First polarimetric observations and modeling of the FeH F^4 Delta-X^4 Delta system

Lines of diatomic molecules are more temperature and pressure sensitive than atomic lines, which makes them ideal tools for studying cool stellar atmospheres an internal structure of sunspots and starspots. The FeH F^4 Delta-X^4 Delta system represents such an example that exhibits in addition a large magnetic field sensitivity. The current theoretical descriptions of these transitions including the molecular constants involved are only based on intensity measurements because polarimetric observations have not been available so far, which limits their diagnostic value. We present for the first time spectropolarimetric observations of the FeH F^4 Delta-X^4 Delta system measured in sunspots to investigate their diagnostic capabilities for probing solar and stellar magnetic fields. We investigate whether the current theoretical model of FeH can reproduce the observed Stokes profiles including their magnetic properties. The polarimetric observations are compared with synthetic Stokes profiles modeled with radiative transfer calculations. This allows us to infer the temperature and the magnetic field strength of the observed sunspots. We find that the current theory successfully reproduces the magnetic properties of a large number of lines in the FeH F^4 Delta-X^4 Delta system. In a few cases the observations indicate a larger Zeeman splitting than predicted by the theory. There, our observations have provided additional constraints, which allowed us to determine empirical molecular constants. The FeH F^4 Delta-X^4 Delta system is found to be a very sensitive magnetic diagnostic tool. Polarimetric data of these lines provide us with more direct information to study the coolest parts of astrophysical objects.Comment: 4 pages, 3 figure

Surface differential rotation and photospheric magnetic field of the young solar-type star HD 171488 (V889 Her)

We present spectropolarimetric observations of the young, single early G-dwarf HD 171488. These observations were obtained over a five-night period in 2004 September at the 3.9-m Anglo-Australian Telescope using the SEMPOL spectropolarimeter visitor instrument. Using the technique of least-squares deconvolution to increase the signal-to-noise ratio of the data, we have applied Zeeman Doppler imaging to reconstruct brightness and magnetic surface topologies of the star. The brightness image shows a large polar spot with weaker low- to mid-latitude features, confirming an earlier Doppler imaging observation. The reconstruction of the surface magnetic field shows regions of radial field at all latitudes (except near the pole) and regions of azimuthal field predominantly at high latitudes (60°-70°), with the azimuthal field almost forming a ring around the polar regions. We have incorporated a solar-like differential rotation law into the imaging process to determine the surface differential rotation of cool spots on HD 171488. This gives an equatorial rotation rate of 1.313 ± 0.004 d and a surface shear of dΩ= 0.402 ± 0.044 rad-d−1. This means that the equator of HD 171488 laps the poles every ∼16 ± 2 d and that HD 171488 has a photospheric shear approximately seven times the solar value. This is the largest measurement of surface differential rotation yet obtained using the Doppler imaging method and is over twice the value of previously observed early G-dwarf

Critical evaluation of magnetic field detections reported for pulsating B-type stars in the light of ESPaDOnS, Narval and reanalyzed FORS1/2 observations

Recent spectropolarimetric studies of 7 SPB and $\beta$ Cep stars have suggested that photospheric magnetic fields are more common in B-type pulsators than in the general population of B stars, suggesting a significant connection between magnetic and pulsational phenomena. We present an analysis of new and previously published spectropolarimetric observations of these stars. New Stokes $V$ observations obtained with the high-resolution ESPaDOnS and Narval instruments confirm the presence of a magnetic field in one of the stars ($\epsilon$ Lup), but find no evidence of magnetism in 5 others. A re-analysis of the published longitudinal field measurements obtained with the low-resolution FORS1/2 spectropolarimeters finds that the measurements of all stars show more scatter from zero than can be attributed to Gaussian noise, suggesting the presence of a signal and/or systematic under-estimation of error bars. Re-reduction and re-measurement of the FORS1/2 spectra from the ESO archive demonstrates that small changes in reduction procedure lead to substantial changes in the inferred longitudinal field, and substantially reduces the number of field detections at the 3$\sigma$ level. Furthermore, we find that the published periods are not unique solutions to the time series of either the original or the revised FORS1/2 data. We conclude that the reported field detections, proposed periods and field geometry models for $\alpha$ Pyx, 15 CMa, 33 Eri and V1449 Aql are artefacts of the data analysis and reduction procedures, and that magnetic fields at the reported strength are no more common in SPB/$\beta$ Cep stars than in the general population of B stars.Comment: 10 pages, 5 figures, accepted for publication in ApJ, 2012, typo correcte

