UvA-DARE (Digital Academic Repository) Dusty disks around young stars Verhoeff, A. Publication date 2009 Document Version Final published version Link to publication Citation for published version (APA): Verhoeff, A. (2009). Dusty disks around young stars. General rights 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), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:06 Oct 2021 Dusty Disks around Dusty Disks around Stars are formed through the collapse of giant molecular clouds.. During this contraction the matter spins up and naturally forms a circumstellar disk.. OnceOnce accretionaccretion comescomes toto aa halt,halt, thesethese disksdisks arare relatively stable.. SomeSome disksdisks areare kknown to last up to 10 Myrs.. MostMost disks however,, dissipatedissipate onon shorshorter time scales under the inuence of photoevaporation and planet formation. These disks,, consistingconsisting of 99% gas and 1% dust, have revealed a high variety of dust composition and geometry.. IIt is not clear what determines this variety and if higher mass stars also display this variety.. InIn thisthis thesisthesis we analyzed a large sample of young stars,, coveringcovering aa massmass rangerange of ~2 to ~20 solar masses.. MMidid infraredinfrared imagingimaging andand specspectroscopy have been obtained, to determine their composition and geometry. The results were placed in a multi-wavelength context as provided Y Y oung Stars oung Stars by the literature and a survey for any possible trends was carried out. In addition, case studies were perfoformed of two special stars.. Comprehensive data sets were gathered and a radiative transfer code was used to create detailed models of their disk geometry. Arjan Arjan Dusty Disks around Dusty Disks around Verhoe Verhoe Y Y oung Stars oung Stars Arjan Arjan Verhoe Verhoe Dusty Disks around Young Stars Arjan Verhoe Dusty Disks around Young Stars Academisch Proefschrift ter verkrijging van de graad van doctor aan de Universiteit van Amsterdam op gezag van de Rector Magnificus prof. dr. D. C. van den Boom ten overstaan van een door het college voor promoties ingestelde commissie, in het openbaar te verdedigen in de Agnietenkapel op dinsdag 10 november 2009, te 12:00 uur door Arjan Verhoeff geboren te Soest Promotiecommissie Promotores Prof. dr. L. B. F. M. Waters Prof. dr. A. G. G. M. Tielens Co-promotor Prof. dr. J. W. Pel Overige leden Dr. E. Pantin Dr. M. Min Dr. M. van den Ancker Prof. dr. A. de Koter Prof. dr. C. Dominik Prof. dr. M. B. M. van der Klis Faculteit der Natuurwetenschappen, Wiskunde en Informatica Cover Illustration: Artist impression of a dusty disk around a young star. Credit: NASA/JPL- Caltech. Contents 1 Introduction 9 1.1 Homo Astronomiae . 9 1.2 Star and Planet Formation . 9 1.3 Protoplanetary Disks . 10 1.3.1 Structure . 12 1.3.2 Composition . 14 1.3.3 Evolution . 16 1.4 Diagnostics . 18 1.4.1 Observations . 18 1.4.2 VISIR . 20 1.5 Questions . 24 2 VISIR spectroscopic and spatial survey of Herbig Ae stars 27 2.1 Introduction . 28 2.2 Sample . 30 2.2.1 Selection . 30 2.2.2 Stellar parameters . 31 2.2.3 SEDs and IR-excess . 31 2.3 Observations . 33 2.3.1 VISIR . 33 2.3.2 ISO, Spitzer & TIMMI2 . 33 2.4 Data Reduction . 34 2.4.1 Spectral extraction . 34 2.4.2 FWHM extraction . 35 2.5 The PSF . 36 2.6 Results . 41 2.6.1 Spectra . 41 2.6.2 Spatial extension of science targets . 44 2.6.3 Comparing flux and extent . 47 2.7 Analysis . 47 2.7.1 Feature strength . 47 2.7.2 Deconvolution of the continuum . 52 2.7.3 Deconvolution of the PAH-features . 52 2.8 Discussion of individual stars . 54 2.9 Discussion . 60 5 6 Contents 2.9.1 PAH and silicate strength . 62 2.9.2 Disk sizes in the continuum . 63 2.9.3 Disk sizes in PAH emission . 64 2.10 Conclusions . 65 3 A mid IR study of Herbig Be stars 67 3.1 Introduction . 67 3.2 Sample . 69 3.2.1 Selection . 69 3.2.2 SEDs . 72 3.2.3 Stellar parameters . 72 3.3 Observations . 75 3.3.1 Imaging . 75 3.3.2 Spectroscopy . 76 3.4 Data reduction . 76 3.5 Analysis of the images . 79 3.5.1 Photometry . 79 3.5.2 Spatial emission profile . 84 3.6 Analysis of the spectra . 88 3.6.1 Extinction correction . 88 3.6.2 Compositional fits . 88 3.6.3 Spatial extent . 90 3.6.4 Differential extractions . 93 3.7 Discussion . 95 3.7.1 IR-excess . 95 3.7.2 PAHs . 97 3.7.3 Silicates . 99 3.7.4 IR extent . 101 3.7.5 Relation to B[e] and classical Be stars . 101 3.7.6 Emerging picture . 102 3.8 Conclusions . 103 4 HD 95881: A gas rich to gas poor transition disk? 105 4.1 Introduction . 105 4.2 Stellar parameters . 108 4.3 Observations . 108 4.3.1 AMBER . 108 4.3.2 VISIR imaging . 109 4.3.3 VISIR spectroscopy . 109 4.3.4 MIDI . 109 Contents 7 4.3.5 Additional data . 110 4.4 Analysis . 110 4.4.1 AMBER . 110 4.4.2 [O I] data . 112 4.4.3 Spitzer . 113 4.4.4 VISIR imaging . 113 4.4.5 VISIR spectroscopy . 115 4.4.6 MIDI . 117 4.4.7 Observational picture . 118 4.5 Modeling . 120 4.5.1 Initial constraints . 120 4.5.2 Fitting the SED . 121 4.5.3 Spatial distribution of the gas . 122 4.5.4 Final model . 123 4.6 Discussion . 124 4.6.1 Comparison of the model with the observations . 124 4.6.2 The distribution of gas and dust . 126 4.6.3 Context . 126 4.6.4 PAH emission . 127 4.7 Conclusions . 127 5 The complex circumstellar environment of HD 142527 129 5.1 Introduction . 129 5.2 Stellar Parameters . 130 5.3 Observations and data reduction . 132 5.3.1 SEST . 132 5.3.2 ATCA . 133 5.3.3 VISIR imaging . 134 5.3.4 VISIR spectroscopy . 135 5.3.5 Additional data . 136 5.4 Analysis of the millimeter data . 136 5.5 Analysis of the Spitzer spectrum . 137 5.6 VISIR imaging analysis . 138 5.6.1 The observed images . 138 5.6.2 Central component subtraction . 139 5.6.3 18.72 versus 24.5 µm . 140 5.6.4 Deconvolution . 141 5.7 VISIR spectroscopy analysis . 144 5.7.1 N-band . 144 8 Contents 5.7.2 Q-band . 145 5.8 Modeling . 148 5.8.1 Fitting the observations . 148 5.8.2 Final Model . 150 5.9 Discussion . 151 5.9.1 Comparison of the model with the observations . 151 5.9.2 General picture . ..