OER Evidence Report 2013-2014

The Open Educational Resources Research Hub (OER Research Hub) provides a focus for research, designed to give answers to the overall question ‘What is the impact of OER on learning and teaching practices?’ and identify the particular influence of openness. We do this by working in collaboration with projects across four education sectors (K12, college, higher education and informal) extending a network of research with shared methods and shared results. The project combines: – Targeted research collaboration with high profile OER projects – A programme of international fellowship – Global networking and expertise in OER implementation and evaluation – A hub for research data and excellence in practice This report is an interim review of evidence recorded against the key hypotheses that focus the research of the OER Research Hub project

First Astronomical Application of a Cryogenic TES Spectrophotometer

We report on the first astronomical observations with a photon counting pixel detector that provides arrival time- (delta t = 100ns) and energy- (delta E_gamma < 0.15eV) resolved measurements from the near IR through the near UV. Our test observations were performed by coupling this Transition Edge Sensor (TES) device to a 0.6m telescope; we have obtained the first simultaneous optical near-IR phase-resolved spectra of the Crab pulsar. A varying infrared turnover gives evidence of self-absorption in the pulsar plasma. The potential of such detectors in imaging arrays from a space platform are briefly described.Comment: 4 pages, 5 figure

A Concept for an STJ-based Spectrograph

We describe a multi-order spectrograph concept suitable for 8m-class telescopes, using the intrinsic spectral resolution of Superconducting Tunneling Junction detectors to sort the spectral orders. The spectrograph works at low orders, 1-5 or 1-6, and provides spectral coverage with a resolving power of R~8000 from the atmospheric cutoff at 320 nm to the long wavelength end of the infrared H or K band at 1800 nm or 2400 nm. We calculate that the spectrograph would provide substantial throughput and wavelength coverage, together with high time resolution and sufficient dynamic range. The concept uses currently available technology, or technologies with short development horizons, restricting the spatial sampling to two linear arrays; however an upgrade path to provide more spatial sampling is identified. All of the other challenging aspects of the concept - the cryogenics, thermal baffling and magnetic field biasing - are identified as being feasible.Comment: Accepted in Monthly Notices of the Royal Astronomical Society, 12 pages with 10 figure

Habitability of known exoplanetary systems based on measured stellar properties

At present, because of observational selection effects, we know of no exoplanetary systems with any planetary masses close to that of the Earth. We have therefore used computer models to see whether such planets could be dynamically stable in the presence of the more massive planets known to be present, and in particular whether planets with roughly an Earth mass could remain confined to the classical habitable zone (HZ) for long enough for life to have emerged. Measured stellar properties have been used to determine for each system the present location of the HZ. We have also determined the critical distances from the orbit of each giant planet within which an Earth-mass planet would suffer large orbital changes. We then evaluated the present habitability of each and every exoplanetary system by examining the penetration of these critical distances into the HZ. The critical distances can be obtained by extensive computer modelling of an exoplanetary system. This is far too time consuming to apply to all of the 150 or so systems already known, and to keep up with the latest discoveries. Therefore, in earlier work we studied a few systems in great detail, and developed a speedier means of obtaining the critical distances. We summarize this comparatively quick method here. We can then evaluate comparatively quickly the present habitability of each exoplanetary system by examining the penetration of the critical distance(s) into the HZ. The results are encouraging for astrobiology.Comment: Accepted for publication by The Astrophysical Journal. A few revisions have been made following suggestions by the refere

First results of a cryogenic optical photon counting imaging spectrometer using a DROID array

Context. In this paper we present the first system test in which we demonstrate the concept of using an array of Distributed Read Out Imaging Devices (DROIDs) for optical photon detection. Aims. After the successful S-Cam 3 detector the next step in the development of a cryogenic optical photon counting imaging spectrometer under the S-Cam project is to increase the field of view using DROIDs. With this modification the field of view of the camera has been increased by a factor of 5 in area, while keeping the number of readout channels the same. Methods. The test has been performed using the flexible S-Cam 3 system and exchanging the 10x12 Superconducting Tunnel Junction array for a 3x20 DROID array. The extra data reduction needed with DROIDs is performed offline. Results. We show that, although the responsivity (number of tunnelled quasiparticles per unit of absorbed photon energy, e- /eV) of the current array is too low for direct astronomical applications, the imaging quality is already good enough for pattern detection, and will improve further with increasing responsivity. Conclusions. The obtained knowledge can be used to optimise the system for the use of DROIDs.Comment: 7 pages, 9 figures, accepted for publicaiton in A&

Microstructure of the Local Interstellar Cloud and the Identification of the Hyades Cloud

