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Late-type Giants in the Inner Galaxy
and kinematics of its gas and stars can be studied in unique detail due to
their relative proximity. However, being located well within the Galactic disk
and thereby observing the Milky Way in nonlinear projection makes it difcult
to properly map its large-scale morphology.
One of the interesting ndings has been that observations of molecular line
emission (CO, HI) and stellar motions show signatures of a Galactic Bar in the inner
Galaxy. However, its characteristics such as elongation, thickness and viewing
angle are still poorly constrained. One of the main obstacles has been the
strong obscuration by interstellar dust toward the inner Galaxy, which makes
optical studies of the stellar population in that region almost impossible. The
extinction is less severe at near- and mid-infrared wavelengths. To characterise
the structure and...Show moreThe Milky Way is the cornerstone of our understanding of galaxies. The structure
and kinematics of its gas and stars can be studied in unique detail due to
their relative proximity. However, being located well within the Galactic disk
and thereby observing the Milky Way in nonlinear projection makes it difcult
to properly map its large-scale morphology.
One of the interesting ndings has been that observations of molecular line
emission (CO, HI) and stellar motions show signatures of a Galactic Bar in the inner
Galaxy. However, its characteristics such as elongation, thickness and viewing
angle are still poorly constrained. One of the main obstacles has been the
strong obscuration by interstellar dust toward the inner Galaxy, which makes
optical studies of the stellar population in that region almost impossible. The
extinction is less severe at near- and mid-infrared wavelengths. To characterise
the structure and formation history of the Milky Way, several infrared surveys
were conducted during the past decade: ISOGAL, MSX, DENIS, 2MASS. These
data contain a wealth of information on the structure of the stellar populations
that has yet to be fully analysed. Having entered a golden age for Galactic astronomy,
soon even more detailed imaging and spectroscopy will be provided by
the Spitzer Space Telescope, while the GAIA satellite will provide unprecedented
astrometry.
My thesis research has focused on the structure and stellar population of the
inner 4 kpc of the Milky Way. I have analysed data from recent infrared surveys
and obtained SiO radio maser line observations of late-type giants to study the
star formation history and the gravitational potential of the inner Galaxy. With
ages ranging from less than 1 to 15 Gyr, the infrared-luminous late-type giant
stars are representative of the bulk of the Galactic stellar population, and hence
trace its star formation history. Their spatial abundance variation maps the stellar
mass distribution, and thereby probes the Galactic gravitational potential. The
reddening of their spectral energy distribution can be used to map the interstellar
extinction. Their envelopes often emit strong molecular masers (OH, SiO) that
can be detected throughout the Galaxy, and through the precise measurement of
the maser line velocity they reveal the stars' line-of-sight velocities. Therefore
they are ideal tracers of the Galactic kinematics and gravitational potential.Show less
- All authors
- Messineo, M.
- Supervisor
- Habing, H.J.
- Committee
- Lub, J.; Burton, W.B.; Cioni, M.R.; Kuijken, K.H.; Menten, K.M.; Omont, A.; Zeeuw, P.T. de
- Qualification
- Doctor (dr.)
- Awarding Institution
- Leiden Observatory , Faculty of Science , Leiden University
- Date
- 2004-06-30
Juridical information
- Court
- LEI Universiteit Leiden