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Piskunov, Nikolai, professorORCID iD iconorcid.org/0000-0001-5742-7767
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Publications (10 of 184) Show all publications
Hahlin, A., Kochukhov, O., Chaturvedi, P., Guenther, E., Hatzes, A., Heiter, U., . . . Shulyak, D. (2025). Comparative study of small-scale magnetic fields on ξ Boo A using optical and near-infrared spectroscopy. Astronomy and Astrophysics, 696, Article ID A4.
Open this publication in new window or tab >>Comparative study of small-scale magnetic fields on ξ Boo A using optical and near-infrared spectroscopy
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2025 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 696, article id A4Article in journal (Refereed) Published
Abstract [en]

Magnetic field investigations of Sun-like stars, using Zeeman splitting of non-polarised spectra, in the optical and H-band have found significantly different magnetic field strengths for the same stars, the cause of which is currently unknown. We aim to further investigate this issue by systematically analysing the magnetic field of ξ Boo A, a magnetically active G7 dwarf, using spectral lines at different wavelengths. We used polarised radiative transfer accounting for the departures from local thermodynamic equilibrium to generate synthetic spectra. To find the magnetic field strengths in the optical, H-band, and K-band, we employed MCMC sampling analysis of high-resolution spectra observed with the spectrographs CRIRES+, ESPaDOnS, NARVAL, and UVES. We also determine the formation depth of different lines by calculating the contribution functions for each line employed in the analysis. We find that the magnetic field strength discrepancy between lines in the optical and H-band persists even when treating the different wavelength regions consistently. In addition, the magnetic measurements derived from the K-band appear to more closely align with the optical. The H-band appears to yield magnetic field strengths ~0.4 kG with a statistically significant variation while the optical and K-band is stable at ~0.6 kG for observations spanning about two decades. The contribution functions reveal that the optical lines form at a significantly higher altitude in the photosphere compared to those in the H- and K-band. While we find that the discrepancy remains, the variation of formation depths could indicate that the disagreement between magnetic field measurements obtained at different wavelengths is linked to the variation of the magnetic field along the line of sight and between different structures, such as star spots and faculae, in the stellar photosphere.

Place, publisher, year, edition, pages
EDP Sciences, 2025
Keywords
stars: magnetic field, techniques: spectroscopic, stars: individual: $\xi$ Boo A
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-552260 (URN)10.1051/0004-6361/202453016 (DOI)001455406500020 ()2-s2.0-105001647530 (Scopus ID)
Available from: 2025-03-12 Created: 2025-03-12 Last updated: 2025-04-29Bibliographically approved
Nortmann, L., Lesjak, F., Yan, F., Cont, D., Czesla, S., Lavail, A., . . . Seemann, U. (2025). CRIRES+ transmission spectroscopy of WASP-127 b: Detection of the resolved signatures of a supersonic equatorial jet and cool poles in a hot planet. Astronomy and Astrophysics, 693, Article ID A213.
Open this publication in new window or tab >>CRIRES+ transmission spectroscopy of WASP-127 b: Detection of the resolved signatures of a supersonic equatorial jet and cool poles in a hot planet
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2025 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 693, article id A213Article in journal (Refereed) Published
Abstract [en]

Context. General circulation models of gas giant exoplanets predict equatorial jets that drive inhomogeneities in the atmospheric physical parameters across the planetary surface. Aims. We studied the transmission spectrum of the hot Jupiter WASP-127 b during one transit in the K band with CRIRES+. Methods. Telluric and stellar signals were removed from the data using SYSREM and the planetary signal was investigated using the cross-correlation technique. After detecting a spectral signal indicative of atmospheric inhomogeneities, we employed a Bayesian retrieval framework with a two-dimensional modelling approach tailored to address this scenario. Results. We detected strong signals of H2O and CO, which exhibited not one but two distinct cross-correlation peaks. The doublepeaked signal can be explained by a supersonic equatorial jet and muted signals at the planetary poles, with the two peaks representing the signals from the planet's morning and evening terminators. We calculated an equatorial jet velocity of 7.7 +/- 0.2 km s(-1) from our retrieved overall equatorial velocity and the planet's tidally locked rotation, and derive distinct atmospheric properties for the two terminators as well as the polar region. Our retrieval yields a solar C/O ratio and metallicity, and shows that the muted signals from the poles can be explained by either significantly lower temperatures or a high cloud deck. It provides tentative evidence for the morning terminator to be cooler than the evening terminator by -175(-117)(+133) K. Conclusions. Our detection of CO challenges previous non-detections of this species in WASP-127b's atmosphere. The presence of a clear double-peaked signal highlights the importance of taking planetary three-dimensional structure into account during interpretation of atmospheric signals. The measured supersonic jet velocity and the lack of signal from the polar regions, representing a detection of latitudinal inhomogeneity in a spatially unresolved target, showcases the power of high-resolution transmission spectroscopy for the characterisation of global circulation in exoplanet atmospheres.

