Water Ice in 2060 Chiron and its Implications for Centaurs and Kuiper Belt Objects

We report the detection of water ice in the Centaur 2060 Chiron, based on near-infrared spectra (1.0 - 2.5 micron) taken with the 3.8-meter United Kingdom Infrared Telescope (UKIRT) and the 10-meter Keck Telescope. The appearance of this ice is correlated with the recent decline in Chiron's cometary activity: the decrease in the coma cross-section allows previously hidden solid-state surface features to be seen. We predict that water ice is ubiquitous among Centaurs and Kuiper Belt objects, but its surface coverage varies from object to object, and thus determines its detectability and the occurrence of cometary activity.Comment: 18 pages, 3 figures, accepted by ApJ Letter

Population of the Scattered Kuiper Belt

We present the discovery of three new Scattered Kuiper Belt Objects (SKBOs) from a wide-field survey of the ecliptic. This continuing survey has to date covered 20.2 square degrees to a limiting red magnitude of 23.6. We combine the data from this new survey with an existing survey conducted at the University of Hawaii 2.2m telescope to constrain the number and mass of the SKBOs. The SKBOs are characterized by large eccentricities, perihelia near 35 AU, and semi-major axes > 50 AU. Using a maximum-likelihood model, we estimate the total number of SKBOs larger than 100 km in diameter to be N = 3.1 (+1.9/-1.3) x 10^4 (1 sigma) and the total mass of SKBOs to be about 0.05 Earth masses, demonstrating that the SKBOs are similar in number and mass to the Kuiper Belt inside 50 AU.Comment: 15 pages, 3 figure

The rotation and coma profiles of comet C/2004 Q2 (Machholz)

Aims. Rotation periods of cometary nuclei are scarce, though important when studying the nature and origin of these objects. Our aim is to derive a rotation period for the nucleus of comet C/2004 Q2 (Machholz). Methods. C/2004 Q2 (Machholz) was monitored using the Merope CCD camera on the Mercator telescope at La Palma, Spain, in January 2005, during its closest approach to Earth, implying a high spatial resolution (50km per pixel). One hundred seventy images were recorded in three different photometric broadband filters, two blue ones (Geneva U and B) and one red (Cousins I). Magnitudes for the comet's optocentre were derived with very small apertures to isolate the contribution of the nucleus to the bright coma, including correction for the seeing. Our CCD photometry also permitted us to study the coma profile of the inner coma in the different bands. Results. A rotation period for the nucleus of P = 9.1 +/- 0.2 h was derived. The period is on the short side compared to published periods of other comets, but still shorter periods are known. Nevertheless, comparing our results with images obtained in the narrowband CN filter, the possibility that our method sampled P/2 instead of P cannot be excluded. Coma profiles are also presented, and a terminal ejection velocity of the grains v_gr = 1609 +/- 48 m/s is found from the continuum profile in the I band.Comment: 11 pages, 9 figures, accepted by A&

Taking an Extended Embodied Perspective of Touch: Connection-Disconnection in iVR

Bringing touch into VR experiences through haptics is considered increasingly important for user engagement and fostering feelings of presence and immersion, yet few qualitative studies have explored users' iVR touch experiences. This paper takes an embodied approach–bringing attention to the tactile-kinaesthetic body–to explore users' wholistic experiences of touch in iVR, moving beyond the cutaneous and tactile elements of “feeling” to elaborate upon themes of movement and kinetics. Our findings show how both touch connections and disconnections emerged though material forms of tactility (the controller, body positioning, tactile expectations) and through “felt proximities” and the tactile-kinaesthetic experience thus shaping the sense of presence. The analysis shows three key factors that influence connection and disconnection, and how connection is re-navigated or sought at moments of experienced disconnection: a sense of control or agency; identity; and bridging between the material and virtual. This extended notion of touch deepens our understanding of its role in feelings of presence by providing insight into a range of factors related to notions of touch – both physical and virtual–that come into play in creating a sense of connection or presence (e.g., histories, expectations), and highlights the potential for iVR interaction to attend to the body beyond the hands in terms of touch

Making sense of digitally remediated touch in virtual reality experiences

Touch, often called the ‘first sense’, is fundamental to how we experience and know ourselves, others and the world. Increasingly, touch is being brought into the digital landscape. This paper explores this shifting landscape to understand the ways in which touch is re-mediated in the context of virtual reality. With attention to the sensoriality and sociality of touch, it asks what ‘counts’ as touch in VR, how is touch experienced and how is it incorporated into meaning making. We present and discuss findings from a multimodal and multisensory study of 16 participants interacting in two VR experiences to describe: the participants’ material encounters with the virtual through a focus on touch practices, expectations and norms; the ways in which participants made meaning of (and with) virtual touch through their dynamic selection and orchestration of the range of semiotic and experiential resources available; and how these virtual touch experiences translated into discourses of touch in VR to emphasize continuities and change between the past, present and futures. The paper comments on the methodological challenges of researching touch in the emergent landscape of VR and asks how multimodality might engage newly with touch, perhaps the most under-rated and neglected of modes and senses, and its digital remediation