SNAQ May 2022

Wednesday 11 May 2022, 13:45 → 17:30 Europe/Brussels

online (virtual)

Camilla J. Hansen (Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany), Andreas Korn (Uppsala University, Sweden), Arūnas Kučinskas (Vilnius University), Konrad Schmidt (HZDR)

ChETEC-INFRA SNAQs [snacks] Schools on Nuclear Astrophysics Questions

Question in May 2022: Accurate abundances of chemical elements in stars: why and how?

Scroll down for registration.

We highly encourage young scientists (Master's and PhD students, as well as young postdocs) to give scientific talks at this SNAQ related to the question above. If you are interested, please submit an abstract of your talk at the lower end of the registration form. Deadline for abstract submission is May 6, 2022. Successful candidates who give a talk after this competitive selection will receive the SNAQs Scientific Talk Award.

This is the 12th edition of a monthly, virtual school format discussing questions related to nuclear astrophysics.

Previous events:

SNAQ Febrauary 2021 SNAQ March 2021 SNAQ April 2021 SNAQ May 2021 SNAQ June 2021 SNAQ October 2021

SNAQ November 2021 SNAQ December 2021 SNAQ January 2022 SNAQ February 2022 SNAQ April 2022

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A new event of SNAQs is organized always on the 2nd Wednesday in each month with a break in summer. SNAQs last about 3.5 hours, including breaks, with lectures and scientific talks around a given question in nuclear astrophysics. Lectures are held by senior researchers and scientific talks preferably by young researchers, as master and PhD students. Further, SNAQs put a special focus on the interaction between participants to allow young scientists networking even if traveling to schools, workshops and conferences is not an option.

SNAQs join the community of schools related to nuclear astrophysics that partner with ChETEC-INFRA:

• Carpathian Summer School of Physics (well established)
• European Summer School on Experimental Nuclear Astrophysics (well established)
• Intercontinental School on Nuclear Astrophysics (new)
• International school on nuclear physics, neutron physics and applications (well established)
• Nuclear Physics in Astrophysics School (new)
• Rußbach School on Nuclear Astrophysics (well established)
• School on observations and spectroscopic tools (new)

The aim of this community is to give all students and young researchers the same, multidisciplinary knowledge about nuclear astrophysics. SNAQs will support this idea and strengthen the community of schools by providing a frequent lecture series to train and educate the next generation of scientist with knowledge across the three types of infrastructures used by nuclear astrophysicists:

• astronuclear laboratories supplying reaction data,
• supercomputer facilities performing stellar structure and nucleosynthesis computations, and
• telescopes and mass spectrometers collecting elemental and isotopic abundance data.

Those infrastructures are networked by ChETEC-INFRA, Chemical Elements as Tracers of the Evolution of the Cosmos - INFRAstructures for Nuclear Astrophysics, a new European starting community of 32 partner institutions.

We are looking forward to meet you at the 9th SNAQ.

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SNAQ April organizers

SNAQs organizing committee

Camilla Juul Hansen (Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany) Andreas Korn (Uppsala University, Sweden) Arūnas Kučinskas (Vilnius University, Lithu

Rosanna Depalo (Università degli Studi di Milano, Italy) Camilla Juul Hansen (Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany) Marcel Heine (Hubert Curien Pluridisciplinary Institute, France) Ann-Cecilie Larsen (University of Oslo, Norway) Andreas Korn (Uppsala University, Sweden) Arūnas Kučinskas (Vilnius University, Lithuania) Sara Palmerini (University of Perugia, Italy) Gianluca Pizzone (Laboratori Nazionali del Sud, Italy) Konrad Schmidt (Helmholtz-Zentrum Dresden-Rossendorf, Germany) Olivier Sorlin (Grand Accélérateur National d'Ions Lourds, France) Livius Trache (Horia Hulubei National Institute for Physics & Nuclear Engineering, Romania) Aurora Tumino (Kore University of Enna, Italy)

Guidelines for participants of SNAQs Please, … … rename yourself in the Zoom sessions to match your registration name and institution – this will serve as your “nametag”. … mute your microphone during talks. … use the public chat only for questions related to the lecture; for discussions, please use the private chat. … write your questions in the chat – due to the high number of participants, a moderator will read a selection of questions but can choose a limited number only. … use breakout rooms to talk and chat to each other in smaller groups. Breakout rooms will be available during coffee breaks and participants can choose rooms freely. … behave professionally and respectfully. … follow ethical standards as professional integrity and honesty. … foster a welcoming and inclusive work environment.

