HERMES: revisions in the design for a high-resolution multi-element spectrograph for the AAT

Barden, Samuelk C.; Jones, Damien; Barnes, Stuart; Heijmans, Jeroen; Heng, Anthony; Knight, Greg; Orr, David; Smith, Greg; Churilov, Vladimir; Brzeski, Jurek; Waller, Lewis; Shortridge, Keith; Horton, Anthony; Mayfield, Don; Haynes, Roger; Haynes, Dionne; Whittard, Denis; Goodwin, Michael; Smedley, Scott; Saunders, I.J.; Gillingham, Peter; Penny, Ed; Farrell, Tony; Vuong, Minh; Heald, Ron; Müller, Rolf; Freeman, K. C.; Bland-Hawthorn, Joss; Zucker, D. B.; Silva, Gayandhi De

doi:10.1117/12.856103

Cited by 27 publications

(17 citation statements)

References 9 publications

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“…This survey brings a unique perspective to Galactic archaeology by measuring accurate radial velocities and up to 30 elemental abundances for about a million stars (De Silva et al 2015;Martell et al 2017). The HERMES instrument was designed and optimised for the GALAH survey specifically for the pursuit of Galactic archaeology (Freeman & Bland-Hawthorn 2008;Barden et al 2010). The GALAH selection criteria were designed to be as simple as possible to avoid problems that adversely affect earlier surveys (Sharma et al 2011).…”

Section: Introductionmentioning

confidence: 99%

The GALAH survey and Gaia DR2: dissecting the stellar disc’s phase space by age, action, chemistry, and location

Bland-Hawthorn

Sharma

Tepper-García

et al. 2019

Monthly Notices of the Royal Astronomical Society

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193

132

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We use the second data releases of the ESA Gaia astrometric survey and the highresolution GALAH spectroscopic survey to analyse the structure of our Galaxy's disc components. With GALAH, we separate the α-rich and α-poor discs (with respect to Fe), which are superposed in both position and velocity space, and examine their distributions in action space. We examine the distribution of stars in the zV z phase plane, for both V φ and V R , and recover the remarkable "phase spiral" discovered by Gaia. We identify the anticipated quadrupole signature in zV z of a tilted velocity ellipsoid for stars above and below the Galactic plane. By connecting our work with earlier studies, we show that the phase spiral is likely to extend well beyond the narrow solar neighbourhood cylinder in which it was found. The phase spiral is a signature of corrugated waves that propagate through the disc, and the associated non-equilibrium phase mixing. The radially asymmetric distribution of stars involved in the phase spiral reveals that the corrugation, which is mostly confined to the α-poor disc, grows in zamplitude with increasing radius. We present new simulations of tidal disturbance of the Galactic disc by the Sagittarius (Sgr) dwarf. The effect on the zV z phase plane lasts 2 Gyr but a subsequent disc crossing wipes out the coherent structure. We find that the phase spiral was excited 0.5 Gyr ago by an object like Sgr with total mass ∼ 3 × 10 10 M (stripped down from ∼ 5 × 10 10 M when it first entered the halo) passing through the plane.

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Section: Introductionmentioning

confidence: 99%

The GALAH survey and Gaia DR2: dissecting the stellar disc’s phase space by age, action, chemistry, and location

Bland-Hawthorn

Sharma

Tepper-García

et al. 2019

Monthly Notices of the Royal Astronomical Society

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193

132

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“…The Galactic Archaeology with HERMES (GALAH) survey 1 brings a unique perspective to the outstanding problem of understanding the Galaxy's history (De Silva et al 2015;Martell et al 2017). Our study makes use of the High Efficiency and Resolution Multi-Element Spectrograph (HERMES) at the Anglo-Australian Telescope (Barden et al 2010;Sheinis et al 2015). This unique instrument employs the Two Degree Field (2dF) fibre positioner on the Anglo-Australian Telescope to provide multi-object (n ∼ 392), high-resolution (R ∼ 28, 000) spectra optimized for elemental abundance studies for up to 30 elements in four optical windows.…”

