Third list of new double stars

List of Contents

Graph Choosability and Double List Colorability

In this paper, we give a sufficient condition for graph choosability, based on Combinatorial Nullstellensatz and a specific property, called “double list colorability”, which means that there is a list assignment for which there are exactly two admissible colorings.

Anti-Ramsey numbers of spanning double stars

In this paper we shall prove and sharpen a conjecture of A. Bialostocki on anti-Ramsey colorings of the complete graph Kn. Assume the edges of a Kn are colored by t colors. The basic question is how many colors ensure that Kn has a spanning subtree of diameter at most d in which each edge has a different color. The surprising fact is that the answers are the same for every d ≥ 3. Moreover, we c...

Formation of Double Rings around Evolved Stars

I propose a scenario for the formation of double-ring systems, as observed in some planetary nebulae and in the outer rings of SN 1987A. In this scenario, two jets, one jet on each side of the equatorial plane, expand into a thin, dense shell. Such a flow is expected in binary systems where the mass-losing primary undergoes an impulsive mass loss episode which forms a thin, dense shell. I assum...

Coalescence Rates of Double Neutron Stars

Merger events of close double neutron stars (DNS) lie at the basis of a number of current issues in relativistic astrophysics, such as the indirect and possible direct detection of gravitational waves, the production of gamma-ray bursts at cosmological distances, and the origin of rprocess elements in the universe. In assessing the importance or relevance of DNS coalescence to these issues, kno...