Crires-Pop

Lebzelter, T.; Seifahrt, Andreas; Uttenthaler, S.; Ramsay, Suzanne; Hartman, Henrik; Nieva, M. F.; Przybilla, N.; Smette, A.; Wahlgren, G. M.; Wolff, B.; Hussain, G. A. J.; Käufl, H. U.; Seemann, U.

doi:10.1051/0004-6361/201117728

Cited by 32 publications

(35 citation statements)

References 114 publications

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“…In-dispersion stray light from the CRIRES grating causes 1-3% residual flux in the absorption cores of the observed line profiles for regions with fully saturated telluric features (Lebzelter et al 2012). For pointlike sources such as stars, this effect cannot yet be corrected for.…”

Section: Observationsmentioning

confidence: 99%

A CRIRES-search for H₃⁺emission from the hot Jupiter atmosphere of HD 209458 b

Lenz

Reiners

Seifahrt

et al. 2016

A&A

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Close-in extrasolar giant planets are expected to cool their thermospheres by producing H + 3 emission in the near-infrared (NIR), but simulations predict H + 3 emission intensities that differ in the resulting intensity by several orders of magnitude. We want to test the observability of H + 3 emission with CRIRES at the Very Large Telescope (VLT), providing adequate spectral resolution for planetary atmospheric lines in NIR spectra. We search for signatures of planetary H + 3 emission in the L band, using spectra of HD 209458 obtained during and after secondary eclipse of its transiting planet HD 209458 b. We searched for H + 3 emission signatures in spectra containing the combined light of the star and, possibly, the planet. With the information on the ephemeris of the transiting planet, we derive the radial velocities at the time of observation and search for the emission at the expected line positions. We also apply a cross-correlation test to search for planetary signals and use a shift and add technique combining all observed spectra taken after secondary eclipse to calculate an upper emission limit. We do not find signatures of atmospheric H + 3 emission in the spectra containing the combined light of HD 209458 and its orbiting planet. We calculate the emission limit for the H + 3 line at 3953.0 nm [Q(1, 0)] to be 8.32 × 10 18 W and a limit of 5.34 × 10 18 W for the line at 3985.5 nm [Q(3, 0)]. Comparing our emission limits to the theoretical predictions suggests that we lack 1 to 3 magnitudes of sensitivity to measure H + 3 emission in our target object. We show that under more favorable weather conditions the data quality can be improved significantly, reaching 5 × 10 16 W for star-planet systems that are close to Earth. We estimate that pushing the detection limit down to 10 15 W will be possible with ground-based observations with future instrumentation, for example, the European Extremly Large Telescope.

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Section: Observationsmentioning

confidence: 99%

A CRIRES-search for H₃⁺emission from the hot Jupiter atmosphere of HD 209458 b

Lenz

Reiners

Seifahrt

et al. 2016

A&A

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“…Nevertheless, for precise wavelength calibration on the basis of telluric CO 2 lines, one should take into account that the line centroids may vary depending on the ambient climate above the observatory at the time when the spectrum is obtained. Thus, to assure precise calibration, we adopted methods for telluric spectral synthesis similar to those used in Seifahrt & Käufl (2008), Seifahrt et al (2010) and Lebzelter et al (2012).…”

