| 1. |
- Eriksson, Urban, 1968-, et al.
(författare)
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Limits of ultra-high-precision optical astrometry : stellar surface structures
- 2007
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 476:3, s. 1389-1400
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Tidskriftsartikel (refereegranskat)abstract
- Aims. To investigate the astrometric effects of stellar surface structures as a practical limitation to ultra-high-precision astrometry (e.g. in the context of exoplanet searches) and to quantify the expected effects in different regions of the HR-diagram. Methods. Stellar surface structures (spots, plages, granulation, non-radial oscillations) are likely to produce fluctuations in the integrated flux and radial velocity of the star, as well as a variation of the observed photocentre, i.e. astrometric jitter. We use theoretical considerations supported by Monte Carlo simulations (using a starspot model) to derive statistical relations between the corresponding astrometric, photometric, and radial velocity effects. Based on these relations, the more easily observed photometric and radial velocity variations can be used to predict the expected size of the astrometric jitter. Also the third moment of the brightness distribution, interferometrically observable as closure phase, contains information about the astrometric jitter. Results. For most stellar types the astrometric jitter due to stellar surface structures is expected to be of the order of 10 micro-AU or greater. This is more than the astrometric displacement typically caused by an Earth-size exoplanet in the habitable zone, which is about 1-4 micro-AU for long-lived main-sequence stars. Only for stars with extremely low photometric variability (< 0.5 mmag) and low magnetic activity, comparable to that of the Sun, will the astrometric jitter be of the order of 1 micro-AU, sufficient to allow the astrometric detection of an Earth-sized planet in the habitable zone. While stellar surface structure may thus seriously impair the astrometric detection of small exoplanets, it has in general a negligible impact on the detection of large (Jupiter-size) planets and on the determination of stellar parallax and proper motion. From the starspot model we also conclude that the commonly used spot filling factor is not the most relevant parameter for quantifying the spottiness in terms of the resulting astrometric, photometric and radial velocity variations.
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| 2. |
- Airey, John, 1963-, et al.
(författare)
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Unpacking the Hertzsprung-Russell Diagram : A Social Semiotic Analysis of the Disciplinary and Pedagogical Affordances of a Central Resource in Astronomy
- 2019
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Ingår i: Designs for Learning. - Stockholm : Stockholm University Press. - 1654-7608 .- 2001-7480. ; 11:1, s. 99-107
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we are interested in the relationship between disciplinary knowledge and its representation. We carry out a social semiotic analysis of a central tool used in astronomy—the Hertzsprung-Russell (H-R) diagram—in order to highlight its disciplinary and pedagogical affordances. The H-R diagram that we know today combines many layers of astronomical knowledge, whilst still retaining some rather quirky traces of its historical roots. Our analysis shows how these ‘layers of knowledge’ and ‘historical anomalies’ have resulted in a number of counterintuitive aspects within the diagram that have successively lowered its pedagogical affordance. We claim that these counterintuitive aspects give rise to potential barriers to student disciplinary learning. Using our analysis as a case study, we generalise our findings, suggesting four types of barrier to understanding that are potentially at work when students meet disciplinary-specific semiotic resources for the first time. We finish the paper by making some general suggestions about the wider use of our analysis method and ways of dealing with any barriers to learning identified. In the specific case of the H-R diagram, we suggest that lecturers should explicitly tease out its disciplinary affordances by the use of ‘unpacked’ resources that have a higher pedagogical affordance.
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| 3. |
- Linder, Cedric, et al.
(författare)
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The overlooked challenge of learning to extrapolate three-dimensionality
- 2013
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Ingår i: Book of Abstracts. - : Charles University.
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Konferensbidrag (refereegranskat)abstract
- Learning astronomy has many learning challenges due to the highly diverse, conceptual, and theoretical thinking used in the discipline. One taken for granted challenge is the learning to extrapolate three-dimensionality. Although we have the ability to see our surroundings in threedimensional terms, beyond a distance of about 200m this ability quickly becomes very limited. So, when looking up at the night sky, learning to discern critical features that are embedded in dimensionality does not come easily. There have been several articles addressing how fruitful 3D simulations are for astronomy education, but they do not address what students discern, nor the nature of that discernment. Taking the concept of discernment to be about noticing something and assigning meaning to it, our research question is: In terms of dimensionality, what do astronomy/physics students and professors discern when engaging with a simulated video flythrough of our Galaxy and beyond?A web-based questionnaire was designed using links to video clips drawn from a well-regarded simulation-video of travel through our galaxy and beyond. 137 physics and astronomy university students and teaching professors, who were drawn from nine countries, completed the questionnaire. The descriptions provided by them were used to formulate six categories of discernment in relation to multidimensionality. These results are used to make the case that astronomy learning that aims at developing the ability to extrapolate three-dimensionality needs to be grounded in the creation of meaningful motion parallax experiences. Teaching and learning implications are discussed.
