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Science with the VO: Spectroscopic studies of pre-main sequence stars

Deborah Baines European Space Astronomy Centre Science Archives and VO Team 5 th July 2011. Science with the VO: Spectroscopic studies of pre-main sequence stars. OUTLINE. Introduction: VO Tools: VOSpec and VOScript VOScript Science Case: Herbig Ae/Be stars. Building SEDs with VOSpec.

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Science with the VO: Spectroscopic studies of pre-main sequence stars

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  1. Deborah Baines European Space Astronomy Centre Science Archives and VO Team 5th July 2011 Science with the VO: Spectroscopic studies of pre-main sequence stars Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 1

  2. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 2 OUTLINE • Introduction: • VO Tools: VOSpec and VOScript • VOScript Science Case: Herbig Ae/Be stars • Building SEDs with VOSpec • Initial Results: SEDs and spectroscopic line analysis • Conclusions

  3. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 3 ISO PHT HST FOS IUE ISO LWS HST INES HUT EUVE Line fitting Polynomial fitting ESA VO TOOLS: VOSPEC • Create SED from spectra registered in the VO: • XMM, FUSE, IUE, HST, ESO (high resolution UVES), ISO…. • local data (FITS, VOT) • Multi-wavelength spectral analysis tool developed at ESAC by ESA-VO • Synthetic Spectra Tool • Uses the Spanish VO Filter Profile Service • More than 300 filters • Compare synthetic photometry with observed photometry • Analysis Tools: • Line fitting (Gaussian, Lorentzian, Voigt) • EW, Integrated flux & line flux calculations • Redshift correction • Spectral arithmetic and convolution between spectra. • De-reddening • Continuum fitting(BB, polynomial) • λ-to-ν conversion • Access to theoretical models registered in the VO • Access to atomic and molecular line databases

  4. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 4 VOSPEC EXAMPLE: HD 100546 ISO & HERSCHEL IUE HST FUSE PHOTOMETRY (VOSED) MODEL FITTING (Kurucz)

  5. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 5 ESA VO TOOLS: VOSCRIPT • The scripting counterpart of VOSpec: provides access from scripting interfaces to most VOSpec functionalities. • Being developed as a direct response from feedback from the astronomy community. • Jar Library  can be integrated with user pre-existent spectral analysis code in any language with Java Virtual Machine equivalent (C, Python, Jython, Tcl, Pascal, etc) or other jar libraries (STILTS). • Library includes a shell parsing module  can be called from the command line (c-shell, bash, etc), and integrated with pre-existing scripts in these languages. • Capabilities: • Search the VO for spectra from multiple targets. • Perform batch oriented analysis on a large number of spectra: VOSpec functionalities: EW, Line flux, Gaussian, etc. • SAMP interoperability. • Spectral Data Model 1.03 compliant, spectra format conversions.

  6. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 6 VOSCRIPT SCIENCE CASE: HERBIG AE/BE STARS Project Aim Using VOScript, VOSpec and other VO Tools (mainly TOPCAT/STILTS and VOSED): • Produce a database of line properties (EWs, FWHMs, velocities, profiles) for the pre-main sequence Herbig Ae/Be stars, from spectra within the VO. • Classify the SED types using spectra and photometry within the VO. • Analyse the results: What trends can be found? E.g. between Line Strengths, effective Temperatures, Accretion Rates, Line Profiles, SED types, etc.

  7. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 7 VOSCRIPT SCIENCE CASE: HERBIG AE/BE STARS Introduction to Herbig Ae/Be stars: • Intermediate-mass pre-main sequence stars (2 - 8 solar masses). • ‘e’ = emission. • B, A and F spectral types. • Similar characteristics to T Tauri stars (solar masses): • Irregular photometric & spectroscopic variability • Strong Hydrogen Balmer & other emission lines • Have a near- &/or far-IR excess • Located near the Zero Age main sequence in HR diagram.

  8. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 8 VOSCRIPT SCIENCE CASE: Why are Herbig Ae/Be stars interesting to study? • Star Formation: • HAEBEs bridge the gap between low-mass T Tauri stars and the optically invisible, near-IR faint Massive Young Stellar Objects (MYSOs). • It isherethat thestar formation mechanism switchesfrom magnetically controlled accretion from disks with inner holes (T Tauris) to accretion disks reaching directly onto the star (MYSOs). • Planet Formation: • HAEBEs are surrounded by circumstellar disks, believed to be the site of ongoing planet formation. Do planets form around all Herbig Ae/Be stars?

