M.Sc. in Astronomy, 1988, UNLP, Argentina, "CCD study of the dwarf galaxy D2
associated with NGC 3115"
Ph.D. in Astronomy, 1994, UNLP, Argentina, "Study of structural properties
and stellar populations in low surface brightness galaxies"
Current position: Researcher & Director, Complejo Astronomico El Leoncito (CASLEO),
Professor, Faculty of Astronomical and Geophysical Sciences,
University of La Plata (FCAyG-UNLP), Argentina
Personal page, outside GARRA
Since 1988 I have been working on topics related to galactic and
extragalactic stellar systems, as well as a few breakthroughs in Solar
System small bodies. These subjects include:
- Collaborations with GARRA members:
- Optical microvariability of Active Galactic Nuclei (AGNs). Intraday
variability of AGNs like quasars and BL Lac objects was discovered 10
years ago during extensive monitoring campaigns of large samples of
northern objects. The origin of these variations is still unknown. Shocks
propagating down the parsec-scale jet of the objects have been suggested
as a possible cause, but the most extreme cases of variability impose
severe constraints on the shock thickness and required Doppler factors.
Extrinsic models invoke gravitational microlensing. Since 1997 we have
made numerous observations of rapid flux variability in southern AGNs,
detecting many outstanding outbursts (including the observation of extreme
intranight events with amplitudes of up to 1.2 magnitudes in 24 hs). Since
2001, we have also made optical polarimetric observations of blazars,
detecting fast polarization variations in some objects.
- X-ray binaries (XRBs) are composed by a neutron star or a black hole
-the results of a supernova explosion- which orbit a normal star. These
sources are powered by the energy released when matter is transferred from
the normal star to its compact companion. I have collaborated in the
polarimetric study of LS 5039, a high-mass XRB with a microquasar
- Other works
- Dwarf galaxies, due to their low masses and sizes, are key objects for
the study of star formation in stellar systems. Largely outnumbering their
brighter counterparts, dwarfs are also main characters in evolutive
scenarios of clusters and groups of galaxies, involving mergers, stripping
and interactions. In several works on nearby clusters we have studied the
structure and stellar populations in dwarf elliptical galaxies; the
results include the first quantification of the luminosity vs. profile
shape relation for dwarfs, and the photometric detection of disk-like
features in dwarf ellipticals.
- Extragalactic globular clusters are excellent test particles to study
the kinematics and chemical properties in nearby galaxies out to large
galactocentric radii. We have made several observational studies of
Galactic globular clusters as well as extragalactic globular clusters
systems, involving photometry, polarimetry and medium-resolution
spectroscopy, which lead to the detection of dust in Milky Way clusters
and the possible identification of free-floating globulars in the Fornax
cluster of galaxies.
- Asteroids may contain dynamical and chemical information on the
origins of our Solar System. Between 1997 and 2001 I was involved in
astrometric and photometric studies of asteroids and centaurs.
- Between 1996 and 1997 I was Resident Astronomer at the Complejo
Astronůmico El Leoncito (CASLEO), the Argentinian astronomical facility
which operates a 2.15-m optical telescope. My main duties were:
instruments testing (CCD camera, two polarimeters, medium-resolution
spectrograph), software developing (under IRAF), creation and maintenance
of the web pages, and assitance to observers.