| 1. |
- Nicholls, Christine P, et al.
(författare)
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CRIRES-POP : a library of high resolution spectra in the near-infrared II. Data reduction and the spectrum of the K giant 10 Leonis
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 598
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Tidskriftsartikel (refereegranskat)abstract
- Context. High resolution stellar spectral atlases are valuable resources to astronomy. They are rare in the 1 − 5 μm region for historical reasons, but once available, high resolution atlases in this part of the spectrum will aid the study of a wide range of astrophysical phenomena. Aims. The aim of the CRIRES-POP project is to produce a high resolution near-infrared spectral library of stars across the H-R diagram. The aim of this paper is to present the fully reduced spectrum of the K giant 10 Leo that will form the basis of the first atlas within the CRIRES-POP library, to provide a full description of the data reduction processes involved, and to provide an update on the CRIRES-POP project. Methods. All CRIRES-POP targets were observed with almost 200 different observational settings of CRIRES on the ESO Very Large Telescope, resulting in a basically complete coverage of its spectral range as accessible from the ground. We reduced the spectra of 10 Leo with the CRIRES pipeline, corrected the wavelength solution and removed telluric absorption with Molecfit, then resampled the spectra to a common wavelength scale, shifted them to rest wavelengths, flux normalised, and median combined them into one final data product. Results. We present the fully reduced, high resolution, near-infrared spectrum of 10 Leo. This is also the first complete spectrum from the CRIRES instrument. The spectrum is available online. Conclusions. The first CRIRES-POP spectrum has exceeded our quality expectations and will form the centre of a state-of-the-art stellar atlas. This first CRIRES-POP atlas will soon be available, and further atlases will follow. All CRIRES-POP data products will be freely and publicly available online.
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| 2. |
- Pathak, P., et al.
(författare)
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High-contrast imaging at ten microns : A search for exoplanets around Eps Indi A, Eps Eri, Tau Ceti, Sirius A, and Sirius B
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 652
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Tidskriftsartikel (refereegranskat)abstract
- Context. The direct imaging of rocky exoplanets is one of the major science goals of upcoming large telescopes. The contrast requirement for imaging such planets is challenging. However, the mid-IR (infrared) regime provides the optimum contrast to directly detect the thermal signatures of exoplanets in our solar neighbourhood.Aims. We aim to exploit novel fast-chopping techniques newly developed for astronomy with the aid of adaptive optics to look for thermal signatures of exoplanets around bright stars in the solar neighbourhood.Methods. We used the upgraded Very Large Telescope Imager and Spectrometer for the mid-InfraRed (VISIR) instrument with high-contrast imaging capability optimised for observations at 10 μm to look for exoplanets around five nearby (d < 4 pc) stars. The instrument provides an improved signal-to-noise ratio (S/N) by a factor of ~4 in the N-band compared to standard VISIR for a given S/N and time.Results. In this work, we achieve a detection sensitivity of sub-mJy, which is sufficient to detect a few Jupiter mass planets in nearby systems. Although no detections are made, we achieve most sensitive limits within <2″ for all the observed targets compared to previous campaigns. For ϵ Indi A and ϵ Eri, we achieve detection limits very close to the giant planets discovered by RV, with the limits on ϵ Indi A being the most sensitive to date. Our non-detection therefore supports an older age for ϵ Indi A. The results presented here are promising for high-contrast imaging and exoplanet detections in the mid-IR regime.
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| 3. |
- Wilson, T. L., et al.
