sub-terahertz (sub-THz) component of radio emission from solar flares, which is characterized by the increase flux with frequency in the 100-400 GHz range, is considered. On the basis of equations of 1D non-LTE radiation hydrodynamics we simulated the altitude distribution of the plasma density and temperature inside the flare loop caused by the interaction of non-stationary beam of accelerated electrons in the form of a triangular pulse with the chromospheric plasma. The FLARIX numerical code was used to calculate the dynamics of the flare plasma parameters at different heights which are compared with the RADYN numerical code. We found that the characteristic heights of the formation of sub-THz emission vary over a wide range with time for both codes. The main contribution to the sub-THz emission comes from the chromospheric and transition region plasma with temperatures of 104–105K.

Two planetary nebulae have sofar been observed with JWST. Both show stellar companions. The paper discusses how and what we can learn from the companions.

Solar-type stars, including the Sun, have magnetic fields that extend from their interiors to the surface and beyond, influencing both the stellar activity and interplanetary medium. Magnetic activity phenomena, such as coronal mass ejections (CMEs), significantly impacts space weather. These CMEs, composed of plasma clouds with magnetic fields ejected from the stellar corona, pose a potential threat to planets by affecting their magnetosphere and atmosphere. Despite advancements in detecting stellar CMEs, detection remains limited. We focus on understanding CME propagation by analyzing key parameters like position, velocities, and the configuration of stellar magnetic fields. Using spot transit mapping, we reconstruct magnetograms for Kepler-63 and Kepler-411, employing the ForeCAT model to simulate CME trajectories from these stars. Results indicate that CME deflections generally decrease with radial velocity and increase with ejection latitude. Additionally, stars with stronger magnetic fields, such as Kepler-63, tend to cause more significant CME deflections.

Stellar activity depends on multiple parameters one of which is the age of the star. The members of open clusters are good targets to observe the activity at a given age of the stars since their ages are more precisely determined than that of field stars. Choosing multiple clusters, each with different age, gives us insight to the change in activity during the lifetime of stars. With the analysis of these stars we can also refine the parameters of gyrochronology (Barnes 2003), which is a method for estimating the age of low-mass, main sequence stars from their rotation periods.

MUSE data regarding NGC 3132 were used and analysed through SATELLITE in order to obtain 2D maps of the physico-chemical parameters of the nebula. Furthermore, our results were compared with a 3D photoionisation model built with MOCASSIN with the aim to constrain its parameters. Lastly, we utilized JWST and Spitzer IR data and examined their radial distribution.

The Planetary Nebula H 2-18 is analysed with the full-3D capabilities of the MOCASSIN code. The collected HST images help to constrain the density distribution while the ARGUS 2D spectroscopy provides a new and unique information on kinematics.

The objective of our study was the spectroscopic analysis of the PN NGC 3242, which contains a pair of low-ionization structures (LISs). For our analysis, MUSE data were used in conjunction with the SATELLITE code for a spectroscopic analysis in two spatial dimensions. Additionally, infrared images from Spitzer Space Telescope (SST) were employed to search for potential H2 emission at the LISs. The preliminary results revealed that the electron temperature calculated from [N II] diagnostics lines is approximately 12,000 K at the LISs, while the thorough examination of MUSE data has led to the identification of the [C I] 8727 Å emission line emitted only from the LISs. This result may imply that LISs are the optical counterpart of a dense molecular core. Spitzer’s data didn’t reveal the existence of H2 at LISs, but three rings were identified around the main body of the PN.

The recent acquisition of high-quality deep images of planetary nebulae (PNe) in world-class telescopes has allowed the detection for the first time of a wealth of small-scale morphological features and structures that highlight the complexity of their formation history and the physical processes modeling them. In this work we present the discovery of a series of clumps embedded within the ionized nebular shell of the evolved PN NGC 3587, the Owl Nebula, that had escaped previous detections. The multi-wavelength analysis provided by GEMINI, NOT and Aristarchos in the optical and CFHT and Spitzer infrared images indicates that these clumps are formed by denser and colder material, with a notable content of molecular H2.

We present new high-spectral resolution échelle spectra of IC 4997 obtained in 2023 June to study the evolution of its recently reported variable Hα emission line profile. Compared with similar spectra from 2020 September, the new ones also show a single-peaked profile but the full velocity width of the Hα wings has increased by a factor of; 1.2. Besides, we use our high-resolution échelle spectra to investigate the internal kinematics of the nebula. Preliminary analysis suggests that the two shells of IC 4997 are kinematically resolved: the outer shell expands at; 10–14 km s-1 and the inner shell at; 25 km s-1.

OH masers are signpost of planetary nebulae (PNe) at a very young stage. In particular, Vy 2-2 was the first OH maser-emitting PN ever identified. It consists of a bright compact shell and a faint bipolar structure. The reported values for its O+2/H+ abundance discrepancy factor (ADF) are inconsistent:; 4.3, and; 11.8. To characterize the ionized gas and to redetermine the ADF(O+2), we have obtained medium-resolution optical spectra. We found that the ionized gas is oxygen-rich (C/O; 0.15), and an ADF(O+2); 13.6. Also, the N/O abundance ratio is; 0.39, implying a low-mass progenitor (Mi ≤ 1.5 Me). Unexpectedly, the detection of stellar weak emission lines (wels) suggests that the central star is carbon-rich. Alternatively, the wels may be emitted by an irradiated companion in a post-common envelope system. We have also obtained high-resolution optical spectroscopy on Vy 2-2. Our spectra kinematically resolve the bright shell and bipolar structure. We found that these expand at: 10 and: 20 km s-1, respectively.

Optical spectra of the Very Late Thermal Pulse (VLTP) object V4334 Sgr have shown a rapidly changing spectrum resulting from shocks in the outflow, which created a new bipolar nebula inside the old nebula. We see C II and C III emission lines emerging typical of a [WC 11-10]-type star. The strong increase of [O III] and [S III] emission lines indicate the possible onset of photoionisation in the new ejecta.

V510 Pup (IRAS 08005-2356) is a binary post-AGB system with a fast molecular outflow that has been noted for its puzzling mixture of carbon- and oxygen-rich features in the optical and infrared. To explore this chemical dichotomy and relate it to the kinematics of the source, we present an ACA spectral line survey detailing fourteen newly detected molecules in this pre-planetary nebula. The simultaneous presence of CN/C2H/HC3N and SO/SO2 support the previous conclusion of mixed chemistry, and their line profiles indicate that the C- and O-rich material trace distinct velocity structures in the outflow. This evidence suggests that V510 Pup could harbor a dense O-rich central waist from an earlier stage of evolution, which persisted after a fast C-rich molecular outflow formed. By studying the gas phase composition of this unique source, we aim to reveal new insights into the interplay between dynamics and chemistry in rapidly evolving post-AGB systems.

Meeting number 384 in the IAU’s Symposium series, Planetary Nebulae: a Universal Toolbox in the Era of Precision Astrophysics, featured an overwhelming array of exciting observational and theoretical developments in the study of planetary nebulae. I attempt to identify the themes and threads that ran through the meeting, some of them popping up in unexpected ways and connecting otherwise disparate science sessions. I also highlight key open questions that this meeting has raised for the benefit of future planetary nebula research.