SN 1987A's Circumstellar Envelope, II: Kinematics of the Three Rings and the Diffuse Nebula

We present several different measurements of the velocities of structures within the circumstellar envelope of SN 1987A, including the inner, equatorial ring (ER), outer rings (ORs), and the diffuse nebulosity at radii < 5 pc, based on CTIO 4m and HST data. A comparison of STIS and WFPC2 [N II]6583 loci for the rings show that the ER is expanding in radius at 10.5+-0.3 km/s, with the northern OR expanding along the line of sight at about 26 km/s, and for the southern OR, about 23 km/s. Similar results are found with CTIO 4m data. Accounting for inclination, the best fit to all data show both ORs with an expansion from the SN of 26 km/s. The ratio of the ER to OR velocities is nearly equal to the ratio of ER to OR radii, so the rings are roughly homologous, all having kinematic ages corresponding to about 20,000 yr before the SN explosion. This makes previously reported, large compositional differences between the ER and ORs difficult to understand. Additionally, a grid of longslit 4m/echelle spectra centered on the SN shows two velocity components over a region roughly coextensive with the outer circumstellar envelope extending about 5 pc (20 arcsec) from the SN. One component is blueshifted and the other redshifted from the SN centroid by about 10 km/s each. These features may represent a bipolar flow expanding from the SN, in which the ORs are propelled 10-15 km/s faster than that of the surrounding envelope into which they propogate. The kinematic timescale for the entire nebula is at least about 350,000 yr. The kinematics of these various structures constrain possible models for the evolution of the progenitor and its formation of a mass loss nebula.Comment: 25 pages AASTeX text plus 12 figures. ApJ, in pres

The Three-Dimensional Circumstellar Environment of SN 1987A

We present the detailed construction and analysis of the most complete map to date of the circumstellar environment around SN 1987A, using ground and space-based imaging from the past 16 years. PSF-matched difference-imaging analyses of data from 1988 through 1997 reveal material between 1 and 28 ly from the SN. Careful analyses allows the reconstruction of the probable circumstellar environment, revealing a richly-structured bipolar nebula. An outer, double-lobed ``Peanut,'' which is believed to be the contact discontinuity between red supergiant and main sequence winds, is a prolate shell extending 28 ly along the poles and 11 ly near the equator. Napoleon's Hat, previously believed to be an independent structure, is the waist of this Peanut, which is pinched to a radius of 6 ly. Interior to this is a cylindrical hourglass, 1 ly in radius and 4 ly long, which connects to the Peanut by a thick equatorial disk. The nebulae are inclined 41\degr south and 8\degr east of the line of sight, slightly elliptical in cross section, and marginally offset west of the SN. From the hourglass to the large, bipolar lobes, echo fluxes suggest that the gas density drops from 1--3 cm^{-3} to >0.03 cm^{-3}, while the maximum dust-grain size increases from ~0.2 micron to 2 micron, and the Si:C dust ratio decreases. The nebulae have a total mass of ~1.7 Msun. The geometry of the three rings is studied, suggesting the northern and southern rings are located 1.3 and 1.0 ly from the SN, while the equatorial ring is elliptical (b/a < 0.98), and spatially offset in the same direction as the hourglass.Comment: Accepted for publication in the ApJ Supplements. 38 pages in apjemulate format, with 52 figure

Dynamics of charge-displacement channeling in intense laser-plasma interactions

The dynamics of transient electric fields generated by the interaction of high intensity laser pulses with underdense plasmas has been studied experimentally with the proton projection imaging technique. The formation of a charged channel, the propagation of its front edge and the late electric field evolution have been characterised with high temporal and spatial resolution. Particle-in-cell simulations and an electrostatic, ponderomotive model reproduce the experimental features and trace them back to the ponderomotive expulsion of electrons and the subsequent ion acceleration.Comment: 5 figures, accepted for publication in New Journal of Physic

RF spectroscopy in a resonant RF-dressed trap

We study the spectroscopy of atoms dressed by a resonant radiofrequency (RF) field inside an inhomogeneous magnetic field and confined in the resulting adiabatic potential. The spectroscopic probe is a second, weak, RF field. The observed line shape is related to the temperature of the trapped cloud. We demonstrate evaporative cooling of the RF-dressed atoms by sweeping the frequency of the second RF field around the Rabi frequency of the dressing field.Comment: 7 figures, 8 pages; to appear in J. Phys.

