Mass-loss via stellar-feedback driven outflows is predicted to play a critical role in the baryon cycle of low-mass galaxies. However, observational constraints on warm winds are limited as outflows are transient, intrinsically low-surface brightness events and, thus, difficult to detect. Here, we search for outflows in a sample of eleven nearby starburst dwarf galaxies which are strong candidates for outflows. Despite deep H? imaging on galaxies, only a fraction of the sample show evidence of winds. The spatial extent of all detected ionized gas is limited and would still be considered part of the ISM by simulations. These new observations indicate that the physical extent of warm phase outflows is modest and most of the mass will be recycled to the galaxy. The sample is part of the panchromatic STARBurst IRegular Dwarf Survey (STARBIRDS) designed to characterize the starburst phenomenon and its impact on the evolution of low-mass galaxies.

We carried out a high contrast imaging search for (sub)stellar companions of young pre-main sequence stars in the Lupus star forming region. For this project we utilized NACO/ESO-VLT, operated at the Paranal observatory. On this poster, we presented the results of this survey. In several observing campaigns we could obtain diffraction limited deep IR imaging data and detected faint co-moving companions around our targets, whose astro- and photometry was determined in all observing epochs. The co-moving companions found in our survey exhibit angular separations in the range between about 0.1 and a few arcsecs, i.e. projected separations between about 10 and a few hundreds of au, at the average distance of our targets of about 140 pc. Beside several new binary and triple star systems, whose multiplicity was revealed in this survey, also faint co-moving companions in the substellar mass regime could be identified close to some of our targets.

Using 3D spectroscopy data from the TYPHOON Project (PI: B. Madore), I show convincing observational evidence that the ISM oxygen abundance traced by HII regions presents systematic azimuthal variations in NGC 1365 and NGC 2997. I discuss a possible physical origin and on-going efforts to explore the prevalence and cause of such variations.

Emission lines from CO and Hi are the standard tracers of molecular and atomic interstellar medium, respectively. In the past two decades, a consensus has formed that a substantial fraction of Galactic molecular gas evades detection by these two tracers, thus giving rise to the empirical concept of dark molecular gas (DMG). Largely based on the experience and evidence garnered from the Arecibo Millennium survey, we have formed an international consortium, the Pacific Rim Interstellar Matter Observers (PRIMO), to pursue alternative tracers of DMG, particularly absorption against background radio sources (quasars). PRIMO have carried out observing programs at Arecibo, JVLA, Delingha 13.7m, ATCA and ALMA, among others. Our observations reveal abundant hydrides, namely OH and CH, in DMG clouds. The historical difficulty of mapping OH can be explained by the measured OH excitation temperature$f(T_{{\rm{ex}}}^{{\rm{OH}}}) \propto \frac{1}{{\sqrt {2\pi } \sigma }}{\rm{exp}}[ - {(ln(T_{ex}^{OH}) - ln(3.4\;K))^2}/(2{\sigma ^2})],$

which is a modified log-normal function peaking close to the numerical value of the L-band Galactic continuum background (synchrotron + CMB). Both OH and CH are shown to be better tracers of molecular hydrogen than CO, particularly in the intermediate extinction regions (Av ~ 0.05-2 magnitude), where DMG dominates. http://ism.bao.ac.cn/primo

We determine Zr and Nb elemental abundances in barium stars to probe the operation temperature of the s-process that occurred in the companion asymptotic giant branch (AGB) stars. Along with Zr and Nb, we derive the abundances of a large number of heavy elements. They provide constraints on the s-process operation temperature and therefore on the s-process neutron source. The results are then compared with stellar evolution and nucleosynthesis models. We compare the nucleosynthetic profile of the present sample stars with those of CEMP-s, CEMP-rs and CEMP-r stars. One barium star of our sample is potentially identified as the highest-metallicity CEMP-rs star yet discovered.

