MIKE: A Double Echelle Spectrograph for the Magellan Telescopes at Las Campanas Observatory

Bernstein, R. A.; Shectman, Stephen; Gunnels, Steven M.; Mochnacki, S. W.; Athey, Alex

doi:10.1117/12.461502

Cited by 461 publications

(177 citation statements)

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“…Spectra of seven stars with infrared colours and magnitudes compatible with being He-clump stars of the stellar cluster Gaia1 have been secured using the Magellan Inamori Kyocera Echelle (MIKE) spectrograph (Bernstein et al 2003) mounted on the Magellan II Telescope at Las Campanas Observatory. Table 1 lists the coordinates, the 2MASS magnitudes, RVs, and atmospheric parameters for the observed targets.…”

Section: Observationsmentioning

confidence: 99%

Chemical composition of the stellar cluster Gaia1: no surprise behind Sirius

Mucciarelli

Monaco

Bonifacio

et al. 2017

A&A

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We observed six He-clump stars of the intermediate-age stellar cluster Gaia1 with the MIKE/Magellan spectrograph. A possible extra-galactic origin of this cluster, recently discovered thanks to the first data release of the ESA Gaia mission, has been suggested, based on its orbital parameters. Abundances for Fe, α, proton-and neutron-capture elements have been obtained. We find no evidence of intrinsic abundance spreads. The iron abundance is solar ([FeI/H] = +0.00 ± 0.01; σ = 0.03 dex). All the other abundance ratios are generally solar-scaled, similar to the Galactic thin disk and open cluster stars of similar metallicity. The chemical composition of Gaia1 does not support an extra-galactic origin for this stellar cluster, which can be considered as a standard Galactic open cluster.

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Section: Observationsmentioning

confidence: 99%

Chemical composition of the stellar cluster Gaia1: no surprise behind Sirius

Mucciarelli

Monaco

Bonifacio

et al. 2017

A&A

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“…Doppler measurements taken with the MIKE echelle spectrograph (Bernstein et al 2003) on the 6.5-m Magellan II (Clay) telescope have revealed (Minniti et al 2009) the nearby solartype star HD 43848 (HIP 29804) to be orbited by a companion with M c sin i = 25 M J on a high-eccentricity orbit with P ≈ 6.5 yr (for completeness, Table 1 also reports the summary of the properties of the primary and of the orbital parameters of detected companion). This system also appears to be of potential interest for future direct-imaging observations, with a separation at apoastron of ≈0.2 arcsec.…”

Section: Hd 43848mentioning

confidence: 99%

Hipparcos preliminary astrometric masses for the two close-in companions to HD 131664 and HD 43848

Sozzetti¹,

Desidera

2009

A&A

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Context. Several mechanisms for forming brown dwarfs have been proposed, which today are not believed to be mutually exclusive. Among the fundamental characteristics of brown dwarfs that are intrinsically tied to their origins, multiplicity is particularly relevant. Any successful determination of the actual mass for such objects in any systems is thus worthwhile, as it allows one to improve on the characterization of the multiplicity properties (e.g., frequency, separation, mass-ratio distribution) of sub-stellar companions. Aims. We attempt to place better constraints on the masses of two Doppler-detected substellar companions to the nearby G dwarfs HD 131664 and HD 43848. Methods. We carried out orbital fits to the Hipparcos Intermediate Astrometric Data (IAD) for the two stars, taking advantage of the knowledge of the spectroscopic orbits, and solving for the inclination angle i and the longitude of the ascending node Ω, the two orbital elements that can be determined in principle solely by astrometry, A number of checks were carried out to assess the reliability of the orbital solutions thus obtained.Results. The best-fit solution for HD 131664 yields i = 55 ± 33 deg and Ω = 22 ± 28 deg. The resulting inferred true companion mass is then M c = 23 +26 −5 M J . For HD 43848, we find i = 12 ± 7 deg and Ω = 288 ± 22 deg, and a corresponding M c = 120 +167 −43 M J . Based on the statistical evidence from an F-test, the study of the joint confidence intervals of variation in i and Ω and the comparison of the derived orbital semi-major axes with a distribution of false astrometric orbits obtained for single stars observed by Hipparcos, the astrometric signal of the two companions to HD 131664 and HD 43848 is then considered detected in the Hipparcos IAD, with a level of statistical confidence not exceeding 95%. Conclusions. We constrain the true mass of HD 131664b to that of a brown dwarf to within a somewhat statistically significant degree of confidence (∼2 − σ). For HD 43848b, a true mass in the brown dwarf regime is ruled out at the 1 − σ confidence level. The results are discussed in the context of the properties of the (few) close substellar and massive planetary companions to nearby solar-type stars and their implications for proposed models of formation and structure of massive planets and brown dwarfs.

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“…The Magellan Inamori Kyocera Echelle (MIKE), a highthroughput double echelle spectrograph (Bernstein et al 2003), was used. The entrance slit was set at 0.35 arcsec, which corresponds to a resolving power R 60 000, i.e.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

The C/O ratio at low metallicity: constraints on early chemical evolution from observations of Galactic halo stars

Fabbian

Nissen

Asplund

et al. 2009

A&A

105

130

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Aims. We present new measurements of the abundances of carbon and oxygen derived from high-excitation C i and O i absorption lines in metal-poor halo stars, with the aim of clarifying the main sources of these two elements in the early stages of the chemical enrichment of the Galaxy. Methods. We target 15 new stars compared to our previous study, with an emphasis on additional C/O determinations in the crucial metallicity range −3 < ∼ [Fe/H] < ∼ −2. The stellar effective temperatures were estimated from the profile of the Hβ line. Departures from local thermodynamic equilibrium were accounted for in the line formation for both carbon and oxygen. The non-LTE effects are very strong at the lowest metallicities but, contrary to what has sometimes been assumed in the past due to a simplified assessment, of different degrees for the two elements. In addition, for the 28 stars with [Fe/H] < −1 previously analysed, stellar parameters were re-derived and non-LTE corrections applied in the same fashion as for the rest of our sample, giving consistent abundances for 43 halo stars in total.

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MIKE: A Double Echelle Spectrograph for the Magellan Telescopes at Las Campanas Observatory

Cited by 461 publications

References 1 publication

Chemical composition of the stellar cluster Gaia1: no surprise behind Sirius

Chemical composition of the stellar cluster Gaia1: no surprise behind Sirius

Hipparcos preliminary astrometric masses for the two close-in companions to HD 131664 and HD 43848

The C/O ratio at low metallicity: constraints on early chemical evolution from observations of Galactic halo stars

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