Scientific work and research
interests
(Klaus-Peter Schroeder)
Most of the past 20 years of my scientific career have been devoted
to both observational and theoretical astrophysics, especially to
interesting problems in connection with highly evolved giant stars (including
the distant fate of Earth when the Sun will have become a giant, the
astronomical "doomsday" scenario), stellar activity, heavy mass-loss and
the consequences for the evolution of galaxies:
How well can we 'calibrate' stellar evolutionary tracks and
lifetimes? - Critical empirical quantification of
post-MS stellar evolution, using wide binaries with giant
primaries and characteristic star counts in the solar neighbourhood
HR diagram.
How far does stellar activity (of single stars) and coronal
plasma "survive" into late stellar evolution, what are the
related changes of chromospheric structure, and in which way does it
depend on stellar mass and evolution?
What exactly happens in the final 10^5 yrs on the AGB?
- Consistent computations of intermediate mass, tip-AGB evolution
in the presence of heavy mass-losses, derived from state-of-the-art
hydrodynamic models of dust-driven ("super-") winds.
What are the galactic gas and dust (re-)injection rates
of the stellar
component for a given chemistry, IMF and SFR-history? - A
quantitative contribution to galaxy evolution by using synthetic
HRD's and detailed mass-loss models.
My future research plans are focusing on two topics:
Galactic archeology: what can we learn from counting (old) stars?
Galactic astrophysics will make a quantum leap once the far-reaching
astrometric and photometric data of the DIVA and GAIA missions become
available. I prepare for a robust, quantitative interpretation by means
of comparing synthetic stellar samples with the observed records
(i.e., counts of stars and giants in complete, volume-limited
samples, discriminating for age and z-value), presently still
coming from the Hipparcos Catalogue. This approach yields the
IMF (initial mass function) and SFR (star formation rate) history
of the galactic disk stellar component, as well as structure,
dynamics and evolution of the galactic disk.
"Superwinds", mass-loss rates, PNe, and the future of the Sun:
Detailed theoretical models of tip-AGB stellar evolution
in the presence of heavy mass-loss ("superwind") give the
total mass lost by a single star, as a function of its mass (see
Fig. below). From the mass-loss histories, PN density profiles can be
derived, and, in particular for the case of the Sun, a survival prognosis
for planets can be given from the radii of the stellar models for these
last giant stages - i.e. to discuss the distant future of Earth or the
chances of finding Planets around White Dwarfs.
Aditionally, I keep an interest in stellar activity among highly evolved
stars - here, the Hamburg Robotic Telescope will provide new insight
with a wealth of high resolution spectra over the next decade.
Fig.: Total mass lost by a giant star on the RGB (front), on the AGB
(middle), and during its final 30,000 years (superwind, back),
as a function of the initial stellar mass.
Observational experience
In the past 20 years, I have gained hands-on experience in all standard
ground-based observing techniques and their data processing, as well as
with space-born missions, including (repeatedly):
High resolution spectroscopy with CoudeŽ spectrograph and
CCD-camera at ESO (CAT), Calar Alto (2.2 m) and Lick (CAT, echelle).
Space-born observations, as a frequent PI, with IUE
(low and high resolution UV
spectra) and ROSAT (deep PSPC X-ray exposures).
Direct CCD imaging, including deep UBV photometry, at the
ESO 1.5 m and other telescopes.
Conventional UBV photometry at the Calar Alto 1.2 m,
the Lick 0.6 m, and many other telescopes.
Conventional wide-field Schmidt photography (on hypersensitised plates)
for survey purposes, with and without objective prism at the Calar Alto
Schmidt.
I also take part, as a Co.I., in projects based on HST (GHRS) and SOHO (SUMER)
observations. In the more recent years I have temporarily reduced my
observing activities to invest more time into valuable
theoretical "tools" - i.e., stellar evolution and mass-loss models -
which now supply a strong background and motivation for my future observing
plans.
Other experience - i.e., lecturing, science-management,
technical
From 1986 to 1992, as an assistant professor at the University
of Hamburg, I gave a variety of astrophysical lectures. I continued
lecturing at the Technical Universities of Braunschweig and, presently, Berlin.
I received the German university-lecturing qualification 'Habilitation'
in 1993 at the University of Hamburg. Altogether, I have a university-lecturing
experience of more than 10 years.
From 1986 to 1992, I was also heavily involved in science management
for the spectroscopy group at Hamburg Observatory, including
internal organisation
of team work, soft-money dependent projects, observing campaigns and
the supervision of various PhD projects. Presently,
I supervise graduate students and PhD work at the
Technical University of Berlin.
In 1993/94, as a senior research associate at the optical department of
the 'Physikalisch-Technische Bundesanstalt' in Braunschweig (Germany),
I worked for an EEC project on microscopic measurements with
nm-accuracy and studied the diffraction effects at edges of a pronounced
profile. Beside some work with near-field diffraction models,
I particularly gained valuable experience in contemporary optical and
opto-electronic technology.
My time at the University of Sussex (Jan. 2000 to Sept. 2005) and my
two years (1994 to 1996) at the Institute of Astronomy (Cambridge, UK),
plus many research visits to Cambridge (including 6 months in 1992 as a
visiting scolar of St. John's College) were not only very valuable
for me scientifically - I also treasure my time in the UK
as an important social and cultural life experience. Now, I'm working
at the University of Guanajuato, Departamento de Astronomia and again
enjoy the different culture and a very friendly team of colleagues!