Hectochelle: A Multiobject Optical Echelle Spectrograph for the MMT

Szentgyorgyi, Andrew; Fürész, Gábor; Cheimets, Peter; Conroy, Maureen A.; Eng, Roger; Fabricant, Daniel G.; Fata, Robert G.; Gauron, Thomas; Geary, John C.; McLeod, B. A.; Zajac, Joseph; Amato, Stephen M.; Bergner, Henry; Caldwell, Nelson; Dupree, A. K.; Goddard, Richard E.; Johnston, Everett; Meibom, S.; Mink, Jessica; Pieri, Mario R.; Roll, John; Tokarz, S.; Wyatt, William F.; Epps, Harland W.; Hartmann, L.; Meszaros, Szabolcz

doi:10.1086/662209

Cited by 64 publications

(52 citation statements)

References 30 publications

(19 reference statements)

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“…3.1. Observations Data are obtained with the medium-resolution Hectochelle spectrograph (Szentgyorgyi et al 2011) on the MMT. Hectochelle employs a robotic fiber positioning system (Fabricant et al 2005), enabling the placement of 240 fibers over a 1 • diameter field of view.…”

Section: Observations and Data Analysismentioning

confidence: 99%

Mapping the Stellar Halo with the H3 Spectroscopic Survey

Conroy

Bonaca

Cargile

et al. 2019

ApJ

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Modern theories of galaxy formation predict that the Galactic stellar halo was hierarchically assembled from the accretion and disruption of smaller systems. This hierarchical assembly is expected to produce a high degree of structure in the combined phase and chemistry space; this structure should provide a relatively direct probe of the accretion history of our Galaxy. Revealing this structure requires precise 3D positions (including distances), 3D velocities, and chemistry for large samples of stars. The Gaia satellite is delivering proper motions and parallaxes for > 1 billion stars to G ≈ 20. However, radial velocities and metallicities will only be available to G ≈ 15, which is insufficient to probe the outer stellar halo ( 10 kpc). Moreover, parallaxes will not be precise enough to deliver high-quality distances for stars beyond ∼ 10 kpc. Identifying accreted systems throughout the stellar halo therefore requires a large ground-based spectroscopic survey to complement Gaia. Here we provide an overview of the H3 Stellar Spectroscopic Survey, which will deliver precise stellar parameters and spectrophotometric distances for ≈ 200, 000 stars to r = 18. Spectra are obtained with the Hectochelle instrument at the MMT, which is configured for the H3 Survey to deliver resolution R ≈ 23, 000 spectra covering the wavelength range 5150Å−5300Å. The survey is optimized for stellar halo science and therefore focuses on high Galactic latitude fields (|b| > 30 • ), sparsely sampling 15, 000 sq. degrees. Targets are selected on the basis of Gaia parallaxes, enabling very efficient selection of bone fide halo stars. The survey began in the Fall of 2017 and has collected 88,000 spectra to-date. All of the data, including the derived stellar parameters, will eventually be made publicly available via the survey website: h3survey.rc.fas.harvard.edu.

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Section: Observations and Data Analysismentioning

confidence: 99%

Mapping the Stellar Halo with the H3 Spectroscopic Survey

Conroy

Bonaca

Cargile

et al. 2019

ApJ

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“…We observed the GD-1 stellar stream using the MMT/Hectochelle multi-object spectrograph (Szentgyorgyi et al 2011). Focusing on the perturbed area at φ 1 ≈ −40 • (φ 1,2 are coordinates oriented along and perpendicular to GD-1, respectively; Koposov et al 2010), we targeted 4 fields in the main stream, and 4 fields in the lower-density spur (Figure 2, top).…”

Section: Spectroscopymentioning

confidence: 99%

High-resolution Spectroscopy of the GD-1 Stellar Stream Localizes the Perturber near the Orbital Plane of Sagittarius

Bonaca

Conroy

Hogg

et al. 2020

ApJL

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The 100 • -long thin stellar stream in the Milky Way halo, GD-1, has an ensemble of features that may be due to dynamical interactions. Using high-resolution MMT/Hectochelle spectroscopy we show that a spur of GD-1-like stars outside of the main stream are kinematically and chemically consistent with the main stream. In the spur, as in the main stream, GD-1 has a low intrinsic radial velocity dispersion, σ Vr 1 km s −1 , is metal-poor, [Fe/H] ≈ −2.3, with little [Fe/H] spread and some variation in [α/Fe] abundances, which point to a common globular cluster progenitor. At a fixed location along the stream, the median radial velocity offset between the spur and the main stream is smaller than 0.5 km s −1 , comparable to the measurement uncertainty. A flyby of a massive, compact object can change orbits of stars in a stellar stream and produce features like the spur observed in GD-1. In this scenario, the radial velocity of the GD-1 spur relative to the stream constrains the orbit of the perturber and its current on-sky position to ≈ 5, 000 deg 2 . The family of acceptable perturber orbits overlaps the stellar and dark-matter debris of the Sagittarius dwarf galaxy in present-day position and velocity. This suggests that GD-1 may have been perturbed by a globular cluster or an extremely compact dark-matter subhalo formerly associated with Sagittarius.

