We performed numerical simulations of the common envelope (CE) interaction between two intermediate-mass asymptotic giant branch (AGB) stars and their low-mass companions. For the first time, formation and growth of dust in the envelope is calculated explicitly. We find that the first dust grains appear as early as ∼1–3 yrs after the onset of the CE, and are smaller than grains formed later. As the simulations progress, a high-opacity dusty shell forms, resulting in the CE photosphere being up to an order of magnitude larger than it would be without the inclusion of dust. At the end of the simulations, the total dust yield is ∼8.2×10−3 M⊙ (∼2.2×10−2 M⊙) for a CE with a 1.7 M⊙ (3.7 M⊙) AGB star. Dust formation does not substantially lead to more mass unbinding or substantially alter the orbital evolution.

Magnetic fields are important physics in stellar evolutionary theory, which seriously affects the stellar structure and evolutionary statues. The small-scale magnetic fields in the photosphere are ubiquitous, and float on the stellar surface, which usually couple with the acoustic waves, affecting the propagation of the acoustic waves. Considering the effect of the magnetic fields in the stellar photosphere on the oscillation frequencies, we calculate the asteroseismology for solar-like star KIC 11295426 and KIC 10963065. We obtain the stellar fundamental parameters, especially the strength of small-scale magnetic fields in the stellar photosphere. We find that the small-scale magnetic fields in the stellar photosphere may obviously improve the agreement between the observations and the theoretical models for two stars. The magnetic strength for KIC 11295426 and KIC 10963065 from asteroseismology are in agreement with the stellar period-activity relation.

Planetary nebulae (PNe) are remnants of evolved stars, fundamental for understanding stellar life cycles and galactic enrichment. In this work, we present a summary of our recent work using three-dimensional models and spatially resolved constraints to examine the physical and chemical properties of PNe, with a particular focus on preliminary results for the PN NGC 3132. Our results indicate that a star of about 3M⊙, surrounded by a shell, wind, or disk with approximately 5.0×10−6M⊙ and extending to about 300AU is necessary to adequately reproduce the observations, consistent with recent JWST findings. We also discuss the importance of this methodology in studying the properties of the progenitor stars and making abundance determinations.

The formation of the Magellanic Bridge during an encounter between the Magellanic Clouds ∼ 200 Myr ago would be imprinted in the chemical evolution and kinematics of its stellar population, with sites of active star formation. Since it contains hundreds of stellar clusters and associations, we combined deep photometry from VISCACHA and SMASH surveys to explore this topic, by deriving structural parameters, age, metallicity, distance and mass for 33 Bridge clusters with robust statistical tools. We identified a group of 13 clusters probably stripped from the Small Magellanic Cloud (0.5 − 4.7 Gyr, [Fe/H] < −0.6 dex) and another 15 probably formed in-situ (< 200 Myr, [Fe/H] ∼ −0.4 dex). Two metallicity dips were detected in the age-metallicity relation, coeval to the Stream and Bridge formation epochs. Cluster masses range from 500 to ∼ 104 M⊙, and a new estimate of 3 − 5 × 105 M⊙ is obtained for the Bridge stellar mass.

I discuss circumgalactic gas flows in the extended Milky Way halo in the context of the on-going formation and evolution of the Local Group. UV absorption-line measurements, in combination with H i 21 cm observations, provide detailed information on the chemical composition, dust content, physical conditions, and large-scale kinematics of the so-called high-velocity clouds, which are believed to trace neutral and ionized gas in the gaseous halos of the Milky Way, M31, and in the intragroup medium of the Local Group. Recent results in this field and ideas for future observational studies are being presented.

Extinction correction is the quintessence of astronomy. To achieve precision astrophysics in plasma diagnostics as in the theme of the present Proceedings, one must perform extinction correction properly before executing any line diagnostics of line-emitting objects including planetary nebulae. By making use of the inseparable relationship between extinction correction and plasma diagnostics, we establish a novel method to determine the physical conditions of a line-emitting target and the extinction characteristics along the line of sight toward the target simultaneously and self-consistently. This approach is made possible by the exact analytical expressions for the extinction parameters in terms of the emission properties of the target and by statistical optimization of the extinction parameters to find the robust physical conditions of the target.

