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Drew J.E.,University of Hertfordshire | Gonzalez-solares E.,University of Cambridge | Greimel R.,University of Graz | Irwin M.J.,University of Cambridge | And 31 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2014

The VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+) is surveying the southern Milky Way in u, g, r, i and Hα at ~1 arcsec angular resolution. Its footprint spans the Galactic latitude range -5o < b < +5° at all longitudes south of the celestial equator. Extensions around the Galactic Centre to Galactic latitudes ±10° bring in much of the Galactic bulge. This European Southern Observatory public survey, begun on 2011 December 28, reaches down to ~20th magnitude (10σ) and will provide single-epoch digital optical photometry for ~300 million stars. The observing strategy and data pipelining are described, and an appraisal of the segmented narrow-band Hα filter in use is presented. Using model atmospheres and library spectra, we compute main-sequence (u - g), (g - r), (r - i) and (r - Hα) stellar colours in the Vega system. We report on a preliminary validation of the photometry using test data obtained from two pointings overlapping the Sloan Digital Sky Survey. An example of the (u - g, g - r) and (r - Hα, r - i) diagrams for a full VPHAS+ survey field is given. Attention is drawn to the opportunities for studies of compact nebulae and nebular morphologies that arise from the image quality being achieved. The value of the u band as the means to identify planetary-nebula central stars is demonstrated by the discovery of the central star of NGC 2899 in survey data. Thanks to its excellent imaging performance, the VLT Survey Telescope (VST)/OmegaCam combination used by this survey is a perfect vehicle for automated searches for reddened early-type stars, and will allow the discovery and analysis of compact binaries, white dwarfs and transient sources. © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society.

Bally J.,University of Colorado at Boulder | Ginsburg A.,ESO Headquarters | Kasliwal M.M.,California Institute of Technology
EAS Publications Series | Year: 2016

AO imaging of the near IR [Fe ii] and H2 lines and ALMA CO J = 2-1 data confirms the explosive nature of the BN/KL outflow in Orion. N-body interactions in compact groups may be responsible for the production of powerful, explosive protostellar outflows and luminous infrared flares. The Orion event may have been triggered by a protostellar merger. First results of a search for Orion-like events in 200 nearby galaxies with the SPitzer InfraRed Intensive Transients Survey (SPIRITS) are briefly discussed. © 2016 EAS, EDP Sciences.

Eisner J.A.,University of Arizona | Bally J.M.,University of Colorado at Boulder | Ginsburg A.,ESO Headquarters | Sheehan P.D.,University of Arizona
Astrophysical Journal | Year: 2016

We present ALMA observations of the Orion Nebula that cover the OMC1 outflow region. Our focus in this paper is on compact emission from protoplanetary disks. We mosaicked a field containing ∼600 near-IR-identified young stars, around which we can search for sub-millimeter emission tracing dusty disks. Approximately 100 sources are known proplyds identified with the Hubble Space Telescope. We detect continuum emission at 1 mm wavelengths toward ∼20% of the proplyd sample, and ∼8% of the larger sample of near-IR objects. The noise in our maps allows 4σ detection of objects brighter than ∼1.5 mJy, corresponding to protoplanetary disk masses larger than 1.5 M J (using standard assumptions about dust opacities and gas-to-dust ratios). None of these disks are detected in contemporaneous CO(2-1) or C18O(2-1) observations, suggesting that the gas-to-dust ratios may be substantially smaller than the canonical value of 100. Furthermore, since dust grains may already be sequestered in large bodies in Orion Nebula cluster (ONC) disks, the inferred masses of disk solids may be underestimated. Our results suggest that the distribution of disk masses in this region is compatible with the detection rate of massive planets around M dwarfs, which are the dominant stellar constituent in the ONC. © 2016. The American Astronomical Society. All rights reserved.

Piqueras L.,University of Lyon | Piqueras L.,Laval University | Piqueras L.,Ecole Normale Superieure de Lyon | Richard J.,University of Lyon | And 10 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

MUSE (Multi Unit Spectroscopic Explorer) is an integral-field spectrograph which will be mounted on the Very Large Telescope (VLT). MUSE is being built for ESO by a European consortium under the supervision of the Centre de Recherche Astrophysique de Lyon (CRAL). In this context, CRAL is responsible for the development of dedicated software to help MUSE users prepare and submit their observations. This software, called MUSE-PS, is based on the ESO SkyCat tool that combines visualization of images and access to catalogs and archive data for astronomy. MUSE-PS has been developed as a plugin to SkyCat to add new features specific to MUSE observations. In this paper, we present the MUSE observation preparation tool itself and especially its specific functionalities: definition of the center of the MUSE field of view and orientation, selection of the VLT guide star for the different modes of operations (Narrow Field Mode or Wide Field Mode, with or without AO). We will also show customized displays for MUSE (zoom on specific area, help with MUSE mosaïcing and generic offsets, finding charts ...). © 2012 SPIE.

Voronkov M.A.,CSIRO | Voronkov M.A.,Astro Space Center | Walsh A.J.,James Cook University | Caswell J.L.,CSIRO | And 6 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2011

We report the first detection of a methanol maser in the 101-92 A- transition at 23.4 GHz, discovered during the H2O southern Galactic Plane Survey (HOPS) with the 22-m Mopra Radio Telescope. In the region covered by HOPS, the 23.4-GHz maser was found at only one location, G357.97-0.16, which was also a prominent source of maser emission in the J2-J1 E series near 25GHz. The Australia Telescope Compact Array (ATCA) was used to follow up these detections at high angular resolution and prove the maser nature of the observed emission. The analysis shows that the new methanol maser at 23.4GHz is a class I maser, which has properties similar to the 9.9- and 25-GHz masers (i.e. traces strong shocks with higher than average temperature and density). All class I masers were found to originate at the same spatial location (within the measurement uncertainty of 0.5arcsec) in the vicinity of the dominant infrared source, but at a clearly distinct position from nearby OH, H2O and class II methanol masers at 6.7GHz. All maser species are distributed approximately on a line, but it is not clear at present whether this has any physical significance. We also detected a weak (1.3mJy) continuum source at 25GHz near the OH maser (at the most northern site, associated with a class II methanol maser and an H2O maser renowned for its extremely wide spread of velocity components). The continuum source has not been reported at lower frequencies and is therefore a candidate hypercompact Hii region. We also used the ATCA to find the strongest and only the fifth known 9.9-GHz maser towards G357.97-0.16 and another 23.4-GHz maser towards G343.12-0.06 not seen in HOPS. © 2011 CSIRO Monthly Notices of the Royal Astronomical Society © 2011 RAS.

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