Life on Earth depends on an aqueous biochemistry, and water is a key component of habitability on Earth and for likely other habitable environments in the solar system. While water is ubiquitous in the interstellar medium, and plays a key role in protoplanetary disk chemistry, the inner solar system is relatively dry. We now have evidence for potentially thousands of extrasolar planets, dozens of which may be located in their host stars habitable zones. Understanding how planets in the habitable zone accrete their water, is key to understanding the likelihood for habitability. Given that many disk models show that Earth formed inside the water-ice snow line of our solar system, understanding how the inner solar system received its water is important for understanding the potential for other planetary systems to host habitable worlds. Boundaries for the timing of the water delivery are constrained by cosmochemistry and geochemistry. Possible scenarios for the delivery of water to the inner solar system include adsorption on dust from protoplanetary disk gas, chemical reactions on the early earth, and delivery from planetesimals forming outside the water-ice snow line. This talk will set the stage for understanding the isotopic and geochemical markers along with the dynamical delivery mechanisms that will help uncover the origins of Earths water. This introduction will provide an overview for understanding the distribution of water in the solar system, in particular for the inner solar system and terrestrial planets Xand the details will be developed in the subsequent talks. Additionally information will be presented regarding new inner solar system reservoirs of water that can shed light on origins (the main belt comets), and new research about water in the Earth.

This joint session between FM21 and FM2 (“Astronomical Heritage: Progressing the UNESCO–IAU Initiative”) focused upon the need to preserve the dark skies necessary for the continued functioning of the world's leading optical observatories and whether, if some of the sites concerned could be inscribed on UNESCO's World Heritage List, this could help achieve this objective. Among the main issues addressed were: is a WHL inscription feasible in the first place? how could the strongest case for inscription be made? what progress has been made towards doing this? and what other effects might a WHL inscription have and would they all be desirable to astronomers? Addressing such issues involves not only scientific but also heritage and political considerations.

Massive (Mstellar ⩾ 5×1010 M⊙) Early-Type Galaxies (ETGs) must build an outer stellar envelope over cosmic time in order to account for their remarkable size evolution. This is similar to what occurs to nearby Late-Type Galaxies (LTGs), which create their stellar haloes out of the debris of lower mass systems. We analysed the outer parts of massive ETGs at z < 1 by exploiting the Hubble Ultra Deep Field imaging. These galaxies store 10-30% of their stellar mass at distances 10 < R/kpc < 50, in contrast to the low percentages (< 5%) found for LTGs. We find evidence for a progressive outskirt development with redshift driven solely via merging.

Using images from the Hubble Space Telescope and Sloan Digital Sky Survey, we have computed both parametric and non-parametric measures, and examined the evolution in size, concentration, stellar mass, effective stellar mass density and asymmetry for a sample of 600 disc galaxies from z ~ 1 till z ~ 0. We find that disc galaxies have gained more than 50 per cent of their present stellar mass over the last 8 Gyr. Also, the increase in disc size is found to be peripheral. While the average total (Petrosian) radius almost doubles from z ~ 1 to z ~ 0, the average effective (half-light) radius undergoes a marginal increase in comparison. This indicates that galaxies grow more substantially in their outskirts, and is consistent with the inside-out growth picture. The substantial increase in mass and size indicates that accretion of external material has been a dominant mode of galaxy growth, where the circumgalactic environment plays a significant role.

Light at night (LAN) is now an established environmental problem, not only for astronomers but for the population at large. It has serious ecological effects that are wide ranging, and its environmental effects may be more serious than ever imagined. The ecological and environmental consequences are examined and emphasis is stressed on resolving the problem before it is too late.

Water in form of ice or vapour is observed in comets, transneptunian objects and icy satellites formed in the outer regions of the Solar System, as well as in objects orbiting in the inner Solar System, such as dwarf planet Ceres. I will present an overview of the water content and properties in these objects and the implications in terms of solar system formation and evolution.