. We show that an extragalactic jet with a velocity shear gives rise to Fermi like acceleration process for photons scattering withing the shear layers of the jet. Such photons then gain energy to produce a high energy power law. These power law spectra at high energies are frequently observed in several extragalactic objects such as Gamma Ray Bursts (GRBs). We implement the model on GRBs to show that the obtained range of the photon indices are well within their observed values. The analytic results are confirmed with numerical simulations following Monte Carlo approach.

We present a method to measure the the oblateness parameter q of the dark matter halo of gas rich galaxies that have extended HI disks. We have applied our model to a sample of 20 nearby galaxies that are gas rich and close to face-on, of which 6 are large disk galaxies, 8 have moderate stellar masses and 6 are low surface brightness (LSB) dwarf galaxies. We have used the stacked HI velocity dispersion and HI surface densities to derive q in the outer disk regions. Our most important result is that gas dominated galaxies (such as LSB dwarfs) that have M(gas)/M(baryons)>0.5 have oblate halos (q<55), whereas stellar dominated galaxies have a range of q values from 0.2 to 1.3. We also find a significant positive correlation between q and stellar mass, which indicates that galaxies with massive stellar disks have a higher probability of having halos that are spherical or slightly prolate, whereas low mass galaxies preferably have oblate halos. We briefly also discuss how the halo shape affects the disks of galaxies, especially the oblate halos.

We investigate the evolution of subsurface flows during the emergence and the active phase of sunspot regions using the time–distance helioseismology analysis of the full-disk Dopplergrams from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). We present an analysis of emerging active regions of various types, including delta-type active regions and regions with the reverse polarity order (‘anti-Hale active regions’). The results reveal strong vortical and shearing flows during the emergence of magnetic flux, as well as the process of formation of large-scale converging flow patterns around developing active regions, predominantly in the top 6 Mm deep layers of the convection zone. Our analysis revealed a significant correlation between the flow divergence and helicity in the active regions with their flaring activity, indicating that measuring characteristics of subsurface flows can contribute to flare forecasting.

AutoTAB is a state-of-the-art, fully automatic algorithm that tracks the Bipolar Magnetic Regions (BMRs) in magnetogram observations. AutoTAB employs identified BMR regions from Line-of-Sight magnetograms from MDI and HMI (1996–2022) to track the BMRs through their evolution on the nearside of the Sun. AutoTAB enables us to create a comprehensive and unique catalog of tracked information of 9232 BMRs in the mentioned time period. This dataset is used to study the collective statistical properties of BMRs and particularly to identify the correct theory for the BMR formation. Here, we discuss the algorithm’s functionality and the initial findings obtained from the AutoTAB BMRs catalog.

Due to the contamination from omnipresent interstellar 21 cm emission, atomic hydrogen (H <sc>i</sc>) associated with planetary nebulae (PNe) has been insufficiently investigated. In this proceeding we report a project of searching for H i surrounding PNe using the Five hundred-meter Aperture Spherical radio Telescope (FAST), which is the most sensitive single-dish telescope at L-band. The observations may offer new insights into the interaction processes between PNe and the interstellar medium.

In most of the Babcock–Leighton (BL) type solar dynamo models, the toroidal magnetic field is assumed to be generated in the tachocline. However, magnetic activity of fully convective stars and MHD simulations of global stellar convection have recently raised serious doubts about the importance of the tachocline in the generation of the toroidal field. We have developed a BL-type dynamo model operating in the bulk of the convection zone, and are extending this model to solar-type stars. In this study, we aim at exploring how the starspot properties affect the stellar magnetic cycle. Observations show that faster rotating stars tend to have stronger magnetic activity and shorter magnetic cycles. By considering the higher latitudes and larger tilt angles of starspots for faster rotators, our simulations reproduce observations that faster rotating stars have shorter magnetic cycle and stronger activity.

Planetary nebulae (PNe) represent the final link in the chain of the gas and dust enrichment of low- and intermediate-mass stars. We present a comprehensive study of the relevant observational data of 10 PNe of the Large Magellanic Cloud (LMC). Analysing them from the UV to the IR, we characterise the nature of the central star (CS) and the dust contribution. We link these results to the evolutionary history of these sources.