(författare)
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CONSTRAINTS ON THE PRESENCE OF SiO GAS IN THE DEBRIS DISK OF HD 172555
- 2016
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 826:2
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Tidskriftsartikel (refereegranskat)abstract
- We have carried out two sets of observations to quantify the properties of SiO gas in the unusual HD 172555 debris disk: (1) a search for the J = 8-7 rotational transition from the vibrational ground state, carried out with the Atacama Pathfinder EXperiment (APEX) submillimeter telescope and heterodyne receiver at 863 mu m. and (2) a search at 8.3 mu m for the P(17) ro-vibrational transition of gas phase SiO, carried out with the Very Large Telescope (VLT)/VISIR with a resolution, lambda/Delta lambda, of 30,000. The APEX measurement resulted in a 3.3 sigma detection of an interstellar feature, but only an upper limit to emission at the radial velocity and line width expected from HD 172555. The VLT/VISIR result was also an upper limit. These were used to provide limits for the abundance of gas phase SiO. for a range of temperatures. The upper limit from our APEX detection, assuming an 8000 K primary star photospheric excitation, falls more than an order of magnitude below the self-shielding stability threshold derived by Johnson et al. (2012). Our results thus favor a solid-state origin for the 8.3 mu m feature seen in the Spitzer IRS spectrum of the circumstellar excess emission. and the production of circumstellar O I and Si I by SiO UV photolysis. The implications of these estimates are explored in the framework of models of the HD 172555 circumstellar disk.
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| 4. |
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| 5. |
- Kasper, M., et al.
(författare)
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NEAR: : Low-mass Planets in α Cen with VISIR
- 2017
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Ingår i: The Messenger. ; 169, s. 16-20
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Tidskriftsartikel (refereegranskat)abstract
- ESO, in collaboration with the Breakthrough Initiatives, is working to modify the Very Large Telescope mid-IR imager (VISIR) to greatly enhance its ability to search for potentially habitable planets around both components of the binary Alpha Centauri, part of the closest stellar system to the Earth. Much of the funding for the NEAR (New Earths in the Alpha Cen Region) project is provided by the Breakthrough Initiatives, and ESO mostly provides staff and observing time. The concept combines adaptive optics using the deformable secondary mirror at Unit Telescope 4, a new annular groove phase mask (AGPM) coronagraph optimised for the most sensitive spectral bandpass in the N-band, and a novel internal chopper system for noise filtering based on a concept for longer wavelengths invented by the microwave pioneer Robert Dicke. The NEAR experiment is relevant to the mid-infrared METIS instrument on the Extremely Large Telescope, as the knowledge gained and proof of concept will be transferable.
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| 6. |
- Lundqvist, Martin, et al.
(författare)
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Spectroscopy of the M supergiant alpha Ori in the 1-2.5 µm region
- 2005
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Ingår i: High Resolution Infrared Spectroscopy in Astronomy, Proceedings. - 9783540252566 ; , s. 419-422
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Konferensbidrag (refereegranskat)abstract
- The study of elemental abundances in cool stars via atomic lines in the optical region is made difficult by stellar molecular absorption. At infrared wavelengths this problem is diminished, but ground-based observations suffer from absorption by the earth's atmosphere. Fortunately, there are spectral windows through which we can observe. We have explored several such windows in the spectral region from 1-2.5 mu m, coinciding with the wavelength domain of the new VLT instrument CRIRES, for atomic lines suitable for the study of cool luminous stars, in particular alpha Ori (M21ab). We present preliminary results from this search along with our first results on abundances of iron and the weak s-process elements Sr, Y, Zr.
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| 7. |
- Oliva, E., et al.
(författare)
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Upgrading CRIRES-VLT to cross-dispersed mode
- 2012
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Ingår i: Proceedings of SPIE. - : SPIE. - 9780819491473
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Konferensbidrag (refereegranskat)abstract
- The cryogenic high resolution IR echelle spectrograph CRIRES is the ESO infrared (0.95-5.4 μm) high resolution spectrograph operating at the Nasmyth A focus of VLT-UT1. The instrument provides long-slit (31″) spectroscopy with resolving power up to R=100,000 over a quite narrow wavelengths range, about 1/70 of the central wavelength. Observations of compact objects (e.g. stellar photospheres) could be made much more efficient by implementing a cross-dispersed mode, which increases the simultaneous spectral coverage by an order of magnitude or more. This paper presents the design of a relatively simple system to add cross-dispersed modes to CRIRES with a minimum impact on the instrument optics and mechanics.
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| 8. |
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