Related papers: Possible Solution to the Triple Alpha Fine-Tuning …
The most massive elliptical galaxies apparently formed the fastest, because the ratio of alpha elements (such as oxygen) to iron is the smallest. In fact, iron is mainly produced from type Ia supernovae on a timescale of ~ 0.1-1 billion…
A number of works point to the presence of narrow emission features at unusual energies in the X-ray spectra of active galactic nuclei (AGN) or to potentially low iron abundances as possible evidence for the spallation of iron. With the…
Nucleosynthesis, on the surface of accreting neutron stars, produces a range of chemical elements. We perform molecular dynamics simulations of crystallization to see how this complex composition forms new neutron star crust. We find…
We discuss the fine-tunings of nuclear reactions in the Big Bang and in stars and draw some conclusions on the emergence of the light elements and the life-relevant elements carbon and oxygen. We also stress how to improve these…
Atomic nuclei are transformed into each other in the cosmos by nuclear reactions inside stars: -- the process of nucleosynthesis. The basic concepts of determining nuclear reaction rates inside stars and how they manage to burn their fuel…
Stars with masses of >~ 20 solar masses have short Kelvin times that enable them to reach the main sequence while still accreting from their natal clouds. The resulting nuclear burning produces a huge luminosity and a correspondingly large…
Accreting neutron stars exhibit Type I X-ray bursts from both frequent hydrogen/helium flashes as well as rare carbon flashes. The latter (superbursts) ignite in the ashes of the former. Hydrogen/helium bursts, however, are thought to…
There is an apparent dichotomy between the metal-poor ([Fe/H] <= -2) yet carbon-normal giants and their carbon-rich counterparts. The former undergo significant depletion of carbon on the red giant branch after they have undergone first…
The triple alpha reaction is a key to $^{12}$C production and is expected to occur in weakly-coupled, thermal plasmas as encountered in normal stars. We investigate how Coulomb screening affects the structure of a system of three alpha…
Why the cosmological constant $\Lambda$ observed today is so much smaller than the Planck scale or why the universe is accelerating at present? This is so-called the cosmological constant fine-tuning problem. In this paper, we find that…
New images of young stars are revolutionizing our understanding of planet formation. ALMA detects large grains in planet-forming disks with few AU scale resolution and scattered light imaging with extreme adaptive optics systems reveal…
The process of carbon burning is vital to understanding late stage stellar evolution of massive stars and the conditions of certain supernovae. Carbon burning is a complex problem, involving quantum tunnelling and nuclear molecular states.…
Using the standard infall model of Galactic chemical evolution, we explore the origin of carbon and calculate the abundance evolution of CNO elements for 8 different models of stellar nucleosynthesis yields. The results show that, in the…
Earth's carbon deficit has been an outstanding problem in our understanding of the formation of our Solar System. A possible solution would be the sublimation of carbon grains at the so-called soot line (~300 K) early in the…
Star formation generally proceeds inside-out, with overdense regions inside protostellar cores collapsing rapidly and progressively less dense regions following later. Consequently, a small protostar will form early in the evolution of a…
In this paper we study the production of Li, Be and B nuclei by Galactic cosmic ray spallation processes. We include three kinds of processes: (i) spallation by light cosmic rays impinging on interstellar CNO nuclei (direct processes); (ii)…
The trends of chemical abundances and abundance ratios observed in stars of different ages, kinematics, and metallicities bear the imprints of several physical processes that concur to shape the host galaxy properties. By inspecting these…
Massive stars influence their surroundings through radiation, winds, and supernova explosions far out of proportion to their small numbers. However, the physical processes that initiate and govern the birth of massive stars remain poorly…
Effects of a new triple-alpha reaction rate on the ignition of carbon-oxygen white dwarfs accreting helium in a binary systems have been investigated. The ignition points determine the properties of a thermonuclear explosion of a Type Ia…
The abundances of beryllium and boron have been measured in halo stars of metallicities as low as [Fe/H] =-3. The observations show that the ratios Be/Fe and B/Fe are independent of metallicity and approximately equal to their solar values…