| 1. |
- Wagner, J., et al.
(författare)
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First 230? : GHz VLBI fringes on 3C 279 using the APEX Telescope (Research Note)
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 581
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We report about a 230? GHz very long baseline interferometry (VLBI) fringe finder observation of blazar 3C 279 with the APEX telescope in Chile, the phased submillimeter array (SMA), and the SMT of the Arizona Radio Observatory (ARO). Methods. We installed VLBI equipment and measured the APEX station position to 1? cm accuracy (1σ). We then observed 3C 279 on 2012 May 7 in a 5? h 230? GHz VLBI track with baseline lengths of 2800? Mλ to 7200? Mλ and a finest fringe spacing of 28.6? μas. Results. Fringes were detected on all baselines with signal-to-noise ratios of 12 to 55 in 420? s. The correlated flux density on the longest baseline was ∼0.3? Jy beam-1, out of a total flux density of 19.8? Jy. Visibility data suggest an emission region ≤ 38? μas in size, and at least two components, possibly polarized. We find a lower limit of the brightness temperature of the inner jet region of about 1010? K. Lastly, we find an upper limit of 20% on the linear polarization fraction at a fringe spacing of ∼ 38? μas. Conclusions. With APEX the angular resolution of 230? GHz VLBI improves to 28.6? μas. This allows one to resolve the last-photon ring around the Galactic Center black hole event horizon, expected to be 40? μas in diameter, and probe radio jet launching at unprecedented resolution, down to a few gravitational radii in galaxies like M 87. To probe the structure in the inner parsecs of 3C 279 in detail, follow-up observations with APEX and five other mm-VLBI stations have been conducted (March 2013) and are being analyzed.
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| 2. |
- Desmurs, J. F., et al.
(författare)
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28 SiO j=1-0, v=1, 2 & 3 maser emission from AGB stars
- 2012
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Ingår i: Proceedings of Science. - 1824-8039. ; 2012-October
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Konferensbidrag (refereegranskat)abstract
- The v=1, 2 J=1–0 and v=1 J=2–1 are intense SiO masers, often mapped in AGB stars. Their distribution displays ring-like structures in the regions close to the star. The distribution of the v=1, 2 J=1–0 masers are similar, but the spots are rarely coincident. The v=1 J=2–1 maser ar-rises, however, from a well separated region. It has been argued that this difference can only be explained by models including overlap of two IR lines of SiO and H2O. The v=3 J=1–0 line is not expected to be affected by any line overlap, and its spot structure should be that predicted by the standard models. Our first results on the relative positions of the three lines are surprising but yet consistent with current models including line overlap.
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| 3. |
- Desmurs, J. F., et al.
(författare)
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First VLBA observations of 28SiO J=1-0, v=3 maser emission from AGB stars
- 2014
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Ingår i: Proceedings of Science. - 1824-8039. ; 2014
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Konferensbidrag (refereegranskat)abstract
- The v=1 & v=2 J=1-0 (43 GHz), and v=1 J=2-1 (86 GHz) SiO masers are intense in AGB stars. They have been mapped using VLBI displaying spots ring-like distributions. The rings of the v=1, v=2 J=1-0 masers are similar, but the spots are rarely coincident, while the v=1 J=2-1 maser arises from a well separated region farther out. The v=3 J=1-0 line is not directly affected by any line overlap and its spot structure and position, relative to the other lines, is a good test to the standard pumping models. We present simultaneous single dish and VLBI observations of the v=1, v=2, and v=3 J=1-0 maser transitions of 28SiO in several AGB stars and compare them to model predictions. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
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| 4. |
- Desmurs, J. F., et al.
(författare)
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Preliminary results on SiO v=3 J=1−0 maser emission from AGB stars
- 2012
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Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 8:5287, s. 252-253
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Konferensbidrag (refereegranskat)abstract
- We present the results of SiO maser observations at 43 GHz toward two AGB stars using the VLBA. Our preliminary results on the relative positions of the different J=1–0 SiO masers (v=1,2 and 3) indicate that the current ideas on SiO maser pumping could be wrong at some fundamental level. A deep revision of the SiO pumping models could be necessary.
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| 5. |
- Desmurs, J. F., et al.