After years of thinking the Moon is dry, we now know there are three manifestations in which water appears on the Moon today: 1) Previously hypothesized buried deposits of volatiles at the lunar poles were found at Cabeus crater. There are questions about the origin of such volatiles (i.e., in-falling comets & meteorites, migration of recently formed surficial OH/H2O, and accumulated release from the interior), but there is no doubt the water is there. 2) Widespread, thinly-distributed, surficial OH (or H2O) has been clearly detected across all types of lunar terrain. The consensus is that the OH is derived from solar wind, but we do not know how quickly it forms, nor how mobile it is. 3) The amount of water present soon after the Moon formed is now documented in new analyses of lunar materials in volcanic glass beads, apatites and plagioclase feldspars. Apollo era sample analyses were not precise enough to distinguish between indigenous lunar water and terrestrial contamination. Measurements with modern equipment are more precise (both elemental and isotopic), and can better constrain a host of processes (e.g. diffusion, thermal cycling). Scientists around the world are studying lunar water. Ongoing analyses are informing a number of hypotheses and theories about the connection between the Earth and its wet Moon.

In order to constrain – and understand – the growth of galaxies, we present a sample of ~ 30 galaxies at z ~ 2 with resolved distribution of stellar mass, star-formation rate, and dust attenuation on scales of ~ 1 kpc. We find that low- and intermediate-mass galaxies grow self-similarly, doubling their stellar mass in the centers and outskirts with the same pace. More massive galaxies (~ 1011 M⊙) have a reduced star-formation activity in their center: they grow mostly in the outskirts (inside-out quenching / formation). Similar trends are find in cosmological zoom-in simulations, highlighting that high stellar mass densities are formed in a gas-rich compaction phase. This nuclear ‘starburst’ phase is followed by a suppressed star-formation activity in the center, resulting in growth of the outskirts. All in all, we put forward that we witness at z ~ 2 the dissipative formation of z = 0 M* early-type galaxies.

This session opened with a crucial explanation by Michel Cotte of how astronomers first need to understand how to apply UNESCO World Heritage Criteria if they want to motivate their government(s) to make the case to UNESCO for World Heritage recognition. UNESCO World Heritage cannot be obtained just to protect dark skies.

Much more detail of this and the other presentations in this session, along with many images, can be found at the session website: http://www.noao.edu/education/IAUGA2015FM21.

The next speaker, John Hearnshaw, described the Aoraki Mackenzie International Dark Sky Reserve and the work it carries out . This was followed by a wide-ranging summary (by Dan Duriscoe and Nate Ament) of the U.S. National Park Service (NPS) Night Skies Program. The abstract of Cipriano's Marin's paper, “Developing Starlight connections with UNESCO sites through the Biosphere Smart" was shown in his absence. The final presentation (by Arkadiusz Berlicki, S. Kolomanksi and T. Mrozek) discussed the bi-national Izera Dark Sky Park.

Magnetic fields are an important component in galaxies, and yet, we still do not know how these magnetic fields were originally seeded within galaxies, nor how they have grown to the strengths we observe today. One way we can unravel this complex problem is by measuring the growth of magnetic fields over cosmic time. We present the initial results of a rotation measure study to search for the presence of coherent magnetic fields around young disk-like galaxies at z ~ 0.5. The S-band receiver at the VLA allows us to simultaneously observe Stokes I, Q, U, and V from 2-4 GHz. With these broadband polarization observations we apply multiple methods for determining the rotation measure of each source, improving the fidelity of our results. Beyond magnetogenesis, the results of this study also have implications for the life-cycle of baryons within galaxies and the composition of galactic haloes.

