Magnetic fields are a key component in star formation theories. Nevertheless, their exact role in the formation of stars is still a matter of debate. The process of angular momentum transportation by the disturbance caused during magnetic field reconnection still needs theoretical formulation in terms of the collapsing cloud’s parameters. The purposes of this study are: to model the critical mass of a magnetized, gravitating and turbulent star forming molecular cloud (MC) and to formulate the momentum carried out by a magnetic field through magnetic field reconnection in terms of the MC’s parameters. By applying theoretical modeling, we show how angular momentum transported via an Alfvén wave can be described in terms of mass, radius and dispersion velocity of a collapsing cloud core and a model equation of the critical mass for a gravitating, turbulent, and magnetized molecular cloud core. The outflow of angular momentum by magnetic fields facilitates the inflow of mass. On the other side, magnetic pressure prevents collapse. Therefore, magnetic fields have a dual purpose in the process of star formation. This momentum outflow triggers the inflow of mass to conserve angular momentum. The results show that Alfvén waves are like a machine that extracts angular momentum from a magnetized collapsing cloud core. Thus the total angular momentum transported by magnetic field at a distance R from the core’s center depends on the size, mass and turbulent velocity dispersion of the collapsing cloud core.

We show that the structure of magnetized accretion gas flows between the components of the Beta Lyrae system can cause a scattering gas shell that masks completely these components in soft X-ray region. Also we have calculated the inner structure of the donor that is filling a Roche lobe and is preceding a forming of the degenerate dwarf. We show that mass of the degenerate core of the donor is in region 0.3−0.5M⊙.

Half-dozen of extreme representatives of void dwarf galaxy population were found in our study of evolutionary status of a hundred galaxies in the nearby Lynx-Cancer void. They are very gas-rich, extremely low-metallicity [7.0 < 12 + log(O/H) < ∼ 7.3] objects, with blue colours of outer parts. The colours indicate the ages of the oldest visible stellar population of one to a few Gyr. They all are intrinsically faint, mostly Low Surface Brightness dwarfs, with MB range of –9.5m to –14m. Thus, their finding is a subject of the severe observational selection. The recent advancement in search for such objects in other nearby voids resulted in doubled their total number. We summarize all available data on this group of unusual void dwarf galaxies and discuss them in the general context of very low metallicity galaxies and their possible formation and evolutionary scenarios.

We searched for associations (not for families) amongst the near Earth asteroids (NEAs) and, similarly as in our previous studies (Jopek 2011; Jopek 2015),AQ: Please provide reference detail for Jopek 2012. a dozen groups of 10 or more members was found with high statistical reliability. We present some details of our most numerous finding: association (2061) Anza which, at the moment, incorporates 191 members.

We carried out simultaneous observations of H2O and OH masers, and radio continuum at 1.3 cm with the Karl G. Jansky Very Large Array (VLA) towards 4 water-fountain candidates. Water fountains (WFs) are evolved stars, in the AGB and post-AGB phase, with collimated jets traced by high-velocity H2O masers. Up to now, only 15 sources have been confirmed as WFs through interferometric observations. We are interested in the discovery and study of new WFs. A higher number of these sources is important to understand their properties as a group, because they may represent one of the first manifestations of collimated mass-loss in evolved stars. These observations will provide information about the role of magnetic fields in the launching of jets in WFs. Our aim is to ascertain the WF nature of these candidates, and investigate the spatial distribution of the H2O and OH masers.

The synthesis of dust grains mostly takes place in the circumstellar envelopes (CSEs) of asymptotic giant branch (AGB) stars. What are the precursor seeds of condensation nuclei and how do these particles evolve toward the micrometer sized grains that populate the interstellar medium? These are key questions of the NANOCOSMOS project. In this study, we carried out an observational study to constrain what the main gas-phase precursors of dust in C-rich AGB stars are.

There are clear differences in what sulphur molecules form in AGB circumstellar envelopes (CSEs) across chemical types. CS forms more readily in the CSEs of carbon stars, while SO and SO2 have only been detected towards oxygen-rich stars. However, we have also discovered differences in sulphur chemistry based on the density of the CSE, as traced by mass-loss rate divided by expansion velocity. For example, the radial distribution of SO is drastically different between AGB stars with lower and higher density CSEs. H2S can be found in high abundances towards higher density oxygen-rich stars, whereas SiS accounts for a significant portion of the circumstellar sulphur for higher density carbon stars.

