| 51. |
- Posch, Josefina
(författare)
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EP9 Starlight Reserves
- 2023
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Ingår i: Göteborgs Botaniska Trädgård, GIBCA Extended, 2023-08-19.
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Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- The sculpture EP9 Starlight Reserves was installed in Amerikadammen in Göteborgs Botaniska Trädgård and part of GIBCA Extended 2023. This work is situated in the expanded field of sculpture, where the negotiation with a specific situation plays a central role in material investigations of environmental and sustainability concerns. The shape and title of the sculpture derive from the container of old batteries, "Exposed Pallet 9," which the International Space Station launched into space in 2021 to circulate around the Earth for 2-4 years before entering the Earth's atmosphere and hopefully burn up. [1] Commercial interests, colonization, and tourism led by rich nations and private companies contribute to the increase of space debris. The main inquiry of this research project is how artistic work, through visualization in sculptural form, can draw attention to scientific observations and advocacy in establishing international environmental space law concerning space debris. By using recycled plastic from electronic scrap for the large-scale IRBAM printing of the sculpture, the work highlights the potential for sustainable and ephemeral materials in sculptural production to promote environmental awareness and question the validity of the standard requirement for "permanence" in public sculpture. 3D printing in collaboration with Samuel Johansson and Woodrow Wiest RISE – AM center in Mölndal, Sweden with in-kind funding. Supported by Göteborgs Stad Kultur och Göteborgs Botaniska Trädgård. [1] Mike Wall, “Space station tosses 2.9-ton hunk of space junk overboard. It will stay in orbit for years.”, space.com, accessed January 3, 2024, https://www.space.com/space-station-jettisons-huge-space-junk-pallet
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| 52. |
- Waller, William H., et al.
(författare)
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FM14 Session 2: Communicating Astronomy in our Changing World
- 2018
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Ingår i: Proceedings of the International Astronomical Union. - : Cambridge University Press. - 1743-9213 .- 1743-9221. ; 14:A30, s. 528-530
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Tidskriftsartikel (refereegranskat)abstract
- As the IAU heads towards its second century, many changes have simultaneously transformed Astronomy and the human condition world-wide. Amid the amazing recent discoveries of exoplanets, primeval galaxies, and gravitational radiation, the human condition on Earth has become blazingly interconnected, yet beset with ever-increasing problems of over-population, pollution, and never-ending wars. Fossil-fueled global climate change has begun to yield perilous consequences. And the displacement of people from war-torn nations has reached levels not seen since World War II. © International Astronomical Union 2020.
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| 53. |
- Jones, K., et al.
(författare)
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The stable climate of KELT-9b
- 2022
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 666
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Tidskriftsartikel (refereegranskat)abstract
- Even among the most irradiated gas giants, so-called ultra-hot Jupiters, KELT-9b stands out as the hottest planet thus far discovered with a dayside temperature of over 4500 K. At these extreme irradiation levels, we expect an increase in heat redistribution efficiency and a low Bond albedo owed to an extended atmosphere with molecular hydrogen dissociation occurring on the planetary dayside. We present new photometric observations of the KELT-9 system throughout 4 full orbits and 9 separate occultations obtained by the 30 cm space telescope CHEOPS. The CHEOPS bandpass, located at optical wavelengths, captures the peak of the thermal emission spectrum of KELT-9b. In this work we simultaneously analyse CHEOPS phase curves along with public phase curves from TESS and Spitzer to infer joint constraints on the phase curve variation, gravity-darkened transits, and occultation depth in three bandpasses, as well as derive 2D temperature maps of the atmosphere at three different depths. We find a day-night heat redistribution efficiency of similar to 0.3 which confirms expectations of enhanced energy transfer to the planetary nightside due to dissociation and recombination of molecular hydrogen. We also calculate a Bond albedo consistent with zero. We find no evidence of variability of the brightness temperature of the planet, excluding variability greater than 1% (1 sigma).
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| 54. |
- Nilsson, H., et al.
(författare)
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Experimental transition probabilities for 4p-4d spectral lines in V II
- 2019
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 1432-0746 .- 0004-6361. ; 622
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We aim to measure lifetimes of levels belonging to the 3d(3)(F-4)4d subconfiguration in V II, and derive absolute transition probabilities by combining the lifetimes with experimental branching fractions. Methods. The lifetimes were measured using time-resolved laser-induced fluorescence in a two-photon excitation scheme. The branching fractions were measured in intensity calibrated spectra from a hollow cathode discharge lamp, recorded with a Fourier transform spectrometer. Results. We report lifetimes for 13 levels at an energy around 73 000 cm(-1). Absolute transition probabilities of 78 lines are derived by combining the lifetimes and branching fractions. The experimental values are compared with theoretical data from the literature.