Rolling friction of a viscous sphere on a hard plane

A first-principle continuum-mechanics expression for the rolling friction coefficient is obtained for the rolling motion of a viscoelastic sphere on a hard plane. It relates the friction coefficient to the viscous and elastic constants of the sphere material. The relation obtained refers to the case when the deformation of the sphere $\xi$ is small, the velocity of the sphere $V$ is much less than the speed of sound in the material and when the characteristic time $\xi/V$ is much larger than the dissipative relaxation times of the viscoelastic material. To our knowledge this is the first ``first-principle'' expression of the rolling friction coefficient which does not contain empirical parameters.Comment: 6 pages, 2 figure

3-D Photoionization Structure and Distances of Planetary Nebulae II. Menzel 1

We present the results of a spatio-kinematic study of the planetary nebula Menzel 1 using spectro-photometric mapping and a 3-D photoionization code. We create several 2-D emission line images from our long-slit spectra, and use these to derive the line fluxes for 15 lines, the Halpha/Hbeta extinction map, and the [SII] line ratio density map of the nebula. We use our photoionization code constrained by these data to derive the three-dimensional nebular structure and ionizing star parameters of Menzel 1 by simultaneously fitting the integrated line intensities, the density map, and the observed morphologies in several lines, as well as the velocity structure. Using theoretical evolutionary tracks of intermediate and low mass stars, we derive a mass for the central star of 0.63+-0.05 Msolar. We also derive a distance of 1050+_150 pc to Menzel 1.Comment: To be published in ApJ of 10th February 2005. 12 figure

Quasi-2D Confinement of a BEC in a Combined Optical and Magnetic Potential

We have added an optical potential to a conventional Time-averaged Orbiting Potential (TOP) trap to create a highly anisotropic hybrid trap for ultracold atoms. Axial confinement is provided by the optical potential; the maximum frequency currently obtainable in this direction is 2.2 kHz for rubidium. The radial confinement is independently controlled by the magnetic trap and can be a factor of 700 times smaller than in the axial direction. This large anisotropy is more than sufficient to confine condensates with ~10^5 atoms in a Quasi-2D (Q2D) regime, and we have verified this by measuring a change in the free expansion of the condensate; our results agree with a variational model.Comment: 11 pages, 10 figur

A New View of the Circumstellar Environment of SN 1987A

We summarize the analysis of a uniform set of both previously-known and newly-discovered scattered-light echoes, detected within 30" of SN 1987A in ten years of optical imaging, and with which we have constructed the most complete three-dimensional model of the progenitor's circumstellar environment. Surrounding the SN is a richly-structured bipolar nebula. An outer, double-lobed ``peanut,'' which we believe is the contact discontinuity between the red supergiant and main sequence winds, is a prolate shell extending 28 ly along the poles and 11 ly near the equator. Napoleon's Hat, previously believed to be an independent structure, is the waist of this peanut, which is pinched to a radius of 6 ly. Interior, the innermost circumstellar material lies along a cylindrical hourglass, 1 ly in radius and 4 ly long, which connects to the peanut by a thick equatorial disk. The nebulae are inclined 41o south and 8o east of the line of sight, slightly elliptical in cross section, and marginally offset west of the SN. The 3-D geometry of the three circumstellar rings is studied, suggesting the equatorial ring is elliptical (b/a<0.98), and spatially offset in the same direction as the hourglass. Dust-scattering models suggest that between the hourglass and bipolar lobes: the gas density drops from 1--3 cm^{-3} to >0.03 cm^{-3}; the maximum dust-grain size increases from ~0.2 micron to 2 micron; and the Si:C dust ratio decreases. The nebulae have a total mass of ~1.7 Msun, yielding a red-supergiant mass loss around 5*10^{-6} Msun yr^{-1}.Comment: Accepted for publication in ApJ 2/14/05. 16 pages in emualteapj forma

Cognitive control and capacity for prospective memory in complex dynamic environments

no abstract available ye