The Monχey project will provide a large and homogeneous set of stellar yields for the low- and intermediate- mass stars and has applications particularly to galactic chemical evolution modelling. We describe our detailed grid of stellar evolutionary models and corresponding nucleosynthetic yields for stars of initial mass 0.8 M⊙ up to the limit for core collapse supernova (CC-SN) ≈ 10 M⊙. Our study covers a broad range of metallicities, ranging from the first, primordial stars (Z = 0) to those of super-solar metallicity (Z = 0.04). The models are evolved from the zero-age main-sequence until the end of the asymptotic giant branch (AGB) and the nucleosynthesis calculations include all elements from H to Bi. A major innovation of our work is the first complete grid of heavy element nucleosynthetic predictions for primordial AGB stars as well as the inclusion of extra-mixing processes (in this case thermohaline) during the red giant branch. We provide a broad overview of our results with implications for galactic chemical evolution as well as highlight interesting results such as heavy element production in dredge-out events of super-AGB stars. We briefly introduce our forthcoming web-based database which provides the evolutionary tracks, structural properties, internal/surface nucleosynthetic compositions and stellar yields. Our web interface includes user- driven plotting capabilities with output available in a range of formats. Our nucleosynthetic results will be available for further use in post processing calculations for dust production yields.

This paper briefly reviews some advances and unsolved problems related to the formation of cosmic dust in the evolved environments of AGB stars and supernovae.

The IR emission from galaxies is a unique window into multiple aspects of galaxy evolution including star-formation rates, the age of galaxies, and galactic-scale dust processes. However, asymptotic giant branch (AGB) stars continue to introduce uncertainty into stellar population synthesis (SPS) models and limit our ability to interpret the IR light of galaxies. Here we focus on incorporating circumstellar dust around AGB stars in SPS models and understanding the extent to which they influence the IR light of galaxies. We find that the significance of the AGB dust contribution depends on the characteristics of the galaxy. For quiescent galaxies and metal-poor star forming galaxies, circumstellar dust emission can have a large effect, whereas for dusty star-forming galaxies the circumstellar emission is dwarfed by emission from dust in the ISM. The models with circumstellar dust also suggest, in agreement with previous work, that IR colors can be a powerful age diagnostic for older stellar systems. Models such as these will be essential for interpreting data that will be provided by JWST and other next generation IR facilities.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) operates in the 0.3–240 micron wavelength region, and offers imaging, polarimetric and high-resolution spectroscopic capabilities that can be used for a wide range of observations relevant for stellar physics studies. We summarize the advantages of using SOFIA, list some of the studies related to stellar physics that have been accomplished, and provide an example high-resolution spectrum of a red supergiant.

Interstellar dust is still the dominant uncertainty in Astronomy, limiting precision in e.g., cosmological distance estimates and models of how light is re-processed within a galaxy. When a foreground galaxy serendipitously overlaps a more distant one, the latter backlights the dusty structures in the nearer foreground galaxy. Such an overlapping or occulting galaxy pair can be used to measure the distribution of dust in the closest galaxy with great accuracy. The STARSMOG program uses HST observation of occulting galaxy pairs to accurately map the distribution of dust in foreground galaxies in fine (<100 pc) detail. Furthermore, Integral Field Unit observations of such pairs will map the effective extinction curve in these occulting galaxies, disentangling the role of fine-scale geometry and grain composition on the path of light through a galaxy.

The overlapping galaxy technique promises to deliver a clear understanding of the dust in galaxies: the dust geometry, a probability function of the amount of dimming as a function of galaxy type, its dependence on wavelength, and evolution of all these properties with cosmic time using distant, high-redshift pairs.

The gas-phase metallicity is one of the key insights we have into measuring the chemical feedback of stars in galaxies, yet remains difficult to correctly determine. However, there is a close relation between gas-phase metals and dust in the ISM, which can give us insight into the correct metallicity in galaxies. Here I will present recent work on metallicity gradients in galaxies, and how we can measure the global metallicity and the radial gradients in nearby galaxies using dust, through the dust-to-gas ratio.

