A preliminary design for the GMT-Consortium Large Earth Finder (G-CLEF)

Szentgyorgyi, Andrew; Barnes, Stuart; Bean, Jacob L.; Bigelow, Bruce C.; Bouchez, Antonin H.; Chun, Moo-Young; Crane, Jeffrey D.; Evans, I. N.; Evans, Janet D.; Frebel, Anna; Fürész, Gábor; Glenday, Alex; Guzmán, Dani; Hare, Tyson; Jang, Bi-Ho; Jang, Jeong-Gyun; Jeong, Ueejong; Jordán, Andrés; Kim, Kang-Min; ji-hun, Kim; Li, Chih‐Hao; López‐Morales, Mercedes; McCracken, K. G.; McLeod, B. A.; Mueller, Mark; Nah, Jakyoung; Norton, Timothy; Oh, Hyun-Mee; Oh, Jae Sok; Ordway, Mark; Park, Byeong-Gon; Park, Chan; Park, Sung‐Joon; Phillips, David F.; Plummer, David A.; Podgorski, William; Rodler, F.; Seifahrt, Andreas; Tak, Kyung-Mo; Uomoto, Alan; Dam, Marcos A. van; Walsworth, Ronald L.; Yu, Young Sam; Yuk, In-Soo

doi:10.1117/12.2056741

Cited by 19 publications

(15 citation statements)

References 14 publications

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“…narrow-band photometry such as the Pristine photometric survey (Starkenburg et al 2017). For Boötes I and Hercules, the two most massive satellites targeted in Pristine, we estimate an average number of Pop III red giant branch stars to be about 0.3.…”

Section: Satellite Properties and Implications For Observationsmentioning

confidence: 97%

Predicting the locations of possible long-lived low-mass first stars: importance of satellite dwarf galaxies

Magg

Hartwig

Agarwal

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The search for metal-free stars has so far been unsuccessful, proving that if there are surviving stars from the first generation, they are rare, they have been polluted, or we have been looking in the wrong place. To predict the likely location of Population III (Pop III) survivors, we semi-analytically model early star formation in progenitors of Milky Way-like galaxies and their environments. We base our model on merger trees from the high-resolution dark matter only simulation suite Caterpillar. Radiative and chemical feedback are taken into account self-consistently, based on the spatial distribution of the haloes. Our results are consistent with the non-detection of Pop III survivors in the Milky Way today. We find that possible surviving Population III stars are more common in Milky Way satellites than in the main Galaxy. In particular, low mass Milky Way satellites contain a much larger fraction of Pop III stars than the Milky Way. Such nearby, low mass Milky Way satellites are promising targets for future attempts to find Pop III survivors, especially for high-resolution, high signalto-noise spectroscopic observations. We provide the probabilities of finding a Pop III survivor in the red giant branch phase for all known Milky Way satellites to guide future observations.

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Section: Satellite Properties and Implications For Observationsmentioning

confidence: 97%

Predicting the locations of possible long-lived low-mass first stars: importance of satellite dwarf galaxies

Magg

Hartwig

Agarwal

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Avoiding or mitigating these effects would require using new types of detectors which are not prone to these problems and/or new approaches to reducing echelle spectra. These problems may be addressed on the longer timescales involved in preparing for and building G-Clef on the Giant Magellan Telescope (GMT) (Szentgyorgyi et al 2014) and HIRES on the European Extremely Large Telescope (E-ELT) (Zerbi et al 2014). These telescopes will have much higher light collecting area which will enable significant improvements in S/N ratio and, therefore, statistical uncertainties in ∆α/α measurements.…”

Section: Next-generation Spectrographs and Telescopes: Expected Systementioning

confidence: 99%

High-precision limit on variation in the fine-structure constant from a single quasar absorption system

Kotuš

Murphy

Carswell

2016

Mon. Not. R. Astron. Soc.