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| 55. |
- Ryde, N., et al.
(författare)
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Stellar population astrophysics (SPA) with the TNG. Identification of a sulphur line at λ_air = 1063.6 nm in GIANO-B stellar spectra
- 2019
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 631, s. L3-L5
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Tidskriftsartikel (refereegranskat)abstract
- Context. In the advent of new infrared, high-resolution spectrometers, accurate and precise atomic data in the infrared is urgently needed. Identifications, wavelengths, strengths, broadening and hyper-fine splitting parameters of stellar lines in the near-IR are in many cases not accurate enough to model observed spectra, and in other cases even non existing. Some stellar features are unidentified. Aims. The aim with this work is to identify a spectral feature at lambda(vac) = 1063.891 nm or lambda(air) = 1063.600 nm seen in spectra of stars of different spectral types, observed with the GIANO-B spectrometer. Methods. Searching for spectral lines to match the unidentified feature in linelists from standard atomic databases was not successful. However, by investigating the original, published laboratory data we were able to identify the feature and solve the problem. To confirm its identification, we model the presumed stellar line in the solar intensity spectrum and find an excellent match. Results. We find that the observed spectral feature is a stellar line originating from the 4s'-4p' transition in S I, and that the reason for its absence in atomic line databases is a neglected air-to-vacuum correction in the original laboratory measurements from 1967 for this line only. From interpolation we determine the laboratory wavelength of the S I line to be lambda(vac) = 1063.8908 nm or lambda(air) = 1063.5993 nm, and the excitation energy of the upper level to be 9.74978 eV.
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| 56. |
- Scott, Pat, 1982-
(författare)
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Searches for Particle Dark Matter : Dark stars, dark galaxies, dark halos and global supersymmetric fits
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The identity of dark matter is one of the key outstanding problems in both particle and astrophysics. In this thesis, I describe a number of complementary searches for particle dark matter. I discuss how the impact of dark matter on stars can constrain its interaction with nuclei, focussing on main sequence stars close to the Galactic Centre, and on the first stars as seen through the upcoming James Webb Space Telescope. The mass and annihilation cross-section of dark matter particles can be probed with searches for gamma rays produced in astronomical targets. Dwarf galaxies and ultracompact, primordially-produced dark matter minihalos turn out to be especially promising in this respect. I illustrate how the results of these searches can be combined with constraints from accelerators and cosmology to produce a single global fit to all available data. Global fits in supersymmetry turn out to be quite technically demanding, even with the simplest predictive models and the addition of complementary data from a bevy of astronomical and terrestrial experiments; I show how genetic algorithms can help in overcoming these challenges.
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| 57. |
- Lendl, M., et al.
(författare)
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The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 643
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Tidskriftsartikel (refereegranskat)abstract
- The CHEOPS space mission dedicated to exoplanet follow-up was launched in December 2019, equipped with the capacity to perform photometric measurements at the 20 ppm level. As CHEOPS carries out its observations in a broad optical passband, it can provide insights into the reflected light from exoplanets and constrain the short-wavelength thermal emission for the hottest of planets by observing occultations and phase curves. Here, we report the first CHEOPS observation of an occultation, namely, that of the hot Jupiter WASP-189 b, a MP ≈ 2MJ planet orbiting an A-type star. We detected the occultation of WASP-189 b at high significance in individual measurements and derived an occultation depth of dF = 87.9 ± 4.3 ppm based on four occultations. We compared these measurements to model predictions and we find that they are consistent with an unreflective atmosphere heated to a temperature of 3435 ± 27 K, when assuming inefficient heat redistribution. Furthermore, we present two transits of WASP-189 b observed by CHEOPS. These transits have an asymmetric shape that we attribute to gravity darkening of the host star caused by its high rotation rate. We used these measurements to refine the planetary parameters, finding a ~25% deeper transit compared to the discovery paper and updating the radius of WASP-189 b to 1.619 ± 0.021RJ. We further measured the projected orbital obliquity to be λ = 86.4-4.4+2.9°, a value that is in good agreement with a previous measurement from spectroscopic observations, and derived a true obliquity of ψ = 85.4 ± 4.3°. Finally, we provide reference values for the photometric precision attained by the CHEOPS satellite: for the V = 6.6 mag star, and using a 1-h binning, we obtain a residual RMS between 10 and 17 ppm on the individual light curves, and 5.7 ppm when combining the four visits.
