The galactic metallicity gradient Martín Hernández, Nieves Leticia

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1 The galactic metallicity gradient Martín Hernández, Nieves Leticia IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2002 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Martín Hernández, N. L. (2002). The galactic metallicity gradient: infrared and radio studies of H II regions Groningen: s.n. Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date:

2 RIJKSUNIVERSITEIT GRONINGEN The Galactic Metallicity Gradient Infrared and Radio Studies of H II regions PROEFSCHRIFT ter verkrijging van het doctoraat in de Wiskunde en Natuurwetenschappen aan de Rijksuniversiteit Groningen op gezag van de Rector Magnificus, dr. F. Zwarts, in het openbaar te verdedigen op vrijdag 13 december 2002 om 9.30 uur door Nieves Leticia Martín Hernández geboren op 23 juni 1975 te Santa Cruz de La Palma, Spanje

3 Cover: Digital image created by Carlos Álvarez using the GNU Image Manipulation Program (GIMP).

4 Contents 1 Introduction H II regions: the nurseries of stars An overview of the physical processes in H II regions The forbidden spectrum of H II regions H II regions in the Galactic context In this thesis An ISO spectral catalogue of compact H II regions Introduction Observations The sample The SWS observations The LWS observations Data reduction SWS data reduction LWS data reduction Extended source calibration Line fluxes Gaussian fits Error budget Influence of source morphology and size Comparison with other instruments Comparison with KAO Comparison with IRAS Properties of the H II regions Kinematic distances Morphology Luminosity Notes on individual sources The catalogue of combined SWS-LWS spectra Atomic emission lines Molecular emission lines Dust content

5 6 CONTENTS Ice content Conclusions A Line fluxes and combined SWS-LWS spectra The Galactic metallicity gradient from ISO spectral observations of compact H II regions Introduction Extinction H I recombination lines method Comments on individual sources Density [O III] diagnostic [S III] and [Ne III] diagnostics Abundance determinations: methodology Photoionization models Ionization state Abundances N ++ /O ++ and N/O N/H Ne/H, S/H and Ar/H Comparison of abundance gradients with previous studies Summary The stellar content, metallicity and ionization structure of H II regions Introduction The sample Variations in the ionization structure Influence of the SEDs Influence of the metallicity The case of starburst galaxies Summary and conclusions A radio continuum and infrared study of Galactic H II regions Introduction Observations and data reduction Extended emission Contour maps and description of sources Comments on individual sources The linear feature in IRAS VLA data Physical properties of the ionized gas The n e D relation Stellar content Combining ISO and radio observations Extinction in the near infrared Extinction in the mid infrared

6 Elemental abundances The elemental abundance gradient Stellar luminosity, metallicity and nebular ionization structure Summary and conclusions Metallicity and the spectral energy distribution of O stars Introduction Description of the models Comparison with other model atmosphere codes The spectral energy distribution Comparison of predicted EUV fluxes Comparison of ionizing fluxes EUV fluxes and Q 0 and Q 1 values as a function of metal content Spectral classification Optical classification K-band classification The ionizing structure of single star H II regions Conclusions A VLT spectroscopic study of the compact H II region G Introduction Observations Results The recombination lines Applications The ionizing star of G The dynamics of G The stellar bow shock model The champagne flow model Final remarks Summary Conclusions and future work 209 Nederlandse Samenvatting (Summary in Dutch) 213 Summary in English 227 Bibliography 241 Published papers 251 Acknowledgments 253

7 Promotor: Prof. dr. A. G. G. M. Tielens Referent: Dr. P. R. Roelfsema Beoordelingscommissie: Prof. dr. E. Churchwell Prof. dr. D. Schaerer Prof. dr. J. M. van der Hulst

8 Let s go and see the stars The Milky Way or even Mars Where it could just be ours Let s fade into the Sun Let your spirit fly Where we are one Just for a little fun From the song Fly Away by Lenny Kravitz To Carlos

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