| 1. |
- Tinetti, Giovanna, et al.
(författare)
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The EChO science case
- 2015
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Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 40:2-3, s. 329-391
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Tidskriftsartikel (refereegranskat)abstract
- The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune-all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10(-4) relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength coverage of at least 0.55 to 11 mu m with a goal of covering from 0.4 to 16 mu m. Only modest spectral resolving power is needed, with R similar to 300 for wavelengths less than 5 mu m and R similar to 30 for wavelengths greater than this. The transit spectroscopy technique means that no spatial resolution is required. A telescope collecting area of about 1 m(2) is sufficiently large to achieve the necessary spectro-photometric precision: for the Phase A study a 1.13 m(2) telescope, diffraction limited at 3 mu m has been adopted. Placing the satellite at L2 provides a cold and stable thermal environment as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. EChO has been conceived to achieve a single goal: exoplanet spectroscopy. The spectral coverage and signal-to-noise to be achieved by EChO, thanks to its high stability and dedicated design, would be a game changer by allowing atmospheric composition to be measured with unparalleled exactness: at least a factor 10 more precise and a factor 10 to 1000 more accurate than current observations. This would enable the detection of molecular abundances three orders of magnitude lower than currently possible and a fourfold increase from the handful of molecules detected to date. Combining these data with estimates of planetary bulk compositions from accurate measurements of their radii and masses would allow degeneracies associated with planetary interior modelling to be broken, giving unique insight into the interior structure and elemental abundances of these alien worlds. EChO would allow scientists to study exoplanets both as a population and as individuals. The mission can target super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300-3000 K) of F to M-type host stars. The EChO core science would be delivered by a three-tier survey. The EChO Chemical Census: This is a broad survey of a few-hundred exoplanets, which allows us to explore the spectroscopic and chemical diversity of the exoplanet population as a whole. The EChO Origin: This is a deep survey of a subsample of tens of exoplanets for which significantly higher signal to noise and spectral resolution spectra can be obtained to explain the origin of the exoplanet diversity (such as formation mechanisms, chemical processes, atmospheric escape). The EChO Rosetta Stones: This is an ultra-high accuracy survey targeting a subsample of select exoplanets. These will be the bright "benchmark" cases for which a large number of measurements would be taken to explore temporal variations, and to obtain two and three dimensional spatial information on the atmospheric conditions through eclipse-mapping techniques. If EChO were launched today, the exoplanets currently observed are sufficient to provide a large and diverse sample. The Chemical Census survey would consist of > 160 exoplanets with a range of planetary sizes, temperatures, orbital parameters and stellar host properties. Additionally, over the next 10 years, several new ground- and space-based transit photometric surveys and missions will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO's launch and enable the atmospheric characterisation of hundreds of planets.
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| 2. |
- Tinetti, G., et al.
(författare)
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A chemical survey of exoplanets with ARIEL
- 2018
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Ingår i: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 46:1, s. 135-209
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Tidskriftsartikel (refereegranskat)abstract
- Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10–100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.
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| 3. |
- Kozlowska, K., et al.
