European Astronomical Society
e-Newsletter  11
August 2020

Before moving on I'd like to thank the Kuoni staff, the Leiden team and my colleagues on Council for the enormous efforts they have invested to make Virtual EAS 2020 a success. This is an ambitious aspiration — to run many plenaries and parallel sessions in virtual mode. I'm grateful to all the Chairs and the volunteers who are helping out. If there are technical hitches, please bear with us. We hope to be back meeting face-to-face in Leiden next year and in 2022 we'll be in Valencia, Spain. For more news about your Society please attend the General Assembly at 11.00 (CEST) on Wednesday.

Over the weekend I learned the sad news of the death of Olivier Le Fèvre after a battle with brain cancer. Olivier was a former Director of the Laboratoire d'Astrophysique de Marseilles, a pioneer in the study of the large scale structure of the Universe and PI of VIMOS, one of the first generation instruments on the VLT. Most of all though he was a vibrant and enthusiastic proponent of our subject. I hope you will find a moment in this busy week to reflect on his life and work.

New Prizes: Thanks to the Fritz Zwicky Foundation we have awarded a new Prize, the Zwicky Prize, for fundamental and outstanding work in astrophysics and cosmology to Professor Martin Rees. Martin will give his talk in person (hopefully!) in Leiden next year. The other Prize winners are giving their talks as part of this meeting and they'll receive their Prizes and Medals in person next year. In order to encourage and recognise those who have overcome disadvantage to make an impact in astronomy, or those individuals or organisations that have made a contribution that goes beyond scientific research, we have instigated a new Prize. Take a look at the details on our website. Members will have an opportunity to suggest names for the new prize — I will say more later in the week.

New Councillors: I am delighted to congratulate Antoaneta Antonova and Agata Różańska on their election to Council. Their term of office starts at the General Assembly on Wednesday.

New Organisational Members: I am also grateful to the following institutions for becoming Organisational members:

• The Institute of Astrophysics of the Foundation for Research and Technology - Hellas (IA-FORTH).
• Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing (IAASARS) in Athens.
• Institut d'Estudis Espacials de Catalunya (IEEC).
• Institute of Astrophysics of Andalusia (Instituto de Astrofísica de Andalucía IAA-CSIC).

Organisation members play an important role in securing the financial sustainability of the Society and I invite any institution that is interested in joining to contact me or the Treasurer.

Before I pass on to the next speaker may I wish you a stimulating, enjoyable, and most of all, safe week.

Roger Davies
EAS President

After careful consideration of all candidate options, the EAS Council has decided to name this prize the Jocelyn Bell Burnell Inspiration Medal, after the remarkable British astronomer Dame Jocelyn Bell Burnell. She is the discoverer of the first pulsar and has inspired (and still inspires) entire generations of astronomers. The first Jocelyn Bell Burnell Inspiration Medal will be awarded at the EAS Annual Meeting in Leiden in 2021 and in alternate years thereafter. Nominations are welcome until 31 October 2020 (see Call for nominations for EAS Prizes).

Short biographies of previous years' awardees and full details regarding the different EAS Prizes can be found on the EAS website:

• Tycho Brahe Medal
• MERAC Prizes (in 2021, MERAC Prizes are awarded for Best Early Career Researcher)
• Jocelyn Bell Burnell Inspiration Medal
• No nominations are requested for the Lodewijk Woltjer Lecture as it is decided by EAS Council.
• There is no call for the biannual Fritz Zwicky Prize this year.

Nominations can only be made by EAS members and need to be endorsed by 2 persons, at least one of them being an EAS member. Nominations are only accepted through a web form accessible for EAS members. The deadline for nominations for all EAS Prizes is Saturday 31 October 2020. Note that self-nominations are not allowed.

In a subsequent Council meeting on 2 July 2020, the new Council has discussed the distribution of responsibilities. Lex Kaper has now taken over the role of EAS Vice-President (alongside Sara Lucatello), and Inma Dominguez has become EAS Secretary. An overview of the entire EAS Council with a short viva and a listing of the responsibilities for each Councillor can be found on the EAS Council webpage.

It obtained its current structure in 2012, after the merging of two institutes: the Institute of Astronomy and Astrophysics, which carried on the tradition of optical astronomy in Greece since the establishment of the Observatory of Athens in 1842, and the Institute for Space Applications and Remote Sensing, which evolved from the old Ionospheric Institute, founded in 1955. Currently (Summer 2020), the permanent staff of the institute consists of the Director, 24 researchers, 2 functional scientific personnel, 3 research support specialists and 2 technicians. Moreover, 29 postdoctoral researchers and 27 scientists and engineers under research training (i.e. students) were on term contracts, making IAASARS the largest institute in its field in Greece.

The institute operates a wide range of national facilities aiming to support research and services in the respective disciplines, including:

• The 2.3-m Aristarchos telescope on Mt. Helmos which currently runs its tenth year of successful operations. This telescope is member of the OPTICON network;
• The Kryoneri 1.2-m telescope that has recently been refurbished and has been used continuously ever since, mainly in the framework of the ESA NELIOTA project, monitoring the in-fall of meteorites on the lunar surface;
• The BEYOND center for the monitoring of natural disasters;
• The PANhellenic GEophysical observatory of Antikythera (PANGEA) which is a major climate change monitoring infrastructure.

The excellence of the institute is demonstrated by two recent ERC Grants, one in the field of astrophysics and the other in Earth system sciences. In addition, members of the institute coordinate competitive H2020 projects in the area of space weather and Earth system sciences, indicating European leadership in the specific fields of expertise.

