| 1. |
- Bristow, Paul, et al.
(författare)
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CRIRES+ : Characterisation and preparation during the pandemic
- 2022
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy IX. - : SPIE - International Society for Optical Engineering. - 9781510653504 - 9781510653498
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Konferensbidrag (refereegranskat)abstract
- In early 2020 the upgraded(1) CRIRES2 instrument, was installed at the VLT, however the onset of the global pandemic prevented the completion of some aspects of the installation while characterisation and commissioning had to be conducted with a remote connection from Europe. This resulted in a somewhat experimental, ad-hoc, approach to characterisation that required tight co-ordination between Paranal scientists and the instrument team in Europe. Moreover, with the observatory operating at minimal staffing, we had to find workarounds for some unfinished parts of the installation and adapt our characterisation, calibration and operations strategies accordingly. In particular, we discuss the adaptation made to the metrology strategy that illustrates well the pragmatic and ultimately successful approach adopted for getting CRIRES+ ready for operations.
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| 2. |
- Dorn, Reinhold J., et al.
(författare)
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CRIRES+ on sky : High spectral resolution at infrared wavelength enabling better science at the ESO VLT
- 2022
-
Ingår i: Ground-Based And Airborne Instrumentation For Astronomy IX. - : SPIE - International Society for Optical Engineering. - 9781510653504 - 9781510653498
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Konferensbidrag (refereegranskat)abstract
- CRIRES+ extended the capabilities of CRIRES, the CRyogenic InfraRed Echelle Spectrograph. It transformed this VLT instrument into a cross-dispersed spectrograph to increase the wavelength range that is covered simultaneously by a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 mu m cut-off wavelength replaced the existing detectors. Amongst many other improvements a new spectropolarimetric unit was added and the calibration system has been enhanced. The instrument was installed at the VLT on Unit Telescope 3 beginning of 2020 and successfully commissioned and verified for science operations during 2021, partly remote from Europe due to the pandemic. The instrument was subsequently offered to the community from October 2021 onwards. This article describes the performance and capabilities of this development and presents on sky results.
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| 3. |
- Ryabchikova, Tatiana, et al.
(författare)
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Using Molecular Lines to Determine Carbon and Nitrogen Abundances in the Atmospheres of Cool Stars
- 2022
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous analysis of the C2 and CN molecular bands in the 5100–5200 and 7930–8100 Å spectral regions is a promising alternative for the accurate determination of the carbon (C) and nitrogen (N) abundance in the atmospheres of the solar-like stars. Practical implementation of this new method became possible after recent improvements of the molecular constants for both molecules. The new molecular data predicted the correct line strength and line positions; therefore, they were included in the Vienna Atomic Line Database (VALD), which is widely used by astronomers and spectroscopists. In this paper, we demonstrate that the molecular data analysis provides C and, in particular, N abundances consistent with those derived from the atomic lines. We illustrate this by performing the analysis for three stars. Our results provide strong arguments for using the combination of C2 and CN molecular lines for accurate nitrogen abundance determination keeping in mind the difficulties of using the N i lines in the observed spectra of the solar-like stars.
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| 4. |
- Wehrhahn, Ansgar, et al.
(författare)
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CRIRES+ detection of H2O and CO in the transmission spectra of WASP-107 b
- 2022
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- WASP-107 b is a warm super-Neptune with a large extended atmosphere orbiting a bright K dwarf of solar composition. The planet's size and the brightness of its stellar host make it highly amenable to atmospheric characterisation, with previous detections of both He and H2O. We observe it here for the first time in high-resolution spectroscopy in the K-band. To obtain a transmission spectrum of the exoplanet atmosphere, we observe a transit event of WASP-107 b for a total of 5.4 hours (2.7 hours in transit) in the K-band with an average SNR = 64 for each exposure using the high-resolution infrared CRIRES+ spectrograph on the Very Large Telescope on Cerro Paranal, Chile. We aim to demonstrate the capabilities of this new instrument for exoplanet characterisation by searching for the presence of molecular features of key chemical species in the atmosphere with spectral lines detectable in this band, such as CO, CO2, H2O, and CH4. The search for particular chemical species is conducted by using the cross-correlation method on the observed spectra. The transit spectroscopy observations are first cleaned from the stellar and telluric features using the SYSREM algorithm, and the remaining spectral information is then compared to a model transmission spectrum. The model transmission spectrum is obtained using the petitRADTRANS code based on expectations for a warm Neptune-class planet and the observed orbital parameters. We report the detection of H2O in the atmosphere of WASP-107 b with 4.71 sigma significance, as well as a detection of CO at 3.46 sigma. The velocities of these detections show signs of atmospheric weather patterns, such as day-to-night-side temperature gradients. We do not detect the presence of CO2 or CH4. Our results confirm the chemical composition of the WASP-107 b's atmosphere and pave the way for efficient atmospheric studies of other planets of the same class. They show that the newly upgraded high-resolution spectrograph CRIRES+ is suitable for exoplanet transit observations. All detections and non-detections are in agreement with previous transmission studies of WASP-107 b based on low-resolution spectroscopy.
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