Rocky planets are built through a series of highly energetic accretionary impacts. The accreting bodies are thought to carry small amounts of water to the growing planet, but it is debated whether the planet can retain this water through the accretionary process, or if water needs to be added largely after the planet is complete and cooled. Most of the relatively few measurements of deuterium to hydrogen in cometary water do not match Earths water, though the single example of 103P/Hartley 2 is a good match (Mumma & Charnley 2011, Hartogh et al. 2011). Alexander et al. (2012) point out, however, that organic materials in comets have far higher D/H than does their water, so in bulk no comet matches Earths D/H ratio, not even comet Hartley. Meteorites provide evidence that the material that built planets had small but sufficient amounts of water, and analysis of its isotopic composition demonstrates that water from rocky material, and not comets, provided water to the Earth (Alexander et al. 2012). This current evidence that Earths water came from rocky asteroidal material does not solve the question of whether this material was the accreting material that built the planet, or if it was added later. Mission data from the Moon and Mercury demonstrates that those bodies are not completely devoid of volatiles (McCubbin et al. 2010, Saal et al. 2008, Peplowski et al. 2011). The Moon, in particularly, has small amounts of internal water that survived its energetic origins (Hauri et al. 2011). Thus, the giant accretionary impacts that build planets do not completely dry them, and the water from their initial building blocks can be retained. If volatiles are delivered and partly retained during accretion, then the initial habitability of a young planet may be set by degassing of a magma ocean. Models predict that cooling can result in liquid water oceans within ten or tens of millions of years (Abe and Matsui 1986, Elkins-Tanton 2011). Thus, rocky planets in solar systems similarly composed to our own have a good chance of forming with water oceans, and of being habitable, at least for some period of time.

By proclaiming the IYL2015, the United Nations recognized the importance of light and light based technology in the lives of the citizens of the world and for the development of global society on many levels. Light and application of light science and technology are vital for existing and future advances in many scientific areas and culture. Light is a key element in astronomy: as astronomers, it is what we study and makes our science possible, but it is also what threatens our observations when it is set-off from the ground (light pollution). The UN-designated year 2015 represented a magnificent and unique opportunity for the global astronomical community to disseminate these messages and raise the awareness of the importance and preservation of dark skies for heritage and the natural environment.

As such, the International Year of Light served as a launching pad for several projects during 2015. Two other projects with equally as impressive programs are highlighted and begin the narrative for this section on public education and outreach programs on light pollution issues and solutions.

Local analog galaxies play an important role in understanding the properties of high-redshift galaxies. We present a method to select a type of local analog that closely resembles the ionized interstellar medium conditions in high-redshift galaxies. These galaxies are selected based on their locations in the [O III]/Hβ versus [N II]/Hα nebular emission-line diagnostic diagram. The ionization parameters and electron densities in these analogs are comparable to those in z ≃ 2 − 3 galaxies, but higher than those in normal SDSS galaxies by ≃ 0.6 dex and ≃ 0.9 dex, respectively. We find that the high sSFR and SFR surface density can enhance the electron densities and the ionization parameters, but still cannot fully explain the difference in ISM condition between nearby galaxies and the local analogs/high-redshift galaxies.

The closing session included a panel on the challenge of raising cultural awareness of the negative effects of light pollution and RFI, and a discussion about the means to implement the IAU Resolution on the Right to Starlight. The strongest arguments to the public are that light pollution wastes precious energy and adds greenhouse gases, and that artificial light at night can be damaging to human health and to the natural environment. As astronomers, our community is concerned that the world is blinding itself to the electromagnetic radiation connecting us to the Universe. An outcome of successful advocacy would be to create demand for commercial products that minimize blue light and upward radiation. Implementation of the resolution on the Right to Starlight has multiple aspects. The IAU, through its site protection commission, should provide a clear technical description of "astronomy friendly" lighting and specifications for protection of the near zones around optical observatories. In addition, the commission should provide reference materials for astronomers giving public presentations, provide a forum for those seeking stronger local or national regulation, seek IAU approval for endorsement of protected status of sites and regions, and support the process of gaining UNESCO World Heritage Status for observatories and their regions.

