Detection of arcs in Saturn's F ring during the 1995 Sun ring-plane crossing

Observations of the November 1995 Sun crossing of the Saturn's ring-plane made with the 3.6m CFH telescope, using the UHAO adaptive optics system, are presented here. We report the detection of four arcs located in the vicinity of the F ring. They can be seen one day later in HST images. The combination of both data sets gives accurate determinations of their orbits. Semi-major axes range from 140020 km to 140080 km, with a mean of 140060 +- 60 km. This is about 150 km smaller than previous estimates of the F ring radius from Voyager 1 and 2 data, but close to the orbit of another arc observed at the same epoch in HST images.Comment: 8 pages, 3 figures, 1 table, To appear in A&A, for comments : [email protected]

Nurturing Adolescent Lifelong Discipleship: Implementing a Hermeneutic of “Adoption” at St. Paul United Methodist Church

The purpose of this study is to provide a strategy for youth ministry at St. Paul United Methodist Church, establishing “adoption” as a baseline hermeneutic, making it more likely that adolescents grow into lifelong disciples of Jesus Christ. Although no research exists which proves concretely that a particular youth ministry approach can guarantee an adolescent will embrace discipleship of Jesus Christ for a lifetime (nor is such research likely possible), nevertheless, a church can position itself to make such a trajectory more likely. This project asserts that a hermeneutic of adoption is the polar opposite of, and the Church’s correct response to, systemic abandonment of contemporary American adolescents. The Church can assist adolescents in their journey through individuation—identity, autonomy, and belonging or reconnection—in a more holistic fashion than other institutions through redemptive embrace of both their psychosocial and spiritual needs. This project examines the psychosocial and spiritual development of adolescents. The study reflects on the key theological issues of discipling adolescents for a journey of lifelong discipleship with an emphasis on God’s grace and power to transform the whole person from within. A theology of “adoption” is presented as the Church’s proper response to the “current” of systemic abandonment of youth prevalent in contemporary culture. Biblical, historical, and ecclesiological examples and applications supporting a hermeneutic of adoption are presented. Finally, a strategy for needed change in order to implement a hermeneutical of adoption for youth ministry at St. Paul United Methodist Church is posed. The intended outcome is that St. Paul United Methodist Church will be a more interconnected body of Christ, living a hermeneutic of adoption with respect to the Church’s relationship between adolescents and their families, making it more likely that St. Paul’s “sons and daughters” will become lifelong disciples of Jesus the Christ. Theological Mentor: Chap Clark, Ph

George Pepperdine College Lectures

https://digitalcommons.acu.edu/crs_books/1349/thumbnail.jp

A Survey for Outer Satellites of Mars: Limits to Completeness

We surveyed the Hill sphere of Mars for irregular satellites. Our search covered nearly the entire Hill Sphere, but scattered light from Mars excluded the inner few arcminutes where the satellites Phobos and Deimos reside. No new satellites were found to an apparent limiting red magnitude of 23.5, which corresponds to radii of about 0.09 km using an albedo of 0.07.Comment: 5 figures (1 color), 2 Tables, to appear in AJ Nov. 200

Experimental observation of extreme multistability in an electronic system of two coupled R\"{o}ssler oscillators

We report the first experimental observation of extreme multistability in a controlled laboratory investigation. Extreme multistability arises when infinitely many attractors coexist for the same set of system parameters. The behavior was predicted earlier on theoretical grounds, supported by numerical studies of models of two coupled identical or nearly identical systems. We construct and couple two analog circuits based on a modified coupled R\"{o}ssler system and demonstrate the occurrence of extreme multistability through a controlled switching to different attractor states purely through a change in initial conditions for a fixed set of system parameters. Numerical studies of the coupled model equations are in agreement with our experimental findings.Comment: to be published in Phys. Rev.

Cupid Is Not Doomed Yet: On the Stability of the Inner Moons of Uranus

Some of the small inner moons of Uranus have very closely-spaced orbits. Multiple numerical studies have found that the moons Cressida and Desdemona, within the Portia sub-group, are likely to collide in less than 100 Myr. The subsequent discovery of three new moons (Cupid, Perdita, and Mab) made the system even more crowded. In particular, it has been suggested that the Belinda group (Cupid, Belinda, and Perdita) will become unstable in as little as 10$^5$ years. Here we revisit the issue of the stability of the inner moons of Uranus using updated orbital elements and considering tidal dissipation. We find that the Belinda group can be stable on $10^8$-year timescales due to an orbital resonance between Belinda and Perdita. We find that tidal evolution cannot form the Belinda-Perdita resonance, but convergent migration could contribute to the long-term instability of the Portia group. We propose that Belinda captured Perdita into the resonance during the last episode of disruption and re-accretion among the inner moons, possibly hundreds of Myr ago.Comment: 11 pages, 4 figures, accepted for A