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VOSA - A VO Spectral Energy Distribution Analyzer The case of the

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					              Introduction
             User data file
                        Fit
              HR diagram
              Save results



                      VOSA
A VO Spectral Energy Distribution Analyzer
The case of the young cluster Collinder 69


        Carlos Rodrigo Blanco1,2
           Amelia Bayo Aran1
                          ´
            Enrique Solano1,2
       David Barrado y Navascues1
                              ´

                 1 LAEFF-CAB-INTA
          2 Spanish    Virtual Observatory


      IVOA interoperability meeting
     Baltimore, October 27-31, 2008
         C. Rodrigo Blanco    VOSA
                          Introduction
                         User data file
                                    Fit
                          HR diagram
                          Save results


Outline

  1   Introduction
         VOSA: A science case

  2   User data file
        VO photometry

  3   Fit

  4   HR diagram

  5   Save results


                     C. Rodrigo Blanco    VOSA
                           Introduction
                          User data file
                                     Fit   VOSA: A science case
                           HR diagram
                           Save results


Introduction

                   VOSA (VO Sed Analyzer)

      a web tool: http://svo.laeff.inta.es/theory/vosa
      designed to automatically determine physical parameters.
      of stellar objects from comparison with collections of
      theoretical models.
      for several objects at the same time.

      A difficult task without using the VO.
      Much easier using VO tools.


                      C. Rodrigo Blanco    VOSA
                         Introduction
                        User data file
                                   Fit   VOSA: A science case
                         HR diagram
                         Save results


Workflow

     Read user photometry-tables.
     Query VO photometry catalogs to improve/complete the
     observed SED.

     Fit observed data with theoretical spectra models from the
     VO and estimate physical parameters for the objects. (Chi-
     square test)

     Generate a Hertzsprung-Russel diagram using the esti-
     mated parameters and obtaining isochrones and evolution-
     ary tracks from the VO.

     Save results as VOTable, ASCII, png...


                    C. Rodrigo Blanco    VOSA
                          Introduction
                         User data file
                                    Fit   VOSA: A science case
                          HR diagram
                          Save results


A science case: Collinder 69

           The case of the young cluster Collinder 69
                  (Bayo et al, 2008 A&A, in press)


     IRAC photometry for 167 candidate members of C69.
     VO archival data research (multi-wavelength range).
     Four different collections of theoretical models (with TSAP
     and S3).
     Determination of the best physical parameters for the
     objects and the association (Teff , gravity, mass and age)

     A difficult task without using the VO.
     Much easier using VO tools.
                     C. Rodrigo Blanco    VOSA
                      Introduction
                     User data file
                                Fit   VO photometry
                      HR diagram
                      Save results


User and VO data.


      User and VO photometry data.

         Upload user photometry data.
         Query several photometry catalogs accessible
         through VO services
         (increases the wavelength coverage of the data
         to be analyzed).




                 C. Rodrigo Blanco    VOSA
                      Introduction
                     User data file
                                Fit   VO photometry
                      HR diagram
                      Save results


User data files




                 C. Rodrigo Blanco    VOSA
                        Introduction
                       User data file
                                  Fit   VO photometry
                        HR diagram
                        Save results


Available filters




                   C. Rodrigo Blanco    VOSA
                     Introduction
                    User data file
                               Fit   VO photometry
                     HR diagram
                     Save results


VO photometry




                C. Rodrigo Blanco    VOSA
                     Introduction
                    User data file
                               Fit   VO photometry
                     HR diagram
                     Save results


VO photometry




                C. Rodrigo Blanco    VOSA
                     Introduction
                    User data file
                               Fit   VO photometry
                     HR diagram
                     Save results


VO photometry




                C. Rodrigo Blanco    VOSA
                        Introduction
                       User data file
                                  Fit
                        HR diagram
                        Save results


Fit


      Fit observed data with theoretical models.

          Query VO-compliant theoretical models (spectra)
          and calculate their synthetic photometry.
          Determine which model reproduces best the
          observed data.
          Use the best-fit model to estimate, for each object:
              Values for Teff , Logg, metallicity
              Bolometric luminosity, using the model as a
              correction to the observed data



                   C. Rodrigo Blanco    VOSA
                 Introduction
                User data file
                           Fit
                 HR diagram
                 Save results


Model Fit




            C. Rodrigo Blanco    VOSA
                 Introduction
                User data file
                           Fit
                 HR diagram
                 Save results


Model Fit




            C. Rodrigo Blanco    VOSA
                 Introduction
                User data file
                           Fit
                 HR diagram
                 Save results


Model Fit




            C. Rodrigo Blanco    VOSA
                 Introduction
                User data file
                           Fit
                 HR diagram
                 Save results


Model Fit




            C. Rodrigo Blanco    VOSA
                 Introduction
                User data file
                           Fit
                 HR diagram
                 Save results


Model Fit




            C. Rodrigo Blanco    VOSA
                 Introduction
                User data file
                           Fit
                 HR diagram
                 Save results


Model Fit




            C. Rodrigo Blanco    VOSA
                       Introduction
                      User data file
                                 Fit
                       HR diagram
                       Save results


HR diagram


      Hertzsprung-Russel diagram.

         Use the Luminosity and Teff estimated in the fit.
         Obtain isochrones and evolutionary tracks from
         the VO.
         Interpolate them to estimate values for the Mass
         and Age of each object.




                  C. Rodrigo Blanco    VOSA
                  Introduction
                 User data file
                            Fit
                  HR diagram
                  Save results


HR diagram




             C. Rodrigo Blanco    VOSA
                  Introduction
                 User data file
                            Fit
                  HR diagram
                  Save results


HR diagram




             C. Rodrigo Blanco    VOSA
                        Introduction
                       User data file
                                  Fit
                        HR diagram
                        Save results


Save results


       Save results.

           VOTable, ASCII
           PNG for the images available.
           Download as tar file.




                   C. Rodrigo Blanco    VOSA
                    Introduction
                   User data file
                              Fit
                    HR diagram
                    Save results


Save results




               C. Rodrigo Blanco    VOSA
                         Introduction
                        User data file
                                   Fit
                         HR diagram
                         Save results


Future improvements


      The tool is done so that it is easy to

          Accept other filters
          Access more photometry catalogues in the VO.
          Use other theoretical model servers (spectra,
          isochrones and evolutionary tracks).




                    C. Rodrigo Blanco    VOSA
     Introduction
    User data file
               Fit
     HR diagram
     Save results




THANK YOU!




C. Rodrigo Blanco    VOSA

				
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posted:10/2/2011
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