1,720,968 research outputs found
Optimising spectroscopic observations of transiting exoplanets
No full textContext. When observing the atmospheres of transiting exoplanets using high-resolution spectroscopy, the aim is to detect well-resolved spectral features with high signal-to-noise ratios (S/Ns), as is possible today with modern spectrographs. However, obtaining such high-quality observations comes with a trade-off: a lower cadence of fewer, longer exposures across the transit collects more photons thanks to reduced overheads, enhancing the S/N of each observation, while a higher cadence of several shorter exposures minimises spectral feature smearing due to the continuously changing radial velocity of the planet.
Aims. Considering that maximising S/N and minimising smearing are both beneficial to analysis, there is a need to identify the optimal compromise between the two for a given target. In this work, we aim to establish where this compromise lies for a typical exoplanet transit observation in order to benefit future data collection and subsequent interpretation.
Methods. We modelled real transit events based on targets as they would be observed with VLT/CRIRES+ at Paranal Observatory, Chile. Creating four hypothetical scenarios, we simulated each set of transmission spectra across 100 realisations of the same transit event in order to vary the time resolution only. We removed telluric and stellar lines from these data sets using the SYSREM algorithm and analysed them through cross-correlation with model templates, measuring how successfully each time resolution and case detected the planetary signal and exploring how the results vary.
Results. We demonstrate that there is a continuous change in the significance of the cross-correlation detection based on the trade-off between high and low time resolutions, and that, averaged over a large number of realisations, the function of this significance has clear maxima. The strength and location of these maxima vary depending on, for example, planet system parameters, instrumentation, and the number of removal iterations. We discuss why observers should therefore take several factors into account using a strategy akin to the ‘exposure triangle’ employed in traditional photography where a balance must be struck by considering the full context of the observation. Our method is robust and may be employed by observers to estimate the best observational strategies for other targets
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Characterisation of exoplanet atmospheres with high-resolution spectroscopy
Full text linkHochauflösende spektroskopische Beobachtungen ermöglichen die Untersuchung der Zusammensetzung und Dynamik von exoplanetaren Atmosphären. Absorptions- und Emissionslinien dienen als wertvolle Diagnostik, da ihre Stärke, Position und Form direkt mit den thermischen, chemischen und dynamischen Bedingungen in der Atmosphäre verbunden sind.
Insbesondere die relativ starken spektroskopischen Signale von heißen Jupitern (HJs), einer Klasse heißer Gasriesen mit kurzen Umlaufperioden, bieten die Möglichkeit für detailierte atmosphärische Charakterisierungen.
Diese Arbeit präsentiert die Analyse von Transmissions- und Emissionsspektren von vier verschiedenen HJs unter Verwendung der hochauflösenden Spektrographen CRIRES und CARMENES. Neben dem Nachweis von HO detektieren wir zum ersten Mal CO in der Atmosphäre von WASP-43b und bestimmen darüber hinaus das Temperaturprofil, die chemischen Häufigkeiten und das atmosphärische C/O-Verhältnis. Unsere Analyse zeigt keine eindeutigen Hinweise auf eine Wolkendecke auf der Tagseite des Planeten. Basierend auf der beobachteten Linienverbreiterung bestimmen wir die Geschwindigkeit eines äquatorialen superrotierenden Jet auf 5 km\,s, in Übereinstimmung mit Vorwärtsmodellen und niedrigauflösenden Beobachtungen dieses Planeten.
Bei der Untersuchung der des Emissionsspektrums von WASP-189b detektieren wir starke Signaturen von CO und Fe. Durch die Integration eines neuen zweidimensionalen Linienprofil-Modells in unser Retrieval-Framework ermitteln wir die Windeigenschaften und interpretieren beobachtete Geschwindigkeitsdifferenzen. Unsere Analyse deutet auf einen globalen Tag-Nacht-Wind und insbesondere auf die Abwesenheit eines äquatorialen Jets hin. Diese Ergebnisse liefern konkrete Einblicke in die planetare Atmosphärendynamik, und wir diskutieren, wie Winde und andere Effekte zu den Geschwindigkeitdifferenzen beitragen können.
Schließlich analysieren wir Transmissionsspektren von WASP-69b und KELT-11b, die mit CARMENES beobachtet wurden, und finden kein eindeutiges Signal für alle untersuchten Spezies. Für beide Planeten werden zwar vorläufige HO-Signale nahe der erwarteten planetaren Geschwindigkeit detektiert, aber wir können den planetaren Ursprung dieser Signale nicht eindeutig verifizieren. Wir verwenden zwei unabhängige Ansätze um zu untersuchen, welche Kombinationen von molekularen Häufigkeiten und Wolkenhöhe zu den beobachteten Signalen und Nicht-Detektionen führen würden. Eine Methode basiert auf Injection-Recovery-Tests, während die zweite Methode ein Retrieval-Framework zur Eingrenzung des Parameterraums verwendet. Wir stellen fest, dass beide Ansätze ähnliche Einschränkungen liefern, die wir mit früheren Studien dieser Planeten vergleichen.High-resolution spectroscopic observations offer a powerful approach to investigate planetary atmospheric composition and dynamics. Absorption and emission spectral lines serve as valuable diagnostics, as their strength, position, and shape are directly connected to the thermal, chemical, and dynamical conditions within exoplanetary atmospheres.
Particularly the relatively large spectroscopic signals of hot Jupiters (HJs), a class of hot gas giants with small orbital periods, offer the opportunity for in-depth atmospheric characterisations.
This work presents the analysis of transmission and emission spectra of four different HJs using the high-resolution spectrographs CRIRES and CARMENES. We report the first detection of CO and evidence for the presence of HO in the dayside atmosphere of WASP-43b, and further retrieve the temperature profile, chemical abundances, and atmospheric C/O ratio. Our analysis revealed no conclusive evidence of a cloud deck on the planet's dayside. Based on the observed line broadening, we retrieve an equatorial super-rotating jet with a wind speed of 5 km\,s, in agreement with forward models and low-resolution observations of this planet.
Examining WASP-189b's dayside emission, we detect strong signatures of CO and Fe. By integrating a novel two-dimensional wind-induced line profile model with our retrieval framework, we retrieve wind properties and interpreted observed velocity offsets. Our analysis suggest a global day-to-night wind circulation pattern and notably the absence of an equatorial jet. These results provide nuanced insights into planetary atmospheric dynamics, and we discuss how winds and other effects can contribute to the velocity offsets.
Lastly, we analyse transit observations of WASP-69b and KELT-11b observed with CARMENES, and find no clear signal for any of the investigated species. While tentative HO signals are detected close to the expected planetary rest frame for both planets, we can not unambiguously confirm the planetary origin of these signals. We employ two independent approaches to investigate, which combinations of molecular abundances and cloud height would result in the observed tentative signals and non-detection. One method is based on injection-recovery tests, while the other method applies a retrieval framework to constrain the parameter space. We find that both approaches generally provide similar constraints, which we compare to previous studies of these planets.2025-03-1
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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