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- Meech, K. J., et al.
(författare)
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EPOXI: Comet 103P/Hartley 2 Observations from a Worldwide Campaign
- 2011
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Ingår i: Astrophysical Journal Letters. - London : IOP. - 2041-8213 .- 2041-8205. ; 734:L1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible with an in situ flyby. We report here such observations in support of the EPOXI spacecraft flyby of comet 103P/Hartley 2. The nucleus is small and dark, and exhibited a very rapidly changing rotation period. Prior to the onset of activity, the period was ~16.4?hr. Starting in 2010 August the period changed from 16.6?hr to near 19?hr in December. With respect to dust composition, most volatiles and carbon and nitrogen isotope ratios, the comet is similar to other Jupiter-family comets. What is unusual is the dominance of CO 2 -driven activity near perihelion, which likely persists out to aphelion. Near perihelion the comet nucleus was surrounded by a large halo of water-ice grains that contributed significantly to the total water production.
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| 4. |
- Sisask, M, et al.
(författare)
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Teacher satisfaction with school and psychological well-being affects their readiness to help children with mental health problems
- 2014
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Ingår i: HEALTH EDUCATION JOURNAL. - : SAGE Publications. - 0017-8969 .- 1748-8176. ; 73:4, s. 382-393
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In support of a whole-school approach to mental health promotion, this study was conducted to find out whether and how significantly teachers’ satisfaction with school and their subjective psychological well-being are related to the belief that they can help pupils with mental health problems. Design: Cross-sectional data were collected as a part of the European Union’s, Seventh Framework Programme for Research (FP7) Saving and Empowering Young Lives in Europe (SEYLE) study. One of the elements of the SEYLE study was to evaluate teachers’ attitudes and knowledge related to pupils’ mental health issues and their own psychological well-being, as well as their satisfaction with the school environment. Setting: The sample of schools from the SEYLE study sites representing 11 European countries was randomly chosen according to prior defined inclusion and exclusion criteria. The final cross-sectional database used for analysis in the current study comprised 2485 teachers from 158 randomly selected schools. Method: Respondents’ belief that teachers can help pupils with mental health problems served as the outcome variable in our predictions with probability of the positive answer being modelled in the logistic regression analysis. Teachers’ subjective psychological well-being and school satisfaction were included as independent variables in the logistic regression model and several other relevant variables were added to statistically control for them. Multiple models were tested in order to obtain the final model. Results: Logistic regression models showed that better satisfaction with general school climate, higher psychological well-being, and the ability to understand pupils’ mental health problems increased the odds of teachers’ readiness to help pupils with mental health problems. Conclusion: By providing a good school environment, by valuing the subjective psychological well-being of the teachers, and by providing adequate training to fulfil their ‘gatekeeper’ role, the preconditions to improve the mental health of the pupils they teach will be achieved. These suggestions are in line with a whole-school approach to mental health promotion.
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| 7. |
- Mottola, S., et al.
(författare)
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The rotation state of 67P/Churyumov-Gerasimenko from approach observations with the OSIRIS cameras on Rosetta
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 569, s. L2-
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Tidskriftsartikel (refereegranskat)abstract
- Aims. Approach observations with the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) experiment onboard Rosetta are used to determine the rotation period, the direction of the spin axis, and the state of rotation of comet 67P's nucleus. Methods. Photometric time series of 67P have been acquired by OSIRIS since the post wake-up commissioning of the payload in March 2014. Fourier analysis and convex shape inversion methods have been applied to the Rosetta data as well to the available ground-based observations. Results. Evidence is found that the rotation rate of 67P has significantly changed near the time of its 2009 perihelion passage, probably due to sublimation-induced torque. We find that the sidereal rotation periods P-1 = 12.76129 +/- 0.00005 h and P2 = 12.4043 +/- 0.0007 h for the apparitions before and after the 2009 perihelion, respectively, provide the best fit to the observations. No signs of multiple periodicity are found in the light curves down to the noise level, which implies that the comet is presently in a simple rotation state around its axis of largest moment of inertia. We derive a prograde rotation model with spin vector J2000 ecliptic coordinates lambda = 65 degrees +/- 15 degrees, beta = + 59 degrees +/- 15 degrees, corresponding to equatorial coordinates RA = 22 degrees, Dec = +76 degrees. However, we find that the mirror solution, also prograde, at lambda = 275 degrees +/- 15 degrees, beta = + 50 degrees +/- 15 degrees (or RA = 274 degrees, Dec = +27 degrees), is also possible at the same confidence level, due to the intrinsic ambiguity of the photometric problem for observations performed close to the ecliptic plane.
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| 9. |
- Sierks, H., et al.
(författare)
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Images of Asteroid 21 Lutetia : A Remnant Planetesimal from the Early Solar System
- 2011
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 334:6055, s. 487-490
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Tidskriftsartikel (refereegranskat)abstract
- Images obtained by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) cameras onboard the Rosetta spacecraft reveal that asteroid 21 Lutetia has a complex geology and one of the highest asteroid densities measured so far, 3.4 +/- 0.3 grams per cubic centimeter. The north pole region is covered by a thick layer of regolith, which is seen to flow in major landslides associated with albedo variation. Its geologically complex surface, ancient surface age, and high density suggest that Lutetia is most likely a primordial planetesimal. This contrasts with smaller asteroids visited by previous spacecraft, which are probably shattered bodies, fragments of larger parents, or reaccumulated rubble piles.
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| 10. |
- Thomas, N., et al.
(författare)
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The geomorphology of (21) Lutetia : Results from the OSIRIS imaging system onboard ESA's Rosetta spacecraft
- 2012
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Ingår i: Planetary and Space Science. - : Elsevier. - 0032-0633 .- 1873-5088. ; 66:1, s. 96-124
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Tidskriftsartikel (refereegranskat)abstract
- The surface of (21) Lutetia is highly complex with significant interactions between ancient and more recent structures. This work attempts to summarize the surface geomorphology observed using the high resolution images from OSIRIS, the imaging system onboard the European Space Agency's Rosetta spacecraft. A wide range of surface morphologies are seen including heavily cratered terrain, extensive sets of lineaments, young impact craters, and a ridge, the height of which is more than 1/5th of the mean radius of the body. Very young and very old terrains (as inferred from crater densities) are seen in close proximity. The longest continuous lineament is over 80 km long. The lineaments show regional-dependent organization and structure. Several categories of lineament can be described. Lineaments radial to impact craters as seen on other asteroidal bodies are mostly absent. Although the lineaments may be of seismic origin (and possibly the result of several impact-induced events), impacts producing recent large craters place constraints on seismic phenomena. In particular, stronger attenuation of shocks than seen on other asteroidal bodies seems to be required. Inhomogeneous energy transport, possibly matching observed inhomogeneous ejecta deposition may offer explanations for some of the observed phenomena. Some impact craters show unusual forms, which are probably the result of impact into a surface with relief comparable to the resultant crater diameter and/or oblique impact. There is evidence that re-surfacing through landslides has occurred at several places on the object. (C) 2011 Elsevier Ltd. All rights reserved.
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