Science

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• Science
• with
• Virtual Observatories
• - A Pilot Case
• Roberto Mignani
• Mullard Space Science Laboratories
• University College London

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Why this talk?
WHAT IS VO SCIENCE
DESCRIBE VO FACILITIES
AN EXAMPLE OF VO SCIENCE
MIN INPUT,MAX OUTPUT
VIRTUAL OBSERVATORIES
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Archive Science

• Not a surprise, data archiving mainly started
  from Space Observatories
• Huge amount of data available in space/ground
  based observatories archives
• Possibility of Data Mining
• Practically changed the way of doing science
  very trendy!
• Full spectral coverage from radio to gamma-rays ?
  multi- ? astronomy
• Possibility of expanding research in the ?,t
  space ? multi- ? studies vs time
• Studying in more detail the Known, discovering
  the Unknown
• PROS
• No effort in preparing observing proposals
• No effort in preparing/executing observations
• No clash with TACs
• CONS
• Data might have been taken with other goals
• Observation strategy/instrument setup might
• not be optimal

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Archive Facilities

• Not just access to data
• Improved facilities for data archives query (nice
  web interfaces)
• Improved facilities for data selection and
  association (selection by band, min/max time
  span, flux limit, object category )
• Improved communications between remote archives
  and/or archives
• reunification (e.g. ESOHST)
• Virtual Observatories (VOs) era
• NASA/HEASARC (early 90s) was a prototype (query
  and X-matches with different MW archives and OTF
  remote data analysis)

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Astrophysical Virtual Observatory
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International Virtual Observatories Alliance
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Catalogue Science

• Archival data still requires reduction and
  analysis, unless OTF data calibration and
  reduction is provided (e.g. for HST and soon
  for VLT)
• Most recent data reduction pipelines include
  source detection algorithms ? production of
  objects catalogues
• 5695 catalogues available in CDS
• Multi-?
• Multi-purpose (astrometric, photometric,
  morphological ..)
• Multi-epoch
• Multi-Sky Coverage
• Best way to maximize scientific return vs
  invested effort
• Mine of opportunities for people with limited
  (null) time for science or with limited resources
• No time to reduce/calibrate/assemble the data
• No time to analyze the data
• Skip directly to final products

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What do I have to do with all that ??
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GSC-II (1998-2001)
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The Project

• Joint project btw NASA, ESA, ESO, GEMINI, INAF
• 7 Photographic Surveys (8000 plates) carried out
  with Schmidt plates
• Observations performed from Mt. Palomar (North)
  and AAT (South)
• DSS-I GSC-I ? DSS-II GSC-II

The Making of GSC-II, available on CD from
www.to.astro.it
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The GSC-II in a nutshell

• 1 Billion objects the Largest Optical
  Catalogue ever
• All-Sky, Multi-epoch (40 years) Multi-band (Bj,
  F, N, V)
• Astrometric catalogue
• Astrometry calibrated with HipparcosTycho2
• lt0.35 absolute
• Proper Motion catalogue
• lt 20 mas/yr
• Photometric Catalogue
• Photometry calibrated with dedicated photometric
  catalogue
• Bj 22.5, F 22, N 19.5 partial coverage in
  V (14-19.5)
• lt 0.2 mag _at_ Bj22
• Morphological Catalogue
• Classification calibrated with Training Sets
• 95 accuracy _at_ bgt20 and _at_ Bj 20.5

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Science with the GSC-II

• Originally conceived to support pointing
  operations of
• HST, GEMINI, VLT and XMM, for BOP of new
  HST
• instruments (STIS), for AO observations at
  the VLT
• Use extended to science applications
• Quality (shallow) vs Quantity (all-sky)
• Extended database for
• multi ? X-correlations, e.g., with the BMW-ROSAT
  
• (Panzera et al. 2003) and the BMW-CHANDRA
• (Romano et al. 2004) X-ray catalogues and the
  FIRST
• radio catalogue (White et al. 2000)
• object statistics,
• population studies,
• galactic dynamics,
• search for fast moving objects,
• variability studies (from the GSC-II DB),
• search for star/galaxy cluster,

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A comprehensive study of Planetary Nebulae
(PNe) and their Central Stars (CSs) F. Kerber
(ST-ECF), R. Mignani (MSSL-UCL), A. Wicenec
(ESO), F. Guglielmetti (STScI), H.M. Adorf
(MPA), T. Rauch (U. Tubingen), E.M. Pauli (U.
Bamberg), M. Roth (LCO)
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Why a good example?

