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Title: Period-Luminosity-Colour distribution and classification of Galactic oxygen-rich LPVs I. Luminosity calibrations
Author: Barthès, D.
Luri Carrascoso, Xavier
Alvarez, R.
Mennessier, M. O.
Keywords: Evolució estel·lar
Cinemàtica galàctica
Stars: variables: long period variables
Fundamental parameters
Issue Date: 1999
Publisher: EDP Sciences
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 HIPPARCOS 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.
Note: Reproducció del document publicat a
It is part of: Astronomy and Astrophysics Supplement Series, 1999, vol. 140, p. 55-67.
ISSN: 0365-0138
Appears in Collections:Articles publicats en revistes (Física Quàntica i Astrofísica)

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