Spyros Basilakos
Director of IAASARS-NOA
Director of Research, Research Center for Astronomy & Applied Mathematics, Academy of Athens, Greece
President of the Greek National Committee for Astronomy

IEEC is structured in four Research Units, each belonging to a university or research institution: The Institute of Cosmos Sciences (UB, University of Barcelona); the Centre of Space Studies and Research (UAB, Autonomous University of Barcelona); the Research Group in Space Sciences and Technologies (UPC, Polytechnic University of Catalonia); and the Institute of Space Sciences (CSIC, Spanish Research Council).

Researchers at IEEC address a broad range of topics within space sciences, including solar physics, planetary sciences, astrophysics, cosmology, Earth observation, and space technology in general, and make use of the entire electromagnetic spectrum, particle physics and gravitational wave detection. IEEC also develops instrumentation for ground-based projects and for space missions, in collaboration with ESA and other space agencies, thanks to a team of engineers with extensive experience in the aerospace sector and in sectors with high value in innovation.

Finally, IEEC manages the Montsec Astronomical Observatory (OAdM, Observatori Astronòmic del Montsec), equipped with two robotic telescopes (the 0.8-m Joan Oró Telescope and the 0.5-m Baker-Nunn Fabra-ROA Montsec Telescope) and a number of smaller facilities (all-sky bolide camera, wide-field photometric monitoring telescope, air pollution monitoring station, etc). The main goals of OAdM are to provide means to carry out cutting-edge research in astronomy, to serve as testbed for the development of new astronomical instrumentation, and to provide space-related services to public institutions and industry. In addition to imaging and spectroscopic astronomical observations, the OAdM telescopes also dedicate a fraction of time to space situational awareness and satellite surveillance and tracking programs.

Both its staff (~190 members in December 2019) and the number of available facilities provide the IAA with the necessary clout to cover all major fields of astrophysics and space science, from quantum gravity over the Solar System to galaxy evolution and cosmology, and enables it to play a leading role in large international projects. Our research is based on the three pillars of modern astrophysics: Observation, instrumental development, and theoretical and numerical studies, all of which are firmly established and interconnected. The broad scope of its assets and activities is one of the main characteristics and strengths of IAA covering almost all fields of astrophysics/space science and being engaged both in remote (Earth-bound) and in-situ (space-based) observations with technological development.

IAA is leader in a significant number of ambitious international scientific projects, concerning both science and technology/Instrumentation; IAA plays a leading role in the development of space-borne and ground-based instruments. This is a unique feature and strength of the IAA. Examples for recent IAA important contributions to instruments on board successful missions are GIADA and OSIRIS (ROSETTA), ImaX, BeLA/Bepi Colombo, NOMAD/Exomars, and SO/PHI in space, and CARMENES and PANIC at CAHA (Almería), and MEGARA at GTC (La Palma). The IAA is involved in the 4 ESFRI initiatives related to Astronomy: CTA, ELT, EST and SKA. Referring to SKA, IAA coordinates since 2011 the Spanish scientific and technological participation. Since June 2018, Spain is associate member of the SKA organization. Under the Severo Ochoa award, the IAA is developing a prototype of the SKA Regional Center (SRC).

IAA co-manages the Calar Alto Observatory (CAHA), the largest observatory in mainland Europe, and hosts and operates the OSN (Observatorio de Sierra Nevada), mostly dedicated to complementary long-term projects. Our Unit for Instrumental and Technical Development (UITD) provides technical support from the development of electronic components to the design of optical and NIR instruments.

Finally, our award-winning activity of our Outreach and Communication unit has a well-known reputation in the professional dissemination of astrophysics in Spain. In their high quality, diversity, and sheer number, the outreach activities carried out at the IAA are unmatched within Spain.

In the last decade, the advent of facilities like ALMA and NOEMA provided the sensitivity to probe molecular gas in star-forming galaxies across a wide redshift range, while surveys from optical and near-infrared integral field spectrographs (like MUSE, MANGA, KMOS) allowed to get a detailed view of the ionised gas properties and its interplay with star formation in both local and distant galaxies. The goal of the Symposium was to connect the different communities focussing on the interplay between the gas content and star formation processes in galaxies at high and low redshift, from UV to radio wavelengths.

The scientific programme was divided into four sub-sessions across two days, spanning large range of topics as summarised below:

• Observing gas in star-forming galaxies across cosmic time (day 1): How do the different phases of the interstellar medium vary with galaxy properties and cosmic time, and how do the morphologies of gas, dust and stars relate to each other?
• The laws of star formation (day 1): What is the physical origin of the various scaling relations connecting cold gas and star formation and are these relationships fundamental?
• Evolution of gas kinematics (day 2): What are the roles of mergers, gas accretion, and outflows at different redshift and how are they affecting the gas supply for star formation? What regulates the transition of primordial clumpy, unrelaxed objects to modern rotators?
• Gas-phase chemical abundances (day 2): How does the interplay between gas flows, star formation and chemical enrichment evolve with time and how does it affect the observed metallicity scaling relations on global and local scales?

We hosted eight invited speakers in total (two for each sub-session), covering and reviewing different aspects of the programme. More specifically, the first day begun with Eva Schinnerer highlighting recent observational results obtained in the framework of the PHANGS collaboration about the interplay of the various gas phases in local galaxies on different spatial scales. Linda Tacconi reviewed methods, challenges and results of molecular gas measurements in high-z galaxies from surveys like PHIBSS and xCOLDGASS, while Amelie Saintonge talked about what can be learned from studying gas fraction and star formation efficiency in galaxies. Finally, Cecilia Bacchini illustrated the concept of "volumetric star-formation law" and its observational signatures in nearby disc galaxies.

