PNe are known to be photoionized objects. However they also have low-ionization structures (LIS) with different excitation behavior. We are only now starting to answer why most LIS have lower electron densities than the PN shells hosting them, and whether or not their intense emission in low-ionization lines is the key to their main excitation mechanism. Can LIS line ratios, chemical abundances and kinematics enlight the interplay between the different excitation and formation processes in PNe? Based on the spectra of five PNe with LIS and using new diagnostic diagrams from shock models, we demonstrate that LIS’s main excitation is due to shocks, whereas the other components are mainly photoionized. We propose new diagnostic diagrams involving a few emission lines ([N II], [O III], [S II]) and fshocks/f*, where fshocks and f* are the ionization photon fluxes due to the shocks and to the central star ionizing continuum, respectively.

The Planck all-sky submillimetre observations have made it possible to study Galactic cold clumps in diverse environments, to probe dust properties and to examine the earliest stages of star formation. The TOP-SCOPE joint survey program aims to statistically study the evolution of molecular clouds and the initial conditions of star formation in a wide variety of environments. In this work we carry out an investigation of the 200 brightest compact sources detected by Planck.

Low-mass stars form from the gravitational collapse of dense molecular cloud cores. While a general consensus picture of this collapse process has emerged, many details on how mass is transferred from cores to stars remain poorly understood. MASSES (Mass Assembly of Stellar Systems and their Evolution with the SMA), an SMA large project, has just finished surveying all 74 Class 0 and Class I protostars in the nearby Perseus molecular cloud to reveal the interplay between fragmentation, angular momentum, and outflows in regulating accretion and setting the final masses of stars. Scientific highlights are presented in this proceedings, covering the topics of episodic accretion, hierarchical thermal Jeans fragmentation, angular momentum transfer, envelope grain sizes, and disk evolution.

We perform six N-body simulations reproducing the interaction between the Milky Way and its satellite galaxies, in order to address the deposit of satellite debris in the Galactic environment. We find that most of the baryons survive inside their host satellites and that most of the baryonic debris ends up in the inner regions of the Milky Way, in contrast to the more uniform distribution of dark matter debris. We also look at the debris Inertia tensor in the inner regions of the Milky Way and find a lower minor-to-major axis ratio for baryons than dark matter. We plan to explore the phase-space distribution of the debris ending in the Galactic disk and bulge. We also plan further simulations including gas dynamics to study the impact of gas on the process.

WD+AGB star systems have been suggested as an alternative way for producing type Ia supernovae (SNe Ia), known as the core-degenerate (CD) scenario. In the CD scenario, SNe Ia are produced at the final phase during the evolution of common-envelope through a merger between a carbon-oxygen (CO) WD and the CO core of an AGB secondary. However, the rates of SNe Ia from this scenario are still uncertain. In this work, I carried out a detailed investigation on the CD scenario based on a binary population synthesis approach. I found that the Galactic rates of SNe Ia from this scenario are not more than 20% of total SNe Ia due to more careful treatment of mass transfer, and that their delay times are in the range of ∼90 − 2500 Myr, mainly contributing to the observed SNe Ia with short and intermediate delay times.

Several problems contribute to difficulties in interpreting transient celestial phenomena as described in Chinese records. Frameworks are an overarching problem. Tianwen, the modern Chinese term for astronomy, in pre-modern times included meteorological phenonemena and was concerned with omenology. Manuscripts that include star charts and comets but also meteorological phenomena and omen reading texts were routinely reframed in modern scholarship to appear as if they included only astronomical content. The scope of pre-modern tianwen, however, was broader than its modern sense. Pre-modern celestial phenomena had political and religious significance. Apparent ambiguity arises from the presence of both meteorological and astronomical phenomena in a single category and from features of the classical Chinese language. Accounting for these problems is essential for research into transient phenomena using historical archives.