(författare)
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Patterns of healthy lifestyle and positive health attitudes in older Europeans
- 2008
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Ingår i: The Journal of Nutrition, Health & Aging. - 1279-7707 .- 1760-4788. ; 12:10, s. 728-733
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To determine (i) the extent to which recommended lifestyle healthy behaviors are adopted and the existence of positive attitudes to health; (ii) the relative influence of socio-demographic variables on multiple healthy lifestyle behaviors and positive attitudes to health; (iii) the association between healthy lifestyle behaviors and positive attitudes to health. Design: two distinct healthy behavioral measures were developed: (i) healthy lifestyles based on physical activity, no cigarette smoking, no/moderate alcohol drinking, maintaining a "healthy" weight and having no sleeping problems and (ii) positive health attitudes based on having positive emotional attitudes, such as: self-perceived good health status, being calm, peaceful and happy for most of the time, not expecting health to get worse and regular health check-ups. A composite healthy lifestyle index, ranging from 0 (none of behaviors met) to 5 (all behaviors met) was calculated by summing up the individual's scores for the five healthy lifestyle items. Afterwards, each individual's index was collapsed into three levels: 0-2 equivalent to 'level 1' (subjectively regarded as 'too low'), a score of 3 equivalent to 'level 2' ('fair') and 4-5 as 'level 3' satisfactory 'healthy lifestyle' practices. The same procedure was applied to the positive health attitudes index. Multinomial logistic regression analyses by a forward selection procedure were used to calculate the adjusted odds ratio (OR) with 95% confidence interval (95% CI). Participants: a multi-national sample consisting of 638 older Europeans from 8 countries, aged 65-74 and 75+, living alone or with others. Results and conclusions: maintaining a "healthy" weight was the most frequently cited factor in the healthy lifestyles index and therefore assumed to be the most important to the older Europeans in the study; positive attitudes to health were relatively low; participants achieved a 'satisfactory' level for healthy lifestyles index (level 3) more frequently than a satisfactory level for positive attitudes to health; having a satisfactory 'healthy lifestyle' was directly related to having a satisfactory level of positive attitudes to health based on the positive health attitudes index; income and geographical location in Europe appeared to be key predictors for meeting both the recommended healthy lifestyle factors in the index and having positive health attitudes however, the composition and nature of the study sample should be taken into consideration when considering the impact of the location on healthy lifestyles and attitudes to health across Europe.
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| 4. |
- Turrini, D., et al.
(författare)
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The GAPS programme at TNG : XLVIII. The unusual formation history of V1298 Tau
- 2023
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 679
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Tidskriftsartikel (refereegranskat)abstract
- Context. Observational data from space- and ground-based campaigns have revealed that the 10-30 Ma old V1298Tau star hosts a compact and massive system of four planets. Mass estimates are available for the two outer giant planets and point to unexpectedly high densities for their young ages.Aims. We investigate the formation of these two outermost giant planets, V1298 Tau b and e, and the present dynamical state of V1298 Tau's global architecture in order to shed light on the history of this young and peculiar extrasolar system.Methods. We performed detailed N-body simulations to explore the link between the densities of V1298 Tau b and e and their migration and accretion of planetesimals within the native circumstellar disk. We combined N-body simulations and the normalized angular momentum deficit (NAMD) analysis of the architecture to characterize V1298 Tau's dynamical state and connect it to the formation history of the system. We searched for outer planetary companions to constrain V1298 Tau's planetary architecture and the extension of its primordial circumstellar disk.Results. The high densities of V1298 Tau b and e suggest they formed at quite a distance from their host star, likely beyond the CO2 snowline. The higher nominal density of V1298 Tau e suggests it formed farther out than V1298 Tau b. The current architecture of V1298 Tau is not characterized by resonant chains. Planet-planet scattering with an outer giant planet is the most likely cause for the lack of a resonant chain between V1298 Tau's planets, but currently our search for outer companions using SPHERE and Gaia observations can exclude only the presence of planets more massive than 2 MJ.Conclusions. The most plausible scenario for V1298 Tau's formation is that the system formed by convergent migration and resonant trapping of planets born in a compact and plausibly massive disk. In the wake of their migration, V1298 Tau b and e would have left a dynamically excited protoplanetary disk, naturally creating the conditions for the later breaking of the resonant chain by planet-planet scattering.
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| 5. |
- Damasso, M., et al.