Place, publisher, year, edition, pages
EDP Sciences, 2025
Keywords
techniques: spectroscopic, planets and satellites: atmospheres, planets and satellites: individual: WASP-127b
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-555205 (URN)10.1051/0004-6361/202450438 (DOI)001402042500002 ()2-s2.0-85216225321 (Scopus ID)
Funder
Knut and Alice Wallenberg FoundationKnut and Alice Wallenberg Foundation, 2018.0192Swedish Research Council, 2019-03548Swedish Research Council, 2023-03667Swedish National Space BoardSwedish Research Council
Available from: 2025-04-24 Created: 2025-04-24 Last updated: 2025-04-24Bibliographically approved
Koehler, J., Zechmeister, M., Hatzes, A., Chamarthi, S., Nagel, E., Seemann, U., . . . Smoker, J. V. (2025). viper: High-precision radial velocities from the optical to the infrared Reaching 3 m/s in the K band of CRIRES+ with telluric modelling. Astronomy and Astrophysics, 698, Article ID A44.
Open this publication in new window or tab >>viper: High-precision radial velocities from the optical to the infrared Reaching 3 m/s in the K band of CRIRES+ with telluric modelling
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2025 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 698, article id A44Article in journal (Refereed) Published
Abstract [en]

Context. High-precision radial velocity (RV) measurements with slit spectrographs require the instrument profile (IP) and Earth's atmospheric spectrum to be known and to be incorporated into the RV calculation. Aims. We developed an RV pipeline, called Velocity and IP EstimatoR (viper), to achieve high-precision RVs in the near-infrared (NIR). The code is able to process observations taken with a gas cell and includes modelling of the IP and telluric lines. Methods. We utilised least-square fitting and telluric forward modelling to account for instrument instabilities and atmospheric absorption lines. As part of this process, we demonstrate the creation of telluric-free stellar spectra. Results. By applying viper to observations obtained with the upgraded CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES+) and a gas absorption cell in the K band, we are able to reach an RV precision of around 3 m/s over a time span of 2.5 years. For observations using telluric lines for the wavelength reference, an RV precision of 10 m/s is achieved. Conclusions. We demonstrate that despite telluric contamination, a high RV precision is possible at NIR wavelengths, even for a slit spectrograph with varying IP. Furthermore, we show that CRIRES+ performs well and is an excellent choice for science studies requiring precise stellar RV measurements in the infrared.

Place, publisher, year, edition, pages
EDP Sciences, 2025
Keywords
instrumentation: spectrographs, methods: data analysis, techniques: radial velocities, techniques: spectroscopic, planets and satellites: detection
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-559535 (URN)10.1051/0004-6361/202553919 (DOI)001496235200006 ()2-s2.0-105006814294 (Scopus ID)
Funder
Knut and Alice Wallenberg FoundationGerman Research Foundation (DFG), HA 3279/15-1Swedish Research Council, 2019-03548Swedish Research Council, 2023-03667
Available from: 2025-06-17 Created: 2025-06-17 Last updated: 2025-06-17Bibliographically approved
Kochukhov, O., Amarsi, A. M., Lavail, A., Ruh, H. L., Hahlin, A., Hatzes, A., . . . Shulyak, D. (2024). A conclusive non-detection of magnetic field in the Am star o Peg with high-precision near-infrared spectroscopy. Astronomy and Astrophysics, 689, Article ID A36.
Open this publication in new window or tab >>A conclusive non-detection of magnetic field in the Am star o Peg with high-precision near-infrared spectroscopy
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2024 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 689, article id A36Article in journal (Refereed) Published
Abstract [en]

Context. The A-type metallic-line (Am) stars are typically considered to be non-magnetic or to possess very weak sub-G magnetic fields. This view has been repeatedly challenged in the literature; most commonly for the bright hot Am star o Peg. Several studies claim to have detected 1-2 kG field of unknown topology in this object, possibly indicating a new process of magnetic-field generation in intermediate-mass stars. Aims. In this study, we revisit the evidence of a strong magnetic field in o Peg using new high-resolution spectropolarimetric observations and advanced spectral fitting techniques.

