The lithium isotope ratio in the metal-poor halo star G271-162 from VLT/UVES observations

A high resolution (R = 110.000), very high S/N (>600) spectrum of the metal-poor turnoff star G271-162 has been obtained in connection with the commissioning of UVES at VLT/Kueyen. Using both 1D hydrostatic and 3D hydrodynamical model atmospheres, the lithium isotope ratio has been estimated from the LiI 670.8 nm line by means of spectral synthesis. The necessary stellar line broadening (1D: macroturbulence + rotation, 3D: rotation) has been determined from unblended KI, CaI and FeI lines. The 3D line profiles agree very well with the observed profiles, including the characteristic line asymmetries. Both the 1D and 3D analyses reveal a possible detection of 6Li in G271-162, 6Li/7Li = 0.02 +-0.01 (one sigma). It is discussed if the smaller amount of 6Li in G271-162 than in the similar halo star HD84937 could be due to differences in stellar mass and/or metallicity or whether it may reflect an intrinsic scatter of the Li isotope ratio in the ISM at a given metallicity.Comment: 5 pages with 6 figures. Accepted as a letter in A&

Galactic Halo substructure in the Sloan Digital Sky Survey: the ancient tidal stream from the Sagittarius dwarf galaxy

Two studies have recently reported the discovery of pronounced Halo substructure in the Sloan Digital Sky Survey (SDSS) commissioning data. Here we show that this Halo substructure is almost in its entirety due to the expected tidal stream torn off the Sagittarius dwarf galaxy during the course of its many close encounters with the Milky Way. This interpretation makes strong predictions on the kinematics and distances of these stream stars. Comparison of the structure in old horizontal branch stars, detected by the SDSS team, with the carbon star structure discovered in our own survey, indicates that this halo stream is of comparable age to the Milky Way. It would appear that the Milky Way and the Sagittarius dwarf galaxy have been a strongly interacting system for most of their existence. Once complete, the SDSS will provide a unique dataset with which to constrain the dynamical evolution of the Sagittarius dwarf galaxy, it will also strongly constrain the mass distribution of the outer Milky Way.Comment: 7 pages, 3 figures (1 color figure chunky due to PS compression), minor revisions,accepted by ApJ

First LOFAR results on galaxy clusters

Deep radio observations of galaxy clusters have revealed the existence of diffuse radio sources related to the presence of relativistic electrons and weak magnetic fields in the intracluster volume. The role played by this non-thermal intracluster component on the thermodynamical evolution of galaxy clusters is debated, with important implications for cosmological and astrophysical studies of the largest gravitationally bound structures of the Universe. The low surface brightness and steep spectra of diffuse cluster radio sources make them more easily detectable at low-frequencies. LOFAR is the first instrument able to detect diffuse radio emission in hundreds of massive galaxy clusters up to their formation epoch. We present the first observations of clusters imaged by LOFAR and the huge perspectives opened by this instrument for non-thermal cluster studies.Comment: Proceedings of the 2012 week of the French Society of Astronomy and Astrophysics (SF2A) held in Nice, June 5th-8t

Status and Commissioning of the CMS Experiment

After a brief overview of the Compact Muon Solenoid (CMS) experiment, the status of construction and installation is described in the first part of the note. The second part of the document is devoted to a discussion of the general commissioning strategy of the CMS experiment, with a particular emphasis on trigger, calibration and alignment. Aspects of b-physics, as well as examples for early physics with CMS are also presented. CMS will be ready for data taking in time for the first collisions in the Large Hadron Collider (LHC) at CERN in late 2007.Comment: Talks given at the 11th Intl. Conference on B-Physics at Hadron Machines BEAUTY 2006, Oxford (UK), September 200

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

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

Status Report on the Low-Energy Demonstration Accelerator (LEDA)