High Resolution Spectroscopy and Spectropolarimetry of some late F-/early G-type sun-like stars as targets for Zeeman Doppler imaging

High resolution spectroscopy and spectropolarimetry have been undertaken at the Anglo-Australian Telescope in order to identify suitable targets for magnetic studies of young sun-like stars, for the proxy study of early solar evolution. This study involved the investigation of some variable late F-/early G-type sun-like stars originally identified by the Hipparcos mission. Of the 38 stars observed for this study, HIP 31021, HIP 64732, HIP 73780 were found to be spectroscopic binary stars while HIP 19072, HIP 67651 and HIP 75636 are also likely to be binaries while HIP 33111 could even be a triple system. Magnetic fields were detected on a number of the survey stars: HIP 21632, HIP 43720, HIP 48770, HIP 62517, HIP 71933, HIP 77144, HIP 89829, HIP 90899 and HIP 105388, making these stars good candidates for follow-up Zeeman Doppler imaging studies.Comment: 16 pages, 16 figures, 4 tables Accepted for publication in PAS

Magnetic fields and differential rotation on the pre-main sequence I: The early-G star HD 141943 - brightness and magnetic topologies

Spectroscopic and spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at four observing epochs (in 2006, 2007, 2009 and 2010). The observations were undertaken at the 3.9-m Anglo-Australian Telescope using the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. Brightness and surface magnetic field topologies were reconstructed for the star using the technique of least-squares deconvolution to increase the signal-to-noise of the data. The reconstructed brightness maps show that HD 141943 had a weak polar spot and a significant amount of low latitude features, with little change in the latitude distribution of the spots over the 4 years of observations. The surface magnetic field was reconstructed at three of the epochs from a high order (l <= 30) spherical harmonic expansion of the spectropolarimetric observations. The reconstructed magnetic topologies show that in 2007 and 2010 the surface magnetic field was reasonably balanced between poloidal and toroidal components. However we find tentative evidence of a change in the poloidal/toroidal ratio in 2009 with the poloidal component becoming more dominant. At all epochs the radial magnetic field is predominantly non-axisymmetric while the azimuthal field is predominantly axisymmetric with a ring of positive azimuthal field around the pole similar to that seen on other active stars.Comment: 18 pages, 17 figures, accepted by MNRA

The first magnetic maps of a pre-main sequence binary star system - HD 155555

We present the first maps of the surface magnetic fields of a pre-main sequence binary system. Spectropolarimetric observations of the young, 18 Myr, HD 155555 (V824 Ara, G5IV + K0IV) system were obtained at the Anglo-Australian Telescope in 2004 and 2007. Both datasets are analysed using a new binary Zeeman Doppler imaging (ZDI) code. This allows us to simultaneously model the contribution of each component to the observed circularly polarised spectra. Stellar brightness maps are also produced for HD 155555 and compared to previous Doppler images. Our radial magnetic maps reveal a complex surface magnetic topology with mixed polarities at all latitudes. We find rings of azimuthal field on both stars, most of which are found to be non-axisymmetric with the stellar rotational axis. We also examine the field strength and the relative fraction of magnetic energy stored in the radial and azimuthal field components at both epochs. A marked weakening of the field strength of the secondary star is observed between the 2004 and 2007 epochs. This is accompanied by an apparent shift in the location of magnetic energy from the azimuthal to radial field. We suggest that this could be indicative of a magnetic activity cycle. We use the radial magnetic maps to extrapolate the coronal field (by assuming a potential field) for each star individually - at present ignoring any possible interaction. The secondary star is found to exhibit an extreme tilt (~75 deg) of its large scale magnetic field to that of its rotation axis for both epochs. The field complexity that is apparent in the surface maps persists out to a significant fraction of the binary separation. Any interaction between the fields of the two stars is therefore likely to be complex also. Modelling this would require a full binary field extrapolation.Comment: 17 pages, 12 figures, accepted for publication in MNRA