A major difficulty hampering the accuracy of UV/optical star formation rate tracers is the effect of interstellar dust, absorbing and scattering light produced by both young and old stellar populations (SPs). Although empirically calibrated corrections or energy balance SED fitting are often used for fast de-reddening of galaxy stellar emission, eventually only radiative transfer calculations can provide self-consistent predictions of galaxy model spectra, taking into account important factors such as galaxy inclination, different morphological components, non-local heating of the dust and scattered radiation. In addition, dust radiative transfer can be used to determine the fraction of monochromatic dust emission powered by either young or old SPs. This calculation needs to take into account the different response of the dust grains to the UV and optical radiation field, depending on the grain size and composition. We determined the dust heating fractions, on both global and local scales, for a high-resolution galaxy model by using our 3D ray-tracing dust radiative transfer code “DART-Ray”. We show the results obtained using this method and discuss the consequences for star formation rate indicators.

We present new EAGLE (“Evolution and Assembly of GaLaxies and their Environments”, Schaye et al. 2015) zoom simulations of a range of Milky Way-like galaxies that can uniquely reproduce the metallicities of galactic stars, the ISM, and now the circumgalactic medium (CGM) as probed by quasar absorption line surveys. The surprising result is that the average L* galaxy loses more oxygen to the CGM out to hundreds of kpcs from a galaxy than it retains in its stars. These zooms not only follow the nucleosynthetic yields of 11 elements, they follow the non-equilibrium ionization and cooling of 133 ions, which allow direct comparison to observations of the COS-Halos survey of O VI in galactic halos out to 150 kpc (Tumlinson et al. 2011). The result is a new understanding of the galactic nucleosynthetic yield budget in simulations where galaxies are dramatically shaped by supernovae and black hole feedback. We are now closer to reconciling observed stellar, ISM, and now CGM metallicities with the nucleosynthetic production of the stellar component.

Dust is a ubiquities component of the interstellar medium (ISM) of galaxies, and manifests itself in many different ways. Yet, its origin, composition, and size distribution are still a matter of great debate. Most of the thermally condensed dust is produced in the explosively expelled ejecta of core collapse supernovae (CCSNe) and in the quiescent winds of AGB stars. Following its injection into the ISM it is destroyed by supernova (SN) shock waves. Knowing the relative rates of these processes is crucial for understanding the nature and evolution of dust in galaxies. In the following we will review three aspects of the evolution of dust in galaxies: the evolution of dust in the ejecta of SN1987A; the rates of dust production and destruction rates in the Magellanic Clouds (MCs), and the evolution of dust in CLASH 2882, a gravitationally-lensed galaxy at z=1.

The star formation rate (SFR) is a fundamental property of galaxies and it is crucial to understand the build-up of their stellar content, their chemical evolution, and energetic feedback. The SFR of galaxies is typically obtained by observing the emission by young stellar populations directly in the ultraviolet, the optical nebular line emission from gas ionized by newly-formed massive stars, the reprocessed emission by dust in the infrared range, or by combining observations at different wavelengths and fitting the full spectral energy distributions of galaxies. In this brief review we describe the assumptions, advantages and limitations of different SFR indicators, and we discuss the most promising SFR indicators for high-redshift studies.

We undertake a comprehensive comparative test of seven widely-used spectral synthesis models using multi-band HST photometry of a sample of eight YMCs in two galaxies. We provide a first quantitative estimate of the accuracies and uncertainties of new models, show the good progress of models in fitting high-quality observations, and highlight the need of further comprehensive comparative tests.

I review the implementation of the effects from varying chemical element abundance ratios in stellar population modelling. Recent highlights include the adoption of new flux calibrated libraries, the inclusion of a wide range of chemical elements, the calculation of error estimates on the model, and the consideration of element variation effects on full spectra. Some key results on the element ratios measured in early-type galaxies are discussed.

