CfA: Gamma-Ray Scientists "Dust Off" Intensity Interferometry

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CfA: Gamma-Ray Scientists "Dust Off" Intensity Interferometry

Post by bystander » Tue Jul 21, 2020 3:50 pm

Gamma-Ray Scientists "Dust Off" Intensity Interferometry, Upgrade Technology
with Digital Electronics, Larger Telescopes, and Improved Sensitivity

Harvard Smithsonian Center for Astrophysics | 2020 Jul 20
Scientists in the VERITAS Collaboration have measured the angular diameter of stars using stellar intensity interferometry for the first time in nearly 50 years, and demonstrated both improvements to the sensitivity of the technique and its scalability using digital electronics.

... VERITAS (Very Energetic Radiation Imaging Telescope Array System) scientists measured the angular diameters of Beta Canis Majoris -- a blue giant star located 500 light-years from the Sun -- and Epsilon Orionis -- a blue supergiant star located 2,000 light-years from the Sun. ...

VERITAS used all four of its gamma-ray telescopes, located at the Fred Lawrence Whipple Observatory in Amado, Arizona, to increase its coverage and provide greater resolution for observation. ...

The first telescopes to perform stellar measurements using intensity interferometry were the Narrabri telescopes in the 1970s. “Narrabri measured 32 stars in the southern hemisphere, and to significantly improve upon that result required a large leap in technology,” said Wystan Benbow, Director, VERITAS. “Right now we are pathfinding for the future Cherenkov Telescope Array (CTA); we have proven that we can add 100 telescopes to this design, enabling astronomers to image features on stellar surfaces with unparalleled optical resolution.” ...

Demonstration of stellar intensity interferometry with the four VERITAS telescopes ~ A. U. Abeysekara et al
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Re: CfA: Gamma-Ray Scientists "Dust Off" Intensity Interferometry

Post by neufer » Tue Jul 21, 2020 4:40 pm wrote:
Demonstration of stellar intensity interferometry with the four VERITAS telescopes
A. U. Abeysekara, W. Benbow, […]T. J. Williamson
Nature Astronomy (2020) Published: 20 July 2020

Abstract: <<High angular resolution observations at optical wavelengths provide valuable insights into stellar astrophysics and enable direct measurements of fundamental stellar parameters and the probing of stellar atmospheres, circumstellar disks, the elongation of rapidly rotating stars and the pulsations of Cepheid variable stars. The angular size of most stars is of the order of one milliarcsecond or less. We report on the implementation of a stellar intensity interferometry system developed for the four VERITAS imaging atmospheric Cherenkov telescopes. The system was used to measure the angular diameter of the two sub-milliarcsecond stars β Canis Majoris and ϵ Orionis with a precision of greater than 5%. The system uses an offline approach in which starlight intensity fluctuations that are recorded at each telescope are correlated post observation. The technique can be readily scaled onto tens to hundreds of telescopes, providing a capability that has proven technically challenging to the current generation of optical amplitude interferometry observatories. This work demonstrates the feasibility of performing astrophysical measurements using imaging atmospheric Cherenkov telescope arrays as intensity interferometers and shows the promise for integrating an intensity interferometry system within future observatories such as the Cherenkov Telescope Array.>>
Art Neuendorffer