Methods. We estimated the mean magnetic field strength in o Peg from the high-precision CRyogenic InfraRed Echelle Spectrograph (CRIRES+) measurement of near-infrared (NIR) sulphur lines. We modelled this observation with a polarised radiative transfer code, including treatment of the departures from local thermodynamic equilibrium. In addition, we used the least-squares deconvolution multi-line technique to derive longitudinal field measurements from archival optical spectropolarimetric observations of this star.

Results. Our analysis of the NIR S I lines reveals no evidence of Zeeman broadening, ruling out magnetic field with a strength exceeding 260 G. This null result is compatible with the relative intensification of Fe II lines in the optical spectrum, taking into account blending and uncertain atomic parameters of the relevant diagnostic transitions. Longitudinal field measurements on three different nights also yield null results with a precision of 2 G.

Conclusions. This study refutes the claims of kG-strength dipolar or tangled magnetic field in o Peg. This star therefore appears to be non-magnetic, with surface magnetic field characteristics no different from those of other Am stars.

Place, publisher, year, edition, pages
EDP Sciences, 2024
Keywords
stars: chemically peculiar, stars: early-type, stars: magnetic field, stars: individual: o Peg
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-538858 (URN)10.1051/0004-6361/202450543 (DOI)001303205700030 ()
Funder
Swedish Research Council, 2020-03940Swedish Research Council, 2019-03548Swedish Research Council, 2023-03667Swedish National Space Board
Available from: 2024-10-15 Created: 2024-10-15 Last updated: 2024-11-19Bibliographically approved
Brucalassi, A., Tozzi, A., Oliva, E., Araiza-Duran, J. A., Ferruzzi, D., Savio, D., . . . Zanutta, A. (2024). ANDES, the high resolution spectrograph for the ELT: evolution of the Fiber-Link subsystem after the System Architecture Review. In: Julia J. Bryant; Kentaro Motohara; Joël R. D. Vernet (Ed.), Ground-Based and Airborne Instrumentation for Astronomy X: . Paper presented at Conference on Ground-Based and Airborne Instrumentation for Astronomy X, June 16-21, 2024, Yokohama, Japan. SPIE - The International Society for Optics and Photonics, 13096, Article ID 130964I.
Open this publication in new window or tab >>ANDES, the high resolution spectrograph for the ELT: evolution of the Fiber-Link subsystem after the System Architecture Review
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2024 (English)In: Ground-Based and Airborne Instrumentation for Astronomy X / [ed] Julia J. Bryant; Kentaro Motohara; Joël R. D. Vernet, SPIE - The International Society for Optics and Photonics, 2024, Vol. 13096, article id 130964IConference paper, Published paper (Refereed)
Abstract [en]

With this work we summarise the design evolution and challenges of the Fiber-Link module for ANDES (ArmazoNes high Dispersion Echelle Spectrograph), the high resolution spectrograph for ESO ELT. The instrument just passed the System Architecture Review of Phase-B1. The Fiber-Link subsystem carries and redistributes the light from the telescope to the spectrometers via several selectable optical paths. The general updated layout for the Fiber-Link module is presented giving element characteristics and obtained performances. First results from laboratory test and prototype activities are also shown. Moreover, we include the reasoning for selected solutions and explaining how requirements are met. Finally, we summarise the compliance against the science top-level requirements and the issues to address moving forward.

Place, publisher, year, edition, pages
SPIE - The International Society for Optics and Photonics, 2024
Series
Proceedings of SPIE, ISSN 0277-786X, E-ISSN 1996-756X ; 13096
Keywords
ELT, high resolution spectrograph, ANDES, fiber link
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-546584 (URN)10.1117/12.3018950 (DOI)001327608101060 ()2-s2.0-85205557607 (Scopus ID)9781510675155 (ISBN)9781510675162 (ISBN)
Conference
Conference on Ground-Based and Airborne Instrumentation for Astronomy X, June 16-21, 2024, Yokohama, Japan
Available from: 2025-01-15 Created: 2025-01-15 Last updated: 2025-01-15Bibliographically approved
Marconi, A., Abreu, M., Adibekyan, V., Alberti, V., Albrecht, S., Alcaniz, J., . . . Zimara, J. (2024). ANDES, the high resolution spectrograph for the ELT: science goals, project overview and future developments. In: Julia J. Bryant; Kentaro Motohara;, Joël R. D. Vernet (Ed.), Ground-Based and Airborne Instrumentation for Astronomy X: . Paper presented at Conference on Ground-Based and Airborne Instrumentation for Astronomy X, June 16-21, 2024, Yokohama, Japan. SPIE - The International Society for Optics and Photonics, 13096, Article ID 1309613.
Open this publication in new window or tab >>ANDES, the high resolution spectrograph for the ELT: science goals, project overview and future developments
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2024 (English)In: Ground-Based and Airborne Instrumentation for Astronomy X / [ed] Julia J. Bryant; Kentaro Motohara;, Joël R. D. Vernet, SPIE - The International Society for Optics and Photonics, 2024, Vol. 13096, article id 1309613Conference paper, Published paper (Refereed)
Abstract [en]