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| 58. |
- Eriksson, Urban, 1968-, et al.
(författare)
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Disciplinary discernment in astronomy education : Hertzsprung-Russell-diagrams
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper aim at investigating what astronomy students and experts discern from the multitude of different disciplinary affordances available in Hertzsprung-Russell (HR) diagrams. HR-diagrams are central to all of astronomy and astrophysics and used extensively in teaching. However, knowledge about what students and experts discern from these disciplinary representations are not well known at present. HR-diagrams include many disciplinary affordances that may be hidden to the novice student, hence we aim at investigating and describing what astronomy students at different university levels (introductory, undergraduate, graduate), and astronomy educators/professors, discern from such representation – referred to as disciplinary discernment. Data from a web based questionnaire were analysed using the Anatomy of Disciplinary Discernment (ADD) framework by Eriksson et al.(2014). Preliminary results show (1) the developmental nature of disciplinary discernment from the HR-diagram by the participants and (2) the large discrepancy between disciplinary discernment by the astronomy educators and their students. We describe and discuss the qualitative nature of these differences and implications for teaching and learning astronomy.
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| 59. |
- Eriksson, Urban, 1968-, et al.
(författare)
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Extrapolation of 3D and its importance for teaching and learning physics and astronomy : an example from astrophysics
- 2019
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Konferensbidrag (refereegranskat)abstract
- Learning astronomy at higher level can be both exciting and challenging. Entering the discipline of astronomy involves learning the way that astronomers communicate knowledge, using a multitude of disciplinary specific semiotic recourses to understand the multidimensional universe. A new-to-the-discipline student will need to learn to “read” and “write” all these resources in her endeavour to learn astronomy and become part of the discipline. In this paper, we present a study where university students and professors are presented by different 2D and pseudo-3D resources—representations of astronomical objects—and asked about how these objects may look in 3D, i.e. we ask them to extrapolate three-dimensionality from 2D inputs. These inputs are 2D pictorial representation and world-class 3D rotating volumetric models presented on flat screens. Data were collected using a web-based questionnaire from 53 participants in four different countries. From the results, we find that all participants struggle to find cues for depth perception in the 2D pictorial representations. As could be expected, the student participants were much worse in doing so than the astronomers, but with one exception: students used the offered motion parallax as their main cue when this was available. The astronomers used many cues in their struggle to perceive depth but surprisingly did not use the presented parallax motion to a large extent. We interpret this as follows: for the students, they lack the knowledge to use disciplinary cues and used the only cue that they know from experience, namely, parallax motion. For the astronomers, they used a multitude of disciplinary cues based on their extensive disciplinary knowledge, and did not find the new cue, motion parallax, as useful as the ones that they were used to use. In this paper, we present and discuss these results and its implication for teaching astronomy.
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| 60. |
- Eriksson, Urban, 1968-
(författare)
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Reading the sky and the spiral of teaching and learning in astronomy
- 2015
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Konferensbidrag (refereegranskat)abstract
- Teaching and learning astronomy is known to be both exciting and challenging. To learn astronomy demands not only disciplinary knowledge, but also ability to discern affordances from disciplinary specific representations used within the discourse, which we call disciplinary discernment, and ability to think spatially, which we refer to as extrapolating three-dimensionality from a two dimensional input. Disciplinary knowledge involves all the knowledge that constitutes the discipline, disciplinary discernment involves discernment of the affordances of disciplinaryspecific representations, and extrapolating three-dimensionality involves the ability to visualize in ones mind how a three-dimensional astronomical object may look from a two-dimensional input (image or simulation). In this paper we argue that these abilities are intertwined and to learn astronomy at any level demands becoming fluent in all three. A framework is presented for how these abilities can be described and combined as a new and innovative way to frame teaching and learning in astronomy for optimizing the learning outcome of students - what we refer to as developing the ability to Read the Sky. We conclude that this is a vital competency needed for learning astronomy and suggest strategies for how to implement this to improve astronomy education.
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