The second day started with the session on gas kinematics, as Roberto Maiolino reviewed the current observational evidence and properties of galactic outflows in the local and distant Universe. Later on, Federico Lelli presented an overview on tracers, methodologies and results from studies of gas dynamics in local and high-z galaxies. In the last sub-session, focused on chemical abundances, Filippo Mannucci reviewed the methods for gas metallicity measurements and discussed the impact of the diffuse ionised gas, while Ryan Sanders presented a comprehensive overview of the current picture of the evolution of metallicity scaling relations at high redshift.

In each sub-session, the invited talks were complemented by five contributed talks (hence 20 in total), offering a broad and high-quality view of recent advances in all the covered fields. Posters were uploaded in a dedicated folder together with short video presentations and made available to all the attendees.

We managed to keep a good gender and seniority balance among both invited and contributed speakers: invited speakers were 50% female, with 3 out of 8 early career researchers, whereas for contributed talks we had 55% of women and a prevalence of graduate students and post-doctoral researchers.

Overall, the Symposium was very well attended, with around 100 people on average simultaneously connected on the platform and a peak of 198 participants. The activity on the social media platforms has also been very lively, as the dedicated slack channel counted more than 200 members. Despite the challenges posed by a fully virtual environment, the EAS organisation provided all the elements to make the Symposium a success and we would like to warmly thank them for this opportunity.

Mirko Curti (University of Cambridge, UK)
Alice Concas (University of Cambridge, UK)

EAS 2020 Symposium 3 website

The first session, chaired by Camila Correa (University of Amsterdam, The Netherlands), focused on the stellar angular momentum of galaxies, used to trace galaxy morphology and to compare with cosmological simulations of galaxy formation. The session began with the invited talk of Eric Emsellem (ESO, Germany) on morpho-kinematic evolution of galaxies, and continued with contribution talks from Sarah Sweet (University of Queensland, Australia), Jesse van de Sande (University of Sydney, Australia), Juan Espejo (Swinburne University, Australia) and Claudia Lagos (University of Western Australia, Australia).

Claudia Lagos moderated the second session which started with Glenn van de Ven (University of Vienna, Vienna) as invited speaker, who talked about the formation history of galaxies through population-dynamics of their stars. Trevor Mendel (Australia National University, Australia), Anna de Graaf (Leiden University, The Netherlands), Rhea-Silvia Remus (Munich Observatory, Germany) and Annalisa Pillepich (Mpia Heidelberg, Germany) followed as contribution speakers. The contribution talks focused on the structural evolution of galaxies, theoretical results from simulations TNG50 and Magneticum were presented, along with findings from the MAGPI and LEGA-C survey. The session concluded with 5 poster presentations.

Thierry Contini (Institut de Recherche en Astrophysique et Planétologie, France) chaired the third session, which started with Natascha Forster-Schreiber as invited speaker reviewing recent studies of galaxy kinematics. The contribution talks that followed were given by Lucy Hogarth (UCL, UK), Debora Pelliccia (University of California, US), Johannes Zabl (Centre De Recherche Astrophysique De Lyon, France), Veselina Kalinova (MPI Bonn, Germany). Various topics were covered in this session, from high spatial resolution molecular maps to feedback-driven outflows and CGM kinematics. The session concluded with 5 poster presentations.

The fourth session was chaired by Claudia Lagos. Filippo Fraternali (University of Groningen, The Netherlands) started the session with a review talk on gas dynamics, and was followed by contribution talks from Lorenzo Posti (Strasbourg Observatory, France), Alice Concas (Kavli Institute for Cosmology, UK), Matilde Mingozzi (Astronomical Observatory of Padova, Italy) and Luca Cortese (University of Western Australia, Australia). The session focused on outflows and feedback efficiencies of discs and spheroids, and on the impact of environment in inducing ram-pressure stripping and morphological transformations. The session also included 3 poster presentations.

Federico Lelli (Cardiff University, UK) chaired the fifth session, which consisted of contribution talks from Carlo Cannarozzo (Universita di Bologna, Italy), Francesca Pinna (Mpia Heidelberg, Germany), Sharon Meidt (Ghent University, Belgium), Tirna Deb (University of Groningen, The Netherlands), Pavel Manera Pina (Kapteyn Institute, The Netherlands) and Sylvia Ploeckinger (Leiden University, The Netherlands). The speakers presented exciting results on the topics of merger-driven evolution of galaxies, nuclear star clusters and CO/HI gas kinematics.

The sixth and final session was chaired by Annalisa Pillepich. The invited speaker of the session was Benoit Epinat (Laboratoire d?Astrophysique de Marseille, France) who discussed various gas morpho-kinematics studies using MUSE. The speakers, Gandhali Joshi (Mpia Heidelberg, Germany), Sara Cazzoli (IAA-CSIC, Spain), Valentina Abril Melgarejo (Laboratoire d?Astrophysique de Marseille, France) and Wilfried Mercier (Irap, France) gave contribution talks. The session focused on galaxy evolution in dense environments and it concluded with 5 poster presentations.

The total virtual attendance of the symposium vastly exceeded the initially foreseen participation. We are particularly grateful to all our speakers, who gave excellent talks, making the Symposium S6 a success. We also warmly thank all the organisers of the EAS 2020 virtual platform, without their effort the Symposium would not have been possible.

