We draw the K-band luminosity functions (CLFs) of young massive clusters (YMCs) hosted by 34 SUNBIRD targets to evaluate the impact of the host galaxy environment on their YMC properties. The depth and high resolution of the NIR images (PSF ∼ 0.1”) allow us to test whether CLF power-law slopes (α) of high star-forming galaxies are similar to those of gas-poor low star formation rate (SFR) galaxies. We found that α ranges between 1.53 and 2.41 with a median value of 1.87 ± 0.23. We also performed correlation searches between α and the host global properties and noticed that α decreases with an increasing SFR and SFR density. On sub-galactic scales, CLF slopes of cluster-rich galaxies differ by ∼0.5. Our NIR CLF analyses suggest that the extreme environment of high SFR galaxies such as the SUNBIRD sample is likely to affect the formation mechanisms of YMCs and hence to govern the ongoing small-scale SF processes of the host galaxy.

Blazars are the most numerous type of observed high-energy gamma-ray emitters. However, their emission mechanisms and population properties are still not well-understood. Crucial to this understanding are their cosmological redshifts, which are often not easy to obtain. This presents a great challenge to the next-generation ground-based observatory for very-high-energy gamma rays, the Cherenkov Telescope Array (CTA), which aims to detect a large number of distant blazars to study their intrinsic emission properties and to place tight constraints on the extragalactic background light density, amongst others. The successful investigation of these subjects needs a precise redshift determination. Motivated by these challenges, the CTA redshift task force initiated more than 3 years ago a spectroscopic observing program using some of the largest optical and infrared telescopes to measure the redshifts of a large fraction of blazars that are likely to be detected with CTA. In this proceedings, we give an overview of the CTA redshift task force, discuss some of the difficulties associated with measuring the redshifts of blazars and present our sample selection and observing strategies. We end the proceedings with reporting selected results from the program, the on-going collaborative efforts and our plans for the future.

In this work we seek to derive simultaneously the stellar and wind parameters of massive stars, mainly A and B type supergiant stars. Our stellar properties encompass the effective temperature, the surface gravity, the micro-turbulence velocity and, silicon abundance. For wind properties we consider the line–force parameters (α, k and δ) obtained from the standard line-driven wind theory. To model the data we use the radiative transport code Fastwind considering the hydrodynamic solutions derived with the stationary code Hydwind. Then, ISOSCELES, a grid of stellar atmosphere and hydrodynamic models of massive stars is created. Together with the observed spectra and a semi-automatic tool the physical properties from these stars are determined through spectral line fittings. This quantitative spectroscopic analysis provide an estimation about the line–force parameters. In addition, we confirm that the hydrodynamic solutions, called δ-slow solutions, describe quite reliable the radiation line-driven winds of B supergiant stars.

Stars interact with their planets through gravitation, radiation, and magnetic fields. Although magnetic activity decreases with time, reducing associated high-energy (e.g., coronal XUV emission, flares), stellar winds persist throughout the entire evolution of the system. Their cumulative effect will be dominant for both the star and for possible orbiting exoplanets, affecting in this way the expected habitability conditions. However, observations of stellar winds in low-mass main sequence stars are limited, which motivates the usage of models as a pathway to explore how these winds look like and how they behave. Here we present the results from a grid of 3D state-of-the-art stellar wind models for cool stars (spectral types F to M). We explore the role played by the different stellar properties (mass, radius, rotation, magnetic field) on the characteristics of the resulting magnetized winds (mass and angular momentum losses, terminal speeds, wind topology) and isolate the most important dependencies between the parameters involved. These results will be used to establish scaling laws that will complement the lack of stellar wind observational constraints.

Azimuthal variations in HI velocity dispersion do not correlate with variations in the star formation rate per unit area, SFR/A, suggesting that local star formation does not increase HI turbulence significantly. These variations are determined for each pixel in HI and FUV maps of THINGS and LITTLE THINGS galaxies by subtracting the average radial profiles from the measured quantities. The kinetic energy density and HI surface density increase slightly with SFR/A, suggesting that feedback goes into pushing the local dense gas around without increasing the velocity dispersion. We suggest that star formation feedback does not promote large-scale stability against gravitational forces through turbulence regulation, and that gravitational energy from recurrent instabilities drives turbulence on galactic scales.

