Size determination of the Centaur Chariklo from millimeter-wavelength bolometer observations

Using the Max-Planck Millimeter Bolometer Array (MAMBO) at the IRAM 30m telescope we detected emission at 250 GHz from the Centaur Chariklo (1997 CU26). The observed continuum flux density implies a photometric diameter of 273 km. The resulting geometric albedo is 0.055, somewhat higher than expected from a comparison with most of the other few Centaurs and cometary nuclei for which such data are available.Comment: 4 pages, 1 Postscript figure, to appear in Astronomy & Astrophysic

Digitally-mediated parent–baby touch and the formation of subjectivities

This article examines how the use of emergent smart baby monitors re-mediates parent–baby touch, notions of connection, parental sensing and the interpretation of babies’ bodies, and contributes to the formation of subjectivities. Domestic baby monitors are a mid 20th-century phenomenon which normalizes parental anxieties. While baby monitoring is not new, the ‘next generation’ of wearable bio-sensing baby monitors offers a different relationship to the body via the physiological tracking of babies, and the sending of information or alerts to parents’ via connected mobile apps. These devices have been associated with creating unnecessary parental anxiety and the digital ‘replacement’ of parental touch, although little research exists on their use in the context of parent–infant interaction or touch. The authors present a qualitative case study of one such technology, Owlet, to explore how parents experienced, understood and negotiated the discourses of parent–infant touch that circulate around and through Owlet, with particular attention to the relationship between visual and tactile resources. The study focuses on both its multimodal design and take-up by parents through analysis of interviews with the Owlet designer, Owlet as a product, focus groups with parents and families’ home experiences of Owlet. Data is analysed through a tri-part lens, which first combines multimodal social semiotic and sensory ethnographic approaches, and then the analytical concept of governmentality. The findings are discussed in relation to four analytical themes: (1) creating a desire for digitally mediated touch; (2) spatiality of digitally mediated connection; (3) formulating the ‘right kind’ of touch; and (4) reconfiguring ‘knowing touch’. The authors discuss multimodal discourses pertinent to the shaping of parent–baby touch practices including: rationality and efficiency; individualism, autonomy and freedom; and self-improvement and empowerment. They conclude that the discourses that coalesce around Owlet contribute to the reconfiguration of parent–baby touch and the formation of neoliberal subjectivities

P/2010 A2 LINEAR II: dynamical dust modelling

P/2010 A2 is an object on an asteroidal orbit that was observed to have an extended tail or debris trail in January 2010. In this work, we fit the outburst of P/2010 A2 with a conical burst model, and verify previous suspicions that this was a one--time collisional event rather than an sustained cometary outburst, implying that P/2010 A2 is not a new Main Belt Comet driven by ice sublimation. We find that the best--fit cone opening angle is about 40 to 50 degrees, in agreement with numerical and laboratory simulations of cratering events. Mapping debris orbits to sky positions suggests that the distinctive arc features in the debris correspond to the same debris cone inferred from the extended dust. From the velocity of the debris, and from the presence of a velocity maximum at around 15 cm/s, we infer that the surface of A2 probably has a very low strength (<1 kPa), comparable to lunar regolith.Comment: 14 pages, 25 figures; accepted by Astronomy and Astrophysic

The re-mediating effects of bio-sensing in the context of parental touch practices

This article investigates the remediating effect of bio-sensing technology on touch practices in the context of parent-infant interaction. We examine how the entry of a biosensing technology into the social, sensory and technological ecology of family homes interacts with the ways in which parents and babies know each other and communicate through touch. The paper centres on an exploratory case study of the Owlet Smart Sock (OSS), a bio-sensing baby monitoring device. We bring the social critical and experiential lenses of multimodality and sensory ethnography to studying the OSS as a socio-technological probe across a range of research encounters, including focus groups, home visits and video re-enactments with parents. In doing so, we provide an account of the ways in which the technology affects how babies and parents’ bodies are (re)imagined, assessed, controlled, interrelated, experienced, and cared for and move beyond generic social debate around the quantified-objectified baby and fears of touch deprivation in contemporary digital culture

The nucleus of 103P/Hartley 2, target of the EPOXI mission

103P/Hartley 2 was selected as the target comet for the Deep Impact extended mission, EPOXI, in October 2007. There have been no direct optical observations of the nucleus of this comet, as it has always been highly active when previously observed. We aimed to recover the comet near to aphelion, to a) confirm that it had not broken up and was in the predicted position, b) to provide astrometry and brightness information for mission planning, and c) to continue the characterisation of the nucleus. We observed the comet at heliocentric distances between 5.7 and 5.5 AU, using FORS2 at the VLT, at 4 epochs between May and July 2008. We performed VRI photometry on deep stacked images to look for activity and measure the absolute magnitude and therefore estimate the size of the nucleus. We recovered the comet near the expected position, with a magnitude of m_R = 23.74 \pm 0.06 at the first epoch. The comet had no visible coma, although comparison of the profile with a stellar one showed that there was faint activity, or possibly a contribution to the flux from the dust trail from previous activity. This activity appears to fade at further epochs, implying that this is a continuation of activity past aphelion from the previous apparition rather than an early start to activity before the next perihelion. Our data imply a nucleus radius of \le 1 km for an assumed 4% albedo; we estimate a ~6% albedo. We measure a colour of (V-R) = 0. 26 \pm 0.09.Comment: 5 pages, 4 figures, accepted for publication in A&

Indonesia's contested domains: deforestation, rehabilitation and conservation-with-development in Central Kalimantan's tropical peatlands

