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Infrared emission features: probing the interstellar PAH population and circumstellar environment of Herbig Ae/Be stars

11 December 2009

PhD Ceremony: C. Boersma, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Infrared emission features: probing the interstellar PAH population and circumstellar environment of Herbig Ae/Be stars

Promotor(s): prof.dr. A.G.G.M. Tielens, prof.dr. L.B.F.M. Waters

Faculty: Mathematics and Natural Sciences

Contact: Christiaan Boersma, tel. 050-363 4087, e-mail:

PAHs are omnipresent and provide an excellent probe to study the multitude of objects spanning the Universe. Specifically in regions of star and planet formation, PAHs help disentangle the large-scale structure of the area. PAH stands for Polycyclic Aromatic Hydrocarbon and they constitute a family of large chicken-wire shaped molecules made up from carbon and hydrogen. On Earth they are commonly found in the combustion products from fossil fuels. PAHs form the transition zone from micron-sized dust particles to molecular sized 'gas'. PAHs are unique in two ways. First, they fluorescence under the absorption of an ultraviolet photon, allowing them to be seen in very cold regions, far away from their illuminating sources. Second, with the complexity these molecules represent, they may well have played a key role in the emergence of life itself. Using state-of-the-art space- and ground-based observatories like e.g., Spitzer and the 10-meter class telescopes at Chili, the PAH emission towards intermediate-mass forming stars has been investigated. Both through imaging and spectroscopy, morphological and evolutionary aspects of the PAH emission have been determined.

The NASA Ames PAH IR Spectroscopic Database is a collection of over 600 calculated and some 200 experimentally determined spectra. This unique database will be made available end 2009. Utilising this database a systematic search for possible candidates responsible for the observed emission in two, to-date, not well studied regions of the PAH spectrum was made.

Last modified:15 September 2017 3.38 p.m.
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