SNAQ April 2021

virtual (online)



Link will be provided after registration.
Andreas Korn (Uppsala University, Sweden) , Arūnas Kučinskas (Vilnius University, Lithuania) , Camilla J. Hansen (MPIA, Germany) , Konrad Schmidt (HZDR, Germany)


Schools on Nuclear Astrophysics Questions

Question in April 2021: How to get from starlight to stellar abundances?

Update: Below, all talks are available as PDF for download.

Update: Congratulation to the 3 winners of our SNAQs Scientific Talk Award in recogrecognition and appreciation for giving a scientic talk at the April 2021 edition of SNAQs:

  • Martina Baratella (University of Padova, Italy)
  • Moritz Reichert (Technical University of Darmstadt, Germany)
  • Shreeya Shetye (Université Libre de Bruxelles, Belgium)

And thanks to all other applicants who submitted an abstract.

This is the 3rd edition of a new, monthly, virtual school format discussing questions related to nuclear astrophysics.

Previous events:

Next event:

  • SNAQ May 2021 (Registration and abstract submission is open. We highly encourage young scientists (master and PhD students, as well as young postdocs) to give scientific talks related to the question in May: How can we query nature to determine nuclear inputs in the cosmos? To apply, please submit an abstract of your talk at the lower end of the May registration form. Deadline for abstract submission is April 28, 2021.)

We plan to organize a new event of SNAQs always on the 2nd Wednesday in each month with a break in summer. SNAQs will last about 3.5 hours, including breaks, with lectures and scientific talks around a given question in nuclear astrophysics. Lectures will be held by senior researchers and scientific talks preferably by young researchers, as master and PhD students. Further, SNAQs will 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 will 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 will be networked by ChETEC-INFRA, Chemical Elements as Tracers of the Evolution of the Cosmos - INFRAstructures for Nuclear Astrophysics, a new European network of 32 partner institutions. Please note that even the official start of ChETEC-INFRA is planned for May 2021 the involved institutions already jointly created SNAQs.

We are looking forward to meet you at the third SNAQ.

SNAQ April 2021 organizers SNAQs organizing committee
  • Camilla Juul Hansen (Max Planck Institute for Astronomy Heidelberg, Germany)
  • Andreas Korn (Uppsala University, Sweden)
  • Arūnas Kučinskas (Vilnius University, Lithuania)
  • Camilla Juul Hansen (Max Planck Institute for Astronomy Heidelberg, 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)
  • Mohamad Moukaddam (University of Strasbourg, France)
  • 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 14:00
      Zoom available 15m
    • 14:00 14:03
      Welcome 3m
      Speaker: Konrad Schmidt (HZDR, Germany)
    • 14:03 14:10
      ChETEC-INFRA Observation School 7m
      Speaker: Andreas Korn (Uppsala University, Sweden)
    • 14:10 14:55
      From starlight to spectra — Observations for stellar abundance determinations 45m

      First lecture on astronomical observations for stellar abundance analysis

      Speaker: Heidi Korhonen (ESO, Chile)
    • 14:55 15:05
      Moderated questions 10m
      Speaker: Andreas Korn (Uppsala University, Sweden)
    • 15:05 15:50
      From idea to science - The path to stellar abundance determinations 45m

      Second lecture on methods and tools for stellar abundance analysis

      Speaker: Andreas Koch-Hansen (University of Heidelberg, Germany)
    • 15:50 16:00
      Moderated questions 10m
      Speaker: Arūnas Kučinskas (Vilnius University, Lithuania)
    • 16:00 16:15
      Breakout session 15m

      Small groups of up to 5 participants are assigned to breakout rooms 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.

