AStars and the Virtual Observatory

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• A-Stars and the Virtual Observatory
• Paolo Padovani, ST-ECF/ESO
• AVO Science Manager

The Virtual Observatory and A-Stars

• The Virtual Observatory (VO)
• Europe and the VO the Astrophysical Virtual
  Observatory
• A-Stars and the (A)VO concrete applications
• Disclaimer n. 1 Big topic, good for a whole
  workshop
• Disclaimer n. 2 Extragalactic astronomer!

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Astronomy in the XXI century

• Radical changes are needed!
• Huge surveys 100M sources at lt3k spectra/night
  ? gt100 yr!
• Ever fainter sources surpassed the
  identification limits of 8 - 10m telescopes (Rmag
  25)
• Huge data collections downloading Sloan Digital
  Sky Survey (SDSS) DR2 ( 1/3 of total) images (5
  Tb) ? 1 yr at 200 kb/s (ESOs speed) catalogs
  (1.4 Tb) ? 3 months. On DVDs ? 1,000 of
  them. And analysis?? (similar size for MACHO,
  2MASS etc )
• Ever increasing amount of data

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R 25.5, VLT/FORS2, texp 2.5 hrs (Szokoly et
al. 2004)
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Astronomical Data Explosion
100 Gb/night
P. Quinn
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ESO/ST-ECF Science Archive Facility holdings
?
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The solution?

• Data mining to increase observing efficiency ?
  intelligent pre-selection
• Statistical identification to diminish need for a
  spectrum ? multi-wavelength, multi-parameter
  analysis
• In-situ analysis to avoid download
• Easy and smart access to all archives and data
  providers

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The name Virtual Observatory

• An innovative, evolving system, which takes
  advantage of astronomical data explosion
• It will allow users to interrogate multiple data
  centres in a seamless and transparent way and to
  utilize at best astronomical data
• Data analysis tools and models will be made more
  accessible
• It will allow new science by moving Astronomy
  beyond era of classical identification by
  combining all available information
• Good communication ? common language! Adoption
  and definition of VO standards and protocols
  within the International Virtual Observatory
  Alliance (IVOA http//ivoa.net)
• And its all happening now

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International Virtual Observatory Alliance
Mission To facilitate the international
coordination and collaboration necessary for the
development and deployment of the tools, systems
and organizational structures necessary to enable
the international utilization of astronomical
archives as an integrated and interoperating
virtual observatory
SVO
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So what ?

• The VO will make life much easier for all
  astronomers, even those not involved with
  colossal surveys, huge teams, and Tb of data!
• Web all documents of the world inside your
  computer
• VO all astronomical databases in the world
  inside your computer
• Concrete example
• Find all the high-resolution spectra of A-type
  stars available in all astronomical archives in a
  given wavelength range
• Tell me which ones are in raw or processed form
• Allow me to retrieve them
• If raw, give me access to the tools to reduce
  them on-the-fly
• Very time consuming, if at all possible, at
  present

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Virtual Observatory in Europe

• AVO Project started November 2001
• Three-year, 5 M, Phase A project, funded by the
  European Commission (FP5) and six organizations
  ESO, ESA, AstroGrid, CNRS (CDS, TERAPIX),
  University Louis Pasteur, JBO
• Manpower 17 FTEs/yr total, 50/50 EC and
  partners
• Next step EURO-VO, implementation phase (some EC
  funding secured, need more)
• Visit us at http//www.euro-vo.org
• Science Working Group established two years ago
  to provide scientific advice to AVO Project
  implementation of selected science cases through
  demonstrations

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The AVO Prototype

• Evolution of Aladin (Centre de Donnés
  astronomiques de Strasbourg CDS)
• Downloadable Java application
  (http//www.euro-vo.org/twiki/bin/view/Avo/SwgDow
  nload)
• Extensible toolset with plug-ins which allows
  easy access to images, spectra, catalogues, with
  overlays, plotting facilities, and a
  cross-correlation utility
• Still prototype but also research tool first
  refereed, VO-based scientific paper Discovery of
  optically faint obscured quasars with Virtual
  Observatory tools, P. Padovani et al., AA, in
  press (astro-ph/0406056)

ST-ECF/ESO Press release May 28
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A-star VO Cases

