| 1. |
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| 2. |
- Meech, K. J., et al.
(author)
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EPOXI: Comet 103P/Hartley 2 Observations from a Worldwide Campaign
- 2011
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In: Astrophysical Journal Letters. - London : IOP. - 2041-8213 .- 2041-8205. ; 734:L1, s. 1-9
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Journal article (peer-reviewed)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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| 3. |
- Hudson, Lawrence N, et al.
(author)
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The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
- 2017
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In: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 7:1, s. 145-188
-
Journal article (peer-reviewed)abstract
- The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.
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| 4. |
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Highlights from the first year of Odin observations
- 2003
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 402, s. L39-L46
-
Journal article (peer-reviewed)abstract
- Key Odin operational and instrumental features and highlights from our sub-millimetre and millimetre wave observations of H2O, H218O, NH3, 15NH3 and O2 are presented, with some insights into accompanying Odin Letters in this A&A issue. We focus on new results where Odin's high angular resolution, high frequency resolution, large spectrometer bandwidths, high sensitivity or/and frequency tuning capability are crucial: H2O mapping of the Orion KL, W3, DR21, S140 regions, and four comets; H2O observations of Galactic Centre sources, of shock enhanced H2O towards the SNR IC443, and of the candidate infall source IRAS 16293-2422; H218O detections in Orion KL and in comet Ikeya-Zhang; sub-mm detections of NH3 in Orion KL (outflow, ambient cloud and bar) and ρ Oph, and very recently, of 15NH3 in~Orion KL. Simultaneous sensitive searches for the 119 GHz line of O2 have resulted in very low abundance limits, which are difficult to accomodate in chemical models. We also demonstrate, by means of a quantitative comparison of Orion KL H2O results, that the Odin and SWAS observational data sets are very consistently calibrated. Odin is a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), and the Centre National d'études Spatiales (CNES, France). The Swedish Space Corporation (SSC) has been the prime industrial contractor, and is also responsible for the satellite operation from its Odin Mission Control Centre at SSC in Solna and its Odin Control Centre at ESRANGE near Kiruna in northern Sweden. See also the SNSB Odin web page: http://www.snsb.se/eng_odin_intro.shtml
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| 5. |
- Serrano, L. M., et al.
(author)
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The HD 93963 A transiting system: A 1.04d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS
- 2022
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 667
-
Journal article (peer-reviewed)abstract
- We present the discovery of two small planets transiting HD 93963A (TOI-1797), a GOV star (M-* = 1.109 +/- 0.043M(circle dot), R-* = 1.043 +/- 0.009 R-circle dot) in a visual binary system. We combined TESS and CHEOPS space-borne photometry with MuSCAT 2 ground-based photometry, 'Alopeke and PHARO high-resolution imaging, TRES and FIES reconnaissance spectroscopy, and SOPHIE radial velocity measurements. We validated and spectroscopically confirmed the outer transiting planet HD 93963 A c, a sub-Neptune with an orbital period of P-c approximate to 3.65 d that was reported to be a TESS object of interest (TOI) shortly after the release of Sector 22 data. HD 93963 A c has amass of M-c = 19.2 +/- 4.1 M-circle plus and a radius of R-c = 3.228 +/- 0.059 R-circle plus, implying a mean density of rho(c) = 3.1 +/- 0.7 g cm(-3). The inner object, HD 93963 A b, is a validated 1.04 d ultra-short period (USP) transiting super-Earth that we discovered in the TESS light curve and that was not listed as a TOI, owing to the low significance of its signal (TESS signal-to-noise ratio approximate to 6.7, TESS + CHEOPS combined transit depth D-b = 141.5(-8.3)(+8.5) ppm). We intensively monitored the star with CHEOPS by performing nine transit observations to confirm the presence of the inner planet and validate the system. HD 93963 A b is the first small (R-b = 1.35 +/- 0.042 R-circle plus) USP planet discovered and validated by TESS and CHEOPS. Unlike planet c, HD 93963 Ab is not significantly detected in our radial velocities (M-b = 7.8 +/- 3.2 M-circle plus). The two planets are on either side of the radius valley, implying that they could have undergone completely different evolution processes. We also discovered a linear trend in our Doppler measurements, suggesting the possible presence of a long-period outer planet. With a V-band magnitude of 9.2, HD 93963 A is among the brightest stars known to host a USP planet, making it one of the most favourable targets for precise mass measurement via Doppler spectroscopy and an important laboratory to test formation, evolution, and migration models of planetary systems hosting ultra-short period planets.
