Establishing the zero point of near infrared photometry and the calibration of a standard star network

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K05019
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: The University of Tokyo
• Principal Investigator: FUKUGITA Masataka 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)
• 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)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: near infrared / AB magnitude / zero point / black-body stars

Outline of Final Research Achievements

In the quasar target-candidate catalogue in SDSS we noted one object that shows a spectrum, without any spectral features but being close to the blackbody radiation. We then serached through the entire spectral catalogue of SDSS of 800000 objects, we found 17 similar objects. We called them "blackbody stars" (Suzuki and Fukugita 2018), and speculated them being DB white dwarfs. Afterwards, GAIA published a catalogue of nearby stars. Searching through this catalogue, we found that they are stars at 70-220 pc. Using the atmosphere model, we showed that helium atmosphere emits a spectrum close to blackbody if its temperaure is 7000 -12000K. Indeed, all blackbody stars lie in this range. We conclude that all aspects are consistent with DB white dwarfs. (Serenelli, Rohrmann, and Fukugita 2019). These blackbody stars can be used as the flux standard through the entire range of the wavelength, including near infrared regions (Fukugita 2019).

Free Research Field

天文学

Academic Significance and Societal Importance of the Research Achievements

赤外領域での光束のcgs系での標準値は実験室での光束標準の測定がない故,存在しない。我々の與へた黒色輻射星は赤外を含む全波長領域での標準星として利用出来る筈である。尚、天軆物理學の知見には世俗的な利用価値のあるものはない。