Section: Wavelength Calibrationmentioning

confidence: 99%

Precise radial velocities of giant stars

Trifonov

Reffert

Zechmeister

et al. 2015

A&A

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Context. We have been monitoring 373 very bright (V ≤ 6 mag) G and K giants with high precision optical Doppler spectroscopy for more than a decade at Lick Observatory. Our goal was to discover planetary companions around those stars and to better understand planet formation and evolution around intermediate-mass stars. However, in principle, long-term, g-mode nonradial stellar pulsations or rotating stellar features, such as spots, could effectively mimic a planetary signal in the radial velocity data. Aims. Our goal is to compare optical and infrared radial velocities for those stars with periodic radial velocity patterns and to test for consistency of their fitted radial velocity semiamplitudes. Thereby, we distinguish processes intrinsic to the star from orbiting companions as reason for the radial velocity periodicity observed in the optical. Methods. Stellar spectra with high spectral resolution have been taken in the H-band with the CRIRES near-infrared spectrograph at ESO's VLT for 20 stars of our Lick survey. Radial velocities are derived using many deep and stable telluric CO 2 lines for precise wavelength calibration. Results. We find that the optical and near-infrared radial velocities of the giant stars in our sample are consistent. We present detailed results for eight stars in our sample previously reported to have planets or brown dwarf companions. All eight stars passed the infrared test. Conclusions. We conclude that the planet hypothesis provides the best explanation for the periodic radial velocity patterns observed for these giant stars.

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“…We used a CRIRES spectrum from the library of Lebzelter et al (2012) 3 . HD 83240 is classified as a K1 III star and has a T eff = 4680 K, log g = 2.45 dex, v mic = 1.3 km s −1 and [Fe/H] = −0.02 dex.…”

Section: Sulphur Abundance Of the Sun And Hd 83240mentioning

confidence: 99%

Galactic evolution of sulphur as traced by globular clusters

Kacharov

Koch

Caffau³

et al. 2015

A&A

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Context. Sulphur is an important volatile α element, but its role in the Galactic chemical evolution is still uncertain, and more observations constraining the sulphur abundance in stellar photospheres are required. Aims. We derive the sulphur abundances in red giant branch (RGB) stars in three Galactic halo globular clusters (GC) that cover a wide metallicity range (−2. However, some light and α elements show star-to-star variations within individual GCs, and it is as yet unclear whether the α element sulphur also varies between GC stars. Methods. We used the infrared spectrograph CRIRES to obtain high-resolution (R ∼ 50 000), high signal-to-noise (S /N ∼ 200 per px) spectra in the region of the S I multiplet 3 at 1045 nm for 15 GC stars selected from the literature (six stars in M 4, six stars in M 22, and three stars in M 30). Multiplet 3 is better suited for S abundance derivation than the more commonly used lines of multiplet 1 at 920 nm, since its lines are not blended by telluric absorption or other stellar features at low metallicity. Results. We used spectral synthesis to derive the [S/Fe] ratio of the stars assuming local thermodynamic equilibrium (LTE). We find mean [S/Fe] LTE = 0.58 ± 0.01 ± 0.20 dex (statistical and systematic error) for M 4, [S/Fe] LTE = 0.57 ± 0.01 ± 0.19 dex for M 22, and [S/Fe] LTE = 0.55 ± 0.02 ± 0.16 dex for M 30. The negative NLTE corrections are estimated to be in the order of the systematic uncertainties. We do not detect star-to-star variations of the S abundance in any of the observed GCs, with the possible exception of two individual stars, one in M 22 and one in M 30, which appear to be highly enriched in S. Conclusions. With the tentative exception of two stars with measured high S abundances, we conclude that sulphur behaves like a typical α element in the studied Galactic GCs, showing enhanced abundances with respect to the solar value at metallicities below [Fe/H] − 1.0 dex without a considerable spread.

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Crires-Pop

Cited by 32 publications

References 114 publications

A CRIRES-search for H₃⁺emission from the hot Jupiter atmosphere of HD 209458 b

A CRIRES-search for H₃⁺emission from the hot Jupiter atmosphere of HD 209458 b

Precise radial velocities of giant stars

Galactic evolution of sulphur as traced by globular clusters

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Crires-Pop

Cited by 32 publications

References 114 publications

A CRIRES-search for H3+emission from the hot Jupiter atmosphere of HD 209458 b

A CRIRES-search for H3+emission from the hot Jupiter atmosphere of HD 209458 b

Precise radial velocities of giant stars

Galactic evolution of sulphur as traced by globular clusters

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A CRIRES-search for H₃⁺emission from the hot Jupiter atmosphere of HD 209458 b

A CRIRES-search for H₃⁺emission from the hot Jupiter atmosphere of HD 209458 b