Letters of Intent received in 2018

LoI 2020-2044
Stars at the Extreme

Topics

Session 1: Extreme in mass: from very massive stars to supermassive stars (1 day)
Session 2: Extreme in mass loss (1 day)
Session 3: Extreme in rotation: from Be stars to spinstars and long Gamma Ray Burst progenitors (1 day)
Session 4: Extreme in composition: from the most iron poor first generation stars to the most metal rich in the present-day Universe (1/2 day)
Session 5: Extreme energetic events: kilonovae, gamma ray bursts, gravitational wave events (1/2 day)
Session 6: Extreme in multiplicity: the role of binarity and multiplicity in massive star formation and evolution (1 day)

Rationale

Dear Colleagues,

This letter of intent briefly describes the project of an IAU Symposium in June, 2020. Two possible venues are being considered: 1) Tartu Observatory (Estonia) and 2) Natal (Brazil).

The title of the Symposium would be:
STARS AT THE EXTREME.


Massive stars are extreme objects in the Universe. Extreme in their composition: first-born stars are made of material having been processed only by the Big Bang nucleosynthesis, and having a content in dark matter likely very different from the one of present-day stars, while the youngest stars can be very metal rich. Extreme metal content, from zero to very high, present a challenge for stellar evolution models.
Extreme in their properties: what is the most massive star that can be formed at different metallicities? This core question for studies of the Early Universe is far from being settled, as it depends on magnetic fields, composition, dark matter content. Could these stars be the seeds for supermassive black-holes?
Extreme in their physics: the physics of candidate dark matter particles may have a significant effect on the evolution of the earliest stars in the Universe. The combination of very fast-rotation, extreme radiation fields, complex transport mechanisms, and intense mass loss episodes implies that several physical mechanisms ruling these star are elusive in their complex interrelations.

The “Stars at the Extreme” IAU Symposium will be at the crossroad of topics such as stellar physics, nucleosynthesis, hydrodynamics, evolution of galaxies, and will potentially engender ground-breaking consequences for observational cosmology, astrophysics and even fundamental physics (fluid dynamics and dark matter properties). It will bring together specialists working both on theory and observations of massive stars, in order to determine which observable features can be used to constrain the composition (baryonic and dark matter), the properties (masses, rotation, magnetic field, multiplicity) and the physics of massive stars in extreme conditions. These observables will be collected by present-day and future facilities as, for instance, the JWST, ELT, GMT, TMT, adLigo, VIRGO, LISA, and are linked to ionizing fluxes, nucleosynthesis, radiation of both stellar populations and transient events, and gravitational waves.

Alex C. Carciofi (chair, Brazil) and Sylvia Ekström (co-chair, Switzerland) will set up a scientific organizing committee and will also set up a local organizing committee once the venue is decided.

The symposium will consist of probably 6 sessions spread out in 5 days. A possibility might be (but this will be fixed in the final proposition):

Session 1: Extreme in mass: from very massive stars to supermassive stars (1 day)
Session 2: Extreme in mass loss (1 day)
Session 3: Extreme in rotation: from Be stars to spinstars and long Gamma Ray Burst progenitors (1 day)
Session 4: Extreme in composition: from the most iron poor first generation stars to the most metal rich in the present-day Universe (1/2 day)
Session 5: Extreme energetic events: kilonovae, gamma ray bursts, gravitational wave events (1/2 day)
Session 6: Extreme in multiplicity: the role of binarity and multiplicity in massive star formation and evolution (1 day)

A detailed rationale and all the needed organizational details will be provided in the final submission before 15 December, 2018.
With my best regards,
Alex C. Carciofi
(in the name of the SOC)