Camila Correa (University of Amsterdam, The Netherlands)
Claudia Lagos (International Centre for Radio Astronomy Research, Australia)

EAS 2020 Symposium 6 website

Whilst these data are still being exploited to explain the vast amounts of substructure, there is currently a dearth of large-scale spectroscopic follow-up. With the advent of instruments such as 4MOST and MOONS, as well as continuing contributions from existing projects (such as APOGEE-S, MAGIC and MagES), this relative lack of spectroscopic data will be addressed, thereby completing our dynamical and chemical views of the Magellanic System.

This two-day Symposium brought together observers and theorists within the community to coordinate our efforts and discuss how these ancillary data will further transform our understanding of this unique system. Within our Symposium, we had 10 invited talks and 14 contributed talks. The invited talks were given by researchers at different stages of their career, from starting postdoc through to professor. We also included three short poster sessions where we offered the possibility to briefly present posters. Among all speakers of our Symposium, 42 per cent were female. The Symposium was well attended with up to 80 participants at each session.

The following topics were addressed during the Symposium:

• The Magellanic Clouds in context
• Massive stars and star clusters
• Morphology and structure
• Kinematics and dynamics
• Star formation history and chemistry
• The Magellanic Clouds as a distance scale anchor
• Ongoing and future surveys

Pascale Jablonka started the Symposium with a review of existing spectroscopic surveys and an outlook on future surveys. Sergey Koposov presented a comprehensive overview on what the morphology of the Magellanic Clouds can tell us about their history. Marius Cautun then talked about the EAGLE simulation and its predictions for LMC-mass galaxies. Marcel Pawlowski presented his work on possible satellite galaxies of the LMC.

In the second session of the Symposium, Tomer Shenar presented an overview of spectroscopic studies of Wolf-Rayet stars in the Magellanic Clouds. Noelia Noel gave a review on stellar substructures in the Magellanic Clouds and Camila Navarrete talked about her work on blue horizontal stars in the periphery of the LMC. The last talk of the session was given by Dalal El Youssoufi who presented morphological maps of the Magellanic Clouds from near-infrared surveys.

Laura Cullinane started the third session by introducing the Magellanic Edges Survey which maps the outer regions of the Clouds. Denis Erkal presented various techniques to measure the mass of the LMC, showing that it is larger than previously thought. Pol Massana talked about his work on the star formation history of the SMC using data from the SMASH survey. Michele De Leo gave the last talk of the day, presenting his studies of the stellar kinematics of the SMC.

The second day of the Symposium started with the talk by Douglas Boubert who presented a search for hypervelocity stars that might have been ejected from the LMC. Laura Inno gave a review of the three-dimensional structure of the Magellanic Clouds traced by Cepheids. Bertrand Lemasle presented a new method to derive atmospheric parameters of Cepheids and future spectroscopic observations with 4MOST. Anna Jacyszyn-Dobrzeniecka gave the final talk of the session, presenting her studies of Cepheids within the Magellanic Bridge using data from the OGLE survey and follow-up spectroscopic observations.

Sebastian Kamann started the fifth session of the Symposium with a comprehensive overview of the studies of star clusters within the Magellanic Clouds. Joachim Bestenlehner gave a review talk on massive stars in the Magellanic Clouds focussing on results from recent spectroscopic surveys. Sarah Brands presented her work on modelling the wind properties of massive stars in the R136 cluster. Julia Bodensteiner talked about her study of the binary fraction and physical properties of the massive stellar population within the young cluster NGC 330 using MUSE data.

The last session of the Symposium was opened by Guillaume Guiglion who introduced a novel method based on machine learning to derive physical properties and chemical abundances from stellar spectra. Maria-Rosa Cioni presented the forthcoming One Thousand and One Magellanic Fields survey on 4MOST which aims to measure the kinematics and chemical abundances of various stellar populations within the Magellanic Clouds. Alessio Mucciarelli introduced MOONS, the new multi-object spectrograph at the VLT and its capabilities to study the Magellanic Clouds. The last speaker of the Symposium was Eric Pellegrini who introduced SDSS-V's Local Volume Mapper which will provide a full optical spectroscopic image of the Magellanic Clouds at 10 pc resolution.

We thank all the speakers and the numerous attendees for making Symposium 7 a successful one. We are particularly grateful to the organisers for setting up the platform as well as the tools for the virtual meeting and the support during the sessions.

Cameron Bell (AIP Potsdam, Germany)
Florian Niederhofer (AIP Potsdam, Germany)
Dalal El Youssoufi (AIP Potsdam, Germany)
Maria-Rosa Cioni (AIP Potsdam, Germany)

EAS 2020 Symposium 7 website

Post CE systems are well known in population synthesis, both among low- and high-mass stars, but constraining the physics of the common envelope ejection from population studies is a very difficult task. Incoming observations, such as those from the Zwicky Transient Factory, deliver new data on the different post-CE populations in the Galaxy. Of great interest are currently massive binary systems that result in black hole (BH-BH) pairs and neutron star pairs (NS-NS) whose mergers are observed by gravitational-wave detectors. It is of prime interest to establish what were their progenitors and arguments for cool supergiants were discussed. It was also proposed that some of low-mass post-CE systems, such as envelope-stripped helium stars, can be observable by the next-generation gravitational-wave detectors.