• Science project carried on using ONLY public
  catalogues
• Capitalize on ALL catalogue information
• Domino Effect Catalogue Science ? Catalogue
  Science
• Makes use of already available tools and services
  
• Cheap Chic
• All-sky catalogues ? First systematic all-sky
  studies ever
• Cover a wide range of topics (ISM, stellar
  physics, dynamics,)
• Produce good quality scientific results

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Planetary Nebulae Evolution

• Progenitors of Suns class
• Ejection of the outer shell during the AGB phase
  ( 20 km/s wind)
• WD nebula
• Nebula ionized by the UV radiation from the
  central WD (Tgt30,000 K)
• Nebula swept by a fast (gt1000 km/s) thin wind
  from the WD
• For young PNe density of the nebula gtgt ISM
  density ? free expansion
• For older PNe density of the nebula ISM density
  ? expansion slowdown
• Expansion goes on until density of the Nebula lt
  ISM density
• Compression ? deformation of the nebula
• Brightening of the nebula rim at the shock with
  ISM
• Formation of knots and filaments
• Dispersion of the nebula in the ISM, WD cools
  down (t 10,000 years)

SIMILAR TO THE PSR/SNR CASE
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Planetary Nebulae Morphology

• PNe shapes depends on
• the density profile of the ISM
• dynamics and geometry of gas outflow in the AGB
  phase
• Spherical outflow
• Collimated outflow (jets)
• Disk outflow
• Single/repeated outflow episodes
• the stage of the PN evolution
• the motion of the PN though the ISM
• the motion of the CS wrt the nebula

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The PNe Catalogue
Madamina, il catalogo è questoDelle belle che
amò il padron mioun catalogo egli è che ho
fatt'ioOsservate, leggete con me.. Don
Giovanni, W.A. Mozart (1787)

• Starting point for our work the Strasbourg-ESO
  Catalogue (SEC), plus its Supplement.
• The SEC is the main compilation of PNe
  information available so far with 1500 objects
  (90 )
• Limiting magnitude of PNe in the SEC GSC-II one
  
• The SEC lists PNe detected in Radio, Optical, IR
  
• The SEC is a compilation of results from
  different works (surveys, pointed observations,
  serendipitous identifications)
• The SEC is non-homogeneous by definition

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I. Coordinates AssessmentGSC-II Astrometric
Catalogue

• Coordinates from SEC are highly uncertain
• Finding chart based recognition
• Problems in
• X-correlations
• (30 wrong mismatches)
• Proposal preparation
• Spectroscopy NO blind ACQ
• NF imaging (e.g. WFPC2,STIS)
• Never reassessed systematically !
• Good test case for the GSC-II

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II. PNe ClassificationGSC-II Morphological
Catalogue

• Determination of PNe position driven by its
  morphology
• CS
• CS is resolved (15)
• peak of the star PSF
• STELLAR
• PN is stellar-like (25)
• PHOTO center of the PNe
• NON STELLAR
• CS not resolved (45)
• PHOTO center of the PNe
• (could be ambiguous)
• EXTENDED
• CS ambiguous (15)
• GEOMETRIC center
• (arbitrary for asymmetric or
• irregular PNe)

CS
STELLAR
NON STELLAR
EXTENDED
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The Method

