1,985 research outputs found

    Mode identification for Balloon 090100001 using combined multicolour photometry and spectroscopy

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    In this paper, we show that method of mode identification using combined multicolour photometry and spectroscopy can be successfully applied to the pulsating subdwarf B star Balloon 090100001. The method constrains the spherical degree, l.We confirm that the dominant mode is radial and we show that for some other modes the method provides values of l consistent with the observed rotationally split triplet. Moreover, we derive a radius variation of 1.7 per cent for the dominant mode. The identification opens the possibility for constraining the internal structure of the star by means of seismic methods.Comment: MNRAS, in press, already at the online-early stag

    Time resolved spectroscopy of the multiperiodic pulsating subdwarf B star PG1605+072

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    We present results for the 2m spectroscopic part of the MultiSite Spectroscopic Telescope campaign, which took place in May/June 2002. In order to perform an asteroseismological analysis on the multiperiodic pulsating subdwarf B star PG 1605+072 we used over 150 hours of time resolved spectroscopy in order to search for and analyse line profile variations by using phase binning. We succeeded in finding variations in effective temperature and gravity for four modes. A pilot analysis using the \textit{BRUCE} and \textit{KYLIE} programs and assuming strong rotation and low inclination favours models with l=1l=1 or l=2l=2 with m≤0m\leq0.Comment: 2 pages, 2 figures, proceedings of the "Vienna Workshop on the Future of Asteroseismology", to appear in Communications in Asteroseismology v. 14

    Evidence for a planetary mass third body orbiting the binary star KIC 5095269

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    In this paper, we report the evidence for a planetary mass body orbiting the close binary star KIC 5095269. This detection arose from a search for eclipse timing variations among the more than 2,000 eclipsing binaries observed by Kepler. Light curve and periodic eclipse time variations have been analysed using Systemic and a custom Binary Eclipse Timings code based on the Transit Analysis Package which indicates a 7.70±0.08MJup7.70\pm0.08M_{Jup} object orbiting every 237.7±0.1d237.7\pm0.1d around a 1.2M⊙1.2M_\odot primary and 0.51M⊙0.51M_\odot secondary in an 18.6d orbit. A dynamical integration over 10710^7 years suggests a stable orbital configuration. Radial velocity observations are recommended to confirm the properties of the binary star components and the planetary mass of the companion.Comment: 8 pages, 7 figures, Accepted for publication in MNRA

    The MultiSite Spectroscopic Telescope campaign: 2m spectroscopy of the V361 Hya variable PG1605+072

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    We present results and analysis for the 2m spectroscopic part of the MultiSite Spectroscopic Telescope (MSST) campaign undertaken in May/June 2002. The goal of the project was to observe the pulsating subdwarf B star PG1605+072 simultaneously in velocity and photometry and to resolve as many of the >50 known modes as possible, which will allow a detailed asteroseismological analysis. We have obtained over 150 hours of spectroscopy, leading to an unprecedented noise level of only 207m/s. We report here the detection of 20 frequencies in velocity, with two more likely just below our detection threshold. In particular, we detect 6 linear combinations, making PG1605+072 only the second star known to show such frequencies in velocity. We investigate the phases of these combinations and their parent modes and find relationships between them that cannot be easily understood based on current theory. These observations, when combined with our simultaneous photometry, should allow asteroseismology of this most complicated of sdB pulsators.Comment: 9 pages, 5 figures, accepted for publication in A&A; Figure 1 at lower resolution than accepted versio

    Weak magnetic fields in white dwarfs and their direct progenitors?

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    We have carried out a re-analysis of polarimetric data of central stars of planetary nebulae, hot subdwarfs, and white dwarfs taken with FORS1 (FOcal Reducer and low dispersion Spectrograph) on the VLT (Very Large Telescope), and added a large number of new observations in order to increase the sample. A careful analysis of the observations using only one wavelength calibration for the polarimetrically analysed spectra and for all positions of the retarder plate of the spectrograph is crucial in order to avoid spurious signals. We find that the previous detections of magnetic fields in subdwarfs and central stars could not be confirmed while about 10% of the observed white dwarfs have magnetic fields at the kilogauss level.Comment: 6 pages, Proceedings of the 18th European White Dwarf Workshop, ASP Conference Serie

    Multi-wavelength photometric variation of PG1605+072

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    In a large coordinated attempt to further our understanding of the pp-mode pulsating sdB star PG1605+072, the Multi-Site Spectroscopic Telescope (MSST) collaboration has obtained simultaneous time-resolved spectroscopic and photometric observations. The photometry was extended by additional WET data which increased the time base. This contribution outlines the analysis of the MSST photometric light curve, including the four-colour BUSCA data from which chromatic amplitudes have been derived, as well as supplementary FUV spectra and light curves from two different epochs. These results have the potential to complement the interpretation of the published spectroscopic information.Comment: 6 pages, to be published in "Interpretation of asteroseismic data", proceedings of the HELAS NA5 Workshop, eds. W. Dziembowski, M. Breger and M. Thompson, Communications in Asteroseismology, 15

    A Qualitative Exploration of Practitioners' Understanding of and Response to Child-to-Parent Aggression.

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    There has been limited research and policy directed toward defining and understanding child-to-parent aggression (CPA), resulting in inconsistent definitions, understandings, and responses, which has a detrimental impact on families. In particular, there have been limited qualitative studies of those working on the frontline of CPA, hindering the development of effective policy. The present qualitative study therefore aimed to explore practitioner perspectives of CPA. Twenty-five practitioners from diverse fields (e.g., youth justice, police, charities) participated in four focus groups relating to their experiences of working with CPA in the United Kingdom. Thematic analysis of focus groups revealed three key themes: definitions of CPA, understanding of CPA risk factors, and responding to CPA. Practitioners understood CPA to be a broad use of aggression to intimidate and control parents and highlighted a range of individual (e.g., mental health, substance abuse) and social (e.g., parenting, gangs) risk factors for CPA. Further, practitioners felt that current methods of reporting CPA were ineffective and may have a detrimental impact on families. The findings of this study have implications for CPA policy and support the need for a multiagency and coordinated strategy for responding to CPA
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