(författare)
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Photometric follow-up of the 20 Myr old multi-planet host star V1298 Tau with CHEOPS and ground-based telescopes
- 2023
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 680
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Tidskriftsartikel (refereegranskat)abstract
- Context. The 20 Myr old star V1298 Tau hosts at least four planets. Since its discovery, this system has been a target of intensive photometric and spectroscopic monitoring. To date, the characterisation of its architecture and planets’ fundamental properties has been very challenging.Aims. The determination of the orbital ephemeris of the outermost planet V1298 Tau e remains an open question. Only two transits have been detected so far by Kepler/K2 and TESS, allowing for a grid of reference periods to be tested with new observations, without excluding the possibility of transit timing variations. Observing a third transit would allow for better constraints to be set on the orbital period and would also help in determining an accurate radius for V1298 Tau e because the previous transits showed different depths.Methods. We observed V1298 Tau with the CHaracterising ExOPlanet Satellite (CHEOPS) to search for a third transit of planet e within observing windows selected to test three of the shortest predicted orbital periods. We also collected ground-based observations to verify the result found with CHEOPS. We reanalysed Kepler/K2 and TESS light curves to test how the results derived from these data are affected by alternative photometric extraction and detrending methods.Results. We report the CHEOPS detection of a transit-like signal that could be attributed to V1298 Tau e. If so, that result would imply that the orbital period calculated from fitting a linear ephemeris to the three available transits is close to ~45 days. Results from the ground-based follow-up marginally support this possibility. We found that i) the transit observed by CHEOPS has a longer duration compared to that of the transits observed by Kepler/K2 and TESS; and ii) the transit observed by TESS is >30% deeper than that of Kepler/K2 and CHEOPS, and it is also deeper than the measurement previously reported in the literature, according to our reanalysis.Conclusions. If the new transit detected by CHEOPS is found to be due to V1298 Tau e, this would imply that the planet experiences TTVs of a few hours, as deduced from three transits, as well as orbital precession, which would explain the longer duration of the transit compared to the Kepler/K2 and TESS signals. Another and a priori less likely possibility is that the newly detected transit belongs to a fifth planet with a longer orbital period than that of V1298 Tau e. Planning further photometric follow-up to search for additional transits is indeed necessary to solve the conundrum, as well as to pin down the radius of V1298 Tau e.
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| 6. |
- Orfanos, P., et al.
(författare)
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Eating at restaurants, at work or at home. Is there a difference? : a study among adults of 11 European countries in the context of the HECTOR* project
- 2017
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Ingår i: European Journal of Clinical Nutrition. - : Springer Science and Business Media LLC. - 0954-3007 .- 1476-5640. ; 71:3, s. 407-419
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND/OBJECTIVES: To compare macronutrient intakes out of home-by location-to those at home and to investigate differences in total daily intakes between individuals consuming more than half of their daily energy out of home and those eating only at home.SUBJECTS/METHODS: Data collected through 24-h recalls or diaries among 23 766 European adults. Participants were grouped as 'non-substantial', 'intermediate' and 'very substantial out-of-home' eaters based on energy intake out of home. Mean macronutrient intakes were estimated at home and out of home (overall, at restaurants, at work). Study/cohort-specific mean differences in total intakes between the 'very substantial out-of-home' and the 'at-home' eaters were estimated through linear regression and pooled estimates were derived.RESULTS: At restaurants, men consumed 29% of their energy as fat, 15% as protein, 45% as carbohydrates and 11% as alcohol. Among women, fat contributed 33% of energy intake at restaurants, protein 16%, carbohydrates 45% and alcohol 6%. When eating at work, both sexes reported 30% of energy from fat and 55% from carbohydrates. Intakes at home were higher in fat and lower in carbohydrates and alcohol. Total daily intakes of the 'very substantial out-of-home' eaters were generally similar to those of individuals eating only at home, apart from lower carbohydrate and higher alcohol intakes among individuals eating at restaurants.CONCLUSIONS: In a large population of adults from 11 European countries, eating at work was generally similar to eating at home. Alcoholic drinks were the primary contributors of higher daily energy intakes among individuals eating substantially at restaurants.
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| 7. |
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| 8. |
- Turrini, A. A., et al.
