We present a radial velocity and model atmosphere analysis of both components of the spectroscopic binary central star of NGC 1514, based on high-resolution, high-signal-to-noise-ratio spectrograms taken with the CFH and Subaru telescopes at Maunakea, Hawaii. Together with the Gaia parallax and other data from the literature, all this information permits to determine the basic stellar parameters (Teff, L, log g, masses) of both binary components. This allows us to empirically test the theoretical post-AGB mass-luminosity relation.

We present analysis of the evolution of subsurface flows in and around active regions with peculiar magnetic configurations and compare their characteristics with the normal active regions. We also study the zonal and meridional components of subsurface flows separately in different polarity regions separately to better understand their role in flux migration. We use the techniques of local correlation tracking and ring diagrams for computing surface and subsurface flows, respectively. Our study manifests an evidence that the meridional component of the flows near anti-Hale active regions is predominantly equatorward which disagrees with the poleward flow pattern seen in pro-Hale active regions. We also find clockwise or anti-clockwise flows surrounding the anti-Joy active regions depending on their locations in the Southern or Northern hemispheres, respectively.

The radiative mode of AGN feedback, operated through outflows, plays an essential role in the evolution of galaxies. Quasar outflows are detected as blue-shifted broad absorption lines in the UV/optical spectra of quasars. Thanks to the Sloan digital sky survey, 100,000 broad absorption line quasars are available now for ensemble statistical studies. This rich dataset has also enabled us to identify some peculiar cases of these sources. By quantifying the BAL fraction in radio-loud BAL quasars, our studies demonstrate a clear trend of increasing BAL fraction as the viewing angle approaches an edge-on orientation, favoring the orientation model of BAL quasars. Also, by contrasting the properties of BAL quasars with appearing and disappearing BAL troughs, our analysis suggests that the extreme variations in BAL troughs are driven by ionization changes.

We show that, contrary to simple predictions, most AGNs show at best only a small increase of lags with increasing wavelength in the J, H, K, and L bands. We suggest that a possible cause of this near simultaneity from the near-IR to the mid-IR is that the hot dust is in a hollow bi-conical outflow of which we preferentially see the near side. In the proposed model sublimation or re-creation of dust (with some delay relative luminosity variations) along our line of sight in the hollow cone as the flux varies could be a factor in explaining the AGN changing-look phenomenon (CL). Variations in the dust obscuration can help explain changes in relationship of Hβ time delay on Luv variability. The relative wavelength independence of IR lags simplifies the use of IR lags for estimating cosmological parameters.

We report spectroscopic confirmation of a z = 3.757 ± 0.0011 massive $({\rm{log}}({{\rm{M}}_*}/{M_ \odot }) = 10.86_{ - 0.03}^{ + 0.09})$ quiescent galaxy with 11 hours of Keck/MOSFIRE K-band observations. This galaxy was selected from the FENIKS survey, which uses deep Gemini/Flamingos-2 Kb Kr imaging optimized for increased sensitivity to galaxies with strong Balmer/4000 Å breaks. Its rest-frame colors are consistent with a ∼1 Gyr old stellar population. This places it as one of the oldest objects at these redshifts, and challenges the notion that quiescent galaxies at z > 3 are all young post-starbursts. The star formation history suggests that its progenitor was in place by z ∼4 −7, reaching 1010.6 Mȯ by z ∼ 5, which we have confirmed using ultra-deep medium resolution spectroscopy from JWST. These results are in line with the rapid formation and quenching timescales reported for similar massive quiescent galaxies at z > 3, implying extreme baryonic physics within the first billion years of cosmic history.

In this contribution, we present the results from proper motion measurements across the Large Magellanic Cloud (LMC) using data from the VISTA survey of the Magellanic Cloud system (VMC). Using the derived proper motions, we modelled the structure of the LMC and analysed its internal kinematics. Within the central parts of the LMC, we found observational evidence for elongated orbits parallel to the bar’s major axis, which are considered to provide the main contribution for the support of a bar structure. A peculiar kinematic structure in the outer regions of the LMC hints toward stripped material from the Small Magellanic Cloud. We further introduce an observational campaign utilising the Hubble Space Telescope to precisely measure the proper motions of star clusters within the LMC. These motions, combined with radial velocities and 3D positions will be used to trace the gravitational potential of the LMC.

The Magellanic Stream is unique to sample the MW potential from ∼50 kpc to 300 kpc, and is also unique in constraining the LMC mass, an increasingly important question for the Local Group/Milky Way modeling. Here we compare strengths and weaknesses of the two types of models (tidal and ram-pressure) of the Magellanic Stream formation. I will present our modeling for the formation of the Magellanic System, including those of the most recent discoveries in the Stream, in the Bridge and at the outskirts of Magellanic Clouds. This model has been successful in predicting most recent observations in both properties of stellar and gas phase. It appears that it is an over-constrained model and provides a good path to investigate the Stream properties. In particular, this model requires a LMC mass significantly smaller than 1011 M⊙.