In this work we present preliminary results from a systematic search for new Local Group dwarf galaxies in the deep, wide-field Ultraviolet Near-Infrared Optical Northern Survey (UNIONS). The first major result from this work is the discovery of a candidate ultra faint dwarf galaxy, Boötes V. This satellite of the Milky Way has a physical half-light radius of , an absolute V-band magnitude of −4.5 ± 0.4 mag, and resides at a heliocentric distance of approximately 100 kpc. We also announce the discovery of a faint, compact star cluster, UNIONS 1. The end goal of this work will be to put firm constraints on the detectability and completeness of Local Group dwarf galaxies given the broad sky coverage and excellent photometric depth of UNIONS.

The Large Magellanic Cloud (LMC) has a complex dynamics driven by both internal and external processes. The external forces are due to tidal interactions with the Small Magellanic Cloud and the Milky Way, while internally its dynamics mainly depends on the stellar, gas, and dark matter mass distributions. Despite the overall complexity of the system, very often simple physical models can give us important insights about the main driving factors. Here we focus on the internal forces and attempt to model the proper motions of ∼ 106 stars in the LMC as measured by Gaia Data Release 3 with an axisymmetric dynamical model, based on the Jeans equations. We test both cored and cusped spherical Navarro-Frenk-White dark matter halos to fit the LMC gravitational potential. We find that this simple model is very successful at selecting a clean sample of genuine LMC member stars and predicts the geometry and orientation of the LMC with respect to the observer within the constraint of axisymmetry. Our Jeans dynamical models describe well the rotation profile and the velocity dispersion of the LMC stellar disc, however they fail to describe the motions of the LMC bar, which is a non-axisymmetric feature dominating the central region. We plan a triaxial Schwarzschild approach as a next step for the dynamical modelling of the LMC.

The way we look at the sky is connected to the cosmological paradigm embraced by the society we live in. On the other hand, several astronomical concepts reinforce the idea of a common humanity. Yet, scientific outreach is frequenty reaching out only to a specific part of the world population, often excluding people living in extreme social vulnerability, victims of violence and prejudice, fighting for their lives and for the right of living according to their traditions. We present two outreach projects, developed in Brazil, funded by the Office of Astronomy for Development (OAD) of the International Astronomical Union (IAU), i.e. “Under Other Skies” & “OruMbya”, which tackle the importance of ethno-astronomy, and the collaboration with leaders and cultural agents of marginalised communities. We also describe an educational project born in the favela of Cantagalo Pavão Pavãozinho (PPG), in Rio de Janeiro, during the COVID19 pandemic, which started a collaboration with local educators and artists to offer classes of astronomy and English language to children in the favela.

This presentation is an attempt to lay out, in the context of observational studies of the masses of Milky Way dwarf galaxies, what it is I think we want to do, why we want to do it, and how we go about doing it. They are my own personal opinions, and are presented here in the hope that they will stimulate others to step back and consider what are the most important scientific investigations that we should be doing, given the plethora of facilities and data available that are now available to us.

Solar winds originate from the Sun and can be classified as fast or slow. Fast solar winds come from coronal holes at the solar poles, while slow solar winds may originate from the equatorial region or streamers. Spicules are jet-like structures observed in the Sun’s chromosphere and transition region. Some spicules exhibit rotating motion, potentially indicating vorticity and Alfvén waves. Machine learning and the Hough algorithm were used to analyze over 3000 frames of the Sun, identifying spicules and their characteristics. The study found that rotating spicules, accounting for 21% at the poles and 4% at the equator, play a role in energy transfer to the upper solar atmosphere. The observations suggest connections between spicules, mini-loops, magnetic reconnection, and the acceleration of fast solar winds. Understanding these small-scale structures is crucial for comprehending the origin and heating of the fast solar wind.

We present preliminary results from our spectroscopic survey of low-luminosity early-type galaxies in the Coma cluster conducted with the Binospec spectrograph at the 6.5 m MMT. From spatially-resolved profiles of internal kinematics and stellar population properties complemented with high-resolution images, we placed several low-luminosity dEs on the fundamental plane in the low-luminosity extension of the available literature data. We also discovered unusual kpc-sized kinematically-decoupled cores in several dwarf galaxies, which had been probably formed before these galaxies entered the cluster.