Different modelling techniques are currently in use in efforts to understand the process of formation and ejection of the common envelope. The form of mass loss (e.g. via the L2 and L3 points), inclusion of shocks, the role of recombination energy, and formation of jets have been most hotly debated. Inclusion of radiation pressure in such simulations is difficult but has been accomplished in several cases giving us the hope that such more realistic models will be a norm in the future. Theoretical work on the CE formation and ejection encompasses today a wide range of systems, e.g. including binaries with MS, RGB, AGB and red supergiants stars, and even substellar companions. Triple systems also have entered into the CE theoretical research opening new interesting avenues, e.g. in explaining orbital eccentricities in post CE systems and timescales of the CE evolution. Mergers of stars are an important subject of modern CE research and it has been demonstrated that some coalescence scenarios lead to the formation of rejuvenated and magnetic stars that may end their life as magnetars. There are also continuing simulation efforts to explain the shapes of bipolar planetary nebulae and pre-planetary nebulae via the interaction of the common envelope material with stellar wind.

Aside to the massive gravitational-wave sources, other observational aspects of the CE evolution were discussed. A link between some (pre-)planetary nebulae (PPNe & PNe) and CE in AGB and RGB systems has been reinforced by recent observations at optical and submillimeter wavelengths. They allowed detailed studies of the spatio-kinematic structure of the nebulae (atomic and molecular), constrained their masses and chemical compositions (elemental and isotopic), and revealed properties of the central stars (foremost, binarity). There is a building evidence for mass transfer before and after the CE phase. Even more recent is the realization that outbursts of Galactic and extragalactic transients are most likely directly related to the CE phase, including stellar mergers that can be observed in real time. These are known as (luminous) red novae or intermediate-luminosity optical transients (ILOTs). Some of them, called SPIRITS, are so heavily dust-enshrouded that are practically only observable at infrared wavelengths. These past or ongoing mergers are mainly observed in systems of low-mass stars but their characteristics is similar to merger events in more massive systems, like the one that has been hypothetized to explain the Great Eruption of eta Car. The identification of the red transients as manifestations of stellar collisions brought fresh interests in studying cataclysmic outcomes of the CE evolution. The search for systems undergoing a red nova phenomenon and their field progenitors continues. On the high-mass side, the example of V766 Cen shows that we can resolve high-mass binary systems in contact just before or during the common envelope phase.

The session included 6 invited (review) talks, 21 contributed talks, and 21 posters. We thank our invited speakers (J. Andrews, Univ. Arizona; S. de Mink, Harvard; D. Jones, IAC; P. Ricker, Univ. Illinois; G. Nelemans, Nijmegen; M. MacLeod, CfA) and all other authors for their high-quality contributions. The session was well attended with typically 80-150 individual Zoom attendees. Discussions during and after the talks were very lively with nearly 600 massages posted. The S8 group on Slack, although not the most populous (57 active members and 160 members), was the most active group among the science channels on that platform. It was concluded that the field is strongly moving forward with many new ideas and a dedicated, one-week meeting, should be organized to fully explore the different aspects of the common envelope studies.

Science Organizing Committee:
O. de Marco (Macquarie Univ., AU)
N. Blagorodnova (Radboud Univ., NL)
S. Justham (Uni. Amsterdam, NL & Univ. of the Chinese Academy of Sciences)
T. Kaminski (chair, NCAC Torun, PL)
O. Pejcha (Charles Univ., CZ)
S. Toonen (Uni. Birmingham, UK)

EAS 2020 Symposium 8 website

Recent years have brought high-quality data from X-ray observatories (NuSTAR, XMM Newton, Chandra, Swift) and quite a few important discoveries. On the one hand, it has been shown that NSs in close binary systems can be enormously bright, manifesting themselves as pulsating Ultra-Luminous X-ray Sources (ULXs). On the other hand, it is finally becoming possible to detect accreting NS at very low mass accretion rates, where some sources have already shown surprising spectral and timing behaviour. Symposium 9 on extremes in accretion onto strongly magnetised neutron stars was a great opportunity to bring together experts (both observers and theoreticians) who focus their research on different aspects of extreme accretion onto strongly magnetised NSs.

We had six sessions, and different sessions were focused on different aspects of extreme accretion:

• NSs at very low mass accretion rates;
• typical features of binaries hosting extremely bright NS;
• observational features of pulsating ULXs;
• theoretical view on ULX pulsars;
• future X-ray missions.

We were lucky to have 15 invited and 13 contributed talks from experts all over the world. The Symposium was an excellent platform for discussions and sharing ideas.

We see that the observational results nowadays are standing far in front of coherent theoretical models, which face complications in the theoretical description of radiation and matter interaction under conditions of a strong magnetic field. However, there are a few groups that attack the problem, and their results give hope for further progress in the coming years.

In the next few years, a new revolution is expected in observational X-ray astrophysics with the launch of the first X-ray polarimeters (IXPE, eXTP). Since the essential processes in a strong magnetic field are dependent on polarisation, accreting highly magnetized NSs are prime targets for the upcoming X-ray polarimeters. Another revolution is expected with the launch of XRISM X-ray micro-calorimeter, which will improve our capability of detecting winds and cyclotron lines in ULXs and NSs significantly.

We are particularly grateful to all our speakers and the numerous attendees, contributing to making Symposium 9 a success. We also thank all the EAS organization, and all people worked on the conference's interactive platform and helped us at every step.

