*Please note that this seminar will take place at 10am Eastern Time*

Hosted by: Shun Iimura (Rikkyo University)

Hosted by: Avrajit Bandyopadhyay (University of Florida)

*Due to unforeseen circumstances, this seminar is canceled*

Hosted by: Denise Piatti (University of Padova)

Hosted by: Barbara Paes Ribeiro (TANDAR)

Hosted by Eliana Masha (HZDR, Germany)

*Please note that this seminar is at 7pm ET on Thursday, April 13th*

Hosted by Kanji Mori (Fukuoka University, Japan)

Hosted by Erin Good (Michigan State University)

The n-process is a neutron-capture process activated in Core-Collapse Supernovae (CCSNe), when the Supernova shock is passing through the deepest He-rich layers of the massive star progenitor. The peak neutron density generated is typically larger than 1018 neutrons cm-3, and the dominant neutron source is the Ne22(alpha,n)Mg25 reaction where the Ne22 available was left in the ashes of the hydrostatic convective He shell.

Understanding the behavior of white dwarfs in interacting binary systems is critical to determining the rates, distributions, and chemical contributions from transients such as novae and type Ia supernovae. In this talk I will be presenting results from my recent work on novae, which combines population synthesis (binary_c) and galactic chemical evolution modeling (OMEGA+).

Understanding how the heavy elements came into being in the universe presents one of the greatest challenges in nuclear physics and astrophysics.  For some time we have known that elements beyond iron on the periodic table must have been made through neutron-induced reactions, but the environments where they are made and what they can tell us about this history of our galaxy remain a mystery.

Carbon is produced in stars mainly via the triple-alpha process where three helium nuclei fuse to form an excited state of carbon-12 known as the Hoyle state. This is a nuclear resonance (an excited form of a nucleus) that has properties that guide the rate that the triple alpha process takes place. Primarily, the key property is how often the Hoyle state is able to lose energy and end up in the ground state of carbon-12 – known as the radiative width.

Gamma rays from nuclear lines are the most-direct astronomical messenger for the occurrence of nuclear reactions in cosmic sites, next to neutrinos.

Characteristic lines from radioactive decays have been measured with space-borne telescopes, most-recently with ESA’s INTEGRAL mission, for the isotopes 56Ni, 57Ni, 44Ti, 26Al, and 60Fe.

In unresolved galaxies, age, metallicity, α/Fe enhancement of the stellar populations, as well as the IMF and the mass can be constrained via full spectra fitting or via line-strength index analysis. The Lick/IDS system is a prime example of line-strength spectroscopic indices that are sensitive to these parameters in the optical domain. In the Near-Infrared (NIR), where the upcoming generation of telescopes will primarily observe, we lack such a system, and the full spectral fitting technique is not yet reliable.

Abstract: One of the biggest questions in nuclear astrophysics regards how elements are synthesized in stellar environments. Observations of astrophysical phenomena provide us with evidence for different nucleosynthesis processes, and modelling these astrophysical scenarios requires a detailed description of the complex nuclear physics that is involved.

IReNA Online Seminar to begin 11am EST.

White dwarfs are stellar embers that simply cool down for the rest of time, eventually freezing into a solid state. This predictable evolution makes them precise cosmic clocks; they have been used for decades to measure the ages of stellar populations. But data from the Gaia space observatory is now calling into question the accuracy of this age dating technique. The cooling process appears to be much more delayed by the onset of crystallization than predicted by current models. I will present my recent work on the physics of core crystallization.

Core-collapse supernovae (CCSNe) are some of the brightest, most energetic events in the universe. In order to model these phenomena accurately, we need to have a diverse range of physics such as neutrino transport and neutrino interactions, general-relativistic gravity, detailed equations of state (EoS) of dense matter, magnetohydrodynamic (MHD) and detailed progenitor models.

The discovery of radioactive 26Al via the observation of the 1809-keV γ ray in 1982 is one of the most famous pieces of evidence of on-going nucleosynthesis in the cosmos. The 26Al is likely to be produced dominantly in massive stars and supernovae. Nevertheless, a number of additional sources such as classical novae and AGB stars may still contribute considerably to the production of 26Al. Thus, up to 29% of the total observed 26Al abundance is predicted to have a nova origin. 

Light elements were produced in the first few minutes of the Universe through a sequence of nuclear reactions known as Big Bang nucleosynthesis (BBN). Among the light elements produced during BBN, deuterium is an excellent indicator of cosmological parameters because its abundance is highly sensitive to the primordial baryon density.

Title: The CNO cycle and the CNO Neutrinos in our Sun