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confidence: 99%

The GALAH Survey: second data release

Buder

Asplund

Duong

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The Galactic Archaeology with HERMES (GALAH) survey is a large-scale stellar spectroscopic survey of the Milky Way and designed to deliver chemical information complementary to a large number of stars covered by the Gaia mission. We present the GALAH second public data release (GALAH DR2) containing 342,682 stars. For these stars, the GALAH collaboration provides stellar parameters and abundances for up to 23 elements to the community. Here we present the target selection, observation, data reduction and detailed explanation of how the spectra were analysed to estimate stellar parameters and element abundances. For the stellar analysis, we have used a multi-step approach. We use the physics-driven spectrum synthesis of Spectroscopy Made Easy (SME) to derive stellar labels (T eff , log g, [Fe/H], [X/Fe], v mic , v sin i, A K S ) for a representative training set of stars. This information is then propagated to the whole survey with the data-driven method of The Cannon. Special care has been exercised in the spectral synthesis to only consider spectral lines that have reliable atomic input data and are little affected by blending lines. Departures from local thermodynamic equilibrium (LTE) are considered for several key elements, including Li, O, Na, Mg, Al, Si, and Fe, using 1D stellar atmosphere models. Validation tests including repeat observations, Gaia benchmark stars, open and globular clusters, and K2 asteroseismic targets lend confidence to our methods and results. Combining the GALAH DR2 catalogue with the kinematic information from Gaia will enable a wide range of Galactic Archaeology studies, with unprecedented detail, dimensionality, and scope.

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“…For details on ongoing surveys and instruments the interested reader is referred to RAVE, Steinmetz et al (2006); Sloan Extension for Galactic Understanding and Exploration, SEGUE, Yanny et al (2009); and APOGEE. Details on some studies on instrumentation are documented for 4MOST (at the 4.1 m Visible and Infrared Survey Telescope for Astronomy, VISTA) in de Jong (2011), de Jong et al (2012a; GYES at the 3.6 m CFHT, Bonifacio et al (2011); High Efficiency and Resolution Multi-Element Spectrograph, HERMES, at the 4 m Anglo-Australian Telescope, AAT, Barden et al (2010); MOONS, Multi-Object Optical and Near-infrared Spectrograph, at the 8.2 m VLT, Cirasuolo et al (2011); and WEAVE at the 4.2 m William Herschel Telescope, WHT, Balcells et al (2010). In this context, a detailed study of the required performance and characteristics of such spectrographs is of prime importance.…”

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confidence: 99%

Velocity and abundance precisions for future high‐resolution spectroscopic surveys: A study for 4MOST

et al. 2013

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In preparation for future, large-scale, multi-object, high-resolution spectroscopic surveys of the Galaxy, we present a series of tests of the precision in radial velocity and chemical abundances that any such project can achieve at a 4 m class telescope. We briefly discuss a number of science cases that aim at studying the chemo-dynamical history of the major Galactic components (bulge, thin and thick disks, and halo) -either as a follow-up to the Gaia mission or on their own merits. Based on a large grid of synthetic spectra that cover the full range in stellar parameters of typical survey targets, we devise an optimal wavelength range and argue for a moderately high-resolution spectrograph. As a result, the kinematic precision is not limited by any of these factors, but will practically only suffer from systematic effects, easily reaching uncertainties <1km s −1 . Under realistic survey conditions (namely, considering stars brighter than r = 16 mag with reasonable exposure times) we prefer an ideal resolving power of R ∼20 000 on average, for an overall wavelength range (with a common two-arm spectrograph design) of [395;456.5] nm and [587;673] nm. We show for the first time on a general basis that it is possible to measure chemical abundance ratios to better than 0.1 dex for many species (Fe, Mg, Si, Ca, Ti, Na, Al, V, Cr, Mn, Co, Ni, Y, Ba, Nd, Eu) and to an accuracy of about 0.2 dex for other species such as Zr, La, and Sr. While our feasibility study was explicitly carried out for the 4MOST facility, the results can be readily applied to and used for any other conceptual design study for high-resolution spectrographs.

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HERMES: revisions in the design for a high-resolution multi-element spectrograph for the AAT

Cited by 27 publications

References 9 publications

The GALAH survey and Gaia DR2: dissecting the stellar disc’s phase space by age, action, chemistry, and location

The GALAH survey and Gaia DR2: dissecting the stellar disc’s phase space by age, action, chemistry, and location

The GALAH Survey: second data release

Velocity and abundance precisions for future high‐resolution spectroscopic surveys: A study for 4MOST

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