Nathalie Degenaar (Uni. of Amsterdam, The Netherlands)
Paolo Esposito (IUSS, Pavia, Italy)
Felix Fuerst (ESA/ESAC, Spain)
Filippos Koliopanos (IRAP, France)
Matt Middleton (Uni. of Southampton, UK)
Alexander Mushtukov, chair (Leiden Uni., The Netherlands)
Ciro Pinto (ESA, The Netherlands)
Marina Romanova (Cornell Uni., USA)
Sergey Tsygankov (Uni. of Turku, Finland)
Natalie Webb (IRAP, France)

The first session in S10 was dedicated to highlights from the science done with Gaia DR2. May Gade Pedersen kicked off the symposium with a discussion on how Gaia and Kepler can be combined to learn about the internal rotation profiles of B-stars, through asteroseismic modelling. This was followed by a presentation by Giulia de Somma on the application of the first theoretical period-age-colour relation for Cepheids in the Gaia photometric bands, allowing to estimate ages for Cepheids. Moving to the other side of HR diagram Nicholas Chornay presented his work to carefully match the Gaia DR2 catalogue to central stars of known planetary nebulae, thus unlocking the power of Gaia to study PNe. Stefan Krauss then discussed the plans for the VLTI instrument BIFROST which will be used to complement the Gaia binary survey (planned for Gaia DR3), so that precise dynamical masses, ages, and spin-orbit alignments can be derived for a large sample of binaries. The next two talks by Ana Queiroz and Eloisa Poggio discussed the bar and bulge as seen by Gaia DR2 and Apogee, and the evidence for a dynamically evolving Galactic warp from Gaia DR2. Both presentations were the topics of recent press releases, to be found here and here.

The second session was dedicated to the Gaia mission and data processing status. Timo Prusti presented the status of the Gaia mission, showing the impressive numbers of Gaia archive users and the continuing growth in the number of refereed papers based on Gaia DR2 data. Anthony Brown presented a preview of the Gaia EDR3 release, planned for release later in 2020, showing the significant improvements in the astrometric precision of 20 per cent for the parallaxes and a factor of 2 for the proper motions. Francesca De Angeli subsequently showed more details on what can be expected in terms of photometry from Gaia ED3 and DR3. Nic Walton presented the status of the GREAT network, emphasizing the opportunities offered by the ongoing MW-GAIA COST Action. Simon Hodgkin presented the status of the efforts to map the transient sky with Gaia, showing that the survey is mature enough to discuss completeness numbers, for example for detected SNe. The session was closed by an exciting presentation by Kevin Jardine who as a private person made excellent use of Gaia DR2 to produce a beautiful 3D map of the solar neighbourhood, of which a zoomable version can be found here.

Session 3 of S10 was dedicated to the Milky Way and started with two presentations on the topic of hyper-velocity stars. Douglas Boubert reviewed results he and his collaborators obtained on this topic, including a recent discovery of a hyper-velocity star in the S5 spectroscopic survey which can be convincingly show to come from the Galactic centre. Fraser Evans followed up with a discussion of the use of hyper-velocity stars to constrain the mass and scale radius of the Milky Way halo. This was followed by a recent highlight from Gaia DR2, presented by Carme Gallart, the derivation of the star formation history in the Milky Way disk from the Gaia HRD and how this relates to the effects of the Sagittarius dwarf galaxy. This was also the topic of a press release. Next Marius Cautun presented his work on the Milky Way mass profile as obtained from an analysis of Gaia DR2 data for red giants, globular clusters, and satellite galaxies. This was followed by Jonathan Clarke discussing the properties of the bulge as derived form VIRAC/Gaia proper motions, showing clear evidence of bar rotation and streaming motion. The session was closed by Rimpei Chiba who nicely demonstrated that the Gaia DR2 data contains evidence for the deceleration of the rotation of the bar and how the bar's evolutionary history is imprinted in resonance phase space, much like tree rings.

The fourth session was dedicated to synergies between Gaia and ground-based surveys and started with an overview, presented by Joss Bland-Hawthorn, of the results obtained by the GALAH survey, showing how the powerful combination of this spectroscopic survey and Gaia DR2 can be used to dissect the stellar disc's phase space in abundance, action, age, and location. Michael Hayden followed with a presentation of the chemo-dynamics of the solar neighbourhood as seen by GALAH+Gaia. Neige Frankel gave a beautiful exposition of the ways in which stellar disks evolve in the presence of spiral arms, radial migration, and heating and how this can be measure with APOGEE+Gaia. Matthias Steinmetz presented a preview of the final RAVE data release which will be a very nice taster for data forthcoming from the Gaia Radial Velocity Spectrograph in future releases. Maria Tsantaki presented the effort to combine a number of the existing spectroscopic surveys, by matching them to the Gaia DR2 source list and then carefully homogenizing the parameters derived from the spectra, thus enabling a homogeneous view on the different parts of the Galaxy covered by the surveys. The session was closed by the presentation of the PASIPHAE survey by Konstantinos Tassis, which aims at 3D magnetic tomography of the Galaxy, through the measurement of optical polarization of stars. The aim is to better remove the dust foreground from CMB maps. The Gaia parallaxes of course play a crucial role in the 3D aspect.

The topic of session 5 was open clusters and star formation. Alfred Castro-Ginard showed how modern data mining techniques can be put to good use to find new open clusters in the Gaia DR2 data, resulting in over 580 new clusters discovered in his most recent work. Laia Casamiquela showed how open clusters, when studied in detail with spectroscopy, can be used as chemical clocks in the study of the chemical evolution of the Milky Way. Stefan Meingast turned the attention toward the young clusters near the sun, showing newly discovered extended structures around many of them, which are thought to arise from a combination the birth condition of the clusters and their subsequent dynamical evolution. Josefa Grossschedl used the combination of Gaia DR2, APOGEE, and CO gas measurements to derive the 3D shape of the Orion A, cloud and show that it was shaped by feedback from the winds and SNe of massive stars. A very complementary study presented by Sara Rezaei Kh. showed how the combination of Gaia DR2, 2MASS, and WISE can be used to produce 3D dust maps of the Orion region. The results are consistent with the shaping of the detected dust clouds by a population of stars in the foreground of Orion A. The session was close by Gábor Marton who presented a machine learning method to discover young stellar objects in the Gaia DR2 + ALLWISE catalogue.