Tropical peat swamp forests (TPSF) in Indonesia have long faced competition between industrial demand for timber, the subsistence require- ments of local communities and, more recently, global concern about the need to conserve tropical peat carbon stores, ecosystem services and biodiversity. This paper uses concepts of ecological distribution and environmental justice to investigate how tensions between conservation and livelihood goals have played out on the ground and examine who has gained and lost out from recent TPSF exploitation, conservation and rehabilitation initiatives. A central focus is how peat-based communities in Central Kalimantan have adapted their livelihoods to changing peatland conditions and management policies with particular emphasis on the livelihood impacts of conservation-with-development initiatives in the area. It is argued that despite recent emphasis on ‘win-win’ initiatives, the costs of environmental conservation are rarely distributed in proportion to their benefit

Photometric observations of distant active comets

We present CCD VR_C observations of 6 distant comets located at heliocentric distances of 3.4--7.2 AU. Time-series data were obtained on three nights in July, 2000 covering 16 hours. Each comet was observed after the perihelion, when a lower activity was expected. Contrary to expectation, we found well-defined circular comae and extended tails visible out to a few (3-5) arcminutes. We detected a quasi-cyclic light variation of C/1999 J2, while C/1999 N4 showed some hints of a more complex variation. C/2000 K1 was constant to +/-0.04 mag during the observing run. The standard V and R_C data were used to estimate nuclear diameters, while the colour indices implied a slighly reddish (V-R=0.68, C/2000 K1), a neutral (V-R=0.47, C/1999 N4) and a slightly bluish (V-R=0.25, C/1999 J2) coma. Simple fits of the surface brightness distributions are also presented enabling order of magnitude estimates of nuclear radii. Beside the time-series observations, further single-shot observations of three faint comets are briefly described.Comment: 8 pages, 5 figures, accepted for publication in A&

Visual and infrared observations of the distant Comets P/Stephan-Oterma (1980g), Panther (1980u), and Bowell (1980b)

Broadband observations of comets P/Stephan-Oterma (1980g), Bowell (1980b), and Panther (1980u) in the visual [0.5≾ λ(µm)≾0.9] and infrared [1.2≾λ(µm)≾20] wavelength regions are reported together with measurements in the 1.5-2.4-µm wavelength range having 5% spectral resolution. The visual data indicate the existence of solid grains in extended halos around the nuclei of the three comets. The visual photometric profiles of comets P/Stephan- Oterma and Panther are interpreted as evidence that grains around Panther and those close to the nucleus of P/Stephan-Oterma are sublimating. Broadband near-infrared and thermal infrared measurements of comet Panther suggest the presence of 2—4-µm radius particles in the coma. The particles within a 5.8X 10^6-m diameter region centered on the comet have a total cross section of 10^8 m^2 and a near-infrared geometric albedo of about 14%. Comet Bowell presents a total cross section of 3 X 10^8 m^2 within a 1.2 X 10^7-m region centered on the comet and its coma grains also have an albedo of 14%. The near-infrared spectrum of P/Stephan-Oterma is a featureless solar-reflection continuum. The near-infrared spectra of Bowell and Panther exhibit features which are similar in the two comets. The spectral features are not due to H_2O, CH_4, or CO_2 ices nor to emissions from gases released from the nuclei nor to reflection from mineral grains of known composition in the comae. The spectrum of solid ammonia provides the best match to the near infrared; it is nevertheless significantly different from the comet spectra. The synthesis of the visual data with the infrared data is attempted in terms of a model involving a mantle of volatile material on the nuclei of Bowell and Panther, but not on P/Stephan-Oterma. The composition of the mantle cannot be exactly specified from the existing data but a complex molecule incorporating the N-H bond may be present

The Circumstellar Disk Mass Distribution in the Orion Trapezium Cluster

We present the results of a submillimeter interferometric survey of circumstellar disks in the Trapezium Cluster of Orion. We observed the 880 micron continuum emission from 55 disks using the Submillimeter Array, and detected 28 disks above 3sigma significance with fluxes between 6-70 mJy and rms noise between 0.7-5.3 mJy. Dust masses and upper limits are derived from the submillimeter excess above free-free emission extrapolated from longer wavelength observations. Above our completeness limit of 0.0084 solar masses, the disk mass distribution is similar to that of Class II disks in Taurus-Auriga and rho Ophiuchus but is truncated at 0.04 solar masses. We show that the disk mass and radius distributions are consistent with the formation of the Trapezium Cluster disks ~1 Myr ago and subsequent photoevaporation by the ultraviolet radiation field from Theta-1 Ori C. The fraction of disks which contain a minimum mass solar nebula within 60 AU radius is estimated to be 11-13% in both Taurus and the Trapezium Cluster, which suggests the potential for forming Solar Systems is not compromised in this massive star forming region.Comment: Accepted for publication in ApJL (2009 Feb 3

The Kuiper Belt and Other Debris Disks

We discuss the current knowledge of the Solar system, focusing on bodies in the outer regions, on the information they provide concerning Solar system formation, and on the possible relationships that may exist between our system and the debris disks of other stars. Beyond the domains of the Terrestrial and giant planets, the comets in the Kuiper belt and the Oort cloud preserve some of our most pristine materials. The Kuiper belt, in particular, is a collisional dust source and a scientific bridge to the dusty "debris disks" observed around many nearby main-sequence stars. Study of the Solar system provides a level of detail that we cannot discern in the distant disks while observations of the disks may help to set the Solar system in proper context.Comment: 50 pages, 25 Figures. To appear in conference proceedings book "Astrophysics in the Next Decade