2018 Fiscal Year Annual Research Report
Establishing the zero point of near infrared photometry and the calibration of a standard star network
| Project/Area Number |
15K05019
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| Research Institution | The University of Tokyo |
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Principal Investigator |
福来 正孝 東京大学, カブリ数物連携宇宙研究機構, 上級科学研究員 (40100820)
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| Co-Investigator(Kenkyū-buntansha) |
鈴木 尚孝 東京大学, カブリ数物連携宇宙研究機構, 特任助教 (20722804)
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| Project Period (FY) |
2015-04-01 – 2019-03-31
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| Keywords | near infrared / AB magnitude / zero point / black-body stars |
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| Outline of Annual Research Achievements |
Our finding of 17 stars that show black body radiation is now published in Astronomical Journal. This was also reported at the International Astronomical Union General Assembly (2018) upon request from the Organising Committee of the Focus Meeting 17 We have studied the nature of these stars using atmosphere models of DB white dwarfs, and confirmed that they reproduce well the blackbody spectrum accurately if the temperature of the atmosphere is between 7000K and 12000K. This range is, in fact, the temperature of the stars we observed. At the same time we suggest that helium atmosphere is contaminated with hydrogen at the fraction of 10**(-6) to 10**(-7), which is not manifested in the spectra available to us today. This clarified the physical nature of the blackbody stars, and hence the blackbody should continue to the NIR region, and then indicates that we can take them as the photometric and spectrophotometric calibration standard stars in cgs(AB) units to the accuracy of 1\% in particular in the near infrared
(NIR) region which lacks in the flux calibration standards.
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