Black-Body Stars

TL;DR

This paper reports the discovery of 17 stars with spectra close to black-body radiation in SDSS data, highlighting their potential for photometric calibration and examining the internal consistency of SDSS and other photometric systems.

Contribution

The identification of black-body spectrum stars and analysis of their use as calibration standards, providing insights into SDSS photometric zero points and cross-system consistency.

Findings

SDSS photometric zero points are consistent within 0.01 mag.

17 black-body stars identified out of nearly 800,000.

Stars likely are DB white dwarfs with temperatures around 10,000K.

Abstract

We report the discovery of stars that show spectra very close to the black-body radiation. We found 17 such stars out of 798,593 stars in the Sloan Digital Sky Survey (SDSS) spectroscopic data archives. We discuss the value of these stars for the calibration of photometry, whatever is the physical nature of these stars. This gives us a chance to examine the accuracy of the zero point of SDSS photometry across various passbands: we conclude that the zero point of SDSS photometric system is internally consistent across its five passbands to the level below 0.01 mag. We may also examine the consistency of the zero-points between UV photometry of Galaxy Evolution Explorer and SDSS, and IR photometry of Wide-field Infrared Survey Explorer against SDSS. These stars can be used as not only photometric but spetrophotometric standard stars. We suggest that these stars showing the featureless black-body like spectrum of the effective temperature of $10000\pm1500$K are consistent with DB white dwarfs with the temperature too low to develop helium absorption features.