Astronomical Speckle Interferometry In The Infrared

Abstract

In November 1980 we implemented a one-dimensional infrared speckle interferometry system for the University of Hawaii (U H) 2.2-m telescope at Mauna Kea. Currently there are functioning systems on the 2.2-m telescope, the 3-m NASA Infrared Telescope Facility (IRTF), and the 3.8-m United Kingdom Infrared Telescope (UKIRT). With several detectors, these have the capability of operating over a range of wavelengths from 1 to 12 μm; this part of the infra-red is well suited for observing objects with real or apparent temperatures 250 < T < 3000 K. We now routinely measure diffraction-limited visibility functions for a variety of astronomical sources. These include volcanic eruptions on I0, circumstellar dust shells around evolved stars, young stars in giant molecular clouds, and pre-main-sequence stars. Spatial structure as small as 100 milliarcsec has been measured with the largest telescopes. The speckle interferometer has also been used together with a cooled grating spectrometer to achieve high spectral resolution and spatial resolution simultaneously. We have the ability to display real-time power spectra for evaluation of signal-to-noise ratios (SNR) and save all of the raw data for later processing. This latter feature has recently been used successfully to retrieve phases and construct one-dimensional pictures. The current version of the interferometer features an IBM PC that can be moved to various telescope facilities. It has been used on the Kitt Peak 4-m telescope as well as the telescopes on Mauna Kea.