Stellar astrophysics

Ostlie D.A. Carrol B.W. (1996) Modern Stellar Astrophysics (Addison-Wesley, New York). 

Bohm-Vitense, E. 1989 Introduction to stellar astrophysics - volume 2 - Stellar atmospheres. Cambridge University Press, Cambridge. 

Stellar Astrophysics for the Local Group, edited by A. Aparicio, A. Herrero and F. Sanchez (ISBN 0 521 63255 2)... 

E. Bohm-Vitense, Introduction to stellar astrophysics, Vol. 3 - Stellar structure and evolution, Cambridge University Press (1992)... 

Since nuclear astrophysics is not usually taught at the master s level nuclear physics specialization in our universities, these lecture notes are meant to be an introduction to the subject and a pointer to literature and Internet resources5. The emphasis in the first part of these lecture notes is on the nuclear reactions in the stars and how these are calculated, rather than how stars evolve. The latter usually forms a core area of stellar astrophysics. 

The astrochemistty of ions may be divided into topics of interstellar clouds, stellar atmospheres, planetary atmospheres and comets. There are many areas of astrophysics (stars, planetary nebulae, novae, supemovae) where highly ionized species are important, but beyond the scope of ion chemistry . (Still, molecules, including H2O, are observed in solar spectra [155] and a surprise in the study of Supernova 1987A was the identification of molecular species, CO, SiO and possibly ITf[156. 157]. ) In the early universe, after expansion had cooled matter to the point that molecules could fonn, the small fraction of positive and negative ions that remained was crucial to the fomiation of molecules, for example [156]... 

In addition to these laboratory-based experiments it is interesting to note that the Swan bands of C2 are important in astrophysics. They have been observed in the emission spectra of comets and also in the absorption spectra of stellar atmospheres, including that of the sun, in which the interior of the star acts as the continuum source. 

The evidence on which this theory of stellar evolution is based comes not only from known nuclear reactions and the relativistic equivalence of mass and energy, but also from the spectroscopic analysis of the light reaching us from the stars. This leads to the spectral classification of stars, which is the cornerstone of modem experimental astrophysics. The spectroscopic analysis of starlight reveals much information about the... 

Open clusters (OCs) are important tools both for stellar and for galactic astrophysics, as tests of stellar evolution theory for low and intermediate mass stars and as tracers of the Galactic disk properties. Since old OCs allow us to probe the lifetime of the Milky Way disk, up to about 10 Gyr ago, they can be used to study the disk evolution with time, and in particular its chemical history. 

How will we identify the extra astrophysics required to reconcile the properties of CDM dark haloes with those of luminous galaxies We can start by developing knowledge of the evolutionary history of at least one place in at least one galaxy. We would be unlucky if that place were far from the norm alternatively, any theory that predicts such a history to be very unusual might be suspect -the galaxian Copernican principle. Kinematics and current spatial location are of course critical parameters, so that traditional stellar populations analyses are... 

In the next very few years stellar abundances and kinematics will be available for as many stars as redshifts are now available for galaxies. This abundance of information can, provided we approach the analysis and interpretation with due imagination, advance the astrophysics of galaxy formation as much as Cosmology has advanced over the last few decades. No doubt our image of galaxy evolution will be similarly revolutionised. 

D. D. Clayton, Principles of Stellar Evolution and Nucleosynthesis, McGraw-Hill 1968, University of Chicago Press 1984. This classic text is particularly well written and gives more accurate and rigorous arguments for results derived here often in a somewhat heuristic manner. A more up-to-date (though in some ways less complete) description of nuclear astrophysics is given in... 

A more up-to-date treatment of many aspects of stellar evolution and nuclear astrophysics is available in the book by... 

Detailed information about specific nuclear reactions at different stages of stellar evolution and the measurement of nuclear reaction cross-sections is given (together with a good overview of the whole of astrophysics) in... 

All the work involved in astrophysical reflection aims to give meaning to the word star . It turns out that the description of stellar evolution complies with known physical theories and nuclear processes. 

But do we know what cunning enterprise the sky has been engaged upon in order to prepare and mould this bounteous carbon and then to extract it from the great stellar furnace We shall once again follow through the main avenues of nuclear astrophysics, but this time considering life as we know it, or rather, one of the conditions that makes it feasible carbon. 

And so it is that light from the supernova of modern times has come to reassure humankind of its ability to understand how the elements are synthesised in stars. At the same time, the fog of speculation has lifted from the theory of stellar evolution, culmination of astrophysical thinking, appointing it to the rank of a well-established science, based on a firm observational foundation. 

In fact, the quest to find an astrophysical site for the r process is in full swing. It is being helped along by the rapid accumulation of observational data concerning surface abundances in ageing stars gravitating in the galactic halo. Such analyses aim to correlate observed abundances of typical r or s isotopes with stellar metallicities. It has thereby been discovered that the slow process comes later than the rapid process. 

The demonstration that stars are capable of such nuclear fertihty is based upon a combination of knowledge from what appear to be widely separated areas of physics. One of these concerns the internal structure of stars, telling us the temperature and pressure at different depths. The other concerns the probabilities at different energies of all the possible reactions between various nuclei, and between those nuclei and protons or neutrons. In the latter case, the acquisition of the relevant data was greatly accelerated by the Second World War. The beauty of nuclear astrophysics rests upon the success of this marriage and the complementarity of the two disciplines it brings together. The nuclear butterfly has returned to its stellar chrysalis. 

Cameron, A. G. W. (1957) Stellar Evolution, Nuclear Astrophysics, and Nucleogenesis (CRL-41 AECL-454). Chalk River, Ontario Atomic Energy of Canada, Ltd. 

Figure 3.10 shows the abundances of hydrogen, helium, and the CNO isotopes as a function of stellar radius in a 1.5 M star at the end of the main sequence. The horizontal axis represents the position within the star (in units of mass, a rather quirky astrophysics convention). The center of the star is on the left and the surface is on the right. The lines on the diagram show the mass fraction of each isotope at each position inside the star. For example, at the surface of the star, most of the mass consists of hydrogen, helium is the next most abundant, followed by 1 , 12C, 14N, and so forth. The starting composition of this hypothetical star, and the composition that remains at the stellar surface, is the same as that of our Sun. 

Asplund, M. (2005) New light on stellar abundance analyses departures from LTE and homogeneity. Annual Reviews of Astronomy and Astrophysics, 43, 481-530. A review of the determination of stellar abundances using the new three-dimensional modeling of the solar photophere. 

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