• Accuracy determined by the existence of an
  associated GSC-II counterpart
• GSC-II recalibrated DSS2 position used as a
  reference otherwise
• A SkyCat based Procedure set up to automatize
  DSS-II/GSC-II FC comparisons identifications
  implemented
• Objects classified (CS, STELLAR, NON-STELLAR,
  EXTENDED) and coordinates precision graded (A?
  D). Additional Notes.
• Only manual step in the project. Easy and not
  demanding.
• Good for coffee-breaks or after-work
• Easy student job but done independently by 4
  people
• Results X-checked 4 times

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Results

• Coordinates analyzed for 1528 PNe (Kerber et al.
  2003)
• Coordinates reassessed for 1312 PNe
• For 1086 PNe with GSC-II ctp (CS, STELLAR/NON
  STELLAR) 0.35
• For 226 PNe without GSC-II ctp (EXTENDED) lt 1
• 216 PNe discarded because
• No identification reference, e.g., no finding
  chart available
• Finding chart ambiguous, or wrong, or useless
• No DSS-II preview image of the field available
• No clear trend with objects brightness or shape
  or RA, DEC, as expected from a random
  distribution
• Larger positional offset found for PNe along the
  galactic plan ? probability of misidentification
  higher
• Revised PNe coordinates available via CDS with
  field preview and old/new coordinates
  overplotting
• New Standard for PNe coordinates

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PM of CS in Pne Sh 2-68

• Found in the GSC-II database
• Positions from 7 scans (6 different epochs over
  40 yrs) ? PM
• PM confirmed with follow-up observations from
  Calar Alto and LCO
• µ 53.2 /- 5.5 mas/yr SW (PA2026 deg) ?
  Largest PN PM measured from the ground (Kerber
  et al. 2002)
• One of the more precise, comparable to the ones
  obtained with Hipparcos (e.g. 62.8 2 mas/yr for
  A35)

LCO
DSS-II
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III. CSs/PNe Proper MotionsGSC-II Proper
Motion Catalogue

• The first and only PM survey of PNe is the one of
  Cudworth (1974) who found PM for 51 PNe.
• Most recent works using Hipparcos data (Acker et
  al. 1998) but only for very bright PNe
• Object selection for PM study according to
  previous classification i.e. only CS, STELLAR and
  NON STELLAR
• 1123 Objects
• GSC-II PMs still preliminar and incomplete until
  the next release (v2.3)
• Comparison with other PM catalogues
• Hipparcos V 12.4 2.5 mas/yr
• Tycho2 V15 5 mas/yr
• UCAC2 R16 5 mas/yr
• USNO-B F22 lt20 mas/yr

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PM compilations

• X-correlations of PNe with PM catalogues
• Hipparcos 22
• Tycho2 56
• UCAC-2 270
• USNO-B 174
• Differences due to different limiting magnitudes
  and/or PM completeness/sensitivity
• Creation of a master list of 389 PNe with entry
  in at least one catalogue
• 11 PNe X-match ALL catalogues
• 75 PNe X-match MULTIPLE catalogue
• 303 PNe X-match ONE catalogue only
• Consistency checks (e.g. on magnitude) and PM
  error reassessments
• Selection of Good samples (PM gt 3 s) ? 164 PNe
• PM grading according to the available X-matches

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Results

• ? 164 reliable PMs (Mignani et al. in prep.),
  i.e. the largest PM catalogue for PNe (3 x
  Cudworths)
• ? Confirmation of existing measurements, most of
  which never reassessed so far
• ? New PM measurements
• ? Reference for distance estimates and for
  PARALLAX measurements
• ? PM database for
• CS/PNe candidate association studies
• CS orbit computations
• CS nebula/ISM interactions studies

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IV. CSs/PNe Orbits

• PM coupled with PN distance and radial velocity
  to measure its galactocentric orbit
• Simulations using a galactic potential model
  (close encounters with other stars neglected)
• Test cases for a pilot study
• Different populations thin disk, thick disk
  (Kerber et al. 2004)
• More to come using our extended PM catalogue ?
  First systematic study!