We know that the observed H i (and H2) content cannot explain the SFR observed in galaxies. The only way galaxies can sustain that SFR is by accreting HI-rich dwarf galaxies or Inter-Galactic HI clouds. However, no observation to detect those accretion events has been conclusive so far. Instruments having the necessary sensitivity (e.g. GBT) lack the necessary spatial resolution and those with the proper resolution (e.g. VLA) lack the sensitivity. I will show that both are necessary to detect those illusive Hi clouds. The SKA precursor MeerKAT is starting its operation as we speak and will start the Large Survey Programs at the end of 2018. FAST has started its observations in drift scan mode with CRAFTS (Commensal Radio Astronomy Fast Survey). In the near future (2019-20), the best combination to study low column density H i will be to combine the sensitivity of FAST with the spatial resolution of MeerKAT.

The Solo (Solitary local) Dwarf Galaxy Survey is a volume limited sample of all nearby (< 3 Mpc) and isolated (> 300 kpc from the Milky Way or M31) dwarfs, with wide-field g and i imaging. This survey uses resolved stellar populations to parameterize these low mass systems. Comparison to the well studied satellite dwarfs characterizes the evolutionary impact of a large galaxy in close proximity. The deep, wide field nature of this survey also lends itself to searching for nearby substructures, both globular clusters and possible faint satellites.

Current work is focused on the 16 closest Solo dwarfs, all within the virial radius (approximately 1 Mpc) of the Local Group. This subset has been characterized using consistent methods, despite their diversity in stellar mass and apparent size. The analysis highlights the extended stellar structure and morphology. We will examine trends with star formation history, and separation from a large host. This first subset emphasizes the survey’s unique challenges and advantages.

The Solo Survey provides detailed look at the extended structure of dwarfs and characterizes the evolution of galaxies in the faint limit.

. Metallicity gradients are most frequently investigated directly from galaxies observed in emission. We have shown that galaxies detected via strong quasar absorption lines also exhibits a metallicity gradient in the outskirts and circumgalactic medium out to ~40 kpc distance. We infer a metallicity gradient of −0.022 dex kpc−1 for absorption-selected systems at redshifts 0.1 z3. Applying this metallicity gradient and a flattening of the gradient beyond 12 kpc, we demonstrate that absorption-selected galaxies obey the same mass-metallicity relation (MZR) as observed for luminosity-selected galaxies.

Ultra-diffuse galaxies (UDGs) have sizes comparable to the Milky Way and stellar masses of about 1/1000 of it. They attracted a lot of attention as possible “dark galaxies” heavily dominated by dark matter, however, no reliable dynamical mass estimates were done because of their extremely low surface brightness. We have recently found 13 gas free diffuse young (300–500 Myr) post-starburst galaxies (PSGs) without ongoing star formation in Coma and Abell 2147, which, should they continue to evolve passively, will become UDGs in 5 Gyr. We obtained deep spectroscopic observations for 11 diffuse PSGs and derived their internal kinematics and stellar population properties. All of them possess disk-like kinematics (substantial rotation, low stellar velocity dispersion) and likely experienced starburst episodes prior to the star formation quenching by ram pressure stripping. Our results suggest that at least some UDGs were “normal” intermediate to large-sized disk galaxies in the past, which were later quenched by dense environment.

The study of radial metallicity gradients in the disc of the Milky Way is a powerful tool to understand the mechamisms that have been acting in the formation and evolution of the Galactic disc. In this proceeding, I will put the eye on some problems that should be carefully addressed to obtain precise determinations of the metallicity gradients.

We present the NLTE abundances of 10 chemical species in 65 very metal-poor stars in eight dSphs and the Milky Way halo. The classical dSphs Sculptor, Ursa Minor, Sextans, and Fornax reveal a similar plateau at [α/Fe] = 0.3 for each of Mg, Ca, and Ti, similarly to the MW halo. We provide the evidence for a decline in α/Fe in the Boötes I UFD, that is probably due to the ejecta of SNeIa. The dichotomy in the [Sr/Ba] versus [Ba/H] diagram is observed in the classical dSphs, similarly to the MW halo, calling for two different nucleosynthesis channels for Sr. The Boötes I and UMa II UFDs reveal very similar ratios of [Sr/Mg] = −1.3 and [Ba/Mg] = –1. The stars in the Coma Berenices and Leo IV UFDs are even poorer in Sr and Ba. The subsolar Sr/Ba ratios of Boötes I and UMa II indicate a common r-process origin of their n-capture elements.

