Despite the fact that jets from black holes were first understood to exist over 40 years ago, we are still in ignorance about many primary aspects of these systems – including the radiation mechanism at high energies, the particle makeup of the jets, and how particles are accelerated, possibly to energies as high as 100 TeV and hundreds of kpc from the central engine. We focus in particular on the discovery (and mystery) of strong X-ray emission from radio jets on kpc-scales, enabled by the unequaled high resolution of the Chandra X-ray observatory. We review the main evidence for and against the viable models to explain this X-ray emission over the last 20 years. Finally, we present results of a recent study on the X-ray variability of kpc-scale jets, where we find evidence that between 30-100% of the X-ray jet population is variable at the tens-of-percent level. The short (∼years) variability timescale is incompatible with the IC/CMB model for the X-rays and implies extremely small structures embedded within the kpc-scale jet, and thus requires a reconsideration of many assumptions about jet structure and dynamics.

Star-formation is one of the main processes that shape galaxies, defining its stellar population and metallicity production and enrichment. It is nowadays known that this process is ruled by a set of relations that connect three parameters: the molecular gas mass, the stellar mass and the star-formation rate itself. These relations are fulfilled at a wide range of scales in galaxies, from galaxy wide to kpc-scales. At which scales they are broken, and how universal they are (i.e., if they change at different scales or for different galaxy types) it is still an open question. We explore here how those relations compare at different scales using as proxy the new analysis done using Integral Field Spectroscopy data and CO observations data from the EDGE-CALIFA survey and the AMUSSING++ compilation.

Both stars and planets can lose mass through an expansive wind outflow, often constrained or channeled by magnetic fields that form a surrounding magnetosphere. The very strong winds of massive stars are understood to be driven by line-scattering of the star’s radiative momentum, while in the Sun and even lower-mass stars a much weaker mass loss arises from the thermal expansion of a mechanically heated corona. In exoplanets around such low-mass stars, the radiative heating and wind interaction can lead to thermal expansion or mechanical ablation of their atmospheres. Stellar magnetospheres result from the internal trapping of the wind outflow, while planetary magnetospheres are typically shaped by the external impact from the star’s wind. But in both cases the stressing can drive magnetic reconnection that results in observable signatures such as X-ray flares and radio outbursts. This review will aim to give an overview of the underlying physics of these processes with emphasis on their similarities and distinctions for stars vs. planets.

The VISTA Magellanic Clouds Survey (VMC) is a near-infrared survey of the Magellanic system. The VMC data has been exploited to detect and study statistically correlated young groups of stars — also known as “young stellar structures” — in the Large and Small Magellanic Clouds (LMC and SMC). We showcase the ∼ 3000 recently detected young stellar structures in the LMC and their similarity to the fractal interstellar medium. We discuss how their properties indicate their formation mechanisms and that there are no preferred scales of star formation in the LMC.

In this invited review talk I summarize some of the recent observational advances in understanding mass loss from low-mass stars. This can take the form of a relatively steady wind, or stochastically occurring coronal mass ejections (CMEs). In recent years, there has been an expansion of observational signatures used to probe mass loss in low-mass stars. These observational tools span the electromagnetic spectrum. There has also been a resurgence of interest in this topic because of its potential impact on exoplanet space weather and habitability. The numerous recent observational and theoretical results also point to the complexities involved, rather than using simple scalings from solar understanding. This underscores the need to understand reconnection and eruption processes on magnetically active stars as a tool to putting our Sun in context.

We present an observational multiwavelength campaign during 2018–19 for PBC J2333.9–2343, a giant radio galaxy with a bright central core associated to a blazar nucleus, whose structure could be due to a significant jet reorientation. We report flux increases by a factor of two or more on timescales shorter than a month, resembling flaring events. The cross correlation between the NIR and optical bands shows quasi-simultaneous variations arising from the jet. The optical variability properties of PBC J2333.9–2343 are more comparable to a sample of blazars than to non-blazar AGN. The SED of the nucleus shows two peaks, with a derived jet angle of 3 degrees, also typical of a blazar. Therefore, we confirm the presence of a blazar-like core in the center of this galaxy.

Mass loss plays a key role in the evolution of massive stars and their environment. High mass-loss events are traced by complex circumstellar ejecta and intricate line profiles across the upper Hertzsprung-Russell diagram for massive stars in different evolutionary stages. The basic physics of radiation-driven stellar wind for hot stars is well understood. However, the driving mechanisms and related instabilities for their enhanced mass-loss episodes and the driving mechanisms for the mass loss of cool stars are still debated. In this review, the mass-loss characteristics and the possible mechanisms will be surveyed for an observational set of prominent massive stellar populations that experience outflows, strong stellar winds, and periods of enhanced and eruptive mass loss; massive young stellar objects, OB-type stars, red supergiants, warm hypergiants, luminous blue variables, and Wolf-Rayet stars.