The first generation of ELT instruments includes an optical-infrared high resolution spectrograph, indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). ANDES consists of three fibre-fed spectrographs ([U]BV, RIZ, YJH) providing a spectral resolution of similar to 100,000 with a minimum simultaneous wavelength coverage of 0.4-1.8 mu m with the goal of extending it to 0.35-2.4 mu m with the addition of an U arm to the BV spectrograph and a separate K band spectrograph. It operates both in seeing- and diffraction-limited conditions and the fibre-feeding allows several, interchangeable observing modes including a single conjugated adaptive optics module and a small diffraction-limited integral field unit in the NIR. Modularity and fibre-feeding allows ANDES to be placed partly on the ELT Nasmyth platform and partly in the Coude room. ANDES has a wide range of groundbreaking science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars, tests on the stability of Nature's fundamental couplings, and the direct detection of the cosmic acceleration. The ANDES project is carried forward by a large international consortium, composed of 35 Institutes from 13 countries, forming a team of almost 300 scientists and engineers which include the majority of the scientific and technical expertise in the field that can be found in ESO member states.

Place, publisher, year, edition, pages
SPIE - The International Society for Optics and Photonics, 2024
Series
Proceedings of SPIE, ISSN 0277-786X, E-ISSN 1996-756X ; 13096
Keywords
ground-based instruments, high resolution spectrographs, infrared spectrographs, extremely large telescopes, exoplanets, stars and planets formation, physics and evolution of stars, physics and evolution of galaxies, cosmology, fundamental physics
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-546589 (URN)10.1117/12.3017966 (DOI)001327608100032 ()2-s2.0-85200803254 (Scopus ID)9781510675155 (ISBN)9781510675162 (ISBN)
Conference
Conference on Ground-Based and Airborne Instrumentation for Astronomy X, June 16-21, 2024, Yokohama, Japan
Funder
EU, European Research Council, 101052347EU, Horizon 2020, UIDB/04434/2020EU, Horizon 2020, UIDP/04434/2020Swedish Research CouncilEU, European Research Council, 804240Australian Research Council, FT180100194
Available from: 2025-01-09 Created: 2025-01-09 Last updated: 2025-01-09Bibliographically approved
Cheng, Y. S., Dadi, K., Mitchell, T., Thompson, S., Piskunov, N., Wright, L. D., . . . Reid, D. T. (2024). ANDES, the high-resolution spectrograph for the ELT: a 30 GHz UB-band astrocomb from 390-470 nm. In: Ramón Navarro; Ralf Jedamzik (Ed.), Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VI: . Paper presented at Conference on Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VI, June 16-22, 2024, Yokohama, Japan. SPIE - The International Society for Optics and Photonics, Article ID 131003C.
Open this publication in new window or tab >>ANDES, the high-resolution spectrograph for the ELT: a 30 GHz UB-band astrocomb from 390-470 nm
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2024 (English)In: Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VI / [ed] Ramón Navarro; Ralf Jedamzik, SPIE - The International Society for Optics and Photonics, 2024, article id 131003CConference paper, Published paper (Refereed)
Abstract [en]

Next generation extreme precision radial velocity (EPRV) instruments such as the ANDES spectrograph of the Extremely Large Telescope will require an unprecedentedly high-precision calibration approach, particularly in the UB band region in which the most dense stellar absorption lines are present. For this purpose, astrocombs delivering thousands of atomically referenced, evenly-spaced calibration lines across a broad spectrum have the potential to be ideal calibration sources. Here, we report a novel and effective approach to generating a laser frequency comb with a multi-GHz mode spacing covering a broad wavelength range in the UB band. The approach is based on nonlinear mixing between near-infrared ultrafast laser pulses in a MgO:PPLN waveguide. The generated 1-GHz comb, spanning 390-520 nm, was filtered to a 30 GHz sub-comb using a low-dispersion Fabry-Perot etalon. The resultant UB-band astrocomb was then captured on a lab-built cross-dispersion echelle-prism spectrograph, demonstrating well resolved comb lines across the etalon bandwidth of 392-472 nm.