In order to investigate the effect of dust production on the molecular absorption, we model the dust continuum and the 7.5 and 13.7 μm acetylene absorption features in the Spitzer IRS spectra of 148 carbon stars in the Large Magellanic Cloud (LMC). Our preliminary investigation does not find a strong correlation between the dust-production rate and the column density of acetylene for the LMC sample. However, we will construct more models at high optical depths and probe a larger range of dust properties for more robust results.

We have discovered jets in post-AGB binaries. The orbital motion allows us to carry out tomography of the jet as light from the primary star shines through the jet cone. Jets play a major role in many astrophysical environments, from young stellar objects to galaxies. They are also used to study the energetics of accretion phenomena in systems such as red transients and stellar mergers. We use high-resolution, optical, time-series spectra to constrain theories of jet launching, and the impact of jets on the evolution of these post-AGB binaries.

The open-source desktop planetarium Stellarium has become very popular in astronomical education and outreach. Our recent changes aim for its applicability in historical and archaeoastronomical simulation contexts. Apart from visualizing the seemingly perpetual regular motions of the celestial bodies, it can be used to visualize and demonstrate historical solar and lunar eclipses, historical and present comets, meteors, and also novae and supernovae.

This summary captures, in the broadest sense, some of the achievements, challenges and spirit of the astronomy for development community at the 30th General Assembly of the IAU.

. NGC 300 ULX1 is the fourth to be discovered in the class of the ultra-luminous X-ray pulsars. Pulsations from NGC 300 ULX1 were discovered during simultaneous XMM-Newton / NuSTAR observations in Dec. 2016. The period decreased from 31.71 s to 31.54 s within a few days, with a spin-up rate of –5.56×10–7 s s–1, likely one of the largest ever observed from an accreting neutron star. Archival Swift and NICER observations revealed that the period decreased exponentially from ~45 s to ~17.5 s over 2.3 years. The pulses are highly modulated with a pulsed fraction strongly increasing with energy and reaching nearly 80% at energies above 10 keV. The X-ray spectrum is described by a power-law and a disk black-body model, leading to a 0.3–30 keV unabsorbed luminosity of 4.7×1039 erg s–1. The spectrum from an archival XMM-Newton observation of 2010 can be explained by the same model, however, with much higher absorption. This suggests, that the intrinsic luminosity did not change much since that epoch. NGC 300 ULX1 shares many properties with supergiant high mass X-ray binaries, however, at an extreme accretion rate.

Orbital resonances in the Galactic halo have been studied using the Galactic mass model of Pichardo et al. (2003, 2004), including a Galactic bar. For the two moving groups of the Galactic halo, G18-39 and G21-22 (Silva et al. 2012), the majority of stars in both groups appear trapped in two resonances over the Galactic plane, generated by the bar. We have taken the rotation speed of the bar, Ωb, as 45-55 km s-1 kpc-1. So, these two moving groups are part of stellar supergroups which populate these two resonances. The position of these two groups in the Bottlinger diagram can be explained by the mean (U,V) field generated by these two resonances crossing the solar vicinity, in contrast with the alternate explanation of Silva et al. (2012), based on the simulations of Meza et al. (2005), that these two groups, seen as two peaks in the U Galactic velocity, have been created by the accretion of a dwarf galaxy by the Milky Way, such as that of Ω Centauri.

The evolution of galaxies is driven by the birth and death of stars. AGB stars are at the end points of their evolution and therefore their luminosities directly reflect their birth mass; this enables us to reconstruct the star formation history. These cool stars also produce dust grains that play an important role in the temperature regulation of the interstellar medium (ISM), chemistry, and the formation of planets. These stars can be resolved in all of the nearby galaxies. Therefore, the Local Group of galaxies offers us a superb near-field cosmology site. Here we can reconstruct the formation histories, and probe the structure and dynamics, of spiral galaxies, of the many dwarf satellite galaxies surrounding the Milky Way and Andromeda, and of isolated dwarf galaxies. It also offers a variety of environments in which to study the detailed processes of galaxy evolution through studying the mass-loss mechanism and dust production by cool evolved stars. In this paper, I will first review our recent efforts to identify mass-losing Asymptotic Giant Branch (AGB) stars and red supergiants (RSGs) in Local Group galaxies and to correlate spatial distributions of the AGB stars of different mass with galactic structures. Then, I will outline our methodology to reconstruct the star formation histories using variable pulsating AGB stars and RSGs and present the results for rates of mass–loss and dust production by pulsating AGB stars and their analysis in terms of stellar evolution and galaxy evolution.