In the final session the topic was again the synergy between Gaia and ground-based surveys. Sofia Feltzing started off by revisiting an old friend of hers, the HR 1614 moving group. The analysis of the Gaia DR2 data in combination with StarHorse distances (derived in part from Gaia DR2), GALAH and APOGEE spectroscopy, and SkyMapper photometry, shows conclusively that the HR 1614 moving group is not a dissolving cluster, but is most likely of dynamical origin. Diane Feuillet the showed how the Gaia-Enceladus-Sausage stars can be more cleanly isolated by considering metallicity in addition to kinematics in their selection. This leads to more reliable estimates of the properties of the progenitor galaxy, such as its total mass. Stella Reino subsequently showed her predictions on how well the Milky Way potential can be constrained by using stellar streams as probes. This was followed by a discussion, presented by Marcel Pawlowski, on the Milky Way's disk of satellites, showing how the precise Gaia proper motions strengthen the evidence for the existence of a satellite plane. The session was closed by two Canadian colleagues, with Kim Venn presenting the discoveries of extremely and ultra-metal poor stars in the PRISTINE survey where Gaia DR2 was used to constrain stellar parameters and determine obits. Allan Mcconnachie presented the plans for wide field multi-object spectrographs for the Gaia era, motivating this with the need for complementary spectroscopy for stars in the outer halo and dwarf galaxies with good Gaia proper motions, and focusing in particular on the Maunakea Spectroscopic Explorer.

This symposium again demonstrated the enormous impact that Gaia is having on astronomy in almost every field imaginable, which is reflected in the wide variety of topics mentioned above. We thank the EAS organizers for a smooth online experience, including participation from colleagues located in Australia and Canada without any problems. We look forward to hopefully another edition of this symposium at next year's EAS!

Full details of the programme and the presentations for S10 are available at this site.

Anthony Brown, Leiden Observatory, Leiden, NL
Nicholas Walton, Institute of Astronomy, University of Cambridge, UK
Timo Prusti, ESTEC, ESA, Noordwijk, NL

EAS 2020 Symposium 10 website

Meanwhile, multiple surveys (e.g. Saga, PISCeS, Dragonfly, DGSAT) are actively studying galaxy systems beyond the Local Group. These efforts and upcoming advances in observational capabilities (e.g. ELTs, LSST, JWST, Euclid) allow comparisons with model expectations for a growing sample of galaxies and galaxy groups in the larger-scale Local Volume. This is an opportunity to determine how peculiar the Local Group is, to investigate which small-scale challenges are present on a larger scale, and thus to expand the scope of near-field cosmology. Proposed solutions and alternatives to ΛCDM (e.g. warm and self-interacting dark matter, or more radical approaches such as MOND) can now be tested by comparing them to the observed galaxies and satellite systems in the Local Volume.

Our symposium aimed at further stimulating this exciting development, to study small-scale challenges and near-field cosmology in an extended volume and thereby avoiding being affected by possible peculiarities of the Local Group. The first of our six sessions focussed on the Local Group and its dynamical history, to summarize what we know and what the main cosmological challenges are (invited review by Giuseppina Battaglia, Instituto de Astrofisica de Canarias). This was followed by a discussion of observational surveys in the Local Volume, compiling our current knowledge of galaxies, their satellite systems, and groups of isolated dwarf galaxies beyond the Local Group (invited review by Pierre-Alain Duc, Observatoire Astronomique de Strasbourg). We then shifted emphasis towards the cosmological comparisons, with sessions on the status of small-scale problems in the Local Volume (invited review by Mike Boylan-Kolchin, University of Texas), and how these small-scale challenges are currently being addressed by standard cosmological simulations (invited review by Azi Fattahi, ICC, Durham University), but also by alternatives to the Cold Dark Matter model. The influence that the nearby cosmic web and larger-scale structures might have on small-scale problems, as well as current progress in modeling these with constrained cosmological simulations, was also addressed (invited review by Noam Libeskind, Leibniz-Institut für Astrophysik Potsdam), and finally we looked at the immediate future, learning about the capabilities of upcoming and proposed observing facilities (invited review by Marina Rejkuba, ESO), and possible observational tests of new theoretical predictions for the larger-scale Local Volume.

Our symposium brought together observers and theorists, both those working on the Local Group and those studying the larger-scale Local Volume. It was split into six sessions, with one invited talk each, a total of 24 contributed talks, and 10 posters. Our virtual sessions typically had 60-80 participants, ample questions and a lively discussion on the associated Slack channel. There was general agreement that the virtual format worked well and, with some appropriate scheduling, it allowed our speakers to participate not only in Europe, but all over the world, ranging from Australia in the East to Hawaii in the West.

Marcel S. Pawlowski (Leibniz-Institut für Astrophysik Potsdam, Germany)
Alyson Brooks (Rutgers University, USA)
Arianna Di Cintio (Instituto de Astrofísica de Canarias, Spain)
Eva K. Grebel (Heidelberg University, Germany)
Oliver Müller (Observatoire Astronomique de Strasbourg, France)
Justin Read (University of Surrey, UK)

EAS 2020 Symposium 11 website

The programme was split over four blocks, and featured four invited and 14 contributed talks (with exactly half in each category given by male and female speakers). These addressed four broad sub-topics related to our Symposium theme:

1. Where does the cluster environment affect its galaxies?
2. What do we know about the quenching of galaxies in clusters?
3. Are there tracers of environmental influence that precede galaxy quenching?
4. Which other properties of cluster galaxies are affected by their special environment in the cosmic middle ages?

