A silicate carbon star is a carbon star which shows circumstellar silicate dust features. We col- lect a sample of 44 silicate carbon stars from the literature and investigate the validity of the classification. For some objects, it is uncertain whether the central star is a carbon star. We confirm that 29 objects are verified silicate carbon stars. We classify the confirmed objects into three subclasses based on the evolution phase of the central star. To investigate the effect of the chemical transition phase from O to C, we use the radiative transfer models for the detached silicate dust shells. The spectral energy distributions and the infrared two-color diagrams of the silicate carbon stars are compared with the theoretical model results. For the chemical transition model without considering the effect of a disk, we find that the life time of the silicate feature is about 50 to 400 years depending on the initial dust optical depth.

Abstract
1. INTRODUCTION
2. SAMPLE COLLECTION AND CONFIRMATION
    2.1. The CGCS Counterparts
    2.2. The Sample Stars without CGCS Couterparts
    2.3. Two-Color Diagrams
3. UNCONFIRMED OBJECTS
4. SUBCLASSES OF SCSS
    4.1. The Silicate Features at 10 μm
5. DUST SHELL MODELS FOR THE CHEMICAL TRANSITION PHASE
    5.1. Radiative Transfer Model Calculations
    5.2. Basic Model Parameters
    5.3. The Model Setup
    5.4. Evolution of the Silicate Feature
6. TWO-COLOR DIAGRAMS
7. DISCUSSION
8. SUMMARY
REFERENCES

• KYUNG-WON SUH(Department of Astronomy and Space Science, Chungbuk National University) CORRESPONDING AUTHOR
• YOUNG- JOO KWON(Department of Astronomy and Space Science, Chungbuk National University)