174 research outputs found

    The first super-Earth Detection from the High Cadence and High Radial Velocity Precision Dharma Planet Survey

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    The Dharma Planet Survey (DPS) aims to monitor about 150 nearby very bright FGKM dwarfs (within 50 pc) during 2016−-2020 for low-mass planet detection and characterization using the TOU very high resolution optical spectrograph (R≈\approx100,000, 380-900nm). TOU was initially mounted to the 2-m Automatic Spectroscopic Telescope at Fairborn Observatory in 2013-2015 to conduct a pilot survey, then moved to the dedicated 50-inch automatic telescope on Mt. Lemmon in 2016 to launch the survey. Here we report the first planet detection from DPS, a super-Earth candidate orbiting a bright K dwarf star, HD 26965. It is the second brightest star (V=4.4V=4.4 mag) on the sky with a super-Earth candidate. The planet candidate has a mass of 8.47±0.47MEarth\pm0.47M_{\rm Earth}, period of 42.38±0.0142.38\pm0.01 d, and eccentricity of 0.04−0.03+0.050.04^{+0.05}_{-0.03}. This RV signal was independently detected by Diaz et al. (2018), but they could not confirm if the signal is from a planet or from stellar activity. The orbital period of the planet is close to the rotation period of the star (39−-44.5 d) measured from stellar activity indicators. Our high precision photometric campaign and line bisector analysis of this star do not find any significant variations at the orbital period. Stellar RV jitters modeled from star spots and convection inhibition are also not strong enough to explain the RV signal detected. After further comparing RV data from the star's active magnetic phase and quiet magnetic phase, we conclude that the RV signal is due to planetary-reflex motion and not stellar activity.Comment: 13 pages, 17 figures, Accepted for publication in MNRA

    GNOSIS: the first instrument to use fibre Bragg gratings for OH suppression

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    GNOSIS is a prototype astrophotonic instrument that utilizes OH suppression fibres consisting of fibre Bragg gratings and photonic lanterns to suppress the 103 brightest atmospheric emission doublets between 1.47-1.7 microns. GNOSIS was commissioned at the 3.9-meter Anglo-Australian Telescope with the IRIS2 spectrograph to demonstrate the potential of OH suppression fibres, but may be potentially used with any telescope and spectrograph combination. Unlike previous atmospheric suppression techniques GNOSIS suppresses the lines before dispersion and in a manner that depends purely on wavelength. We present the instrument design and report the results of laboratory and on-sky tests from commissioning. While these tests demonstrated high throughput and excellent suppression of the skylines by the OH suppression fibres, surprisingly GNOSIS produced no significant reduction in the interline background and the sensitivity of GNOSIS and IRIS2 is about the same as IRIS2. It is unclear whether the lack of reduction in the interline background is due to physical sources or systematic errors as the observations are detector noise-dominated. OH suppression fibres could potentially impact ground-based astronomy at the level of adaptive optics or greater. However, until a clear reduction in the interline background and the corresponding increasing in sensitivity is demonstrated optimized OH suppression fibres paired with a fibre-fed spectrograph will at least provide a real benefits at low resolving powers.Comment: 15 pages, 13 figures, accepted to A

    SAMI - A new multi-object IFS for the Anglo-Australian telescope

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    SAMI (Sydney-AAO Multi-object Integral field spectrograph) has the potential to revolutionise our understanding of galaxies, with spatially-resolved spectroscopy of large numbers of targets. It is the first on-sky application of innovative photonic imaging bundles called hexabundles, which will remove the aperture effects that have biased previous single-fibre multi-object astronomical surveys. The hexabundles have lightly-fused circular multi-mode cores with a covering fraction of ∼ 73%. The thirteen hexabundles in SAMI, each have 61 fibre cores, and feed into the AAOmega spectrograph at the Anglo-Australian Telescope (AAT). SAMI was installed at the AAT in July 2011 and the first commissioning results prove the effectiveness of hexabundles on sky. A galaxy survey of several thousand galaxies to z ∼ 0.1 will begin with SAMI in mid-2012

    The Sydney-AAO Multi-object Integral field spectrograph (SAMI)

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    We demonstrate a novel technology that combines the power of the multi-object spectrograph with the spatial multiplex advantage of an integral field spectrograph (IFS). The Sydney-AAO Multi-object IFS (SAMI) is a prototype wide-field system at the Anglo-Australian Telescope (AAT) that allows 13 imaging fibre bundles ("hexabundles") to be deployed over a 1-degree diameter field of view. Each hexabundle comprises 61 lightly-fused multimode fibres with reduced cladding and yields a 75 percent filling factor. Each fibre core diameter subtends 1.6 arcseconds on the sky and each hexabundle has a field of view of 15 arcseconds diameter. The fibres are fed to the flexible AAOmega double-beam spectrograph, which can be used at a range of spectral resolutions (R=lambda/delta(lambda) ~ 1700-13000) over the optical spectrum (3700-9500A). We present the first spectroscopic results obtained with SAMI for a sample of galaxies at z~0.05. We discuss the prospects of implementing hexabundles at a much higher multiplex over wider fields of view in order to carry out spatially--resolved spectroscopic surveys of 10^4 to 10^5 galaxies.Comment: 24 pages, 16 figures. Accepted by MNRA

    Effectiveness of screening and brief alcohol intervention in primary care (SIPS trial): pragmatic cluster randomised controlled trial

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    Objective To evaluate the effectiveness of different brief intervention strategies at reducing hazardous or harmful drinking in primary care.The hypothesis was that more intensive intervention would result in a greater reduction in hazardous or harmful drinking. Design Pragmatic cluster randomised controlled trial.Setting Primary care practices in the north east and south east of England and in London.Participants 3562 patients aged 18 or more routinely presenting in primary care, of whom 2991 (84.0%) were eligible to enter the trial: 900(30.1%) screened positive for hazardous or harmful drinking and 756(84.0%) received a brief intervention. The sample was predominantly male (62%) and white (92%), and 34% were current smokers. Interventions Practices were randomised to three interventions, each of which built on the previous one: a patient information leaflet control group, five minutes of structured brief advice, and 20 minutes of brief lifestyle counselling. Delivery of the patient leaflet and brief advice occurred directly after screening and brief lifestyle counselling in a subsequent consultation. Main outcome measures The primary outcome was patients’ self reported hazardous or harmful drinking status as measured by the alcohol use disorders identification test (AUDIT) at six months. A negative AUDITresult (score <8) indicated non-hazardous or non-harmful drinking.Secondary outcomes were a negative AUDIT result at 12 months,experience of alcohol related problems (alcohol problems questionnaire),health utility (EQ-5D), service utilisation, and patients’ motivation to change drinking behaviour (readiness to change) as measured by a modified readiness ruler.Results Patient follow-up rates were 83% at six months (n=644) and 79% at 12 months (n=617). At both time points an intention to treat analysis found no significant differences in AUDIT negative status between the three interventions. Compared with the patient information leaflet group, the odds ratio of having a negative AUDIT result for briefa dvice was 0.85 (95% confidence interval 0.52 to 1.39) and for brief lifestyle counselling was 0.78 (0.48 to 1.25). A per protocol analysis confirmed these findings. Conclusions All patients received simple feedback on their screening outcome. Beyond this input, however, evidence that brief advice or brief lifestyle counselling provided important additional benefit in reducing hazardous or harmful drinking compared with the patient information leaflet was lacking
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