The high-resolution cross-dispersed echelle white-pupil spectrometer of the McDonald Observatory 2.7-m telescope

Tull, Robert G.; MacQueen, Phillip J.; Sneden, Christopher; Lambert, David L.

doi:10.1086/133548

Cited by 476 publications

(419 citation statements)

References 20 publications

(31 reference statements)

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“…High-resolution optical spectra of the program stars were obtained during the nights of 2011 January 12-14 and March 15-18 with the Robert G. Tull echelle coudé spectrograph (Tull et al 1995) on the 2.7-m Harlan J. Smith telescope at the McDonald observatory using a 2048 x 2048 pixel Tektronix charge-coupled device (CCD) as a detector. The spectra correspond to a resolving power of 55,000 (< 6 km s −1 ) as measured by the FWHM of Th I lines in comparison spectra.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447

Reddy

Giridhar

Lambert

2015

Monthly Notices of the Royal Astronomical Society

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We have analyzed high-resolution echelle spectra of red giant members for seven open clusters in the Galactic anticentre direction to explore their chemical compositions. Cluster membership has been confirmed by radial velocity. The spread in temperatures and gravities being very small among the red giants, nearly the same stellar lines were employed for all stars thereby reducing the abundance errors: the errors of the average abundance for a cluster were generally in the 0.02 to 0.05 dex range. Our present sample covers Galactocentric distances of 8.3 to 11.3 kpc and an age range of 0.2 to 4.3 Gyr. A careful comparison of our results for the cluster NGC 2682 (M 67) to other high-resolution abundance studies in the literature shows general good agreement for almost all elements in common.

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Section: Observations and Data Reductionmentioning

confidence: 99%

Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447

Reddy

Giridhar

Lambert

2015

Monthly Notices of the Royal Astronomical Society

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“…Spectra were obtained with a double-pass, cross-dispersed, echelle spectrometer (Tull et al 1995) on the Harlan J. Smith 2.7 m telescope at the McDonald Observatory. A Tektronix 2048 ϫ 2048 CCD was used at the F1 focus with a 0"59 slit to achieve a spectral resolving power of 121,000 with 4.65 pixels per resolution element.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Detection of Strong Magnetic Fields on M Dwarfs

Johns–Krull

Valenti

1996

The Astrophysical Journal

232

242

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We have detected Zeeman splitting of the Fe I line ( g eff ϭ 2.5) at 8468.40 Å in the very active M4.5 Ve stars Gliese 729 and Gliese 873 (EV Lac). High-resolution (R ϭ 120,000), low-noise (10.5%) spectra show clear Zeeman-shifted components from which we infer field strengths of 2-4 kG, independent of uncertainties in model atmospheres. Similar observations of a sequence (M0 V-M5 V ) of low-activity M dwarfs demonstrate that the wing components in the 8468.40 Å line are not due to the ubiquitous TiO lines in the vicinity. This strongly suggests that discrepancies in the shape of the magnetically sensitive iron line are due to magnetic fields rather than differences in photospheric temperature. By fitting the ratio of active to inactive line profiles with simple one-component models, we estimate that 50 H 13% of the photosphere of EV Lac is covered by 3.8 H 0.5 kG magnetic fields, while 50 H 13% of Gliese 729 is covered by 2.6 H 0.3 kG fields. This confirms earlier reports of large magnetic fields on M dwarf flare stars. We see evidence for a distribution of magnetic field strength, spatially across the surface and/or with depth. The twofold increase in field strength relative to G and K dwarfs is predicted by flux tube equilibrium arguments, but the 1 kG difference in the measured field strengths for these two stars suggests that field strengths may also grow with activity as the photospheric filling factor approaches unity.

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“…They reported an asteroseismically determined stellar radius R * = 1.081±0.019 R e , stellar mass M * = 1.069±0.048 M e , and surface gravity log g = 4.399±0.012. Additionally, Huber et al (2013) use Stellar Parameter Classification (SPC, Buchhave et al 2012Buchhave et al , 2014 on spectra from Keck-HIRES (Vogt et al 1994), the TRES spectrograph on the 1.5 m at Whipple Observatory (Furesz 2008) and the Tull spectrograph on the 2.5 m at McDonald Observatory (Tull et al 1995), to obtain a metallicity of [Fe/H] = 0.350±0.101 and effective temperature T eff = 5739±75 K. McQuillan et al (2013) searched for the stellar rotation period of KOI-273 in the autocorrelation function of the Kepler photometry and were unable to detect it.…”

Section: Introductionmentioning

confidence: 99%

The Kepler-454 System: A Small, Not-Rocky Inner Planet, a Jovian World, and a Distant Companion

Gettel

Charbonneau

Dressing

et al. 2016

ApJ

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Kepler-454 (KOI-273) is a relatively bright (V = 11.69 mag), Sun-like star that hosts a transiting planet candidate in a 10.6 day orbit. From spectroscopy, we estimate the stellar temperature to be 5687±50 K, its metallicity to be [m/H] = 0.32±0.08, and the projected rotational velocity to be v sin i<2.4 km s −1 . We combine these values with a study of the asteroseismic frequencies from short cadence Kepler data to estimate the stellar mass to be M 1.028 0.03 0.04 -+  , the radius to be 1.066±0.012 R e , and the age to be 5.25 1.39Gyr. We estimate the radius of the 10.6 day planet as 2.37±0.13 R ⊕ . Using 63 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 36 observations made with the HIRES spectrograph at the Keck Observatory, we measure the mass of this planet to be 6.8±1.4 M ⊕ . We also detect two additional nontransiting companions, a planet with a minimum mass of 4.46±0.12 M J in a nearly circular 524 day orbit and a massive companion with a period >10 years and mass >12.1 M J . The 12 exoplanets with radii <2.7 R ⊕ and precise mass measurements appear to fall into two populations, with those <1.6 R ⊕ following an Earth-like composition curve and larger planets requiring a significant fraction of volatiles. With a density of 2.76±0.73 g cm −3 , Kepler-454b lies near the mass transition between these two populations and requires the presence of volatiles and/or H/He gas.

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The high-resolution cross-dispersed echelle white-pupil spectrometer of the McDonald Observatory 2.7-m telescope

Cited by 476 publications

References 20 publications

Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447

Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447

Detection of Strong Magnetic Fields on M Dwarfs

The Kepler-454 System: A Small, Not-Rocky Inner Planet, a Jovian World, and a Distant Companion

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