We exploit stellar population models of absorption features in the ultraviolet to assess their power in determining the age of the stellar population in galaxies. We focus in particular on features that can differentiate between an old UV-bright population, contributing to the UV upturn, and a young population due to recent star formation. We use a system of 8 indices between 2200 - 3200Å, tracing several chemical elements including Mg and Fe. We apply these models to a large sample of z ~ 0.6 massive galaxies from the Sloan Digital Sky Survey (SDSS) - III / Baryon Oscillation Spectroscopic Survey (BOSS) to derive the ages of the UV-bright populations. We find a subset of indices to be non-degenerate between old and young UV ages allowing us to find evidence for old stars contributing to the UV, rather than new star formation. We find up to 84% of our working sample (274,661 galaxies) to contain a contribution from old UV-bright stars. Those found to have higher contributing mass fractions being on average more massive and redder then those with lower mass fractions.

This talk focuses on the challenges facing the recent discovery of variations of the stellar initial mass function in massive early-type galaxies, with special emphasis on the constraints via gravity-sensitive spectral features.

We present the relative fraction of baryons and dark matter at various radii in galaxies. For spiral galaxies, this fraction measured in a galaxy's inner parts is typically baryon-dominated (maximal) and dark-matter dominated (sub-maximal) in the outskirts. The transition from maximal to sub-maximal baryons occurs within the inner parts of low-mass disk galaxies (with Vtot ≤ 200 km s−1) and in the outer disk for more massive systems. The mean mass fractions for late- and early-type galaxies vary significantly at the same fiducial radius and circular velocity, suggesting a range of galaxy formation mechanisms. A more detailed discussion, and resolution of the so-called “maximal disk problem”, is presented in Courteau & Dutton, ApJL, 801, 20.

I discuss stellar populations in galaxies at high redshift (z > 6), in particular the blue rest-frame UV colours which have been detected in recent years through near-IR imaging with HST. These spectral slopes of β < −2 are much more blue than star-forming galaxies at lower redshift, and may suggest less dust obscuration, lower metallicity or perhaps a different initial mass function. I describe current work on the luminosity function of high redshift star- forming galaxies, the evolution of the fraction of strong Lyman-α emitters in this population, and the contribution of the ionizing photon budget from such galaxies towards the reionization of the Universe. I also describe constraints placed by Spitzer/IRAC on stellar populations in galaxies within the first billion years, and look towards future developments in spectroscopy with Extremely Large Telescopes and the James Webb Space Telescope, including the JWST/NIRSpec GTO programme on galaxy evolution at high redshift.

Understanding the production of ionising photons in galaxies, how these photons propagate, ionise and heat the interstellar medium and possibly leak out of their host galaxies is key to understand many aspects of galaxy evolution and their contribution to reionisation. I will outline some projects currently undertaken to investigate the ionising photon budget.

This focus meeting builds on a small conference “Galaxies meet GRBs at Cabo de Gata” held in September 2013 in Spain, which, for the first time, brought together people from the GRB and starburst communities and proved to be a great success. Focus Meeting 10 at the XXIX IAU GA was the continuation of this interdisciplinary collaboration, supported by Division J (Galaxies and Cosmology), Division D (High Energy Phenomena and Fundamental Physics) and Division G Working Group “Massive Stars”.

The convection-enhanced paradigm behind core-collapse supernovae (SNe) invokes a multi-physics model where convection above the proto-neutron star is able to convert the energy released in the collapse to produce the violent explosions observed as SNe. Over the past decade, the evidence in support of this engine has grown, including constraints placed by SN neutrinos, energies, progenitors and remnants. Although considerable theoretical work remains to utilize this data, our understanding of normal SNe is advancing. To achieve a deeper level of understanding, we must find ways to compare detailed simulations with the increasing set of observational data. Here we review the current constraints and how we can apply our current understanding to broaden our understanding of these powerful engines.

The majority of young massive stars are found in close binary systems. Recently, dedicated observingcampaigns have provided strong constraints on the binary fraction as well as the distribution of the parameters thatcharacterize the binary systems: the masses of both components, the orbital period and eccentricities. Most strikinglythese findings imply that the majority of massive stars experience strong interaction (roche lobe overflow, a commonenvelope phase and or a merger) with a binary companion before their final explosion. I will discuss recent resultsfrom detailed binary star models and population synthesis models.