C. Travaglio1,2, T. Rauscher3,4,11, A. Heger5,6,7,8,12, M. Pignatari8,9, and C. West7,8,10
Astrophysical Journal 854, 18 Link to Article [DOI: 10.3847/1538-4357/aaa4f7]
1INFN—Istituto Nazionale Fisica Nucleare, Turin, Italy
2B2FH Association—Turin, Italy
3Department of Physics, University of Basel, Switzerland
4Centre for Astrophysics Research, University of Hertfordshire, UK
5Monash Centre for Astrophysics, Monash University, Melbourne, Victoria, 3800, Australia
6Astronomy Department, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
7School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
8Joint Institute for Nuclear Astrophysics—Center for the Evolution of the Elements, USA
9E.A. Milne Centre for Astrophysics, University of Hull, HU6 7RX, UK
10Center for Academic Excellence, Metropolitan State University, St. Paul, MN, 55106, USA
11UK Network for Bridging Disciplines of Galactic Chemical Evolution (BRIDGCE), https://www.bridgce.net.
12The NuGrid Collaboration, http://www.nugridstars.org.
The production of the heavy stable proton-rich isotopes between 74Se and 196Hg—the p nuclides—is due to the contribution from different nucleosynthesis processes, activated in different types of stars. Whereas these processes have been subject to various studies, their relative contributions to Galactic chemical evolution (GCE) are still a matter of debate. Here we investigate for the first time the nucleosynthesis of p nuclides in GCE by including metallicity and progenitor mass-dependent yields of core-collapse supernovae (ccSNe) into a chemical evolution model. We used a grid of metallicities and progenitor masses from two different sets of stellar yields and followed the contribution of ccSNe to the Galactic abundances as a function of time. In combination with previous studies on p-nucleus production in thermonuclear supernovae (SNIa), and using the same GCE description, this allows us to compare the respective roles of SNeIa and ccSNe in the production of p-nuclei in the Galaxy. The γprocess in ccSN is very efficient for a wide range of progenitor masses (13 M ⊙–25 M ⊙) at solar metallicity. Since it is a secondary process with its efficiency depending on the initial abundance of heavy elements, its contribution is strongly reduced below solar metallicity. This makes it challenging to explain the inventory of the p nuclides in the solar system by the contribution from ccSNe alone. In particular, we find that ccSNe contribute less than 10% of the solar p nuclide abundances, with only a few exceptions. Due to the uncertain contribution from other nucleosynthesis sites in ccSNe, such as neutrino winds or α-rich freeze out, we conclude that the light p-nuclides 74Se, 78Kr, 84Sr, and 92Mo may either still be completely or only partially produced in ccSNe. The γ-process accounts for up to twice the relative solar abundances for 74Se in one set of stellar models and 196Hg in the other set. The solar abundance of the heaviest p nucleus 196Hg is reproduced within uncertainties in one set of our models due to photodisintegration of the Pb isotopes 208,207,206Pb. For all other p nuclides, abundances as low as 2% of the solar level were obtained.
in the local interstellar medium (ISM) is about 90% of the primordial ratio predicted by Big Bang nucleosynthesis. The high 
implies that only a small fraction of interstellar gas has been processed through stars, which destroy any deuterium they are born with. Using analytic arguments for one-zone chemical evolution models that include accretion and outflow, I show that the deuterium abundance is tightly coupled to the abundance of core collapse supernova (CCSN) elements, such as oxygen. These models predict that the ratio of the ISM deuterium abundance to the primordial abundance is 
, where r is the recycling fraction, 
is the ISM oxygen mass fraction, and 
is the population-averaged CCSN yield of oxygen. Using values r = 0.4 and 
appropriate to a Kroupa initial mass function and recent CCSN yield calculations, solar oxygen abundance corresponds to 
, consistent with the observations. This approximation is accurate for a wide range of parameter values, and physical arguments and numerical tests suggest that it should remain accurate for more complex chemical evolution models. The good agreement with the upper range of observed 
values supports the long-standing suggestion that sightline-to-sightline variations of deuterium are a consequence of dust depletion, rather than a low global 
enhanced by localized accretion of primordial composition gas. This agreement limits deviations from conventional yield and recycling values, including models in which most high-mass stars collapse to form black holes without expelling their oxygen in supernovae, and it implies that Galactic outflows eject ISM hydrogen as efficiently as they eject CCSN metals.
3.2 m s−1) impacts of solid projectiles. Spherical impactors made of glass, steel, or lead are dropped onto a dust aggregate with a packing fraction of 
= 0.35 under vacuum conditions. The impact results in cratering or fragmentation of the dust aggregate, depending on the impact energy. The crater shape can be approximated by a spherical segment and no ejecta are observed. To understand the underlying physics of impacts into dust aggregates, the motion of the solid projectile is acquired by a high-speed camera. Using the obtained position data of the impactor, we analyze the drag-force law and dynamic pressure induced by the impact. We find that there are two characteristic strengths. One is defined by the ratio between impact energy and crater volume and is 
120 kPa. The other strength indicates the fragmentation threshold of dynamic pressure and is 