(författare)
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SiO masers from AGB stars in the vibrationally excited v=1, v=2, and v=3 states
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 565
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Tidskriftsartikel (refereegranskat)abstract
- Context. The v = 1 and v = 2 J = 1-0 (43 GHz), and v = 1 J = 2-1 (86 GHz) SiO masers are intense in asymptotic giant branch (AGB) stars and have been mapped using very long baseline interferometry (VLBI) showing ring-like distributions. Those of the v = 1, v = 2 J = 1-0 masers are similar, but the spots are rarely coincident, while the v = 1 J = 2-1 maser arises from a well-separated region farther out. These relative locations can be explained by models tools that include the overlap of two IR lines of SiO and H2O. The v = 3 J = 1-0 line is not directly affected by any line overlap and its spot structure and position, relative to the other lines, is a good test to the standard pumping models. Aims. The aim of this project are to gain insight into the properties and the general theoretical considerations of the different SiO masers that can help to understand them. Methods. We present single-dish and simultaneous VLBI observations of the v = 1, v = 2, and v = 3 J = 1-0 maser transitions of (SiO)-Si-28 in several AGB stars. The results are compared to the predictions of radiative models of SiO masers that both include and not include the effect of IR line overlap. Results. The spatial distribution of the SiO maser emission in the v = 3 J = 1-0 transition from AGB stars is systematically composed of a series of spots that occupy a ring-like structure (as often found in SiO masers). The overall ring structure is extremely similar to that found in the other 43 GHz transitions and is very different from the structure of the v = 1 J = 2-1 maser. The positions of the individual spots of the different 43 GHz lines are, however, very rarely coincident, which in general is separated by about 0.3 AU (between 1 and 5 mas). These results are very difficult to reconcile with standard pumping models, which predict that the masers of rotational transitions within a given vibrational state require very similar excitation conditions (since the levels are placed practically at the same energy from the ground), while the transitions of different vibrational states (which are separated by an energy of 1800 K) should appear in different positions. However, models including line overlap tend to predict v = 1, v = 2, v = 3 J = 1-0 population inversion to occur under very similar conditions, while the requirements for v = 1 J = 2-1 appear clearly different, and are compatible with the observational results.
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| 6. |
- Desmurs, J.F., et al.
(författare)
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SiO v=3 J=1-0 maser emission from AGB stars
- 2013
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Ingår i: Proceedings of Science, 11th European VLBI Network Symposium & Users Meeting.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Fonseca, Lars, 1963-, et al.
(författare)
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Lärarassistenter och lärare - samarbete, arbetsdelning eller konflikt?
- 2018
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Ingår i: Nordisk netværk for Professionsforskning.
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Konferensbidrag (refereegranskat)abstract
- Problemställning: Internationella studier visar att svenska lärare ägnar mer tid åt administration och mindre åt undervisning och kompetensutveckling än lärare i andra OECD-länder (OECD, 2013). I Sverige styrs skolan offensivt med ökade inslag av granskning och kontroll, vikande PISA-resultat och en ökande lärarbrist (Bejerot m.fl., 2015; UKÄ, 2016).Trycket på svenska lärare är högt och skilda initiativ tas för att lärare ska kunna fokusera på "kärnuppdraget". Bland annat föreslås införandet av avlastande tjänster, lärarassistenter. Innehållet i avlastningen beskrivs emellertid på olika sätt. Introduktionen av lärarassistenter kan ses som ett försök till intern stratifiering av läraryrket, där arbetet delas upp och där delar av arbetet lämnas över till andra yrkesgrupper. Följden blir att professionella domäner behöver förhandlas, förskjutas och fördelas.Frågeställningar:- Vilka delar av lärares arbete förväntar skolledare att redan införda avlastande tjänster skall ta över?- Vilka förväntningar på önskvärda avgränsningar mellan professionella domäner beskrivs av lärarna själva?- Vilka förväntningar om professionell domän för den nya yrkeskategorin lärarassistenter beskrivs i utbildningsinformation för lärarassistentutbildningar?