• Establishing open cluster membership
• Are chemically peculiar A-type stars more likely
  to be X-ray emitters than normal A-type stars?
  (Damiani et al., 2003)

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Open Cluster Membership
Pleiades POSS II image
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Loading catalogues
parallax
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Plotting Data Parallax Histogram
cluster parallax 8.460.22 mas
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Colour-magnitude diagram
ZAMS
can correct for reddening by adding a new column
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Colour-magnitude diagram
parallax
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Open Cluster Membership

• Can be done now with existing
• tool, will be easier to do in the
• near future

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Available archive data
2 clicks away from journal articles!
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MAST data in detail

• Cross-correlation of Sky2000 star catalogue with
  Multi-mission Archive at STScI (MAST Optical/UV)
• Out of 22,400 A-type stars
• 754 have International Ultraviolet Explorer (IUE)
  data, for a total of 10,000 observations
• 128 have non-IUE (FOS, GHRS, STIS, FUSE, EUVE,
  Copernicus, HUT, WUPPE, BEFS) data, for a total
  of 1,700 observations, 60 of which are spectra
• How much else is available?

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Peculiar A Stars in the X-rays
Renson et al. (1991) catalog of 6684 chemically
peculiar stars, 4736 of which A-type (equatorial
projection)
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Peculiar A Stars in the X-rays Comparison Sample
HD catalog (blue 272,150 sources) with A-type
stars (yellow 72,154) selected (equatorial
projection)
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Peculiar A Stars in the X-rays
WGACAT of ROSAT PSPC observations, 88486 sources
(equatorial projection)
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Chemically peculiar A-type stars in the X-rays

• Cross-correlation of Renson et al. CP catalogue
  (A-type only) with WGACAT 79/4736 matches
  1.70.6 (3? spurious matches subtracted).
  Magnetic only 22/1433 1.50.7
• Cross-correlation of HD A-type stars with WGACAT
  392/72154 0.540.03 correcting for CP star
  contamination (10 e.g., Monin et al. 2002) ?
  0.4
• Cross-correlation of SAO A-type stars with
  WGACAT 351/47230 0.70.1 correcting for CP
  stars one gets 0.6

• Chemically peculiar A-type stars are 3 - 4
  times more
• likely to be X-ray sources than normal
  A-type stars.
• Magnetic field appears not to play a role.

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Chemically peculiar A-type stars in the radio
band?

• Cross-correlation of Renson et al. CP catalogue
  (A-type only) with (almost) all-sky radio
  catalogues down to 1 mJy gives null results
• Expected, given fluxes of few detected sources so
  far (? 1 - 2 mJy, e.g., Drake et al. 1987)

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Summary

• The Virtual Observatory is happening, because it
  has to!
• Handling and manipulating astronomical data and
  tools residing at various locations around the
  world will be made much easier than it is now
• Everybody will benefit, including A-type star
  researchers!
• Tools are available now to help you with your work

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AVO Web Page

• AVO prototype downloadable
  at http//www.euro-vo.org/tw
  iki/bin/view/Avo/SwgDownload

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Astronomical Data on the Web
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Whats Next for the European VO?

• Finish the AVO Phase (last demo Jan. 2005)
• We need to move towards EURO-VO
• Work with (not for) the data centres to increase
  interoperability inter-archive tools and
  promote high-quality, science-ready products
  AVO needs these to be truly successful (see last
  demo)!
• Make progress in turning ESO/ST-ECF archive
  VO-compliant
• Funding situation not clear

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The Future
GridNet
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2005
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EURO-VO Resources - 4 Years

• Data Centre Alliance
• UK, France, Germany, Italy, Netherlands, Spain,
  ESO, ESA initially 15 Centres
• 2 FTE per centre 100 kEuro/yr upgrades
• Facility Centre
• 4 support scientists (registries, outreach,
  project support ASTROVIRTEL II)
• Technology Centre
• 11 FTE development staff
• TOTAL 15.5 Million Euro
• EC 8 Million Euro

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VO First Science!

• First refereed, VO-based scientific paper
  Discovery of optically faint obscured quasars
  with Virtual Observatory tools, P. Padovani et
  al., AA, in press

ESA/ESO Press release May 28