(författare)
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Tunable critical correlations in kagome ice
- 2022
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 105:9
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Tidskriftsartikel (refereegranskat)abstract
- We present a comprehensive experimental and theoretical study of the kagome ice Coulomb phase that explores the fine-tuning of critical correlations by applied field, temperature, and crystal orientation. The continuous modification of algebraic correlations is observed by polarized neutron scattering experiments and is found to be well described by numerical simulations of an idealized model. We further clarify the thermodynamics of field-tuned Kasteleyn transitions and demonstrate some dramatic finite-size-scaling properties that depend on how topological string defects wind around the system boundaries. We conclude that kagome ice is a remarkable example of a critical and topological state in a real system that may be subject to fine experimental control.
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| 9. |
- Turrini, D., et al.
(författare)
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The contribution of the ARIEL space mission to the study of planetary formation
- 2018
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Ingår i: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 46:1, s. 45-65
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Tidskriftsartikel (refereegranskat)abstract
- The study of extrasolar planets and of the Solar System provides complementary pieces of the mosaic represented by the process of planetary formation. Exoplanets are essential to fully grasp the huge diversity of outcomes that planetary formation and the subsequent evolution of the planetary systems can produce. The orbital and basic physical data we currently possess for the bulk of the exoplanetary population, however, do not provide enough information to break the intrinsic degeneracy of their histories, as different evolutionary tracks can result in the same final configurations. The lessons learned from the Solar System indicate us that the solution to this problem lies in the information contained in the composition of planets. The goal of the Atmospheric Remote-Sensing Infrared Exoplanet Large-survey (ARIEL), one of the three candidates as ESA M4 space mission, is to observe a large and diversified population of transiting planets around a range of host star types to collect information on their atmospheric composition. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres, which should show minimal condensation and sequestration of high-Z materials and thus reveal their bulk composition across all main cosmochemical elements. In this work we will review the most outstanding open questions concerning the way planets form and the mechanisms that contribute to create habitable environments that the compositional information gathered by ARIEL will allow to tackle.
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| 10. |
- Pirani, S., et al.
(författare)
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Consequences of planetary migration on the minor bodies of the early solar system
- 2019
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 623
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Tidskriftsartikel (refereegranskat)abstract
- Pebble accretion is an efficient mechanism that is able to build up the core of the giant planets within the lifetime of the protoplanetary disc gas-phase. The core grows via this process until the protoplanet reaches its pebble isolation mass and starts to accrete gas. During the growth, the protoplanet undergoes a rapid, large-scale, inward migration due to the interactions with the gaseous protoplanetary disc. In this work, we have investigated how this early migration would have affected the minor body populations in our solar system. In particular, we focus on the Jupiter Trojan asteroids (bodies in the coorbital resonance 1:1 with Jupiter, librating around the L4 and L5 Lagrangian points called, respectively, the leading and the trailing swarm) and the Hilda asteroids. We characterised their orbital parameter distributions after the disc dispersal and their formation location and compare them to the same populations produced in a classical in situ growth model. We find that a massive and eccentric Hilda group is captured during the migration from a region between 5 and 8 au and subsequently depleted during the late instability of the giant planets. Our simulations also show that inward migration of the giant planets always produces a Jupiter Trojans' leading swarm more populated than the trailing one, with a ratio comparable to the current observed Trojan asymmetry ratio. The in situ formation of Jupiter, on the other hand, produces symmetric swarms. The reason for the asymmetry is the relative drift between the migrating planet and the particles in the coorbital resonance. The capture happens during the growth of Jupiter's core and Trojan asteroids are afterwards carried along during the giant planet's migration to their final orbits. The asymmetry and eccentricity of the captured Trojans correspond well to observations, but their inclinations are near zero and their total mass is three to four orders of magnitude higher than the current population. Future modelling will be needed to understand whether the dynamical evolution of the Trojans over billions of years will raise the inclinations and deplete the masses to observed values.
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