Four invited reviews by Meghan Gray, Ian McCarthy, Rhea-Silvia Remus, and Sean McGee laid the foundation for topical updates provided by the contributed talks. The programme was rounded off by short flash talks highlighting posters. All talks were presented live through the online portal, and were followed by active discussions both immediately after the talks and throughout the Symposium on the Slack channel. In addition to the majority of speakers calling in from throughout Europe, we also had five contributed talks by overseas participants, from as far away as California and Australia.

Each session was well-attended by 50-100 participants, reflecting the significant place of this topic at the intersection of galaxy formation, large-scale structure, and cosmology.

Yannick Bahé (Leiden Observatory)
Remco van der Burg (European Southern Observatory)

EAS 2020 Symposium 14 website

The four session blocks were organized around three main topics. Each of these topic started by a review talk given by an invited speaker. Lutz Wisotzki (Leibniz-Institut fur Astrophysik Potsdam) started the session "Mapping of the CGM" by presenting the recent observations of the CGM in emission and highlighting the high complementary of the results obtained with absorption lines studies. The second topic of the Symposium "The flows around galaxies" was introduced by Michele Fumagalli (Durham University) who reviewed recent and ongoing efforts to characterize the impact of gas flows on the evolution of galaxies using observations and simulations. Finally, Celine Peroux (ESO) started the last session of the Symposium by telling us about the baryon content and metal enrichment through the various phases of the CGM.

Besides three review talks, 17 contributed talks were given as well as 3 poster sessions where 16 presenters explained their latest results in a 1.5-minutes slot. The numbers of attendees was between 80 and 110 depending on the session. All the contributions provided us a comprehensive overview of the current status of observational and theoretical studies of the CGM, highlighting, at the same time, the challenges in connecting the circumgalactic gas to its host galaxy.

This Symposium was a success thanks to the very high quality talks given by all the speakers and presenters whom we would like to thank. We also warmly thank the EAS for giving us the opportunity to organise this Symposium.

Floriane Leclercq (University of Geneva)
Maxime Trebitsch (MPlA Heidelberg)
Anna Feltre (SISSA Trieste)
Anne Verhamme (University of Geneva)
Johannes Zabl (CRAL Lyon)
Peter Mitchell (Leiden University)

EAS 2020 Symposium 15 website

The symposium was organized in four sessions, which were led by four invited highlight talks.

1. Cosmological parameters from high-redshift quasars (Guido Risaliti; University of Florence, Italy)
2. Accretion and outflows in low-mass X-ray binaries and transitional milli-second pulsars (Nathalie Degenaar; University of Amsterdam, The Netherlands)
3. The discovery of X-ray quasi-periodic eruptions in the nuclei of the galaxies GSN 069 and RX J1301.9+2747 (Margherita Giustini ; Centro de Astrobiologia, Mardid, Spain)
4. Athena: Europe's next large X-ray facility (D. Barret; IRAP/CNRS Toulouse, France)

Maria Diaz-Trigo chaired the first session, which addressed XMM-Newton's current status and scientific observing opportunities for the next decade, the scientific potential of the 4XMM source catalogue, the X-ray view of hot subdwarf stars, and the determination of cosmological parameters from X-ray / UV correlations, for which XMM-Newton observations are of critical importance (N. Schartel; N, Webb; N, La Palombara; G. Risaliti). One slot was devoted to the presentation of the e-posters (H. Tranin; F. Tombesi; A. Juranova; M. Clavel; A. Vahdat; I. Psaradaki).

Natalie Webb chaired the second session which discussed various aspects of X-ray binaries: the accretion and outflows in low mass X-ray binaries and transitional milli-second pulsars, the stellar wind and accretion structure in high mass X-ray binaries with emphasis on Vela X-1, the X-ray emission of middle-aged pulsars, the spin evolution and orbital ephemeris of the ultra-luminous X-ray source NGC 7793 P13, and the accretion in supergigant fast X-ray transients with XMM-Newton fill-in observations (N. Degenaar; V. Grinberg; B. Posselt; F. Fuerst; C. Ferrigno).

Rudy Wijnands chaired the third session which discussed active galactic nuclei and clusters of galaxies: the discovery of quasi-periodic eruption in the nuclei of GSN 069 and RX J1301.9+2747, the multi-wavelength, long-term evolution of the tidal disruption event AT 2018fyk, the X-ray ultra-fast outflow from the highly accreting supermassive black hole of PG 1448+273, the first results form XMM-Newton follow-up of ~400 galaxy clusters allowing to probe the cosmic isotropy, and the high-ionisation line of the hot interstellar medium (M. Giustini; T. Wevers; M. Laurenti; T. Reiprich; D. Rogantini).

Norbert Schartel chaired the fourth and last session in which first results of the XMM-Newton's multi-year heritage-program on LSST Deep-Drilling Fields was presented, followed by a presentation of Europe's next large X-ray facility, Athena, the development of the X-ray mirrors for Athena, and the prospects of the new X-ray missions IXPE and eXTP (N. Brandt; D. Barret; L Keek; R. Mikusincova; J. In't Zand/M. Hernanz).

Maria Diaz Trigo (ESO, Munich, Germany)
Norbert Schartel (ESA, Madrid, Spain)
Natalie Webb (Institut de Recherche en Astrophysique et Planétologie, Toulouse, France)
Rudy Wijnands (University of Amsterdam, Amsterdam, The Netherlands)

EAS 2020 Symposium 16 website