Place, publisher, year, edition, pages
SPIE - The International Society for Optics and Photonics, 2024
Series
Proceedings of SPIE, ISSN 0277-786X, E-ISSN 1996-756X ; 13100
Keywords
Astrocomb, Ti:sapphire laser, MgO:PPLN waveguide, sum-frequency-mixing
National Category
Atom and Molecular Physics and Optics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-545684 (URN)10.1117/12.3013078 (DOI)001327611800091 ()2-s2.0-85205991781 (Scopus ID)978-1-5106-7523-0 (ISBN)978-1-5106-7524-7 (ISBN)
Conference
Conference on Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VI, June 16-22, 2024, Yokohama, Japan
Funder
Knut and Alice Wallenberg Foundation
Available from: 2024-12-20 Created: 2024-12-20 Last updated: 2024-12-20Bibliographically approved
Cheng, Y. S., Dadi, K., Mitchell, T., Thompson, S., Piskunov, N., Wright, L. D., . . . Reid, D. T. (2024). Continuous ultraviolet to blue-green astrocomb. Nature Communications, 15, Article ID 1466.
Open this publication in new window or tab >>Continuous ultraviolet to blue-green astrocomb
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2024 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 15, article id 1466Article in journal (Refereed) Published
Abstract [en]

Cosmological and exoplanetary science using transformative telescopes like the ELT will demand precise calibration of astrophysical spectrographs in the blue-green, where stellar absorption lines are most abundant. Astrocombs-lasers providing a broadband sequence of regularly-spaced optical frequencies on a multi-GHz grid-promise an atomically-traceable calibration scale, but their realization in the blue-green is challenging for current infrared-laser-based technology. Here, we introduce a concept achieving a broad, continuous spectrum by combining second-harmonic generation and sum-frequency-mixing in an MgO:PPLN waveguide to generate 390-520 nm light from a 1 GHz Ti:sapphire frequency comb. Using a Fabry-Perot filter, we extract a 30 GHz sub-comb spanning 392-472 nm, visualizing its thousands of modes on a high-resolution spectrograph. Experimental data and simulations demonstrate how the approach can bridge the spectral gap present in second-harmonic-only conversion. Requiring only ≈100 pJ pulses, our concept establishes a new route to broadband UV-visible generation at GHz repetition rates.

Place, publisher, year, edition, pages
Springer Nature, 2024
National Category
Astronomy, Astrophysics and Cosmology Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-526270 (URN)10.1038/s41467-024-45924-6 (DOI)001163800700002 ()38368423 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation
Available from: 2024-04-08 Created: 2024-04-08 Last updated: 2024-04-08Bibliographically approved
Scaudo, A., Genoni, M., Li Causi, G., Cabona, L., Landoni, M., Campana, S., . . . Marconi, A. (2024). End-to-End simulation framework for astronomical spectrographs: SOXS, CUBES and ANDES. In: Sébastien Elias Egner; Scott Roberts (Ed.), Modeling, Systems Engineering, and Project Management for Astronomy XI: . Paper presented at Conference on Modeling, Systems Engineering, and Project Management for Astronomy XI, June 16-18, 2024, Yokohama, Japan. SPIE - The International Society for Optics and Photonics, Article ID 1309905.
Open this publication in new window or tab >>End-to-End simulation framework for astronomical spectrographs: SOXS, CUBES and ANDES
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2024 (English)In: Modeling, Systems Engineering, and Project Management for Astronomy XI / [ed] Sébastien Elias Egner; Scott Roberts, SPIE - The International Society for Optics and Photonics, 2024, article id 1309905Conference paper, Published paper (Refereed)
Abstract [en]

We present our numerical simulation approach for the End-to-End (E2E) model applied to various astronomical spectrographs, such as SOXS (ESO-NTT), CUBES (ESO-VLT), and ANDES (ESO-ELT), covering multiple wavelength regions. The E2E model aim at simulating the expected astronomical observations starting from the radiation of the scientific sources (or calibration sources) up to the raw-frame data produced by the detectors. The comprehensive description includes E2E architecture, computational models, and tools for rendering the simulated frames. Collaboration with Data Reduction Software (DRS) teams is discussed, along with efforts to meet instrument requirements. The contribution to the cross-correlation algorithm for the Active Flexure Compensation (AFC) system of CUBES is detailed.

