I. CS towards the young stellar objects:
The CS molecule is well
suited to trace the physical structure of
the protostellar cores. An important question,
however, is whether the CS abundance in these dense regions is changed
relative to the normal interstellar values. Evidence for a
decreased CS abundance in the disk
structure around HL Tauri was recently reported in the literature. It
indicates a strong interaction between the molecules and the grain surfaces
through transformation of molecules by chemical reactions and depletion of gas
phase molecules onto grain mantles at high densities.
With the JCMT and IRAM, I measured several CS transitions in
some high-mass and some low-mass young stellar objects. This project
was processed in colaboration with a research group of the Leiden University,
especially with Prof. E.F. van Dishoeck and F. P. Helmich.
For more details see:
Schreyer K., Helmich F.P., van Dishoeck E.F., Henning Th.,
A molecular line and infrared study of NGC 2264 IRS1,
1997, A&A 326, 347 and
Schreyer K., Henning Th., van der Tak F.,
Boonman A., van Dishoeck E.F.,
The young intermediate-mass stellar object AFGL 490 -
A disk surrounded by a cold envelope
2002, A&A, 394, 561-583
II. Reduction of line measurements in Orion-KL ''hot core'':
The Kleinmann-Low infrared nebula in the Orion molecular
cloud is the most-studied high-mass star-forming
region in the Galaxy (distance 500pc). In a region of 15"x15",
Downes et al. (1981) found 9 infrared sources.
IRc2 is the main energy source of this region and most
prominent in the mid-infrared. The central question is still discussing
in the literature: What is the origin of the source of its
large luminosity (1e+5 Lo).
I reduced line measurements of this region which were measured with the
Plateau de Bure Interferometer. This work was supervised by Dr.
R. Güsten from the Max-Planck-Institut für
Radioastronomie in Bonn.
Schreyer, K., Henning, Th. , Wiesemeyer, H.,
High-resolution submm/mm interferometry
of the Orion-KL region,
In: The Orion Complex Revisited,
ASP Conference Series, Vol 999,
1999, M.J. McCoughrean
Downes D., Genzel R., Becklin E., Wynn-Williams C.G., 1981,
Astrophy. Journal 244, 869