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“…Spectroscopic observations were obtained at the Hobby-Eberly Telescope (HET) with the High Resolution Spectrograph (HRS; Tull 1998) as part of normal queue scheduled observing (Shetrone et al 2007), the Nordic Optical Telescope (NOT) Fibre-fed Echelle Spectrograph (FIES; Telting et al 2014), and the MMT Hectoechelle (Szentgyorgyi et al 2011).…”

Section: Spectroscopy Of Kic 9777062mentioning

confidence: 99%

THE AGE AND DISTANCE OF THE KEPLER OPEN CLUSTER NGC 6811 FROM AN ECLIPSING BINARY, TURNOFF STAR PULSATION, AND GIANT ASTEROSEISMOLOGY^∗

Sandquist

Jessen-Hansen

Shetrone³

et al. 2016

ApJ

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We present the analysis of an eccentric, partially eclipsing long-period (P = 19.23 d) binary system KIC 9777062 that contains main sequence stars near the turnoff of the intermediate age open cluster NGC 6811. The primary is a metal-lined Am star with a possible convective blueshift to its radial velocities, and one star (probably the secondary) is likely to be a γ Dor pulsator. The component masses are 1.603 ± 0.006(stat.)±0.016(sys.) and 1.419 ± 0.003 ± 0.008M , and the radii are 1.744 ± 0.004 ± 0.002 and 1.544 ± 0.002 ± 0.002R . The isochrone ages of the stars are mildly inconsistent: the age from the mass-radius combination for the primary (1.05±0.05±0.09 Gyr, where the last quote was systematic uncertainty from models and metallicity) is smaller than that from the secondary (1.21 ± 0.05 ± 0.15 Gyr) and is consistent with the inference from the color-magnitude diagram (1.00 ± 0.05 Gyr). We have improved the measurements of the asteroseismic parameters ∆ν and ν max for helium-burning stars in the cluster. The masses of the stars appear to be larger (or alternately, the radii appear to be smaller) than predicted from isochrones using the ages derived from the eclipsing stars. The majority of stars near the cluster turnoff are pulsating stars: we identify a sample of 28 δ Sct, 15 γ Dor, and 5 hybrid types. We used the period-luminosity relation for high-amplitude δ Sct stars to fit the ensemble of the strongest frequencies for the cluster members, finding (m − M ) V = 10.37 ± 0.03. This is larger than most previous determinations, but smaller than values derived from the eclipsing binary (10.47 ± 0.05).

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Hectochelle: A Multiobject Optical Echelle Spectrograph for the MMT

Cited by 64 publications

References 30 publications

Mapping the Stellar Halo with the H3 Spectroscopic Survey

Mapping the Stellar Halo with the H3 Spectroscopic Survey

High-resolution Spectroscopy of the GD-1 Stellar Stream Localizes the Perturber near the Orbital Plane of Sagittarius

THE AGE AND DISTANCE OF THE KEPLER OPEN CLUSTER NGC 6811 FROM AN ECLIPSING BINARY, TURNOFF STAR PULSATION, AND GIANT ASTEROSEISMOLOGY^∗

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Hectochelle: A Multiobject Optical Echelle Spectrograph for the MMT

Cited by 64 publications

References 30 publications

Mapping the Stellar Halo with the H3 Spectroscopic Survey

Mapping the Stellar Halo with the H3 Spectroscopic Survey

High-resolution Spectroscopy of the GD-1 Stellar Stream Localizes the Perturber near the Orbital Plane of Sagittarius

THE AGE AND DISTANCE OF THE KEPLER OPEN CLUSTER NGC 6811 FROM AN ECLIPSING BINARY, TURNOFF STAR PULSATION, AND GIANT ASTEROSEISMOLOGY∗

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THE AGE AND DISTANCE OF THE KEPLER OPEN CLUSTER NGC 6811 FROM AN ECLIPSING BINARY, TURNOFF STAR PULSATION, AND GIANT ASTEROSEISMOLOGY^∗