Thanks to the data of the WISE all-sky survey we discovered that the non-thermal infrared emission of blazars, the largest population of associated γ-ray sources, has peculiar spectral properties. Here we provide a summary of all results achieved on the infrared–γ-ray connection. We also show results on the latest statistical analysis of the tight correlation between the mid-infrared colors and the γ-ray spectral index for Fermi blazars, a connection that links both emitted powers and spectral shapes of particles accelerated in blazar jets over ten decades in frequency of the electromagnetic spectrum. Finally, we outline all developments performed in the last decade achieved using the infrared– γ-ray connection to discover hundreds of new blazars within the sample of unidentified γ-ray sources thanks to optical spectroscopic observations.

We report a CO(3-2) detection of 23 molecular clouds in the extended ultraviolet (XUV) disk of the spiral galaxy M83 with ALMA. The observed 1 kpc2 region is at about 1.24R25 from the disk center, where CO(2-1) was previously not detected. The detection and non-detection, as well as the level of star formation (SF) activity in the region, can be explained consistently if the clouds have the mass distribution common among Galactic clouds, such as Orion A – with star-forming dense clumps embedded in thick layers of bulk molecular gas, but in a low-metallicity regime where their outer layers are CO-deficient and CO-dark. The cloud masses, estimated from CO(3-2), range from 8.2×102 to 2.3×104M⊙. The most massive clouds appear similar to Orion A in SF activity as well as in gas mass. The common cloud mass structure also justifies the use of high-J CO transitions to trace the total gas mass of clouds, or galaxies, even in the high-z universe. This study is the first demonstration that CO(3-2) is an efficient tracer of molecular clouds even in low-metallicity environments. This study is published in the Astronomical Journal, entitled “First Detection of the Molecular Cloud Population in the Extended Ultraviolet (XUV) Disk of M83" by J. Koda, L. Watson, F. Combes, M. Rubio, S. Boissier, M. Yagi, D. Thilker, A. M Lee, Y. Komiyama, K. Morokuma-Matsui, and C. Verdugo.

We present the results of the gamma-ray flux distribution analysis on 145 gamma-ray bright blazars observed by Fermi-LAT. For the gamma-ray flux distribution, we applied a log-normal distribution to discuss the nature of the high-energy emission processes of blazars and a power-law distribution convolved with a Poisson distribution to investigate the implications of gamma-ray bright blazars for neutrino emission. Both distributions can represent the observed flux distributions as well. The leptonic models, which give the physical relationship between neutrinos and gamma rays, indicate that the flaring contribution to the neutrino emission can be dominant for the power-law index less than ∼2.5. From the power-law distribution analysis, we found that the power-law index < 2.5 accounts for the 82 % blazars. This result suggests that the flaring contribution of blazars is dominant for high-energy neutrino emission.

We discuss the first detection of deuterated water (HDO) in extragalactic hot cores. The HDO 211–212 line has been detected with the Atacama Large Millimeter/submillimeter Array (ALMA) toward hot cores N 105–2 A and 2 B in the N 105 star-forming region in the low-metallicity Large Magellanic Cloud (LMC), the nearest star-forming galaxy. We compared the HDO line luminosity (LHDO) measured toward two hot cores in N 105 to those observed toward a sample of 17 Galactic hot cores and found that the observed values of LHDO for the LMC hot cores fit very well into the LHDO trends with Lbol and metallicity observed toward the Galactic hot cores. Our results indicate that LHDO seems to be largely dependent on the source luminosity, but metallicity also plays a role. We provide a rough estimate of the H2O column density and abundance ranges toward N 105–2 A and 2 B by assuming that HDO/H2O toward the LMC hot cores is the same as that observed in the Milky Way; the obtained values are systematically lower than those measured in the Galactic hot cores. The spatial distribution and velocity structure of the HDO emission in N 105–2 A is consistent with HDO being the product of the low-temperature dust grain chemistry.

We have recently hit the milestone of 5,000 exoplanets discovered. In stark contrast with the Solar System, most of the exoplanets we know to date orbit extremely close to their host stars, causing them to lose copious amounts of gas through atmospheric escape at some stage in their lives. In some planets, this process can be so dramatic that they shrink in timescales of a few million to billions of years, imprinting features in the demographics of transiting exoplanets. Depending on the transit geometry, ionizing conditions, and atmospheric properties, a planetary outflow can be observed using transmission spectroscopy in the ultraviolet, optical or near-infrared. In this review, we will discuss the main techniques to observe evaporating exoplanets and their results. To date, we have evidence that at least 28 exoplanets are currently losing their atmospheres, and the literature has reported at least 42 non-detections.

Red supergiants (RSGs) are evolved massive stars in a stage preceding core-collapse supernova. Understanding evolved-phases of these cool stars is key to understanding the cosmic matter cycle of our Universe, since they enrich the cosmos with newly formed elements. However, the physical processes that trigger mass loss in their atmospheres are still not fully understood, and remain one of the key questions in stellar astrophysics. We use a new method to study the extended atmospheres of these cold stars, exploring the effect of a stellar wind for both a simple radiative equilibrium model and a semi-empirical model that accounts for a chromospheric temperature structure. We then can compute the intensities, fluxes and visibilities matching the observations for the different instruments at the Very Large Telescope Interferometer (VLTI). Specifically, when comparing with the atmospheric structure of HD 95687 based on published VLTI/AMBER data, we find that our model can accurately match these observations in the K-band, showing the enormous potential of this methodology to reproduce extended atmospheres of RSGs.