The 75-keV injector and 6.7-MeV RFQ that comprise the first portion of the cw, 100-mA proton linac for the accelerator production of tritium (APT) project have been built and operated. The LEDA RFQ has been extensively tested for pulsed and cw output-beam currents <=100 mA. Up to 2.2 MW of cw rf power from the 350-MHz rf system is coupled into the RFQ, including 670 kW for the cw proton beam. The emittance for a 93-mA pulsed RFQ output beam, as determined from quadrupole-magnet-scan measurements, is ex x ey = 0.25 x 0.31 (pi mm mrad)2 [rms normalized]. A follow-on experiment, to intentionally introduce and measure beam halo on the RFQ output beam, is now being installed.Comment: Paper TUD14 for the XX International Linac Conference (LINAC2000), 3 pages, 10 figure

The LAMOST Survey of Background Quasars in the Vicinity of the Andromeda and Triangulum Galaxies -- II. Results from the Commissioning Observations and the Pilot Surveys

We present new quasars discovered in the vicinity of the Andromeda and Triangulum galaxies with the LAMOST during the 2010 and 2011 observational seasons. Quasar candidates are selected based on the available SDSS, KPNO 4 m telescope, XSTPS optical, and WISE near infrared photometric data. We present 509 new quasars discovered in a stripe of ~135 sq. deg from M31 to M33 along the Giant Stellar Stream in the 2011 pilot survey datasets, and also 17 new quasars discovered in an area of ~100 sq. deg that covers the central region and the southeastern halo of M31 in the 2010 commissioning datasets. These 526 new quasars have i magnitudes ranging from 15.5 to 20.0, redshifts from 0.1 to 3.2. They represent a significant increase of the number of identified quasars in the vicinity of M31 and M33. There are now 26, 62 and 139 known quasars in this region of the sky with i magnitudes brighter than 17.0, 17.5 and 18.0 respectively, of which 5, 20 and 75 are newly-discovered. These bright quasars provide an invaluable collection with which to probe the kinematics and chemistry of the ISM/IGM in the Local Group of galaxies. A total of 93 quasars are now known with locations within 2.5 deg of M31, of which 73 are newly discovered. Tens of quasars are now known to be located behind the Giant Stellar Stream, and hundreds behind the extended halo and its associated substructures of M31. The much enlarged sample of known quasars in the vicinity of M31 and M33 can potentially be utilized to construct a perfect astrometric reference frame to measure the minute PMs of M31 and M33, along with the PMs of substructures associated with the Local Group of galaxies. Those PMs are some of the most fundamental properties of the Local Group.Comment: 26 pages, 6 figures, AJ accepte

Commissioning of the CMS High Level Trigger

The CMS experiment will collect data from the proton-proton collisions delivered by the Large Hadron Collider (LHC) at a centre-of-mass energy up to 14 TeV. The CMS trigger system is designed to cope with unprecedented luminosities and LHC bunch-crossing rates up to 40 MHz. The unique CMS trigger architecture only employs two trigger levels. The Level-1 trigger is implemented using custom electronics, while the High Level Trigger (HLT) is based on software algorithms running on a large cluster of commercial processors, the Event Filter Farm. We present the major functionalities of the CMS High Level Trigger system as of the starting of LHC beams operations in September 2008. The validation of the HLT system in the online environment with Monte Carlo simulated data and its commissioning during cosmic rays data taking campaigns are discussed in detail. We conclude with the description of the HLT operations with the first circulating LHC beams before the incident occurred the 19th September 2008

"A step into the abyss" Transmedia in the UK Games and Television Industries

This article uses a media industries studies perspective to investigate the current state of transmedia production in the UK. Analysing the discursive statements of a range of industry participants from both UK television and games industries, the article reveals a series of contradictions and misunderstandings that may be limiting the effectiveness of multi-platform projects. By comparing overlapping discursive patterns around attitudes to risk, measures of success, authorship between the two industries, and repeated concerns over the balance of creative and commercial imperatives, the article argues that existing hierarchies of power between media industries threaten to derail future convergence