We find that five sources listed in the new carbon star catalog are not really carbon-rich objects but oxygen-rich stars, because they all have the prominent 10μm silicate features in absorption and the 1612 MHz OH...We find that five sources listed in the new carbon star catalog are not really carbon-rich objects but oxygen-rich stars, because they all have the prominent 10μm silicate features in absorption and the 1612 MHz OH maser emission or/and the SiO molecular features. These objects were considered as carbon stars in the catalog based only on their locations in the infrared two-color diagram. Therefore to use the infrared two-color diagram to distinguish carbon-rich stars from oxygen- rich stars must be done with caution, because, in general, it has only a statistical meaning.展开更多
文摘We find that five sources listed in the new carbon star catalog are not really carbon-rich objects but oxygen-rich stars, because they all have the prominent 10μm silicate features in absorption and the 1612 MHz OH maser emission or/and the SiO molecular features. These objects were considered as carbon stars in the catalog based only on their locations in the infrared two-color diagram. Therefore to use the infrared two-color diagram to distinguish carbon-rich stars from oxygen- rich stars must be done with caution, because, in general, it has only a statistical meaning.