13:45 Zoom available

1 Introduction

Monthly SNAQs – Introducing a new, virtual school format discussing questions related to nuclear astrophysics

Speaker: Konrad Schmidt (HZDR, Germany)

2 Presenting the NPA-X school

Speaker: Rosanna Depalo (Università degli Studi di Milano and INFN Milano, Italy)

snaq-2022-05-11_NPAX_Presentation.pdf

3 Determining the compositions of stars using 3D non-LTE models

First lecture

The compositions of stars are usually determined by comparing observations of stellar spectra against theoretical models. The accuracy of the inferred compositions is often limited by the accuracy of the models. For stars of similar mass to the Sun, arguably the most accurate models available today are based on three-dimensional radiation-hydrodynamics simulations ("3D"), together with radiative transfer methods that take into account the non-local coupling between light and matter (non-local thermodynamic equilibrium, or "non-LTE"). I shall talk about these 3D non-LTE models and their application to the Sun and other stars in the Milky Way.

Speaker: Anish Amarsi (Uppsala University, Sweden)

snaq-2022-05-11_amarsi.pdf

4 Moderated questions

Speaker: Arūnas Kučinskas (Vilnius University, Lithuania)

5 First Stars - the importance of accurate stellar abundances

Second lecture

The properties of the first stars in the Universe remain elusive. The impact of the first stellar generation was significant, as they provided the first ionising radiation, metals and dust in the Universe, but their study is very challenging. No metal-free star has been observed to date, but we can study them through their chemical imprint left in the second generation of stars. Thus, to correctly interpret the available data, and gain a comprehensive understanding of the first stars, accurate stellar abundances are of utmost importance.

Speaker: Ása Skuladottir (University of Florence, Italy)

snaq_2022-05-11_skuladottir.pdf

6 Moderated questions

Speaker: Andreas Korn (Uppsala University, Sweden)

16:00 Coffee break and breakout rooms

Breakout rooms are available to (1) very briefly introduce yourself, (2) talk about the lectures, (3) clarify lecture items, and (4) phrase questions for the round table discussion.

Afterwards, questions can be written in the chat of the main Zoom room. Please tag questions related to lecture 1 with L1 and questions related to lecture 2 with L2. Moderators can only choose a limited number of questions to be discussed at the round table discussion.

This session also povides the opportunity to establish contacts that can be continued using the private chat. Networking is an important tool not only in science.

7 Abundances of Sr and Zr in the atmospheres of red giants in Galactic globular cluster 47 Tuc

It was a long‐standing assumption that Galactic globular clusters (GGCs) are homogeneous objects consisting of stars that have the same age and chemical composition. However, research done during the last several decades has unexpectedly revealed that almost all GGCs harbour multiple stellar populations (MPs) consisting of stars that differ in: their abundances of light chemical elements (e.g., O, Na, Al); distributions within the cluster; and kinematical properties. By combining abundances of neutron capture and light chemical elements and determining their abundance ratios it is feasible to constrain the possible evolutionary scenarios of GGCs. To identify the possible polluter stars and the possible pollution scenarios we determined abundances of Sr and Zr, both light s‐process chemical elements, and Na in the atmospheres of RGB stars in GGC 47 Tuc. We use the obtained results to discuss the accuracy needed for the abundance determinations to detect the existence of possible correlations/anticorrelations between the abundances of chemical elements in the GGCs, as well as possible connections between the chemical composition of these stars and their kinematical properties and implications for constraining the possible evolutionary scenarios of the GGCs.

Speaker: Edgaras Kolomiecas (Vilnius University, Lithuania)

snaq-2022-05-11_kolomiecas.pdf

8 Moderated questions

Speaker: Camilla J. Hansen (Goethe University, Frankfurt, Germany)

9 Round-table discussion

Questions that were compiled in the chat during and after lectures and breakout session will be answered and discussed.