AGB stars in Gaia DR2

2018 ◽  
Vol 14 (S343) ◽  
pp. 73-76 ◽  
Author(s):  
Thomas Lebzelter ◽  
Nami Mowlavi ◽  
Paola Marigo ◽  
Isabelle Lecoeur-Taibi ◽  
Michele Trabucchi ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Variable Stars ◽  
Light Curves ◽  
Agb Stars ◽  
Long Period ◽  
First Results ◽  
Period Variable ◽  
Photometric Index ◽  
Gaia Dr2 ◽  
And Chemical Properties

AbstractGaia Data Release 2 (DR2; April 25, 2018) provides astrometric and photometric data for more than a billion stars - among them many AGB stars. As part of DR2 the light curves of several hundreds of thousand variable stars, including many long-period variable (LPV) candidates, are made available. The publication of the light curves and LPV-specific attributes in addition to the standard DR2 products offers a unique opportunity to study AGB stars. In this contribution, we present the first results for AGB stars based on the analysis of the Gaia data performed after their release. As an immediate result of the Gaia DR2 LPV database we introduce a new photometric index capable of efficiently distinguishing AGB stars of different masses and chemical properties.

scholarly journals Theoretical Modes Fitting on Miras Light Curves

1993 ◽  
Vol 134 ◽  
pp. 139-140
Author(s):  
D. Barthés ◽  
Y. Tuchman ◽  
M. O. Mennessier ◽  
J. A. Mattei
Keyword(s):  
Power Spectrum ◽  
American Association ◽  
Variable Stars ◽  
Stellar Model ◽  
Light Curves ◽  
Long Period ◽  
Period Variable ◽  
The Common ◽  
Comparison Of The Results ◽  
Two Peaks

Visual observations of long period variable stars over 20 years were provided by the American Association of Variable Stars Observers, and were analysed as part of the preparation of the HIPPARCOS mission.A set of frequencies is extracted from the light curve by using Fourier transform, preliminary Van Cittert deconvolution and comparison of the results obtained through different kinds of spectral windows. The same procedure is applied to the residual obtained after nonlinear fit of the main frequency. After final comparison of both sets, a nonlinear fit of the common frequencies gives the ‘clean’ power spectrum.Different equilibrium stellar model (i) give theoretical linear nonadiabatic pulsation modes (vj) with their growth rates (ηj)i) (Tuchman 1978). The metallicity is taken between 0.005 and 0.02; the mixing length is λ = 1±0.2; the upper bound is r = 0.7. Assuming two peaks of the power spectrum to be the fundamental (vo) and first overtone (v1) modes, one looks for the corresponding models. The best one is selected by checking the other theoretical overtones they give. So are obtained the mass, the luminosity, the effective temperature and the effective radius of each star.

scholarly journals Physics and Evolution of LPVs from HIPPARCOS Kinematics

1999 ◽  
Vol 191 ◽  
pp. 117-122 ◽  
Author(s):  
M.O. Mennessier ◽  
R. Alvarez ◽  
X. Luri ◽  
M. Noirhomme-Fraiture ◽  
E. Rouard
Keyword(s):  
Variable Stars ◽  
Light Curves ◽  
Astronomical Data ◽  
Long Period ◽  
Period Variable

The HIPPARCOS satellite provides astronomical data for about one thousand Long Period Variable stars (LPVs) from which kinematics properties and luminosity calibrations in several bandpasses are deduced using an appropriate method. Several results are deduced: a classification of the LPVs and its relation with the classification from the light curves, a calibration of luminosities inducing properties (age, mass, etc.) along the AGB and a comparison of oxygen to carbon-rich stars.

scholarly journals Spectroscopy of Red Variables and Other Luminous Red Stars

1984 ◽  
Vol 108 ◽  
pp. 171-181 ◽  
Author(s):  
M. S. Bessell
Keyword(s):  
Planetary Nebula ◽  
Direct Evidence ◽  
Variable Stars ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Core Collapse ◽  
Agb Stars ◽  
Long Period ◽  
Period Variable ◽  
First Time

Long period variable stars represent the most advanced stage of asymptotic giant branch evolution prior to planetary nebula ejection or catastrophic core collapse. In the Magellanic Clouds through study of the LPVs it has been possible to identify for the first time, stars on the AGB with luminosities right up to the AGB limit (Mbol ~ −7.1) providing direct evidence that the more massive AGB stars produce supernovae. Because the stars have well defined periods, knowledge of the temperature and luminosity enables the mass to be derived. This review will highlight spectroscopic observations of the LPVs and discuss what information they provide on nucleosynthesis on the AGB in stars of different mass.

scholarly journals Properties of meteoroids from different classes of parent bodies

2006 ◽  
Vol 2 (S236) ◽  
pp. 107-120 ◽  
Author(s):  
Jiří Borovička
Keyword(s):  
Chemical Properties ◽  
Light Curves ◽  
Carbonaceous Chondrites ◽  
Meteor Showers ◽  
Long Period ◽  
Cometary Material ◽  
Physical And Chemical ◽  
Cometary Origin ◽  
And Chemical Properties

AbstractMeteoroids observed to disintegrate in the terrestrial atmosphere can be directly linked to their parent bodies in case that they belong to certain meteor showers. We present a list of two dozens of parent bodies reliably associated with well recognized meteor showers. Among the parent bodies are long period comets, Halley-type comets, Jupiter family comets, comets of the inner solar system (such as 2P/Encke) and asteroids. Physical and chemical properties of meteoroids coming from various parents are compared on the basis of meteor heights, decelerations, light curves and spectra. Jupiter family comets produce meteoroids with the lowest strength, namely porous aggregates of dust grains with bulk densities of about 0.3 g cm−3 or less. Halley type material is somewhat stronger and the material related to comet Encke is even stronger. In addition, small strong constituents, perhaps similar to carbonaceous chondrites, can be encountered within the normal cometary material. The strength of cometary material is also enhanced by long-term exposure to cosmic rays and by solar heating in the vicinity to the Sun (r<0.2 AU). Both these processes lead to the loss of volatile sodium. Southern δ-Aquariids, Geminids and partly also Quadrantids were influenced by solar radiation. We argue that these showers, the asteroids associated with them ((3200) Phaethon and 2003 EH1), and the whole interplanetary complexes they belong to are of cometary origin. The argument is supported by lower than chondritic Fe/Mg ratio found in Geminids as well as in Halley type comets. The typical property of stony meteoroids of asteroidal origin is the presence of internal cracks which cause that the incoming meteoroids are much weaker than the recovered meteorites.

scholarly journals Short and long period variable stars in the Carina dwarf Spheroidal galaxy

2004 ◽  
Vol 193 ◽  
pp. 133-137 ◽  
Author(s):  
M. Monelli ◽  
A.R. Walker ◽  
G. Bono ◽  
R. Buonanno ◽  
F. Caputo ◽  
...  
Keyword(s):  
Main Sequence ◽  
Variable Stars ◽  
Long Period ◽  
The Future ◽  
First Results ◽  
Period Variable ◽  
Red Giant

AbstractWe present first results concerning the detection of variable stars in the Carina dwarf Spheroidal from B, V images collected with the 4-m CTIO telescope. We show a sample of candidate variables spanning from the tip of the Red Giant Branch down to the Main Sequence turn off. Finally, we discuss the future photometric and spectroscopic developments of this project.

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