Bibcode
Boersma, C.; Peeters, E.; Martín-Hernández, N. L.; van der Wolk, G.; Verhoeff, A. P.; Tielens, A. G. G. M.; Waters, L. B. F. M.; Pel, J. W.
Bibliographical reference
Astronomy and Astrophysics, Volume 502, Issue 1, 2009, pp.175-187
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7
2009
Journal
Citations
23
Refereed citations
22
Description
Context: Infrared (IR) spectroscopy and imaging provide a prime tool to
study the characteristics of polycyclic aromatic hydrocarbon (PAH)
molecules and the mineralogy in regions of star formation. Herbig Ae/Be
stars are known to have varying amounts of natal cloud material present
in their vicinity. Aims: Our aim is to study the characteristics
of the mid-IR emission originating in Herbig Ae/Be stars, especially the
extent of the emission and how this relates to the (proto-)stellar
characteristics. Methods: Today's powerful ground- and
space-based telescopes provide images and spectra at unprecedented
spectral and spatial resolution. We analyse the images and spectra from
four Herbig Ae/Be stars (IRAS 06084-0611,
CD-42 11721, TY CrA, and
HD 176386), as obtained with TIMMI2 on the ESO 3.6 m
telescope and VISIR on the VLT. These observations are supplemented with
data from ISO-SWS and Spitzer-IRAC. Results: We find evidence for
large-scale structure and extended emission in all four sources, except
for HD 176386, which only shows silicate emission, all sources show PAH
emission in their spectra. In addition, a spatially resolved silicate
and PAH spectrum could be extracted for TY CrA. Conclusions: The
variety in emission scales distinguishes two classes. In the first, the
morphology and spectral characteristics resemble those of reflection
nebulae. In the second, the characteristics are in-line with Herbig A
stars. This separation simply reflects a difference in stellar
characteristics (e.g. luminosity). In Herbig B stars, dust emission from
the surroundings dominates, where for Herbig A stars, the disk dominates
the emission. In this scheme, IRAS 06084-0611 and CD-42 11721 resemble
reflection nebulae and HD 176386 a more typical Herbig Ae/Be star. TY
CrA shows characteristics common to both genuine reflection nebulae and
Herbig B stars. We propose a geometry for TY CrA, with most notably, a
~70 AU inner gap in the 340 AU circumtertiary disk cleared by a fourth
stellar companion.
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Physics of Ionized Nebulae
The research that is being carried out by the group can be condensed into two main lines: 1) Study of the structure, dynamics, physical conditions and chemical evolution of Galactic and extragalactic ionized nebulae through detailed analysis and modelization of their spectra. Investigation of chemical composition gradients along the disk of our
Jorge
García Rojas