Scientists at the National Institute of Standards and Technology (NIST) have been working to improve methods for calibrating standard stars for more than a decade. Standard stars – or “standard candles” – are stars whose luminosities and distances are well known. These standard stars can be used to as a reference to find out information about other stars. Observations of stars can be compared to these standard stars to see how bright they are relative to each other to determine a star’s distance from Earth. But, even standard candles need to be calibrated.
In an ongoing NIST study, scientists have been observing two nearby, bright stars: Vega and Sirius. The team designed a 4-inch telescope for their purposes and repeatedly observed the spectra – or light split up into its component parts as a function of wavelength – of these two stars from Mount Hopkins in Arizona. Within the next 12 months, the team plans to take all of their data to calibrate the luminosity of these stars over their visible-light wavelengths, and release this data to astronomers.
Next year, the team plans to move their telescope to the European Southern Observatory’s Paranal Observatory in Chile. This location has a drier climate than Arizona, which will allow the team to obtain even better data. At this time, the team also plans to expand their sample to include a few other nearby, bright stars: Arcturus, Gamma Crucis, and Gamma Trianguli Australis. They also plan to observe their entire sample at longer, infrared wavelengths. Additionally, the researchers have obtained a grant to build an even larger telescope, which will allow them to observe fainter stars. Being able to detect fainter sources will allow the team to include more distant stars in their calibration set, which will increase the precision for which further distances are known.
This calibration data could help astronomers who use more distant standard candles, such as type Ia supernovae – or exploded stars. Supernovae are generally used to determine the age and expansion rate of the Universe. Thus, astronomers may be able to use these NIST calibrations to better understand the history of our Universe and be able to predict the fate of our Universe with even greater precision.
Source: phys.org
