Research-practice interaction: Building bridges, closing the gap

Previous work in the CHI community has identified and explored gaps between theory and practice in HCI research [2]. The recently formed SIGCHI Community on Research-Practice Interaction aims to help bridge the gap between research and practice, by for example supporting practitioner-­friendly dissemination of results, and serving as a conduit for feedback from practitioners to researchers. This SIG is an opportunity for interested CHI attendees to meet members of the SIGCHI RPI community, and engage in discussions on RPI issues including the CHI format, dissemination of results, and supporting practice-based research

The Bernoulli Brothers and the Brachistochrone

UMKC Honors Colleg

A Method to Constrain the Size of the Protosolar Nebula

Observations indicate that the gaseous circumstellar disks around young stars vary significantly in size, ranging from tens to thousands of AU. Models of planet formation depend critically upon the properties of these primordial disks, yet in general it is impossible to connect an existing planetary system with an observed disk. We present a method by which we can constrain the size of our own protosolar nebula using the properties of the small body reservoirs in the solar system. In standard planet formation theory, after Jupiter and Saturn formed they scattered a significant number of remnant planetesimals into highly eccentric orbits. In this paper, we show that if there had been a massive, extended protoplanetary disk at that time, then the disk would have excited Kozai oscillations in some of the scattered objects, driving them into high-inclination (i > 50 deg), low-eccentricity orbits (q > 30 AU). The dissipation of the gaseous disk would strand a subset of objects in these high-inclination orbits; orbits that are stable on Gyr time scales. To date, surveys have not detected any Kuiper Belt Objects with orbits consistent with this dynamical mechanism. Using these non-detections by the Deep Ecliptic Survey (DES) and the Palomar Distant Solar System Survey we are able to rule out an extended gaseous protoplanetary disk (R_D > 80 AU) in our solar system at the time of Jupiter's formation. Future deep all sky surveys such as the Large Synoptic Survey Telescope (LSST) will all us to further constrain the size of the protoplanetary disk.Comment: 10 pages, Accepted to A

Pluto's Light Curve in 1933-1934

We are reporting on a new accurate photographic light curve of Pluto for 1933-1934 when the heliocentric distance was 40 AU. We used 43 B-band and V-band images of Pluto on 32 plates taken on 15 nights from 19 March 1933 to 10 March 1934. Most of these plates were taken with the Mount Wilson 60" and 100" telescopes, but 7 of the plates (now at the Harvard College Observatory) were taken with the 12" and 16" Metcalf doublets at Oak Ridge. The plates were measured with an iris diaphragm photometer, which has an average one-sigma photometric error on these plates of 0.08 mag as measured by the repeatability of constant comparison stars. The modern B and V magnitudes for the comparison stars were measured with the Lowell Observatory Hall 1.1-m telescope. The magnitudes in the plate's photographic system were converted to the Johnson B- and V-system after correction with color terms, even though they are small in size. We find that the average B-band mean opposition magnitude of Pluto in 1933-1934 was 15.73 +- 0.01, and we see a roughly sinusoidal modulation on the rotational period (6.38 days) with a peak-to-peak amplitude of 0.11 +- 0.03 mag. With this, we show that Pluto darkened by 5% from 1933-1934 to 1953-1955. This darkening from 1933-1934 to 1953-1955 cannot be due to changing viewing geometry (as both epochs had identical sub-Earth latitudes), so our observations must record a real albedo change over the southern hemisphere. The later darkening trend from 1954 to the 1980s has been explained by changing viewing geometry (as more of the darker northern hemisphere comes into view). Thus, we now have strong evidence for albedo changes on the surface of Pluto, and these are most easily explained by the systematic sublimation of frosts from the sunward pole that led to a drop in the mean surface albedo.Comment: Icarus in press, 24 page

Discovery of carbon monoxide in the upper atmosphere of Pluto

Pluto's icy surface has changed colour and its atmosphere has swelled since its last closest approach to the Sun in 1989. The thin atmosphere is produced by evaporating ices, and so can also change rapidly, and in particular carbon monoxide should be present as an active thermostat. Here we report the discovery of gaseous CO via the 1.3mm wavelength J=2-1 rotational transition, and find that the line-centre signal is more than twice as bright as a tentative result obtained by Bockelee-Morvan et al. in 2000. Greater surface-ice evaporation over the last decade could explain this, or increased pressure could have caused the atmosphere to expand. The gas must be cold, with a narrow line-width consistent with temperatures around 50 K, as predicted for the very high atmosphere, and the line brightness implies that CO molecules extend up to approximately 3 Pluto radii above the surface. The upper atmosphere must have changed markedly over only a decade since the prior search, and more alterations could occur by the arrival of the New Horizons mission in 2015.Comment: 5 pages; accepted for publication in MNRAS Letter