Almost all confirmed optical counterparts of HMXBs in the SMC are OB stars with equatorial decretion disks (OBe). These sources emit strongly in Balmer lines and standout when imaged through narrow-band Hα imaging. The lack of secure counterparts for a significant fraction of the HMXBs motivated us to search for more. Using the catalogs for OB/OBe stars (Maravelias et al.2017) and for HMXBs (Haberl & Sturm 2016) we detect 70 optical counterparts (out of 104 covered by our survey). We provide the first identification of the optical counterpart to the source XTEJ0050-731. We verify that 17 previously uncertain optical counterparts are indeed the proper matches. Regarding 52 confirmed HMXBs (known optical counterparts with Hα emission), we detect 39 as OBe and another 13 as OB stars. This allows a direct estimation of the fraction of active OBe stars in HMXBs that show Hα emission at a given epoch to be at least ∼75% of their total HMXB population.

The chemical evolution of the Universe is governed by the nucleosynthesis contribution from stars, which in turn is determined primarily by the initial stellar mass. The heaviest elements are primarily produced through neutron capture nucleosynthesis. Two main neutron capture processes identified are the slow and rapid neutron capture processes (s and r processes, respectively). The sites of the r and s-process are discussed, along with recent progress and their associated uncertainties. This review is mostly focused on the s-process which occurs in low and intermediate-mass stars which have masses up to about 8 solar masses (M⊙). We also discuss the intermediate-neutron capture process (or i-process), which may occur in AGB stars, accreting white dwarfs, and massive stars. The contribution of the i-process to the chemical evolution of elements in galaxies is as yet uncertain.

In the standard formation scenario of planetary systems, planets form from a protoplanetary disk that consists of gas and dust. The scenario can be divided into three stages: (1) formation of planetesimals from dust, (2) formation of protoplanets from planetesimals, and (3) formation of planets from protoplanets. In stage (1), planetesimals form from dust through coagulation of dust grains and/or some instability of a dust layer. Planetesimals grow by mutual collisions to protoplanets or planetary embryos through runaway and oligarchic growth in stage (2). The final stage (3) of terrestrial planet formation is giant impacts among protoplanets while sweeping residual planetesimals. In the present paper, we review the elementary processes of terrestrial planet formation and discuss the extension of the standard scenario.

In the era of ALMA, we can now resolve polarization within circumstellar disks at (sub)millimeter wavelengths. While many initially hoped that these observations would map magnetic fields in disks, the observed polarization patterns indicate other possible polarization mechanisms. These alternative polarization mechanisms include Rayleigh self-scattering, grains aligning with the radiation anisotropy (k-RAT alignment), and mechanical alignment. Stephens et al. (2017) specifically showed that the polarization morphology in HL Tau changes rapidly with wavelength; the morphology is uniform at 870 μm, azimuthal at 3.1 mm, and ∼50%/50% mix of the two at 1.3 mm. Although it has been suggested that the polarized emission at 870 μm is due to scattering and at 3.1 mm is due to k-RAT alignment, both mechanisms appear to have shortcomings. Specifically, Kataoka et al. (2017) showed that scattering requires much smaller grains (10s of μm) than that suggested by other studies, while k-RAT alignment suggest a significant decrease in polarization along the minor axis, which is not seen. Studies of other disks have suggested that polarization may come from grains aligned with the magnetic fields, but these studies are inconclusive. Understanding and extracting information about the polarized emission from disks requires multi-wavelength and high resolution observations.

We have carried out a wide and deep imaging survey for the Local Group dwarf spheroidal galaxy Ursa Minor (UMi) using Hyper Suprime-Cam (HSC). The data cover out beyond the nominal tidal radius down to ~25 mag in i band, which is ~2 mag below the main sequence turn-off point. The structural parameters of UMi are derived using red giant branch (RGB) stars and sub-giant branch (SGB) stars, and the tidal radius is suggested to be larger than those estimated by the previous studies. It is also found that the distribution of bluer RGB/SGB stars is more extended than that of redder RGB/SGB stars. The fraction of binary systems is estimated to be ~0.4 from the morphology of the main sequences.