NGC7239
Sh 2-216
IC 4593
Sh 2-174
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V. Interactions with ISM

• SHASSA (Southern H-Alpha Sky Survey)
• CTIO, 500 fields of 13x13 deg each, resolution
  47 arcsec/pixel, d lt 15 degrees
• VINT (Virginia Tech Spectral line Survey)
• UVT, 500 Fields of 10.2x10.2 deg each,
  resolution 1.6 arcmin/pixel, d gt -15 degrees
• WHAM (Wisconsin H-Alpha Mapper)
• Kitt Peak

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Sh 2-68

• Ha Observations from LCO
• Ha map from the SHASSA
• Elongated structure with PA21210 deg,
  consistent with the pm direction (2026 deg)
• Direct evidence of interaction with the ISM
  (Kerber et al. 2003)
• Extrapolating back the CS PM to the far end of
  the tail gives lower limit on the age
• More to come using our extended PM catalogue
• First systematic study!

5 arcmin

30 arcmin
CS (45 kyrs)
60 arcmin
CS (now)
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VI. SED of identified CSsGSC-II Photometric
Catalogue

• Optical-to-IR spectral coverage
• GSC-II Bj 22.5, F 22, N 19.5, V 14-19.5
• DENIS I 18.5, J 16.5, K 14
• 2MASS J 15.8, H 15.1, Ks 13.5
• Goals
• Object Classification ? validation of
  proposed/uncertain CS identifications
• (often, CS identifications are claimed on
  position only)
• WD parameters (T, g, chemical composition) ? PN
  properties
• Selection of CS with IR excess ? indicator of
  binary system

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The Method-In Collaboration with GAVO-

• Selection of a good CS sample
• Little contamination from the surrounding nebula
  (well expanded)
• No nearby back/foreground stars
• X-matches with reference catalogues ? Master List
  
• Mag 2 flux conversion ? Observed SED
• Comparison with theoretical SEDs from library of
  Model Spectra
• Correction for interstellar extinction
• Ad-hoc developed tools have been created in
  collaboration with GAVO German Astronomical
  Virtual Observatory - presented at ADASS 2004
  (Adorf et al. 2004)
• Nice user interface

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Catalogue Selection
Catalogue selection
Search radius
Closest/multiple match
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Production of Match-List
All in ONE table !
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Observation Data Preview
Mag 2 Flux conversion
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Model Data Preview
Unnormalized Fluxes
Model params
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SED Classifier Central
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Classification View
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Quick-look Chart
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VII. Search for unidentified CSs

• CS are unidentified for 30 of the EXTENDED
  PNe
• Goal MC-based identification of CSs in PNe
• Additional identification evidence from PM and/or
  from trails in the ISM
• Selection of PNe with candidate CSs from the
  revised Catalogue
• Automatic procedure to produce CMDs and observed
  SEDs (previous step) for all objects in a given
  searching box
• CSs identification through
• CMDs
• SED classification and comparison with SEDs of
  known CSs
• Identification of the CS ? constraints on the PN
  parameters

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Plus .

• The only limit is your imagination
• Just some back-of-the-envelope ideas
• Studying CS metallicity vs orbit (population
  dependance)
• Searching for connections between binarity and PN
  morphology
• Estimate PNe ages from CSs proper motions
• Correlate age with spectral parameters of the CS

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Conclusions

• High-quality science can be obtained with minimum
  effort, no time investment in proposal
  preparation and observations execution, data
  reduction
• Mining of existing catalogues available via CDS !
• Use of public image surveys !
• No use of telescope time !
• Fortran-based tool for objects X-correlations
  and shell scripts for lists administration !
• No use of powerful computing facilities !
• Most steps within reach of an amateur astronomer
  !
• Orbit computation software included in
  collaborations !
• SED simulations and classification code provided
  by AVO tools ? RECYCLABLE FOR OTHER SCIENTIFIC
  GOALS !
• Minimal amount of manual work and of time
  investment
• Scientific return ? the first comprehensive study
  to date of PNe properties
• A variety of scientific projects (I to VII)
• Easy to do ? Easy to expand personal scientific
  interests (I did)

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