The evolution of giant molecular clouds (GMCs), which are the main sites of star formation, is essential for unraveling how stars form and how galaxies evolve. We analyzed the M33 CO(J = 2–1) data with spatial resolution of 39 pc obtained by ALMA-ACA 7 m array combined with IRAM 30 m. We identified 736 GMCs and classified them into three types; Type I: associated with no Hii regions, Type II: associated with Hii regions with the Hα luminosity L(Hα) < 1037.5 erg s-1, Type III: associated with Hii regions with L(Hα) > 1037.5erg s-1. We found that mass, size, and velocity dispersion of GMCs slightly increase in the order of Type I, II, and III GMCs. Type III GMCs mainly exist in the spiral arm, while many of Type I and Type II GMCs are distributed in the inter-arm. Assuming that the star formation proceeds steadily, we roughly estimated the total GMC lifetime of 30 Myr.

We show the application of the δ- and Ω-slow hydrodynamical solutions to describe the velocity profiles of massive stars. In particular, these solutions can help to unravel some of the problems within the winds of massive stars such as the approximation of the β-law for the velocity profile of B supergiant stars and the slow outflow wind observed in Be stars.

Planets open deep gaps in protoplanetary discs when their mass exceeds a gap opening mass, Mgap. We use one- and two-dimensional simulations to study planet gap opening in discs with angular momentum transport powered by MHD disc winds. We parameterise the efficiency of the MHD disc wind angular momentum transport through a dimensionless parameter αdw, which is an analogue to the turbulent viscosity αv. We find that magnetised winds are much less efficient in counteracting planet tidal torques than turbulence is. For discs with astrophysically realistic values of αdw, Mgap is always determined by the residual disc turbulence, and is a factor of a few to ten smaller than usually obtained for viscous discs. We introduce a gap opening criterion applicable for any values of αv and αdw that may be useful for planet formation population synthesis.

Star formation, from cold giant molecular clouds to diverse population of stars, is a complex process involving a wide variety of physical processes. In this work, we constrain the link between the gas-star formation cycle and several secular and environmental probe of galaxies. Specifically, we quantify the spatial correlation between molecular gas and star-forming regions for 49 nearby galaxies using the ALMA and narrowband-Hα imaging from the PHANGS survey. At the resolution (150 pc) at which the individual molecular clouds and star-forming regions can be identified, we find that molecular clouds and star-forming regions do not necessarily coexist. The decoupled molecular clouds and star-forming regions are a signature of evolutionary cycling and feedback of the star formation process. Therefore, the impact of galactic-scale conditions and environments must be considered for a complete understanding of how stars form in galaxies and how this process influences the evolution of the host galaxies.

We characterize the star formation going on in the inner kiloparsec region of the galaxy NGC 1386 as derived from the analysis of a multiwavelength dataset covering the optical, near-IR and mid-IR at subarsec resolution. We detect 61 point sources, distributed in a ring of 960 pc radius around the center of the galaxy. From SED fitting we conclude that these are low mass () young clusters, with age distributed from 1 to 10 Myr, with median at 3.6 Myr. Comparison of the Hα luminosity of the clusters derived from the Hα+[N ii] narrow band image with that expected from the fitted ionizing continuum shows that a large fraction of the ionizing photons escapes from the clusters. Moreover, a large fraction of these photons escapes from the regions around the star forming ring.

The solar hydrologic cycle is the process of comets delivering water and gasses to the planets by collision, and solar wind stripping water and gasses from the planets and delivering them back to the Kuiper Belt. This new theory of solar hydrologic cycle provides that the solar hydrologic cycle is the continuation of planetary formation, and the cause of outer planets becoming gas giants, inner planets staying small rocks.

The interactions and mergers of gas rich galaxies are known to produce star formation which often leads to nuclear activity as well. The star formation is ideally mapped using FUV and NUV emission, since UV traces star formation for longer timescales compared to Hα emission. It is also emitted over a broader range of stellar masses in galaxies. In this study we present FUV and NUV observations of merging and interacting galaxies in our nearby universe conducted using the UVIT. We present the example of a merging system MRK212 that has dual AGN and the triple AGN system NGC7733-7734. The UV emission is associated with the tidal arms, individual nuclei, resonance rings, nuclear spirals as well as AGN/stellar feedback. We also find that radio emission is often closely associated with the UV emission, arising from both star formation as well as AGN activity, and perhaps kpc-scale AGN feedback. We find that a comparison of optical IFU imaging with FUV in NGC7733-7734 reveals unique properties associated with the interaction including the third AGN buried in a tidal arm.

