منابع مشابه
Ring Nebulae around Massive Stars throughout the HR Diagram
Massive stars evolve across the HR diagram, losing mass along the way and forming a variety of ring nebulae. During the main sequence stage, the fast stellar wind sweeps up the ambient interstellar medium to form an interstellar bubble. After a massive star evolves into a red giant or a luminous blue variable, it loses mass copiously to form a circumstellar nebula. As it evolves further into a ...
متن کاملUsing a Hipparcos Derived Hr Diagram to Limit the Metallicity Scatter of Stars in the Hyades – Are Stars Polluted?
Hipparcos parallaxes and proper motions have made it possible to construct Hertzsprung-Russell (HR) diagrams of nearby clusters with unprecedented accuracy. The standard deviation of high fidelity non-binary non-variable stars about a model stellar evolution isochrone in the Hyades cluster is about 0.04 magnitudes. We use this deviation to estimate an upper limit on the scatter in metallicities...
متن کاملSpectral classification and HR diagram for symbiotic stars in the galactic bulge
A sample of 45 symbiotic stars observed in the direction of the galactic bulge are classified in spectral type using TiO λ 6180, 7100 Å and VO λ 7865 Å absorption feature indices and visual comparison. The effective temperatures obtained are used together with K data from the literature to estimate the bolometric luminosity of the giant components if located at d=8.5 kpc. The (T eff , L/L ¤) pa...
متن کاملMaser studies in evolved stars
High resolution maps of maser emission provide very detailed information on processes occurring in circumstellar envelopes of late-type stars. A particularly detailed picture of the innermost shells around AGB stars is provided by SiO masers. Considerable progress is being made to provide astrometrically aligned multi-transition simultaneous observations of these masers, which are needed to bet...
متن کاملReprocessing the Hipparcos data of evolved stars
We analyze the K band luminosities of a sample of galactic long-period variables using parallaxes measured by the Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from measurements by COBE, and are corrected for int...
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ژورنال
عنوان ژورنال: Highlights of Astronomy
سال: 1992
ISSN: 1539-2996
DOI: 10.1017/s1539299600009898