Recent ALMA studies have detected rest-frame far-infrared emission lines in star-forming galaxies at redshift (z) ∼ 6 – 9. To investigate detailed properties of high-z ALMA [O iii] 88 μm emitters, we performed JWST observations with NIRCam and NIRSpec IFU (GO-1840). In the NIRCam observations, six broad- and/or medium-band filters were used to trace rest-frame UV to optical stellar continuum emission, while NIRSpec IFU observations provide information on rest-frame optical emission lines. The powerful combination of JWST and ALMA in this project has revealed a matured stellar population in the core region of the most distant protocluster, A274z7p9OD, at z = 7.9. We also present our results of gas-phase metallicity from a direct-temperature method based on a joint analysis of the optical and far-infrared [O iii] lines, which will form the basis for similar studies combining JWST and ALMA data.

The interplay between dark matter (DM) and baryons has long been ignored when building galaxies semi-empirically and observationally. Here I show that baryonic gravity leads to an adiabatic contraction of DM halos, which is most significant in massive galaxies. Ignoring this effect, the derived DM halos are not guaranteed in dynamical equilibrium. I present a new approach to deriving DM halos from rotation curves, which incorporates the adiabatic contraction. The compressed halos turn out super cuspy with respect to NFW halos, which require smaller baryonic contributions and less concentrated primordial halos. I also examine the semi-empirical approach to building galaxies, and find the adiabatic contraction can shift massive galaxies from the observed radial acceleration relation dramatically. Both approaches lead to super cuspy DM halos for massive galaxies, demonstrating the importance of the baryon-driven contraction, which has to be taken into account in order to make an apple-to-apple comparison with simulations.

Thanks to its characteristic bright cut-off, the planetary nebulae luminosity function (PNLF) has now become a well-established extragalactic distance indicator that is in principle applicable to all types of galaxies. Most recently, several studies have demonstrated how the use of integral-field spectroscopy can lead to even more precise PNLF measurements, in particular as it allows to probe the central regions of galaxies and obtain well-sampled PNLF distributions. In this respect, adaptive optics (AO) is expected to further increase the scope and reach of PNLF measurements, as it should allow for the detection of even more and more distant PNe. This proceeding presents first results of the investigation of the MUSE-AO performance in relation to the detection of PNe in external galaxies, based on all galaxies with wide-field mode AO observations in the ESO archive.

The canonical undestanding of stellar convection has recently been put under doubt due to helioseismic results and global 3D convection simulations. This “convective conundrum” is manifested by much higher velocity amplitudes in simulations at large scales in comparison to helioseismic results, and the difficulty in reproducing the solar differential rotation and dynamo with global 3D simulations. Here some aspects of this conundrum are discussed from the viewpoint of hydrodynamic Cartesian 3D simulations targeted at testing the rotational influence and surface forcing on deep convection. More specifically, the dominant scale of convection and the depths of the convection zone and the weakly subadiabatic – yet convecting – Deardorff zone are discussed in detail.

The Red Rectangle is a nebula surrounding the post-AGB star HD 44179. It is the prototype of a particular class of nebulae associated with post-AGB binaries characterised by the presence of stable circumbinary disks in (quasi-)Keplerian rotation. Here we present the results of new high-resolution (0.″ 02″05) ALMA observations of continuum and line emissions at 0.9 mm. The continuum maps are analysed through a simple model of dust emission, which can reproduce the observational data. We find that most dust emission in the Red Rectangle is concentrated in the central regions of the rotating disk and that the settlement of dust grains onto the equatorial plane is very significant, particularly in comparison with the much larger scale height displayed by the gas distribution. The diameter of the dust-emitting region is about 250 au, with a total width of about 50 au. This region coincides with the warm PDR where certain molecules (like HCN), CI, and CII are presumably formed, as well as probably PAHs. From the spectral index, we confirm the presence in the disk of large grains, with a typical radius of about 150 μm, which supports the long-lived hypothesis for this structure. We also confirm the existence of a compact ionised wind at the centre of the nebula, probably emerging from the accretion disk around the companion, for which we derive an extent of about 10 au and a total flux of 8 mJy. We also briefly present the results on molecular lines of 12CO, 13CO, and other less abundant species.

Tidal forces in close binaries and multiple systems that contain magnetically active component are supposed to influence the operation of magnetic dynamo. Through synchronization the tidal effect of a close companion helps maintain fast rotation, thus supporting an efficient dynamo. At the same time, it can also suppress the differential rotation of the convection zone, or even force the formation of active longitudes at certain phases fixed to the orbit. V815 Her is a four-star system consisting of two close binaries orbiting each other, one of which contains an active G-type main-sequence star. Therefore, the system offers an excellent opportunity to investigate the influence of gravitational effects on solar-type magnetic activity using different methods.