Magnetic confinement of material is observed on both high and low mass stars. On low mass stars, this confinement can be seen as slingshot prominences, in which condensations are supported several stellar radii above the surface by strong magnetic fields. We present a model for generating cooled field lines in equilibrium with the background corona, which we use to populate a model corona. We find prominence masses on the order of observationally derived values. We find two types of solutions: footpoint heavy “solar-like prominences” and summit heavy “slingshot prominences” which are centrifugally supported. These can form within the open field region i.e. embedded in the wind. We generate Hα spectra from different field structures and show that all display behaviour that is consistent with observations. This implies that the features seen in observations could be supported by a range of conditions, suggesting they would be common across rapidly rotating stars.

B supergiants (BSGs) are evolved objects on the cool end of the line-driven wind regime. Studying their atmospheres provides important insights on the stellar wind physics of these objects and their evolutionary status. So far important features of their spectra, especially in the UV region, could not be reproduced consistently with atmosphere models. This translates directly into problems of our understanding of their wind properties. Here, we present new insights about the BSGs on the cooler side of the Bi-Stability Jump, corresponding to spectral types later than B1. Using UV and optical data, we analysed a sample of Galactic cool BSGs. Including for the first time X-rays and clumping the wind models, we show that the spectra of cool BSGs cannot be explained without X-rays, despite any clear detection of the target stars.

IC 10 as a starburst dwarf galaxy in the Local Group (LG) has a large population of newly formed stars that are massive and intrinsically very bright in comparison with other LG galaxies. Using the Isaac Newton Telescope (INT) with the Wide Field Camera (WFC) in the i-band and V-band, we performed an optical monitoring survey to identify the most evolved asymptotic giant branch stars (AGBs) and red supergiant stars (RSGs) in this star-forming galaxy, which can be used to determine the star formation history (SFH). The E(B - V) as an effective factor for obtaining the precise magnitude of stars is measured for each star using a 2D dust map (SFD98) to obtain a total extinction for each star in both the i-band and V-band. We obtained the photometric catalog for 53579 stars within the area of 0.07 deg2 (13.5 kpc2), of which 762 stars are classified as variable candidates after removing the foreground stars and saturated ones from our catalog. To reconstruct the SFH for IC 10, we first identified 424 long-period variable (LPV) candidates within the area of two half-light radii (2rh) from the center of the galaxy. We estimated the recent star formation rate (SFR) at ∼ 0.32 yr-1 for a constant metallicity Z = 0.0008, showing the galaxy is currently undergoing high levels of star formation. Also, a total stellar mass of is obtained within 2rh for that metallicity.

We study the effect of minor mergers on star formation using simulations. We use GADGET4 code which has both collisionless and hydrodynamical particles. Our goal is to establish a relation between gas percentage present in the galaxies and the star formation in the merged galaxy. We use 1:10 minor mergers and we run the isolated simulations with varying gas percentages in the primary galaxy. We observe that the gas particles convert into stars due to the impact of the minor merger. As the gas percentage increases in the primary disk of the galaxy, more number of stars are formed. We also observed that newly formed star particles settle down in the disk of the primary galaxy and increase the thickness of the disk. We also observe that the thickness of the stellar disk containing the old stars also increases due to the impact of the merger.

Massive stars drive strong winds that impact the surrounding interstellar medium, producing parsec-scale bubbles for isolated stars and superbubbles around young clusters. These bubbles can be observed across the electromagnetic spectrum, both the wind itself and the swept up interstellar gas. Runaway massive stars produce bow shocks that strongly compresses interstellar gas, producing bright infrared, optical and radio nebulae. With the detection of non-thermal radio emission from bow shocks, particle acceleration can now also be investigated. I review research on wind bubbles and bow shocks around massive stars, highlighting recent advances in infrared, radio and X-ray observations, and progress in multidimensional simulations of these nebulae. These advances enable quantitative comparisons between theory and observations and allow to test the importance of some physical processes such as thermal conduction and Kelvin-Helmholtz instability in shaping nebulae and in constraining the energetics of stellar-wind feedback to the interstellar medium.

Mass-loss and radiation feedback from evolving massive stars produce galactic-scale superwinds, sometimes surrounded by pressure-driven bubbles. Using the time-dependent stellar population typically seen in star-forming regions, we conduct hydrodynamic simulations of a starburst-driven superwind model coupled with radiative efficiency rates to investigate the formation of radiative cooling superwinds and bubbles. Our numerical simulations depict the parameter space where radiative cooling superwinds with or without bubbles occur. Moreover, we employ the physical properties and time-dependent ionization states to predict emission line profiles under the assumption of collisional ionization and non-equilibrium ionization caused by wind thermal feedback in addition to photoionization created by the radiation background. We see the dependence of non-equilibrium ionization structures on the time-evolving ionizing source, leading to a deviation from collisional ionization in radiative cooling wind regions over time.