We present results from a non-cosmological, three-dimensional hydrodynamic simulation of an outflow from an intermediate-mass black hole in Dwarf Spheroidal Galaxies. Assuming an initial baryonic-to-dark-matter ratio derived from the CMB radiation and a cored, static dark matter potential, we evolved the galactic gas distribution over 3 Gyr, taking into account the outflow of a black hole. Our results indicate that in a homogeneous medium the outflow propagates freely in both directions with the same velocity and its capable of removing a fraction of the gas from the galaxy (it depends on the initial conditions of the outflow). When the SNe are taken into account, the effect of the outflow is substantially reduced. It is necessary an initial velocity around 1000 km/s and a density larger than 0.003 particles.cm−3 for the outflow to propagate. In these conditions, the removal of gas from the galaxy is almost negligible at the end of the 3 Gyr of the simulation.

Magritte is a new deterministic radiative transfer code. It is a ray-tracing code that computes the radiation field by solving the radiative transfer equation along a fixed set of rays for each grid cell. Its ray-tracing algorithm is independent of the type of input grid and thus can handle smoothed-particle hydrodynamics (SPH) particles, structured as well as unstructured grids. The radiative transfer solver is highly parallelized and optimized to have well scaling performance on several computer architectures. Magritte also contains separate dedicated modules for chemistry and thermal balance. These enable it to self-consistently model the interdependence between the radiation field and the local thermal and chemical states. The source code for Magritte will be made publically available at github.com/Magritte-code.

We present evolution calculations from the Asymptotic Giant Branch (AGB) to the Planetary Nebula (PNe) phase for models of mass 1.0 to 2.0 M⊙ over a range of metallicities. The understanding of these objects plays an important role in galactic evolution and composition. Here, we particularly focus on Late Thermal Pulse (LTP) models, which are models that experience an intense helium-shell pulse that occurs just following AGB departure and causes a rapid looping evolution between the AGB and PN phases. The transient phases only last decades and centuries while increasing and decreasing in temperature dramatically. We use our models to make comparisons to V839 Ara (SAO 244567). This star has been observed rapidly heating over more than 50 years. Observations have proven difficult to model because the central star has a small radius, high surface gravity, and low temperature compared to our models.

The origin of the Brγ-line emission in Herbig Ae/Be stars is still an open question and might be related e.g., to a disc wind or the stellar magnetosphere. The study of the continuum and Brγ-emitting region of Herbig Ae/Be stars with high-spectral and high-spatial resolution gives great insights into the sub-au scale hydrogen gas distribution.

We observed the Herbig Be star MWC 120 with the VLTI/AMBER instrument in different spectral channels across the Brγ line with a spectral resolution of R~1500. Using radiative transfer modeling we found a radius of the line emitting region of ~0.4 au that is only two times smaller than the K-band continuum region. This is consistent with a disc wind scenario rather than an origin of magnetospheric emission.

We present near-infrared AMBER (R~12000) observations of the Herbig B[e] star MWC297 in the Brγ-line. We found that the near-infrared continuum emission is ~3.6 times more compact than the expected dust-sublimation radius, possibly indicating the presence of highly refractory dust grains or optically thick gas emission in the inner disk. Our velocity-resolved channel maps marking the first time that kinematic effects in the sub-AU inner regions of a protoplanetary disk could be directly imaged.

A summary is given of the present state of our knowledge of High-Mass X-ray Binaries (HMXBs), their formation and expected future evolution. Among the HMXB-systems that contain neutron stars, only those that have orbital periods upwards of one year will survive the Common-Envelope (CE) evolution that follows the HMXB phase. These systems may produce close double neutron stars with eccentric orbits. The HMXBs that contain black holes do not necessarily evolve into a CE phase. Systems with relatively short orbital periods will evolve by stable Roche-lobe overflow to short-period Wolf-Rayet (WR) X-ray binaries containing a black hole. Two other ways for the formation of WR X-ray binaries with black holes are identified: CE-evolution of wide HMXBs and homogeneous evolution of very close systems. In all three cases, the final product of the WR X-ray binary will be a double black hole or a black hole neutron star binary.

