English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present a study of Lyot style (i.e., classical, band-limited, and Gaussianocculter) coronagraphy on extremely large, highly-segmented telescopes. We showthat while increased telescope diameter is always an advantage for high dynamicrange science (assuming wavefront errors have been corrected sufficientlywell), segmentation itself sets a limit on the performance of Lyotcoronagraphs. Diffraction from inter-segment gaps sets a floor to theachievable extinction of on-axis starlight with Lyot coronagraphy. We derive ananalytical expression for the manner in which coronagraphic suppression of anon-axis source decreases with increasing gap size when the segments are placedin a spatially periodic array over the telescope aperture, regardless of thedetails of the arrangement. A simple Lyot stop masking out pupil edges producesgood extinction of the central peak in the point-spread function (PSF), butleaves satellite images caused by inter-segment gaps essentially unaffected.Masking out the bright segment gaps in the Lyot plane with a reticulated maskreduces the satellite images'intensity to a contrast of 5x10^{-9} on a 30 mtelescope with 10 mm gaps, at the expense of an increase in the brightness ofthe central peak. The morphology of interesting targets will dictate which Lyotstop geometry is preferable: the reticulated Lyot stop produces a convenientlyuni-modal PSF, whereas a simple Lyot stop produces an extended array ofsatellite spots. A cryogenic reticulate Lyot stop will also benefit both directand coronagraphic mid-IR imaging.Comment: 4 pages, 2 figure

Lyot Coronagraphy on Giant Segmented-Mirror Telescopes