In my talk, I will mainly present our observational studies about LPVs, and finally, I will quickly show comparison of astrometric results between VLBI and Gaia. From the new observations, we aim to reveal evolution of LPVs from Miras to OH/IR stars. Gaia is a space observatory of the European Space Agency (ESA), launched in 2013 and expected to operate until 2025. The Gaia space mission of the European Space Agency ESA is constructing an ultraprecise three-dimensional map of our Milky Way galaxy, observing almost two billion stars or roughly one percent of. Miras are thought to be progenitors of OH/IR stars. Recently, we started VLBI observations towards OH/IR stars at 22GHz and also at 43GHz. By observing the Galactic Mira variables, we confirmed a PLR and reported it in Nakagawa et al. We have observed dozens of Mira variables showing typical pulsation periods of ~1 yr. The Gaia EDR3 uncertainties underlying the Gaia DR4 and Gaia DR5 predictions have been inflated by a factor 1.1 to correct for the fact that the external errors of the published astrometry in Gaia EDR3 (like in Gaia DR2) are typically 10 larger than the formal, published uncertainties. Initial interest of our study was a confirmation of Period-luminosity relation (PLR) of the Galactic Mira variable stars. In Kagoshima University, we have been conducting 22GHz astrometric VLBI observations of LPVs using a Japanese VLBI array VERA. For this reason, LPVs are important objects to understand chemical property and chemical evolution of our Galaxy and universe. Astrometric exoplanet detection with Gaia Full Record Related Research Abstract We provide a revised assessment of the number of exoplanets that should be discovered by Gaia astrometry, extending previous studies to a broader range of spectral types, distances, and magnitudes. Gaia delivers incredible precision on its measurements. Astrophysical parameters have been published in Gaia DR2 and a new set is expected to be released with the full Gaia DR3 release. ![]() They represent large mass loss ratio of 10^7 solar mass/yr, and sometimes it reaches 10^4 solar mass/yr. Gaia is an astrometry mission, meaning that it collects accurate positions, parallaxes, and proper motions for all sources to magnitude 20.7 in G band, and provides multi-color photometry and radial velocities for stars brighter than G 17 mag. Long period variables (LPVs) have initial mass of 0.8 to 8 solar mass and show stellar pulsation with typical periods of 100 to 1000 days. ![]() Location: Small Conference Room, 3rd Floor Akiharu Nakagawa (Kagoshima University, Japan) Title: VLBI astrometry of long period variables using VERA
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