The analysis of the organic content of meteorites provides a window into the conditions of the early solar system, such as the extension of aqueous alteration or thermal metamorphism on the meteorite parent bodies. The analysis of the soluble organic content of CM chondrites indicates that extensive aqueous alteration on their meteorite parent body may result on 1) the decomposition of α-amino acids; 2) synthesis of β- and γ-amino acids; 3) higher relative abundances of alkylated polycyclic aromatic hydrocarbons (PAHs); and 4) higher L-enantiomer excess (Lee) value of isovaline. Exogenous delivery of organic matter by meteorites may have contributed to the organic inventory of the early Earth, providing a diversity of resources to the first living organisms on Earth and on other places of our solar system where life could have potentially originated.

The composition of interstellar matter is driven by environmental parameters and results from extreme interstellar medium physico-chemical conditions. Astrochemists must rely on remote observations to monitor and analyze the interstellar solids composition. They bring additional information from the study of analogues produced in the laboratory, placed in simulated space environments. Planetologists and cosmochemists access and spectroscopically examine collected extraterrestrial material in the laboratory. Diffuse interstellar medium and molecular clouds observations set constraints on the composition of organic solids that can then be compared with collected extraterrestrial materials analyses, to shed light on their possible links.

In the Astronomy in Focus series, volume XXIXA, Focus Meeting 4 was omitted from table 2 of the preface (Benvenuti 2016) on page xv. The editor apologizes for this error.

Intracluster light is contributed by both stars and gas and it is an important tracer of the interaction history of galaxies within a cluster. We present here the results obtained from MUSE observations of an intermediate redshift (z~ 0.5) cluster taken from the XXL survey and we conclude that the most plausible process responsible for the observed amount of ICL is ram pressure stripping.

The article originally published on pages 179 - 183 of the 2016 Astronomy in Focus Volume 11, Issue A29A, purportedly by Wesley and Sheshadri, was mistakenly included in the issue and should not have been published. During the compilation of the issue, the first page of Wesley and Sheshadri's legitimate article (Wesley & Sheshadri 2016) was combined with other pages from a wholly unrelated LaTeX file, and published in error. The content of this pseudo-article makes no sense, and should not be used or cited. Therefore, the pages of this pseudo-article have been removed from the online version of the issue and replaced with blank pages watermarked as ‘WITHDRAWN’. We have decided to remove the article completely to avoid confusion with the correct article by Wesley and Sheshadri, who were not involved in the creation of this error.

We apologise to the authors Wesley and Sheshadri, and to readers for this mistake.

Star formation histories of local dwarf galaxies, derived through resolved stellar populations, appear complex and varied. The general picture derived from hydrodynamical simulations is one of cold gas accretion and bursty star formation, followed by feedback from supernovae and winds that heat and eject the central gas reservoirs. This ejection halts star formation until the material cools and re-accretes, resulting in an episodic SFH, particularly at stellar masses below ~ 109 M⊙. Such feedback has often been cited as the driving force behind the observed slowly-rising rotation curves in local dwarfs, due to an under-density of dark matter compared to theoretical models, which is one of the primary challenges to LCDM cosmology. However, these events have not yet been directly observed at high-redshift. Recently, using HST imaging and grism spectroscopy, we have uncovered an abundant population of low-mass galaxies (M* < 109 M⊙) at z = 1 - 2 that are undergoing strong bursts of star formation, in agreement with the theoretical predictions. These Extreme Emission Line Galaxies, with high specific SFRs and shallow gravitational potential wells, are ideal places to test the theoretical prediction of strong feedback-driven outflows. Here we use deep MUSE spectroscopy to search these galaxies for signatures of outflowing material, namely kinematic offsets between absorption lines (in the restframe optical and UV), which trace cool gas, and the nebular emission lines, which define the systemic redshift of the galaxy. Although the EELGs are intrinsically very faint, stacked spectra reveal blueshifted velocity centroids for Fe II absorption, which is indicative of outflowing cold gas. This represents the first constraint on outflows in M* < 109 M⊙ galaxies at z = 1 - 2. These outflows should regulate the star formation histories of low-mass galaxies at early cosmic times and thus play a crucial role in galaxy growth and evolution.