128

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The brightest southern quasar above redshift z = 1, HE 0515−4414, with its strong intervening metal absorption-line system at z abs = 1.1508, provides a unique opportunity to precisely measure or limit relative variations in the fine-structure constant (∆α/α). A variation of just ∼3 parts per million (ppm) would produce detectable velocity shifts between its many strong metal transitions. Using new and archival observations from the Ultraviolet and Visual Echelle Spectrograph (UVES) we obtain an extremely high signal-to-noise ratio spectrum (peaking at S/N ≈ 250 pix −1 ). This provides the most precise measurement of ∆α/α from a single absorption system to date, ∆α/α = −1.42±0.55 stat ±0.65 sys ppm, comparable with the precision from previous, large samples of ∼150 absorbers. The largest systematic error in all (but one) previous similar measurements, including the large samples, was long-range distortions in the wavelength calibration. These would add a ∼2 ppm systematic error to our measurement and up to ∼10 ppm to other measurements using Mg and Fe transitions. However, we corrected the UVES spectra using well-calibrated spectra of the same quasar from the High Accuracy Radial velocity Planet Searcher (HARPS), leaving a residual 0.59 ppm systematic uncertainty, the largest contribution to our total systematic error. A similar approach, using short observations on future, well-calibrated spectrographs to correct existing, high S/N spectra, would efficiently enable a large sample of reliable ∆α/α measurements. The high S/N UVES spectrum also provides insights into analysis difficulties, detector artifacts and systematic errors likely to arise from 25-40-m telescopes.

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“…Atmospheric dispersion compensation (ADC) is integral to this relay system. These optics have been described in an earlier publication 1 .…”

Section: Spectrograph Thermal Enclosurementioning

confidence: 99%

“…Modeling has shown that the GMT adaptive optics system can improve both the near-field stability within the spectrograph and throughput, in some cases by a factor of 2 1 . A provision exists to upgrade the GCFEA to accommodate a wavefront sensor when adaptive optics are implemented on the GMT some time after first light 23 .…”

Section: Spectrograph Thermal Enclosurementioning

confidence: 99%

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The GMT-Consortium Large Earth Finder (G-CLEF): an optical Echelle spectrograph for the Giant Magellan Telescope (GMT)

et al. 2016

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The GMT-Consortium Large Earth Finder (G-CLEF) will be a cross-dispersed, optical band echelle spectrograph to be delivered as the first light scientific instrument for the Giant Magellan Telescope (GMT) in 2022. G-CLEF is vacuumenclosed and fiber-fed to enable precision radial velocity (PRV) measurements, especially for the detection and characterization of low-mass exoplanets orbiting solar-type stars. The passband of G-CLEF is broad, extending from 3500Å to 9500Å. This passband provides good sensitivity at blue wavelengths for stellar abundance studies and deep red response for observations of high-redshift phenomena. The design of G-CLEF incorporates several novel technical innovations. We give an overview of the innovative features of the current design. G-CLEF will be the first PRV spectrograph to have a composite optical bench so as to exploit that material's extremely low coefficient of thermal expansion, high in-plane thermal conductivity and high stiffness-to-mass ratio. The spectrograph camera subsystem is divided into a red and a blue channel, split by a dichroic, so there are two independent refractive spectrograph cameras. The control system software is being developed in model-driven software context that has been adopted globally by the GMT. G-CLEF has been conceived and designed within a strict systems engineering framework. As a part of this process, we have developed a analytical toolset to assess the predicted performance of G-CLEF as it has evolved through design phases.

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A preliminary design for the GMT-Consortium Large Earth Finder (G-CLEF)

Abstract: The GMT-Consortium

Cited by 19 publications

References 14 publications

Predicting the locations of possible long-lived low-mass first stars: importance of satellite dwarf galaxies

Predicting the locations of possible long-lived low-mass first stars: importance of satellite dwarf galaxies

High-precision limit on variation in the fine-structure constant from a single quasar absorption system

The GMT-Consortium Large Earth Finder (G-CLEF): an optical Echelle spectrograph for the Giant Magellan Telescope (GMT)

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