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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

HIRES, a high resolution spectrometer, is one of the first five instrumentsforeseen in the ESO roadmap for the E-ELT. This spectrograph should ideallyprovide full spectral coverage from the UV limit to 2.5 microns, with aresolving power from R$\sim$10,000 to R$\sim$100,000. At visual/bluewavelengths, where the adaptive optics (AO) cannot provide an efficientlight-concentration, HIRES will necessarily be a bulky, seeing-limitedinstrument. The fundamental question, which we address in this paper, iswhether the same approach should be adopted in the near-infrared range, orHIRES should only be equipped with compact infrared module(s) with a muchsmaller aperture, taking advantage of an AO-correction. The main drawbacks of aseeing-limited instrument at all wavelengths are: \textit{i)} Lowersensitivities at wavelengths dominated by thermal background (red part of theK-band). \textit{ii)} Much higher volumes and costs for the IR spectrographmodule(s). The main drawbacks of using smaller, AO-fed IR module(s) are:\textit{i)} Performances rapidly degrading towards shorter wavelengths(especially J e Y bands). \textit{ii)} Different spatial sampling of extendedobjects (the optical module see a much larger area on the sky). In this paperwe perform a trade-off analysis and quantify the various effects thatcontribute to improve or deteriorate the signal to noise ratio. In particular,we evaluate the position of the cross-over wavelength at which AO-fedinstruments starts to outperform seeing-limited instruments. This parameter isof paramount importance for the design of the part of HIRES covering theK-band.

Trade-off study for high resolution spectroscopy in the near infrared with ELT telescopes: seeing-limited vs. diffraction limited instruments