Stellar Astrophysics

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The primary focus of astronomy research at Delaware is on stellar astrophysics; the branch of astronomy concerned with the study of stellar structure and evolution, the atmospheres and winds of stars, and stellar oscillations. NASA has identified four "Big Questions"  for astrophysics aimed at discovering the origin, structure and evolution of the cosmos.

At the end of the Big Bang, normal matter in the Universe was mostly hydrogen and helium, with no elements heavier than boron. However our world today, including life, is possible only because of the existence of heavier elements such as carbon, nitrogen, oxygen, silicon, and iron, which are made by fusion reactions in the hot interiors of stars. Relevant questions being addressed at Delaware include how do the first generations of stars differ from later generations in their evolution, explosions as supernova, and production of heavy elements? What are the mechanisms by which massive stars return heavy elements to the interstellar medium, from which new stars form? How are magnetic fields produced in massive stars? How do magnetic fields influence the evolution of stars, and the way they lose mass? An exciting new idea is that stochastically excited waves in massive stars can transport angular momentum in such a way that the outer parts of the star rotate rapidly. This idea is particularly relevant to models of gamma-ray bursters, the most energetic stellar phenomenon in the Universe.

Selected Publications: 

S. Owocki, Radiatively driven stellar winds from hot stars, review article for Encyclopedia of Astronomy and Astrophysics. [PDF]

B. Riaz and J. E. Gizis, New brown dwarf disks in the TW Hydrae Association, Astrophys. J. 681, 1584 (2009). [URL]

P. A. Cassak, D. J. Mullan, and M. A. Shay, From solar and stellar flares to coronal heating: Theory and observations of how magnetic reconnection regulates coronal conditions, Astrophys. J. 676, L69 (2008). [URL]

T. M. Lawlor, T. R. Young, T. A. Johnson, and J. MacDonald, Single and binary evolution of Population III stars and their supernova explosions, Monthly Notices Royal Astron. Soc. 384, 1533 (2008).

A. Ud-Doula, S. P. Owocki, and R. H. D. Townsend, Dynamical simulations of magnetically channelled line-driven stellar winds - III. Angular momentum loss and rotational spin-down, Monthly Notices Royal Astron. Soc. 392, 1022 (2009).