- Harmonierar dessa olika förväntningar? Finns potentiella eller redan konstaterade konfliktytor? Teoretiska utgångspunkter:Introduktionen av lärarassistenter i den svenska skolan medför med stor sannolikhet att skolorganisationens ekologi rubbas, att professionella rörelser uppstår och att professionella domäner förhandlas, förskjuts och fördelas. (Abbott, 1988). Ett tydliggörande av läraryrkets kärna (Lindqvist & Nordänger, 2007; Gardesten, 2016) och en nyintroducerad arbetsspecialisering kan betraktas som ett sätt att förstärka läraryrkets professionella status. Men introduktionen av nya yrkesgrupper kan lika gärna uppfattas som ett hot mot det professionella. Idén om införandet av lärarassistenter ”översätts” således på olika sätt - i olika praktiker - av olika aktörer (Czarniawska & Joerges, 1996) där uppfattningar om vad som är kärnan i lärararbetet (Gardesten, 2016; Lindqvist & Nordänger, 2007) och vad framstår som ”smutsigt” (Landahl, 2006; Hughes, 1958/1981) kan skilja sig åt. Metoder:- Webb-enkät till skolledare om innehållet i 408 införda avlastande tjänster.- Enkäter till 65 lärare vid tre skolor där lärarassistenter införts. Enkätfrågor om vilka arbetsuppgifter lärarna vill bli av med, vill behålla, vill tillföra respektive vill samarbete med andra yrkesprofessioner om. Uppföljande intervjuer om utfallet av arbetsfördelningen med olika professioner på de tre skolorna.- Innehållsanalys av utbildningsplaner för 18 svenska lärarassistentutbildningarEmpiriskt fält:Professionella domäner i skolan
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| 8. |
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| 9. |
- Olofsson, Hans, 1952, et al.
(författare)
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Detection of Cl line emission from the detached CO shell of the AGB star R Sculptoris
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 582, s. 8-
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Tidskriftsartikel (refereegranskat)abstract
- Context. Stars on the asymptotic giant branch (AGB) lose substantial amounts of matter, to the extent that they are important for the chemical evolution of, and dust production in, the Universe. The mass loss is believed to increase gradually with age on the AGB, but it may also occur in the form of bursts, possibly related to the thermal pulsing phenomenon. Detached, geometrically thin, CO shells around carbon stars are good signposts of brief and intense mass ejection. Aims. We aim to put further constraints on the physical properties of detached CO shells around AGB stars. Methods. The photodissociation of CO and other carbon-bearing species in the shells leads to the possibility of detecting lines from neutral carbon. We have therefore searched for the CI(P-3(1) - P-3(0)) line at 492 GHz towards two carbon stars, S Sct and R Scl, with detached CO shells of different ages, approximate to 8000 and 2300 years, respectively. Results. The CI(3P1 3P0) line was detected towards R Scl. The line intensity is dominated by emission from the detached shell. The detection is at a level consistent with the neutral carbon coming from the full photodissociation of all species except CO, and with only limited photoionisation of carbon. The best fit to the observed (CO)-C-12 and (CO)-C-13 line intensities, assuming a homogeneous shell, is obtained for a shell mass of approximate to 0.002M circle dot, a temperature of approximate to 100 K, and a CO abundance with respect to H-2 of 10(-3). The estimated CI/CO abundance ratio is approximate to 0.3 for the best-fit model. However, a number of arguments point in the direction of a clumpy medium, and a viable interpretation of the data within such a context is provided.
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| 10. |
- Olofsson, Hans, 1952, et al.
(författare)
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First detection of methanol towards a post-AGB object, HD 101584
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 603, s. L2-
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Tidskriftsartikel (refereegranskat)abstract
- The circumstellar environments of objects on the asymptotic giant branch and beyond are rich in molecular species. Nevertheless, methanol has never been detected in such an object, and is therefore often taken as a clear signpost for a young stellar object. However, we report the first detection of CH3OH in a post-AGB object, HD 101584, using ALMA. Its emission, together with emissions from CO, SiO, SO, CS, and H2CO, comes from two extreme velocity spots on either side of the object where a high-velocity outflow appears to interact with the surrounding medium. We have derived molecular abundances, and propose that the detected molecular species are the effect of a post-shock chemistry where circumstellar grains play a role. We further provide evidence that HD 101584 was a low-mass, M-type AGB star.
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