Using high resolution 3D hydrodynamical simulations we quantify the amount of mass accreted onto the secondary star of the binary system η Carinae during periastron passage on its highly eccentric orbit. The accreted mass is responsible for the spectroscopic event occurring every orbit close to periastron passage, during which many lines vary and the x-ray emission associated with the destruction wind collision structure declines. The system is mainly known for its giant eruptions that occurred in the nineteenth century. The high mass model of the system, M1=170M⊙ and M2=80M⊙, gives Macc≍ 3×10−6M⊙ compatible with the amount required for explaining the reduction in secondary ionization photons during the spectroscopic event, and also matches its observed duration. As accretion occurs now, it surely occurred during the giant eruptions. This implies that mass transfer can have a huge influence on the evolution of massive stars.

The first detection of gravitational waves from a merging double neutron star (DNS) binary implies a much higher rate of DNS coalescences in the local Universe than typically estimated on theoretical grounds. The recent study by Chruslinska et al. (2018) shows that apart from being particularly sensitive to the common envelope treatment, DNS merger rates appear rather robust against variations of several factors probed in their study (e.g. conservativeness of the mass transfer, angular momentum loss, and natal kicks), unless extreme assumptions are made. Confrontation with the improving observational limits may allow to rule out some of the extreme models. To correctly compare model predictions with observational limits one has to account for the other factors that affect the rates. One of those factors relates to the assumed history of star formation and chemical evolution of the Universe and its impact on the final results needs to be better constrained.

We explore the Milky Way supershell GS242-03+37. We argue that the observed HI distribution can be explained as an expanding structure about 100 Myr old powered with a modest energy released by an OB association. The formation of star clusters has been triggered less than 30 Myr ago when the ISM density in the supershell increased due to the galactic differential rotation. The observed age sequence of young star clusters is related to the evolution of the column density during the supershell expansion.

The U.S. National Optical Astronomy Observatory’s Education and Public Outreach group has produced a Quality Lighting Teaching Kit. The kits are designed around problem-based learning scenarios. The kit’s six activities allow students to address real lighting problems that relate to wildlife, sky glow, aging eyes, energy consumption, safety, and light trespass. The activities are optimized for 11-16 year olds. As part of the IAU100 celebration, the kits will be manufactured and made available to observatories and communities around the world.

In order to determine the true impact of stellar multiplicity on the formation and evolution of planets, we initiated direct imaging surveys to search for (sub)stellar companions of exoplanet host stars on close orbits, as their gravitational impact on the planet bearing disk at first and on formed planets afterwards is expected to be maximal. According to theory these are the most challenging environments for planet formation and evolution but might occur quite frequently in the milky way, due to the large number of multiple stars within our galaxy. On this poster we showed results, obtained so far in the course of our AO and Lucky-imaging campaigns of exoplanet host stars, conducted with NACO/ESO-VLT for southern and with AstraLux/CAHA2.2m for northern targets, respectively. In addition, we introduced our new high contrast imaging survey with SPHERE/ESO-VLT to search for close companions of southern exoplanet host stars, and presented some first results.

We analyze the data from the 6 gravitational waves signals detected by LIGO through the lens of multifractal formalism using the MFDMA method, as well as shuffled and surrogate procedures. We identified two regimes of multifractality in the strain measure of the time series by examining long memory and the presence of nonlinearities. The moment used to divide the series into two parts separates these two regimes and can be interpreted as the moment of collision between the black holes. An empirical relationship between the variation in left side diversity and the chirp mass of each event was also determined.