We analyze high-resolution UV spectra of the Mg II h and k lines for 18 members of the Hyades Cluster to study inhomogeneity along these proximate lines of sight. The observations were taken by the Space Telescope Imaging Spectrograph (STIS) instrument on board the Hubble Space Telescope (HST). Three distinct velocity components are observed. All 18 lines of sight show absorption by the Local Interstellar Cloud (LIC), ten stars show absorption by an additional cloud, which we name the Hyades Cloud, and one star exhibits a third absorption component. The LIC absorption is observed at a lower radial velocity than predicted by the LIC velocity vector derived by Lallement & Bertin (1992) and Lallement et al. (1995), (v(predicted LIC) - v(observed LIC) = 2.9 +/- 0.7 km/s), which may indicate a compression or deceleration at the leading edge of the LIC. We propose an extention of the Hyades Cloud boundary based on previous HST observations of other stars in the general vicinity of the Hyades, as well as ground-based Ca II observations. We present our fits of the interstellar parameters for each absorption component. The availability of 18 similar lines of sight provides an excellent opportunity to study the inhomogeneity of the warm, partially ionized local interstellar medium (LISM). We find that these structures are roughly homogeneous. The measured Mg II column densities do not vary by more than a factor of 2 for angular separations of < 8 degrees, which at the outer edge of the LIC correspond to physical separations of < 0.6 pc.Comment: 35 pages, 11 figures, AASTEX v.5.0 plus EPSF extensions in mkfig.sty; accepted by Ap

Testing Planet Formation Models with Gaia μ\muas Astrometry

In this paper, we first summarize the results of a large-scale double-blind tests campaign carried out for the realistic estimation of the Gaia potential in detecting and measuring planetary systems. Then, we put the identified capabilities in context by highlighting the unique contribution that the Gaia exoplanet discoveries will be able to bring to the science of extrasolar planets during the next decade.Comment: 4 pages, 1 figure. To appear in the proceedings of "IAU Symposium 248 - A Giant Step: from Milli- to Micro-arcsecond Astrometry", held in Shanghai, China, 15-19 Oct. 200

The visual orbits of the spectroscopic binaries HD 6118 and HD 27483 from the Palomar Testbed Interferometer

We present optical interferometric observations of two double-lined spectroscopic binaries, HD 6118 and HD 27483, taken with the Palomar Testbed Interferometer (PTI) in the K band. HD 6118 is one of the most eccentric spectroscopic binaries and HD 27483 a spectroscopic binary in the Hyades open cluster. The data collected with PTI in 2001-2002 allow us to determine astrometric orbits and when combined with the radial velocity measurements derive all physical parameters of the systems. The masses of the components are 2.65 +/- 0.27 M_Sun and 2.36 +/- 0.24 M_Sun for HD 6118 and 1.38 +/- 0.13 M_Sun and 1.39 +/- 0.13 M_Sun for HD 27483. The apparent semi-major axis of HD 27483 is only 1.2 mas making it the closest binary successfully observed with an optical interferometer.Comment: submitted to Ap

Planetary Companions Around Two Solar Type Stars: HD 195019 and HD 217107

We have enlarged the sample of stars in the planet search at Lick Observatory. Doppler measurements of 82 new stars observed at Lick Observatory, with additional velocities from Keck Observatory, have revealed two new planet candidates. The G3V/IV star, HD 195019, exhibits Keplerian velocity variations with a period of 18.27 d, an orbital eccentricity of 0.03 +/- 0.03, and M sin i = 3.51 M_Jup. Based on a measurement of Ca II H&K emission, this star is chromospherically inactive. We estimate the metallicity of HD 195019 to be approximately solar from ubvy photometry. The second planet candidate was detected around HD 217107, a G7V star. This star exhibits a 7.12 d Keplerian period with eccentricity 0.14 +/- 0.05 and M sin i = 1.27 M_Jup. HD 217107 is also chromospherically inactive. The photometric metallicity is found to be [Fe/H] = +0.29 +/- 0.1 dex. Given the relatively short orbital period, the absence of tidal spin-up of HD 217107 provides a theoretical constraint on the upper limit of the companion mass of < 11 M_Jup.Comment: 15 pages, plus 6 figures. To appear in Jan 1999 PAS

A Ring of Warm Dust in the HD 32297 Debris Disk

We report the detection of a ring of warm dust in the edge-on disk surrounding HD 32297 with the Gemini-N/MICHELLE mid-infrared imager. Our N'-band image shows elongated structure consistent with the orientation of the scattered-light disk. The Fnu(11.2 um) = 49.9+/-2.1 mJy flux is significantly above the 28.2+/-0.6 mJy photosphere. Subtraction of the stellar point spread function reveals a bilobed structure with peaks 0.5"-0.6" from the star. An analysis of the stellar component of the SED suggests a spectral type later than A0, in contrast to commonly cited literature values. We fit three-dimensional, single-size grain models of an optically thin dust ring to our image and the SED using a Markov chain Monte Carlo algorithm in a Bayesian framework. The best-fit effective grain sizes are submicron, suggesting the same dust population is responsible for the bulk of the scattered light. The inner boundary of the warm dust is located 0.5"-0.7" (~65 AU) from the star, which is approximately cospatial with the outer boundary of the scattered-light asymmetry inward of 0.5". The addition of a separate component of larger, cooler grains that provide a portion of the 60 um flux improves both the fidelity of the model fit and consistency with the slopes of the scattered-light brightness profiles. Previous indirect estimates of the stellar age (~30 Myr) indicate the dust is composed of debris. The peak vertical optical depths in our models (~0.3-1 x 1e-2) imply that grain-grain collisions likely play a significant role in dust dynamics and evolution. Submicron grains can survive radiation pressure blow-out if they are icy and porous. Similarly, the inferred warm temperatures (130-200 K) suggest that ice sublimation may play a role in truncating the inner disk.Comment: ApJ accepted, 8 pages, 4 figure