    • 16:15 16:25
      Coffee break 10m
    • 16:25 16:37
      The chemical composition of very young open clusters 12m

      In the last 15 years, several investigations seem to indicate an anomalous behaviour of young Galactic open clusters, which includes (but is not limited to) sub-solar iron (Fe) abundances of the systems in the solar neighbourhood, extreme and unexpected barium (Ba) enhancements, and super-solar abundances of some atomic species (e.g., ionised chromium). Recently, different independent studies have demonstrated that in such young stars, the higher levels of stellar activity can alter the spectral line formation and, consequently, the derived abundances. These results have drawn the attention to the necessity to revise the spectroscopic analysis technique. In this talk I will present a new spectroscopic approach (based mainly on Ti lines) developed to overcome the effects of the increased stellar activity that affects the analysis of very young (ages less than 200 Myr) stars. Moreover, I will present the preliminary results of my study on the abundances of the s−process elements (Cu, Sr, Y, Zr, Ba, La and Ce) and their time evolution. I will discuss the results and the scientific implications on stellar properties and Galactic evolution models.

      Speaker: Martina Baratella (University of Padova, Italy)
    • 16:37 16:40
      Moderated questions 3m
      Speaker: Gabriele Cescutti (Astronomical Observatory of Trieste, Italy)
    • 16:40 16:52
      Extreme r-process enhanced stars in the Fornax dwarf spheroidal galaxy 12m

      There exist still open questions about the r-process and very rare r-process enhanced stars may hold the key to answer them. We analyzed three newly identified r-II stars that are members of the dwarf spheroidal galaxy Fornax. These special stars are relatively metal-rich and contain the highest amount of the r-process element europium ever observed. In addition, their membership to the dwarf galaxy is underlined by their low α-element abundances. The high amount of r-process elements even allowed the element lutetium to be measured for the first time in a dwarf spheroidal galaxy. The sheer existence of the stars is remarkable because they proof that an extreme r-process enhancement is not only a feature of the lightest galaxies, but that it is also found in the heaviest dwarf galaxies. Due to the extreme r-process enhancement, the stars open new opportunities and insights into the r-process site in these very distant galaxies. We have estimated the necessary ejected europium mass per r-process event and conclude that one r-process event is sufficient for such an extreme enhancement and the ejected mass is in agreement with previous findings. In addition, it was possible to link the birth of the stars, and thus the r-process event, with a recent star formation activity of Fornax ∼ 4 Gyr ago. This ultimately made speculations about the responsible r-process event possible.

      Speaker: Moritz Reichert (Technical University of Darmstadt, Germany)
    • 16:52 16:55
      Moderated questions 3m
      Speaker: Gabriele Cescutti (Astronomical Observatory of Trieste, Italy)
    • 16:55 17:07
      Probing stellar abundances of S-type stars in the Gaia era 12m

      S-type stars are late-type giants enhanced with s-process elements originating either from nucleosynthesis during the Asymptotic Giant Branch (AGB) or from a pollution by a binary companion. The former are called intrinsic S stars, and the latter extrinsic S stars. The intrinsic S stars are on the AGB and have undergone third dredge-up events. The atmospheric parameters of S stars are more numerous than those of M-type giants (C/O ratio and s-process abundances affect the thermal structure and spectral synthesis), and hence they are more difficult to derive. These atmospheric parameters are also entangled within each other and the S stars’ spectra are dominated by molecules. Despite the challenges involved in analyzing the S stars, they are ideal candidates to investigate AGB s-process nucleosynthesis.
      In my talk I will present my novel methodology that combines high-resolution spectroscopic data of S stars with the Gaia early data release 3 parallaxes and with the MARCS model atmospheres for S-type stars to derive their effective temperature, surface gravity, and luminosity. These parameters not only allow us to locate the intrinsic and extrinsic S stars in the Hertzsprung-Russell (HR) diagram but also allow the accurate abundance analysis of the s-process elements. I will further present how these stellar abundances led to interesting insights into the AGB nucleosynthesis like (I) the use of zirconium-niobium pair to distinguish extrinsic from intrinsic stars, (II) the first time derivation of technetium abundances helping us to probe the AGB evolution, and (III) the comparison between AGB nucleosynthesis predictions and observations.

      Speaker: Shreeya Shetye (Université Libre de Bruxelles, Belgium)
    • 17:07 17:10
      Moderated questions 3m
      Speaker: Gabriele Cescutti (Astronomical Observatory of Trieste, Italy)
    • 17:10 17:30
      Round table discussion 20m

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