Planning intervention using dynamic assessments: A case study

Dynamic assessments (DA) of language have been shown to be a useful addition to the battery of tests used to diagnose language impairments in children, and to evaluate their skills. The current article explores the value of the information gained from a DA in planning intervention for a child with language impairment. A single case study was used to demonstrate the detailed qualitative information that can be derived from a DA procedure, and how that information may be used to elicit greater gains from intervention. The participant was a boy, aged 9, with a previously diagnosed language impairment. He was receiving language therapy regularly in a language resource base attached to his school. The CELF-3(UK) was used to monitor changes in his language, before and after two periods of intervention. The initial baseline phase consisted of regular ongoing language therapy. The second phase of therapy was modified by the speech and language therapist after receiving a report of the child’s performance on the Dynamic Assessment of Sentence Structure (DASS; Hasson et al., 2012), and observations of the child’s metalinguistic and metacognitive awareness. Greater gains observed in the second phase of therapy reflected the good modifiability shown by the child’s performance on the DASS

Vulnerability to bullying in children with a history of specific speech and language difficulties

This is an electronic version of an article published in Lindsay, Geoff and Dockrell, Julie and Mackie, Clare (2008) Vulnerability to bullying in children with a history of specific speech and language difficulties. European Journal of Special Needs Education, 23 (1). pp. 1-16. European Journal of Special Needs Education is available online at: http://www.informaworld.com/10.1080/0885625070179120

Yield quantitative trait loci from wild tomato are predominately expressed by the shoot

Plant yield is the integrated outcome of processes taking place above and below ground. To explore genetic, environmental and developmental aspects of fruit yield in tomato, we phenotyped an introgression line (IL) population derived from a cross between the cultivated tomato (Solanum lycopersicum) and a wild species (Solanum pennellii). Both homozygous and heterozygous ILs were grown in irrigated and non-irrigated fields and evaluated for six yield components. Thirteen lines displayed transgressive segregation that increased agronomic yield consistently over 2 years and defined at least 11 independent yield-improving QTL. To determine if these QTL were expressed in the shoots or the roots of the plants, we conducted field trials of reciprocally grafted ILs; out of 13 lines with an effect on yield, 10 QTL were active in the shoot and only IL8-3 showed a consistent root effect. To further examine this unusual case, we evaluated the metabolic profiles of fruits from both the homo- and heterozygous lines for IL8-3 and compared these to those obtained from the fruit of their equivalent genotypes in the root effect population. We observed that several of these metabolic QTL, like the yield QTL, were root determined; however, further studies will be required to delineate the exact mechanism mediating this effect in this specific line. The results presented here suggest that genetic variation for root traits, in comparison to that present in the shoot, represents only a minor component in the determination of tomato fruit yield

Financial capability and functional financial literacy in young adults with developmental language disorder

Background: Financial capability is an essential feature of the organisation of one’s personal life and engagement with society. Very little is known of how adequately individuals with developmental language disorder (DLD) handle financial matters. It is known that language difficulties place them at a disadvantage in many aspects of their development and during their transition into adulthood, leading to the possibility that financial issues may prove burdensome for them. This study examines the financial capability and functional financial literacy of young adults with DLD and compares them to those of age matched peers (AMPs). We tested the expectation that those with DLD would find financial management more challenging than would their peers, and that they would need to seek greater support from family members or other people. Methods: Participants completed a detailed individual interview, which included items drawn from the British Household Panel Survey and additional measures of financial capability, functional financial literacy and of perceived support. Nonverbal IQ, language, reading and numeracy measures were also collected. Results: Compared to typically developing AMPs, young people with DLD report less extensive engagement with financial products and lower competence in functional financial literacy. A considerably higher proportion of those with DLD (48% vs 16% of AMPs) report that they draw on support, primarily from parents, in various financial tasks, including paying bills, choosing financial products, and taking loans from family or friends. Conclusions: This is the first study to consider the financial capability skills and functional financial literacy of young adults with DLD. We provide novel evidence that some young adults with DLD lack functional financial skills and require support to successfully manage their finances. This has policy implications that relate not only to engaging affected individuals in discussions about financial management but also to wider familial support