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| 4. |
- Eriksson, Urban
(författare)
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The Spiral of Teaching and Learning in Physics and Astronomy
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- When students start to learn physics and astronomy, they immediately are confronted with a multitude of representations packed with disciplinary information. This information is embedded in these representations and the students need to learn to discern the relevant information. This is not straightforward, and requires a lot of teaching and practice before being mastered. It carries many similarities to learning a new language – the language of physics, astronomy, or other sciences. However, it all starts with disciplinary discernment from those representations, something that has been shown to be challenging for students. Often the teacher who knows the representations and their appresented meaning—their disciplinary affordances—assumes that the students discern the same things in those representations as the teacher does. Research has shown that this is not the case and such assumptions leads to educational problems for the students and make learning physics or astronomy unnecessary difficult, or even inaccessible to the students. The students need be given the opportunity to develop their competency in discerning disciplinary-specific relevant aspects from representations; a competency referred to as Reading the Sky in an astronomy context, and described by the Anatomy of Disciplinary Discernment (Eriksson, 2014a; Eriksson et al., 2014b). Furthermore, physics and astronomy are subjects aiming to describe the real multidimensional world, hence involve a substantial amount of spatial thinking. The students need to learn to extrapolate three-dimensionality in their minds from two-dimensional representations, which have been shown to be challenging to students. Unfortunately, this competency is often taken for granted and rarely addressed in teaching (Eriksson et al., 2014c). In this talk we present a model in which we identify and describe the critical competencies needed to “read” disciplinary-specific representations; it concerns not only disciplinary discernment but also spatial thinking and disciplinary knowledge. These are combined into the Spiral of Teaching and Learning (STL), a new and powerful model for optimizing teaching and learning science (Eriksson, 2014a; Eriksson, 2015). We discuss consequences and possibilities when applying the STL model and give an example of how this model can be used in teaching and learning astronomy.
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| 5. |
- Eriksson, Urban, Lektor i fysik med inriktning mot fysikdidaktik, 1968-
(författare)
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Disciplinary discernment : reading the sky in astronomy education
- 2019
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Ingår i: Physical review physics education research. - : American Physical Society. - 2469-9896. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- This theoretical paper introduces a new way to view and characterize learning astronomy. It describes a framework, based on results from empirical data, analyzed through standard qualitative research method- ology, in which a theoretical model for a vital competency of learning astronomy is proposed: reading the sky, a broad description under with various skills and competencies are included. This model takes into account not only disciplinary knowledge but also disciplinary discernment and extrapolating three dimensionality. Together, these constitute the foundation for the competency referred to as reading the sky. In this paper, these competencies are described and discussed and merged to form a new framework vital for learning astronomy to better match the challenges students face when entering the discipline of astronomy.
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| 6. |
- Eriksson, Urban, 1968-, et al.
(författare)
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Disciplinary discernment from 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 (Eriksson, Linder, Airey, & Redfors, 2014). 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 how this can have implications for teaching and learning astronomy.
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| 7. |
- 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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| 8. |
- 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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| 9. |
- Eriksson, Urban, 1968-
(författare)
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Från Stjärnfläckar till Stjärnobservationer : bland galaxer, stjärnor, planeter och tankar kring dessa
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Att lära sig astronomi, eller naturvetenskap över lag, involverar så mycket och kan liknas vid att lära sig ett nytt språk. Eleven måste lära sig detta språk och det innefattar, förutom skrivet och talat fackspråk, en mängd mer eller mindre begripliga sk representationerna, aktiviteter och verktyg. Det är därför en grannlaga uppgift att lära sig naturvetenskap och eleverna behöver hjälp med att lära sig naturvetenskapens språk. Det sker i allmänhet samtidigt som de lär sig ämnet, men jag kommer att prata om att det krävs träning av vissa speciella färdigheter för att underlätta denna process. Detta involverar disciplinärt urskiljande samt multidimensionellt tänkande. Jag kommer att beskriva ett teoretiskt ramverk, med praktiska exempel från astronomins värld, på hur detta kan ske.
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| 10. |
- Eriksson, Urban, 1968-
(författare)
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“Reading” representations : what does this have to do with teaching and learning physics?
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Learning physics can be compared to learning a new language in several respects. This includes learning to “read and write” the representations that carry the meaning of the language. In the case of physics these representations include text, gestures, mathematics, graphs, images, simulations and animations. For those who are fluent in the language, these representations are full of meaning but for the novice learning to discern the relevant disciplinary aspects of these representations (disciplinary discernment) can be a struggle. Research has shown that often teachers assume that students “see” the same things in a representation that they do. However, this is usually not true. Learning to discern disciplinary aspects of representations is something that students need help with (scaffolding). One important aspect of learning representational fluency in physics is that of spatial thinking, in particular learning to extrapolate three-dimensionality from one- and two-dimensional representations.In this talk I will present a theoretical framework describing the process of teaching and learning representational disciplinary fluency. I will also provide some examples to illustrate the framework, from the perspectives of the instructor and the student.
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