Place, publisher, year, edition, pages
SPIE - The International Society for Optics and Photonics, 2024
Series
Proceedings of SPIE, ISSN 0277-786X, E-ISSN 1996-756X ; 13099
Keywords
SOXS-NTT, CUBES-VLT, ANDES-ELT, End-to-End simulations
National Category
Astronomy, Astrophysics and Cosmology Telecommunications
Identifiers
urn:nbn:se:uu:diva-544689 (URN)10.1117/12.3019941 (DOI)001329061000002 ()2-s2.0-85201299726 (Scopus ID)978-1-5106-7521-6 (ISBN)978-1-5106-7522-3 (ISBN)
Conference
Conference on Modeling, Systems Engineering, and Project Management for Astronomy XI, June 16-18, 2024, Yokohama, Japan
Available from: 2024-12-06 Created: 2024-12-06 Last updated: 2024-12-06Bibliographically approved
Cont, D., Nortmann, L., Yan, F., Lesjak, F., Czesla, S., Lavail, A., . . . Shulyak, D. (2024). Exploring the ultra-hot Jupiter WASP-178b. Astronomy and Astrophysics, 688, Article ID A206.
Open this publication in new window or tab >>Exploring the ultra-hot Jupiter WASP-178b
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2024 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 688, article id A206Article in journal (Refereed) Published
Abstract [en]

Despite recent progress in the spectroscopic characterization of individual exoplanets, the atmospheres of key ultra-hot Jupiters (UHJs) still lack comprehensive investigations. These include WASP-178b, one of the most irradiated UHJs known to date. We observed the dayside emission signal of this planet with CRIRES+ in the spectral K band. By applying the cross-correlation technique and a Bayesian retrieval framework to the high-resolution spectra, we identified the emission signature of 12CO (S/N = 8.9) and H2O (S/N = 4.9), and a strong atmospheric thermal inversion. A joint retrieval with space-based secondary eclipse measurements from TESS and CHEOPS allowed us to refine our results on the thermal profile and thus to constrain the atmospheric chemistry, yielding a solar to super-solar metallicity (1.4 ± 1.6 dex) and a solar C/O ratio (0.6 ± 0.2). We infer a significant excess of spectral line broadening and identify a slight Doppler-shift between the 12CO and H2O signals. These findings provide strong evidence for a super-rotating atmospheric flow pattern and suggest the possible existence of chemical inhomogeneities across the planetary dayside hemisphere. In addition, the inclusion of photometric data in our retrieval allows us to account for stellar light reflected by the planetary atmosphere, resulting in an upper limit on the geometric albedo (0.23). The successful characterization of WASP-178b’s atmosphere through a joint analysis of CRIRES+, TESS, and CHEOPS observations highlights the potential of combined studies with space- and ground-based instruments and represents a promising avenue for advancing our understanding of exoplanet atmospheres.

Place, publisher, year, edition, pages
EDP Sciences, 2024
Keywords
techniques, spectroscopic / planets and satellites, atmospheres / planets and satellites, individual, WASP-178b
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Astronomy and Astrophysics; Astronomy with specialization in Astrophysics
Identifiers
urn:nbn:se:uu:diva-538001 (URN)10.1051/0004-6361/202450064 (DOI)001296908700016 ()
Funder
Knut and Alice Wallenberg Foundation, 2018.0192
Available from: 2024-09-08 Created: 2024-09-08 Last updated: 2024-09-11Bibliographically approved
Projects
Ansökan om konferensbidrag: Inbjudan av talare till konferensen A Stellar Journey A symposium in celebration of Bengt Gustafsson´s 65th birthday, Uppsala, 23-27 juni 2008 [2008-01243_VR]; Uppsala UniversityWorkshop: Precision wavelength calibrations [2009-02823_VR]; Uppsala UniversityStars and Planets: Discovery and characterization [2010-04094_VR]; Uppsala UniversityVALD - an atomic and molecular database for spectroscopic applications [2010-05987_VR]; Uppsala University
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ORCID iD: ORCID iD iconorcid.org/0000-0001-5742-7767

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