  9. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 9 Photometric points (VOSED): Tycho, Stromgrem, 2MASS & IRAS Spectra (VOSpec): FUSE, IUE, HST & ISO The SEDs of Herbig Ae/Be stars can be classified roughly into two groups (Meeus et. al. (2001) A&A 365, 476) SED CLASSIFICATIONS USING VO TOOLS

  10. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 10 Dullemond & Dominik (2004, A&A, 417, 159) disk models link shape of the SED to the disk geometry. SED CLASSIFICATIONS USING VO TOOLS • Group I Large flaring angle of outer disk • Group II Puffed up inner disk protects outer disk from direct stellar radiation

  11. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 11 Agree with Meeus et. al. (2001) A&A 365, 476 & Acke et. al. (2004) A&A, 426, 151. SED CLASSIFICATIONS USING VO TOOLS • Group I: • Group II:

  12. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 12 VOSCRIPT SCIENCE CASE: SPECTROSCOPIC LINEANALYSIS USING VO TOOLS • VOScript: • Searched the VO for spectra for a list of ~320 Herbig Ae/Be stars. • Calculated the Equivalent Widths of some strong spectroscopic lines in the IR, optical and UV. • Output are tables which can be loaded into TOPCAT. • TOPCAT (& STILTS): • Joined all VOScript output tables. • Cross matched with catalogues in the VO (including all of VizieR) for photometry, stellar parameters, line fluxes, etc. • Added the SED classifications determined using VOSpec and VOSED, and any classifications in catalogues. • Produced plots to compare spectroscopic lines, looking for trends and variability.

  13. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 13 EXAMPLE RESULTS: COMPARISON OF LINES • Comparing line strengths (EWs). See a trend for [CII] 158µm vs [OI] 63µm. • Comparing against the literature: Herschel observations and models of Pinte et. al. 2010, A&A, 518, L126

  14. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 14 EXAMPLE RESULTS: COMPARISON OF LINES & CATALOGUE DATA • Comparing line strengths at different wavelength regions (IR and UV), and against catalogue data (Valenti et al, 2003, ApJS, 147, 305). • Near-IR PAH are excited by UV-photons and proportional to the strength of the UV-field of the central star (Acke and van den Ancker, 2004, A&A, 426, 151). • PAH 6.2µm Equivalent Width vs log continuum flux at 2257 & 3060Å:

  15. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 15 EXAMPLE RESULTS: COMPARISON OF LINES & CATALOGUE DATA • PAH 6.2µm EW vs FeII 2362Å and FeII 2600Å line fluxes also show correlation (FeII lines from catalogue of Valenti et al, 2003):

  16. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 16 EXAMPLE RESULTS: COMPARISON OF LINES & SED TYPES • Comparing line strengths and SED types (from VOSpec SED classifications and SED classifications in catalogues). • Only observe Group I sources with [OI] 63µm

  17. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 17 EXAMPLE RESULTS: COMPARISON OF LINES & SED TYPES • Surprise result: [CII]158µm appear stronger in Group II sources than in Group I • Surprise result: [CII]158µm appear stronger in Group II sources than in Group I – Pinte et. al. (2010) disk models show that the line originates from larger radii and lower density regions than the [OI] IR lines.

  18. Science with the VO | Deborah Baines | JENAM 2011, St Petersburg | 5 July 2011 | Pag. 18 CONCLUSIONS • At ESAC, we are developing a scripting counterpart of VOSpec (VOScript) as a direct response from feedback from the astronomy community -> Multi target VO spectral searches, SED building and batch processing. • Using VOScript on various science cases: Project on Herbig Ae/Be stars at an early stage and linked with the development of VOScript: • Will allow the fast analysis of large numbers of spectra and targets, across a large wavelength range. • Using VOScript in combination with other VO Tools (mainly VOSpec, TOPCAT/STILTS and VOSED). • Initial Results: • Automatic searching of VO for spectra and fitting of lines. • SEDs and initial spectroscopic line analysis show good agreement with the literature. Interested? Contactdbaines@sciops.esa.int

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