Studying blazar radio variability on timescales ranging from months to years provides information on the sub-parsec-scale structures of the jets, and the physics of the central active galactic nuclei. In this study, we focus on the radio variability of 1158 blazars observed at 15 GHz through the Owens Valley Radio Observatory Blazar Monitoring Program, where these sources have been observed about twice a week for over a decade. We investigate the dependence of the variability amplitudes and timescales, derived using a simple model fit to the structure function, on the milliarcsecond radio core sizes measured by Very Long Baseline Interferometry. The most compact sources exhibit larger variability amplitudes and shorter variability timescales than the more extended sources; this could be explained by light travel-time effects.

Ultracompact Hii regions (UC-HII) are the young, very dense cores of massive star-forming regions in dwarf galaxies, where newly formed massive OB stars are surrounded by natal molecular clouds. Thermal energy deposited by mechanical feedback from a cluster of massive OB stars can form a superwind, which may lead to a wind-blown bubble as well as radiative cooling. We investigate the formation of radiatively cooling superwinds in UC-HII using a radiative cooling module in the hydrodynamics program. We built a grid of hydrodynamic simulations to determine the dependence of radiative cooling on the cluster radius, mass-deposition rate, wind velocity, and ambient medium in UC-HII. Our findings could help to better understand star formation in massive star-forming regions, where cool superwinds could trigger the formation of molecular clumpy regions.

Recent abrupt changes of CW Leonis may indicate that we are witnessing the moment that the central carbon star is evolving off the Asymptotic Giant Branch (AGB) and entering into the pre-planetary nebula (PPN) phase. The recent appearance of a red compact peak at the predicted stellar position is possibly an unveiling event of the star, and the radial beams emerging from the stellar position resemble the feature of the PPN Egg Nebula. The increase of light curve over two decades is also extraordinary, and it is possibly related to the phase transition. Decadal-period variations are further found in the residuals of light curves, in the relative brightness of radial beams, and in the extended halo brightness distribution. Further monitoring of the recent dramatic and decadal-scale changes of this most well-known carbon star CW Leonis at the tip of AGB is still highly essential, and will help us gain a more concrete understanding on the conditions for transition between the late stellar evolutionary phases.

We use the AREPO numerical code to model the structure of a Milky Way like galaxy (MW) via a suite of simulations composed of a stellar disc and bulge, a dark matter halo, and a gaseous disc under isothermal conditions. For each model, we produce longitude velocity (l-v) maps of the gas surface densities to extract the skeletons of the main features (arms, bar), and the contours defining the terminal velocities of the gas. We compare these with observations via a number of diagnostic tools, and select the model that best reproduces the main observed features of the Milky Way.

In this work, we investigate the formation and early evolution phase of X-shaped radio galaxies using the Back-flow model. We show how the X-like winged morphology evolves over time in a tri-axial ambient medium, naturally. At this early stage of formation, we demonstrated that both the pair of jet lobes are actively pushing the ambient material out of their path of propagation, forming (X-ray) cavities that are surrounded by a shocked shell (X-ray bright rims) of swept materials. We also noticed how turbulent the wing is in comparison to the active lobe, generating sites of random shocks, indicating that the wings are not passively evolving structures. This study demonstrated that the ambiguous morphology observed in jets is also imprinted over the ambient medium, providing an alternative perspective in understanding the underlying physical process causing such ambiguities. Finally, we indicate that shearing instabilities cause mixing of ambient material at the shearing interface.

This contribution is based on the work published by (Pinzón et al. 2021) in which we computed rotation rates for a sample of 79 young stars (∼3 Myr) in a wide range of stellar masses (from T Tauri Stars to Herbig Ae/Be stars) in in the Orion Star Formation Complex (OSFC). We study whether the magnetospheric accretion scenario (MA), valid for young low mass stars, may be applied over a wide range of stellar masses of not. Under the assumption that stellar winds powered by stellar accretion are the main source for the stellar spin down, the hypothesis of an extension of MA toward higher masses seems plausible. A comparison with Ap/Bp stars suggest that HAeBes should suffer a loss of angular momentum by a factor between 12 and 80 during the first 10 Myr in order to match the magnetic Ap/Bp zone in HR diagram.

The depletion of CO molecules is observed in infrared dark clouds. However, only few exsamples are found in pc-scale. An NH3 emission is one of good counter parts of C18O because of similar effective critical density. Our NH3 observations of a molecular filament associated with CMa OB1 or KAG 71, which is a target of Kagoshima Galactic Object survey with Nobeyama 45-m telescope by Mapping in Ammonia lines (KAGONMA) project. Although NH3 data shows similarity in morphology with infrared data suggesting no depletion, C18O in the clumps 4 and 6 are weaker than expected based on NH3 data. After examining the dissipation of the high-density gas, photodissociation, and depletion, we concluded that CO is depleted at least in the clump 4. It is a new example of depletion in pc-scale.