An Optical Ultrahigh‐Resolution Cross‐dispersed Echelle Spectrograph with Adaptive Optics

Ge, Jian; Angel, J. R. P.; Jacobsen, Bruce P.; Woolf, N. J.; Fugate, Robert Q.; Black, J. H.; Lloyd‐Hart, Michael

doi:10.1086/341711

Cited by 43 publications

(15 citation statements)

References 28 publications

(31 reference statements)

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“…In contrast, the AO system at the SOR 3.5m telescope, when used, was capable of concentrating up to ~40% of the energy in the core. 3,4 The FLAO system at the LBTO 8.4m telescope can deliver an encircled energy factor of 83% within a 0.1 arcsec radius for a star of magnitude 7.0<m R <8.4. Different slit widths or fiber diameters would be required when using the spectrograph with other AO systems, as discussed further in the section on fiber considerations.…”

Section: Characteristics Of the Adaptively Corrective Imagementioning

confidence: 99%

A design for high-resolution spectroscopy with adaptive optics at the Large Binocular Telescope

2014

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The use of spectrographs with telescopes having high order adaptive optics systems offers the possibility of achieving near diffraction-limited spectral resolving power. The adaptively corrected echelle spectrograph (ACES) couples the AO-corrected stellar image to the instrument with a near single mode fiber (SMF) for resolution of R~190,000. The First Light Adaptive Optics system (FLAO) at the Large Binocular Telescope (LBT) achieves Strehl of >80% in H band, and also delivers useful Strehls in V and R bands. In this paper we explore the possibility of using ACES with the LBT for simultaneous high resolution, high throughput, and broad wavelength coverage.

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Section: Characteristics Of the Adaptively Corrective Imagementioning

confidence: 99%

A design for high-resolution spectroscopy with adaptive optics at the Large Binocular Telescope

2014

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“…The use of image slicers would limit the number of measurable spectral orders although some remedy could be offered by adaptive optics (Ge et al 2002;Sacco et al 2004). Pasquini et al (2005) and D'Odorico et al (2007) discuss future spectrometers.…”

Section: Spectrometers At the Largest Telescopesmentioning

confidence: 99%

High‐fidelity spectroscopy at the highest resolutions

Dravins¹

2010

Astron Nachr

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High-fidelity spectroscopy presents challenges for both observations and in designing instruments. High-resolution and high-accuracy spectra are required for verifying hydrodynamic stellar atmospheres and for resolving intergalactic absorption-line structures in quasars. Even with great photon fluxes from large telescopes with matching spectrometers, precise measurements of line profiles and wavelength positions encounter various physical, observational, and instrumental limits. The analysis may be limited by astrophysical and telluric blends, lack of suitable lines, imprecise laboratory wavelengths, or instrumental imperfections. To some extent, such limits can be pushed by forming averages over many similar spectral lines, thus averaging away small random blends and wavelength errors. In situations where theoretical predictions of lineshapes and shifts can be accurately made (e.g., hydrodynamic models of solar-type stars), the consistency between noisy observations and theoretical predictions may be verified; however this is not feasible for, e.g., the complex of intergalactic metal lines in spectra of distant quasars, where the primary data must come from observations. To more fully resolve lineshapes and interpret wavelength shifts in stars and quasars alike, spectral resolutions on order R = 300 000 or more are required; a level that is becoming (but is not yet) available. A grand challenge remains to design efficient spectrometers with resolutions approaching R = 1 000 000 for the forthcoming generation of extremely large telescopes.

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“…However, grating spectrometers of very high resolution are non-trivial for matching to large telescopes, and a desired high light efficiency could demand adaptive optics (Ge et al 2002;Sacco et al 2004), not simple at shorter wavelengths. Fourier transform spectrometers give adequate resolution, but in broadband stellar observations they are seriously limited by photon noise.…”

Section: Adequate Spectral Resolution?mentioning

confidence: 99%

“Ultimate” information content in solar and stellar spectra

Dravins¹

2008

A&A

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Context. Spectral-line asymmetries (displayed as bisectors) and wavelength shifts are signatures of the hydrodynamics in solar and stellar atmospheres. Theory may precisely predict idealized lines, but accuracies in real observed spectra are limited by blends, few suitable lines, imprecise laboratory wavelengths, and instrumental imperfections. Aims. We extract bisectors and shifts until the "ultimate" accuracy limits in highest-quality solar and stellar spectra, so as to understand the various limits set by (i) stellar physics (number of relevant spectral lines, effects of blends, rotational line broadening); by (ii) observational techniques (spectral resolution, photometric noise); and by (iii) limitations in laboratory data. Methods. Several spectral atlases of the Sun and bright solar-type stars were examined for those thousands of "unblended" lines with the most accurate laboratory wavelengths, yielding bisectors and shifts as averages over groups of similar lines. Representative data were obtained as averages over groups of similar lines, thus minimizing the effects of photometric noise and of random blends. Results. For the solar-disk center and integrated sunlight, the bisector shapes and shifts were extracted for previously little-studied species (Fe ii, Ti i, Ti ii, Cr ii, Ca i, C i), using recently determined and very accurate laboratory wavelengths. In Procyon and other F-type stars, a sharp blueward bend in the bisector near the spectral continuum is confirmed, revealing line saturation and damping wings in upward-moving photospheric granules. Accuracy limits are discussed: "astrophysical" noise due to few measurable lines, finite instrumental resolution, superposed telluric absorption, inaccurate laboratory wavelengths, and calibration noise in spectrometers, together limiting absolute lineshift studies to ≈50−100 m s −1 . Conclusions. Spectroscopy with resolutions λ/Δλ ≈ 300 000 and accurate wavelength calibration will enable bisector studies for many stars. Circumventing remaining limits of astrophysical noise in line-blends and rotationally smeared profiles may ultimately require spectroscopy across spatially resolved stellar disks, utilizing optical interferometers and extremely large telescopes of the future.

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An Optical Ultrahigh‐Resolution Cross‐dispersed Echelle Spectrograph with Adaptive Optics

Abstract: A prototype ultrahigh resolution spectrograph has been built with an adaptive optics telescope. It provides 250, 000 resolving power, 300Å wavelength coverage and 0.8% efficiency.

Cited by 43 publications

References 28 publications

A design for high-resolution spectroscopy with adaptive optics at the Large Binocular Telescope

A design for high-resolution spectroscopy with adaptive optics at the Large Binocular Telescope

High‐fidelity spectroscopy at the highest resolutions

“Ultimate” information content in solar and stellar spectra

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