arXiv subjects

J. P. Phillips

Publications and source records attributed to J. P. Phillips.

21 records · Page 2Linked to original sources

arXiv2009

The Halos of Planetary Nebulae in the Mid-Infrared: Evidence for Interaction with the Interstellar Medium

The motion of planetary nebulae (PNe) through the interstellar medium (ISM) is thought to lead to a variety of observational consequences, including the formation of bright rims; deformation and fragmentation of the shells; and a shift of the central stars away from the geometric centres of the envelopes. These and other characteristics have been noted through imaging in the visual wavelength regime. We report further observations of such shells taken in the mid-infrared (MIR), acquired through programs of IRAC imaging undertaken using the Spitzer Space Telescope (SST). NGC 2440 and NGC 6629 are shown to possess likely interacting halos, together with ram-pressure stripped material to one side of their shells. Similarly, the outer halos of NGC 3242 and NGC 6772 appear to have been fragmented through Rayleigh-Taylor (RT) instabilities, leading to a possible flow of ISM material towards the inner portions of their envelopes. If this interpretation is correct, then it would suggest that NGC 3242 is moving towards the NE; a suggestion which is also supported through the presence of a 60 microns tail extending in the opposite direction, and curved bands of H-alpha emission in the direction of motion - components which may arise through RT instabilities in the magnetized ISM.

astro-ph.GA↗

arXiv2006

Molecular orientational dynamics of the endohedral fullerene Sc$_{3}$N@C$_{80}$ as probed by $^{13}$C and $^{45}$Sc NMR

We measure 13C and 45Sc NMR lineshapes and spin-lattice relaxation times (T1) to probe the orientational dynamics of the endohedral metallofullerene Sc3N@C80. The measurements show an activated behavior for molecular reorientations over the full temperature range with a similar behavior for the temperature dependence of the 13C and 45Sc data. Combined with spectral data from Magic Angle Spinning (MAS) NMR, the measurements can be interpreted to mean the motion of the encapsulated Sc3N molecule is independent of that of the C80 cage, although this requires the similar temperature dependence of the 13C and 45Sc spin-lattice relaxation times to be coincidental. For the Sc3N to be fixed to the C80 cage, one must overcome the symmetry breaking effect this has on the Sc3N@C80 system since this would result in more than the observed two 13C lines.

cond-mat.mtrl-sci↗

arXiv1996

QCD: Quantum Chromodynamic Diffraction

The first measurements of the diffractive structure function $F_2^{D(3)}$ at HERA are discussed. A factorisable interpretation in which a partonic structure is assigned to the pomeron is investigated through QCD analyses in which both the quark and gluon densities are permitted to vary freely. A method of measuring the longitudinal structure function of the pomeron without changing the $ep$ centre of mass energy is presented. The possibility that the pomeron structure may receive a large contribution from gluons, relative to quarks, at high $β$ is highlighted, and the experimental signatures which may support such a structure are reviewed.

hep-ph↗