Numerous numerical studies suggest that magnetic fields influence the transport of dust and gas, the disk chemistry, the migration of planetesimals within the disk, and above all the accretion of matter onto the star. In short: Magnetic fields are crucial for the evolution of planet-forming disks. First indirect comparisons of theory and observations support this picture (Flock et al. 2017); however, profound observational constraints are still pending. Recent studies show that the intrinsically polarized continuum emission, the classical tracer of magnetic fields, might trace other physics as well (radiation field or dust grain size). The nearly face-on protoplanetary disk HD 142527 shows predominantly radial polarization vectors consistent with aspherical grains aligned by a toroidal magnetic field (Fig. 1; Bertrang et al. 2017a,b; Ohashi et al. 2018). However, the number of cutting-edge polarization observations presenting inconclusive data, for which these three different origins of polarization are not clearly distinguishable, increases continuously. We present a solution to this polarized ambiguity: observations and simulations of the most direct tracer of magnetic fields, polarized gas emission, in combination with multi-wavelength continuum polarization observations will disentangle the sources of continuum polarimetry with ALMA (Bertrang et al. 2017a,b; Bertrang & Cortés in prep.).

We investigate Lyα, [Oiii] λ5007, Hα, and [Cii]158µm emission from 1,124 low-mass galaxies (typically M* ~ 108 Mʘ) at z = 4.9 - 7.0, composed of 1,092 Lyα emitters (LAEs) at z = 4.9 - 7.0 identified by Subaru/Hyper Suprime-Cam (HSC) narrowband surveys and 34 galaxies at z = 5.148 - 7.508 with deep ALMA [Cii]158µm data in the literature. At z = 4.9, we find that the rest-frame Hα equivalent width positively correlates with the rest-frame Lyα equivalent width EW0Lyα. At z = 5.7 - 7.0, there exists an interesting turn-over trend that the [ Oiii]/ Hα flux ratio increases in EW0Lyα ≃ 0 - 30 Å, and then decreases out to EW0Lyα ≃ 130 Å. We also identify an anti-correlation between a [ Cii] luminosity to star-formation rate ratio (L[CII]/SFR) and EW0Lyα at the >99% confidence level. We carefully investigate physical origins of the correlations, and find that a simple anti-correlation between EW0Lyα and metallicity explains self-consistently all of the relations identified in our study.

The theme of this focus meeting is related to the detection, characterization and modeling of nano particles — cosmic dust of sizes of roughly 1 to 100 nm — in space environments like the interstellar medium, planetary debris disks, the heliosphere, the vicinity of the Sun and planetary atmospheres, and the space near Earth. Discussions focus on nano dust that forms from condensations and collisions and from planetary objects, as well as its interactions with space plasmas like the solar and stellar winds, atmospheres and magnetospheres. A particular goal is to bring together space scientists, astronomers, astrophysicists, and laboratory experimentalists and combine their knowledge to reach cross fertilization of different disciplines.

The Magellanic Clouds are nearby dwarf irregular galaxies that represent a unique laboratory for studying galaxy interactions. Their morphology and dynamics have been heavily influenced by their mutual interactions as well as with their interaction(s) with the Milky Way. We use the VISTA near-infrared YJKs survey of the Magellanic Clouds system (VMC) in combination with stellar partial models of the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and the Milky Way to investigate the spatial distribution of stellar populations of different ages across the Magellanic Clouds. In this contribution, we present the results of these studies that allow us to trace substructures possibly related to the interaction history of the Magellanic Clouds.

Be/X-ray binaries are a major subclass of high mass X-ray binaries. Two different X-ray outbursts are displayed in the X-ray light curves of such systems. It is generally believed that the X-ray outbursts are connected with the neutron star periastron passage of the circumstellar disk around the Be star. The optical emission of the Be star should be very important to understand the X-ray emission of the compact object. We have monitored several Be/X-ray binaries photometrically and spectroscopically in the optical band. The relationship between the optical emission and X-ray activity is described, which is very useful to explain the X-ray outbursts in Be/X-ray binaries.