Through the discovery and characterization of three mini-quenched galaxies at z = 4 − 6 in the UNCOVER survey (JWST observations of Abell 2744; PIs Bezanson, Labbe), we discuss the diversity of star formation histories (SFHs) and future prospects for the study of “napping” systems. We find these galaxies with their characteristic features – bright rest-frame UV flux, a weak Balmer/4000Å break, and weak or absent emission lines – corresponding to residual star formation and presence of old stellar populations. With the use of flexible non-parametric SFH models via Prospector, the specific star formation rates of these mini-quenched galaxies place them below the star formation main sequence. The posterior distributions of the time-averaged SFRs show that these systems are outliers in the SFR10/SFR100 parameter space. We demonstrate that this class of galaxies can best be identified and characterized spectroscopically due to the challenge of photometrically capturing the UV flux, weak Balmer/4000Å break, and weak emission lines simultaneously.

Dark matter (DM) halo angular momentum is very challenging to determine from observations of galaxies. In this study, we present a new hybrid method of estimating the dimensionless halo angular momentum, halo spin of a gas-rich dwarf barred galaxy UGC5288 using N-Body/SPH simulations. We forward model the galaxy disk properties- stellar and gas mass, surface densities, disk scalelengths, bar length and bar ellipticity from observations. We use the HI rotation curve to constrain the DM halo density profile and further use the bar properties to determine the models that best represent the observed baryonic disk. We compare the halo spin profile from our models to the halo spin profiles of similar mass dwarf galaxy analogues of UGC5288 in the TNG50 simulations. The halo spin profile from our simulated models matches within ballpark values of the median spin profile of UGC5288 analogues in the TNG50 simulations, although there are some uncertainties due to the DM halo evolutionary history.

I examine the morphologies of the brightest planetary nebulae (PNe) in the Milky Way Galaxy and conclude that violent binary interaction processes eject the main nebulae of the brightest PNe. The typical morphologies of the brightest PNe are multipolar, namely have been shaped by two or more major jet-launching episodes at varying directions, and possess small to medium departures from pure point symmetry. I discuss some scenarios, including a rapid onset of a common envelope interaction and the merger of the companion, mainly a white dwarf, with the asymptotic giant branch core at the termination of the common envelope. Some of these might be progenitors of type Ia supernovae (SNe Ia), as I suggest for SNR G1.9+0.3, the youngest SN Ia in the Galaxy.

In the late 80s of the 20th century, Crimean astronomers, studying the structure of transverse magnetic fields in active regions (ARs), discovered signs of the presence of large-scale vertical electric currents – global electric currents (Abramenko, Gopasyuk 1987). In 2018–2020, we finalized and adapted the method for detecting large-scale electric currents to the data of modern instruments for studying the Sun, and began studying their dynamics on time scales of 3–5 days (Fursyak et. al 2020). Our researches carried out during 2020–2023 showed that: 1) Large-scale electric currents with values of the order of ~ 1013 A exist in ARs with nonzero flare activity. 2) Large-scale electric currents extend to the upper layers of the solar atmosphere in one part of the AR, and close through the chromosphere and corona in the remaining part of the AR. This assumption for the AR NOAA 12192 is confirmed by the results of numerical simulations performed in 2016 (Jiang et al. 2016). 3) The greater the magnitude of the large-scale electric current, the higher the probability of occurrence of M- and X- class solar flares in the AR. 4) At the final stages of AR evolution, a nonzero large-scale electric current can have a stabilizing effect on the sunspot, preventing its decay by its own magnetic field. 5) Large-scale electric currents are involved in coronal heating processes. Ohmic dissipation of a large-scale electric current is one of the mechanisms of quasi-stationary heating of coronal plasma above the AR. Our research on large-scale electric currents and the processes in which they take part continues.

It is routinely assumed that galaxy rotation curves are equal to their circular velocity curves (modulo some corrections) such that they are good dynamical mass tracers. We analysed 33 low-mass galaxies from the APOSTLE simulation suite to explore the limits of validity of this assumption. Only 3 galaxies have rotation curves similar to their circular velocity curves; the rest are undergoing a wide variety of dynamical perturbations. We assessed how many galaxies are likely to be strongly perturbed by processes in several categories: mergers/interactions, bulk gas flows, non-spherical DM halo, warps, and IGM ram pressure. Most galaxies fall into more than one of these categories; only 5/33 are not in any of them. The sum of these effects leads to an underestimation of the low-velocity slope of the baryonic Tully-Fisher relation that is difficult to avoid, and could contribute to the observed diversity in low-mass galaxy rotation curve shapes.

Globular clusters in the nearby universe were formed in the first chapter of our cosmic history, but they show only the current chapter. However, the JWST enables us to see the younger phase of the globular clusters in the distant universe. Galaxy clusters host both galaxy globular clusters and intracluster globular clusters. We present a wide field photometric survey of globular clusters in the nearby to distant galaxy clusters. We discuss the photometric properties of these globular clusters in relation with the structure and assembly history of their host galaxy clusters.