Up: Abstract
Astron. Astrophys. Suppl. Ser. 140, 55-67
Period-Luminosity-Colour distribution and classification
of Galactic oxygen-rich LPVs![[*]](/icons/foot_motif.gif)
I. Luminosity calibrations
D. Barthès1 - X. Luri1 - R. Alvarez2 -
M.O. Mennessier3
1 - Departament d'Astronomia i Meteorologia, Universitat de Barcelona,
Avda. Diagonal 647, E-08028 Barcelona, Spain
2 -
Institut d'Astrophysique, CP 226, Université Libre de
Bruxelles, Bd. du Triomphe, B-1050 Bruxelles, Belgium
3 -
GRAAL (UPRES-A 5024 CNRS), Université Montpellier II,
F-34095 Montpellier Cedex 05, France
Received February 24; accepted September 6, 1999
Abstract:
The absolute
K magnitudes and kinematic parameters of about 350
oxygen-rich Long-Period Variable stars are calibrated, by means of an
up-to-date maximum-likelihood method, using H
IPPARCOS parallaxes
and proper motions together with radial velocities and, as additional
data, periods and
V-
K colour indices. Four groups, differing by
their kinematics and mean magnitudes, are found. For each of them, we also
obtain the distributions of magnitude, period and de-reddened colour of the
base population, as well as de-biased period-luminosity-colour relations
and their two-dimensional projections. The SRa semiregulars do not seem to
constitute a separate class of LPVs.
The SRb appear to belong to two populations of different ages. In a PL
diagram, they constitute two evolutionary sequences towards the Mira
stage. The Miras of the disk appear to pulsate on a lower-order mode. The
slopes of their de-biased PL and PC relations are found to be very different
from the ones of the Oxygen Miras of the LMC. This suggests that a significant
number of so-called Miras of the LMC are misclassified. This also suggests
that the Miras of the LMC do not constitute a homogeneous group, but include
a significant proportion of metal-deficient stars, suggesting a relatively
smooth star formation history. As a consequence, one may not trivially
transpose the LMC period-luminosity relation from one galaxy to the
other
![[*]](/icons/foot_motif.gif)
.
Key words: stars: variables: long period variables -- AGB --
fundamental parameters -- kinematics -- evolution
Up: Abstract
Copyright The European Southern Observatory (ESO)