Presentation Information
[O12-P101]Classification of asteroids discovered by COIAS
*Kiyoka Yokokawa1, *Shota Komi1, *Shunsuke Ochiai1 (1. Hokkaido University of Science High School)
Keywords:
Asteroids,COIAS,Spectral Type
1. Introduction
Asteroids are regarded as "time capsules" that preserve information from the early solar system, offering crucial clues to its evolutionary history. Furthermore, asteroid research is essential for planetary defense and the exploration of future space resources. COIAS (Come On! Asteroid Search) is a citizen science web application that enables users to detect and measure asteroids using archival images from the Hyper Suprime-Cam (HSC) on the Subaru Telescope. While COIAS has facilitated numerous new discoveries, many of these objects remain unclassified. This study aims to determine whether these newly discovered asteroids can be effectively categorized into spectral types using multi-band photometric data.
2. Methodology
We utilized Subaru/HSC imaging data available through COIAS. The classification was performed according to the following procedure:
- Selection: We selected candidate objects with unknown spectral types for which four-filter data (g, r, i, z) were available.
- Calculation: Color indices (g-r, r-i, g-z, z-i) were calculated for each object.
- Analysis: The color indices were plotted on two-color diagrams and compared with reference data of known asteroid taxonomies (Sergeyev and Carry, 2021) to determine their spectral types.
3. Results
Among the 100 provisionally designated objects discovered via COIAS, 18 were selected for analysis based on the criterion that the time interval between filter observations was sufficiently short to ensure high-precision color calculation. Based on the two-color diagrams, 10 objects were successfully classified:
- S-type or V-type: 6 objects
- S, V, or D-type: 2 objects
- S or D-type: 1 object
- C-type: 1 object
4. Discussion
The results indicate a prevalence of stony (S/V-type) and carbonaceous (C-type) asteroids among the sample. While the current sample size is statistically limited compared to the approximately 8,000 candidates in the COIAS database, the clustering within specific taxonomic regions suggests that consistent trends may emerge with a larger dataset. However, due to the inherent degeneracies in visible-light color space (e.g., between S and V-types), future spectroscopic observations and follow-up tracking are essential to validate these photometric classifications and refine our understanding of these new discoveries.
Acknowledgments
We would like to express our sincere gratitude to Mr. Kazuya Doi of the Graduate School of Hokkaido University for his invaluable guidance and advice throughout this study. His professional expertise in asteroid science and data interpretation provided us with insights that significantly deepened our discussion. We are truly grateful for his dedicated support and the time he spared for our research despite his busy academic schedule.
References
Sergeyev, A. V., & Carry, B. (2021). A catalogue of solar system objects observed by the Hyper Suprime-Cam Subaru Strategic Program. Astronomy & Astrophysics, 652, A59.
COIAS: https://web-coias.u-aizu.ac.jp
Small-Body Database Lookup: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/
Asteroids are regarded as "time capsules" that preserve information from the early solar system, offering crucial clues to its evolutionary history. Furthermore, asteroid research is essential for planetary defense and the exploration of future space resources. COIAS (Come On! Asteroid Search) is a citizen science web application that enables users to detect and measure asteroids using archival images from the Hyper Suprime-Cam (HSC) on the Subaru Telescope. While COIAS has facilitated numerous new discoveries, many of these objects remain unclassified. This study aims to determine whether these newly discovered asteroids can be effectively categorized into spectral types using multi-band photometric data.
2. Methodology
We utilized Subaru/HSC imaging data available through COIAS. The classification was performed according to the following procedure:
- Selection: We selected candidate objects with unknown spectral types for which four-filter data (g, r, i, z) were available.
- Calculation: Color indices (g-r, r-i, g-z, z-i) were calculated for each object.
- Analysis: The color indices were plotted on two-color diagrams and compared with reference data of known asteroid taxonomies (Sergeyev and Carry, 2021) to determine their spectral types.
3. Results
Among the 100 provisionally designated objects discovered via COIAS, 18 were selected for analysis based on the criterion that the time interval between filter observations was sufficiently short to ensure high-precision color calculation. Based on the two-color diagrams, 10 objects were successfully classified:
- S-type or V-type: 6 objects
- S, V, or D-type: 2 objects
- S or D-type: 1 object
- C-type: 1 object
4. Discussion
The results indicate a prevalence of stony (S/V-type) and carbonaceous (C-type) asteroids among the sample. While the current sample size is statistically limited compared to the approximately 8,000 candidates in the COIAS database, the clustering within specific taxonomic regions suggests that consistent trends may emerge with a larger dataset. However, due to the inherent degeneracies in visible-light color space (e.g., between S and V-types), future spectroscopic observations and follow-up tracking are essential to validate these photometric classifications and refine our understanding of these new discoveries.
Acknowledgments
We would like to express our sincere gratitude to Mr. Kazuya Doi of the Graduate School of Hokkaido University for his invaluable guidance and advice throughout this study. His professional expertise in asteroid science and data interpretation provided us with insights that significantly deepened our discussion. We are truly grateful for his dedicated support and the time he spared for our research despite his busy academic schedule.
References
Sergeyev, A. V., & Carry, B. (2021). A catalogue of solar system objects observed by the Hyper Suprime-Cam Subaru Strategic Program. Astronomy & Astrophysics, 652, A59.
COIAS: https://web-coias.u-aizu.ac.jp
Small-Body Database Lookup: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/