Galaxies, Volume 8, Issue 1

The formation of low-mass ( $M_{★}\lesssim 2M_{\odot }$ ) stars in molecular clouds involves accretion disks and jets, which are of broad astrophysical interest. Accreting stars represent the closest examples of these phenomena. Star and planet formation...

I argue that the high percentage of planetary nebulae (PNe) that are shaped by jets show that main sequence stars in binary systems can accrete mass at a high rate from an accretion disk and launch jets. Not only does this allow jets to shape PNe, bu...

If dark matter is composed of weakly interacting particles with mass in the GeV-TeV range, their annihilation or decay may produce gamma rays that could be detected by gamma-ray telescopes. Observations of dwarf spheroidal satellite galaxies of the M...

Planetary nebulae (PNe) were expected to be filled with hot pressurized gas driving their expansion. ROSAT hinted at the presence of diffuse X-ray emission from these hot bubbles and detected the first sources of hard X-ray emission from their centra...

This workshop is the second of the WORKPLANS series, which we started in 2016. The main goal of WORKPLANS is to build up a network of planetary nebulae (PNe) experts to address the main open questions in the field of PNe research. The specific aims o...

This is a non-comprehensive review of observations of pre-Planetary Nebulae (pPNe) and young Planetary Nebulae (yPNe) at (sub)mm-wavelengths, a valuable window for probing multi-phased gas and dust in these objects. This contribution focuses on obser...

We use multi-frequency linear polarization observations from the University of Michigan blazar program (UMRAO), in combination with radiative transfer simulations of emission from a relativistic jet, to investigate the time-dependent flow conditions,...

Luminous Blue Variables are massive evolved stars, here we introduce this outstanding class of objects. Described are the specific characteristics, the evolutionary state and what they are connected to other phases and types of massive stars. Our cur...

Spiral galaxies and their rotation curves have key characteristics of differentially spinning objects. Oblate spheroid shapes are a consequence of spin and reasonably describe galaxies, indicating that their matter is distributed in gravitationally i...

The majority of the known extragalactic sky from TeV gamma-ray energies consists of blazars having plasma jets pointing in the direction of the line-of-sight, which results in a large Doppler boosting of their emission. Up to now, only six galaxies w...

The frequency of planets in binaries is an important issue in the field of extrasolar planet studies because of its relevance in the estimation of the global planet population of our galaxy and the clues it can give to our understanding of planet for...

In May 2010, an intermediate luminosity optical transient was discovered in the nearby galaxy NGC 300 by a South African amateur astronomer. In the decade since its discovery, multi-wavelength observations of the misnamed “SN 2010da” have...

We study the existence and stability of circular geodesics in a family of asymptotically AdS static black holes in New Massive Gravity theory. We show that the mathematical sign of the hair parameter determines the existence of such geodesics. For a...

A diverse range of observational results and peculiar properties across the domains of observation have made OJ 287 one of the best-explored BL Lac objects on the issues of relativistic jets and accretion physics as well as the strong theory of gravi...

Spectroscopic observations of a massive star formation in the ultraviolet and their interpretation are reviewed. After a brief historical retrospective, two well-studied resolved star clusters and the surrounding H II regions are introduced: NGC 2070...

The relaxed motion of stars and gas in galactic discs is well approximated by a rotational velocity that is a function of radial position only, implying that individual components have lost any information about their prior states. Thermodynamically,...

We report on seven nights of optical observation taken over a two-week period, and the resultant analysis of the intermediate-frequency peaked BL Lac object (IBL), BL Lac itself, at redshift z = 0.069. The microvariable behavior can be confirmed over...

Very massive stars occasionally expel material in colossal eruptions, driven by continuum radiation pressure rather than blast waves. Some of them rival supernovae in total radiative output, and the mass loss is crucial for subsequent evolution. Some...

The most cited evidence for (non-baryonic) dark matter has been an apparent lack of visible mass to gravitationally support the observed orbital velocity of matter in rotating disk galaxies, yet measurement of the mass of celestial objects cannot be...

The editorial team greatly appreciates the reviewers who have dedicated their considerable time and expertise to the journal’s rigorous editorial process over the past 12 months, regardless of whether the papers are finally published or not [...]

Blazars are highly variable and display complex characteristics. A key characteristic is the flux probability distribution function or flux PDF whose shape depends upon the form of the underlying physical process driving variability. The BL Lacertae...

Comparison with artificial galaxy models is essential for translating the incomplete and low signal-to-noise data we can obtain on astrophysical stellar populations to physical interpretations which describe their composition, physical properties, hi...

The $\mathsf{\Lambda }$ CDM cosmological framework predicts the existence of thousands of subhalos in our own Galaxy not massive enough to retain baryons and become visible. Yet, some of them may outshine in gamma rays provided that the dark matter is made...

Constraining dynamo theories of magnetic field origin by observation is indispensable but challenging, in part because the basic quantities measured by observers and predicted by modelers are different. We clarify these differences and sketch out way...

Finding and classifying astronomical sources is key in the scientific exploitation of radio surveys. Source-finding usually involves identifying the parts of an image belonging to an astronomical source, against some estimated background. This can be...

The low mass star ASASSN-13db experienced an EXor outburst in 2013, which identified it as a Young Stellar Object (YSO). Then, from 2014 to 2017 it had another outburst, longer and more luminous than the earlier. We analyze the observations of the se...

Accreting supermassive black holes in active galactic nuclei (AGN) produce powerful relativistic jets that shine from radio to GeV/TeV γ-rays. Over the past decade, AGN jets have extensively been studied in various energy bands and our knowledg...