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| 6. |
- Fridlund, Malcolm, 1952, et al.
(author)
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Planets observed with CHEOPS: Two super-Earths orbiting the red dwarf star TOI-776
- 2024
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 684
-
Journal article (peer-reviewed)abstract
- Context. M-dwarf stars are the most common of potential exoplanet host stars in the Galaxy. It is therefore very important to understand planetary systems orbiting such stars and to determine the physical parameters of such planets with high precision. Also with the launch of the James Webb Space Telescope (JWST) the observation of atmospheric parameters of planets orbiting these stars has begun. It is therefore required to determine properties of potential targets. Aims. Two planets around the red dwarf TOI-776 were detected by TESS. The objective of our study was to use transit observations obtained by the CHEOPS space mission to improve the current precision of the planetary radii, as well as additional radial velocity (RV) data in order to improve mass estimates of the two planets. Using these quantities, we wanted to derive the bulk densities of those planets, improving the precision in earlier results, and use this information to put them in context of other exoplanetary systems involving very low mass stars. Methods. Utilizing new transit data from the CHEOPS satellite and its photometric telescope, we obtained very high precision planetary transit measurements. Interpretation of these provides updated planetary radii, along with other system parameters. A concurrent ESO large observing program using the high precision spectrograph HARPS has doubled the available radial velocity data. Calculating the power spectrum of a number of stellar activity indices we update the previously estimated stellar rotation period to a lower value. Results. The CHEOPS data provide precise transit depths of 909 and 1177 ppm translating into radii of Rb = 1.798-0.077+0.078 R⊕ and Rc = 2.047-0.078+0.081 R⊕, respectively. Our interpretation of the radial velocities and activity indicator time series data estimates a stellar rotation period for this early M dwarf of ~21.1 days. A further multi-dimensional Gaussian process approach confirm this new estimate. By performing a Skew-Normal (SN) fit onto the Cross Correlation Functions we extracted the RV data and the activity indicators to estimate the planetary masses, obtaining Mb = 5.0-1.6+1.6 M⊕ and Mc = 6.9-2.5+2.6 M⊕. Conclusions. We improve the precision in planetary radius for TOI-776 b and c by a factor of more than two. Our data and modelling give us parameters of both bodies consistent with mini-Neptunes, albeit with a relatively high density. The stellar activity of TOI-776 is found to have increased by a factor larger than 2 since the last set of observations.
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| 7. |
- Akinsanmi, B., et al.
(author)
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The tidal deformation and atmosphere of WASP-12 b from its phase curve
- 2024
-
In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 685
-
Journal article (peer-reviewed)abstract
- Context. Ultra-hot Jupiters present a unique opportunity to understand the physics and chemistry of planets, their atmospheres, and interiors at extreme conditions. WASP-12 b stands out as an archetype of this class of exoplanets, with a close-in orbit around its star that results in intense stellar irradiation and tidal effects. Aims. The goals are to measure the planet's tidal deformation, atmospheric properties, and also to refine its orbital decay rate. Methods. We performed comprehensive analyses of the transits, occultations, and phase curves of WASP-12b by combining new CHEOPS observations with previous TESS and Spitzer data. The planet was modeled as a triaxial ellipsoid parameterized by the second-order fluid Love number of the planet, h2, which quantifies its radial deformation and provides insight into the interior structure. Results. We measured the tidal deformation of WASP-12b and estimated a Love number of h2 = 1.55- 0.49+0.45 (at 3.2σ) from its phase curve. We measured occultation depths of 333 ± 24 ppm and 493 ± 29 ppm in the CHEOPS and TESS bands, respectively, while the nightside fluxes are consistent with zero, and also marginal eastward phase offsets. Our modeling of the dayside emission spectrum indicates that CHEOPS and TESS probe similar pressure levels in the atmosphere at a temperature of ~2900 K. We also estimated low geometric albedos of Ag = 0.086 ± 0.017 and Ag = 0.01 ± 0.023 in the CHEOPS and TESS passbands, respectively, suggesting the absence of reflective clouds in the high-temperature dayside of the planet. The CHEOPS occultations do not show strong evidence for variability in the dayside atmosphere of the planet at the median occultation depth precision of 120 ppm attained. Finally, combining the new CHEOPS timings with previous measurements refines the precision of the orbital decay rate by 12% to a value of - 30.23 ± 0.82 ms yr- 1, resulting in a modified stellar tidal quality factor of Q′∗ = 1.70 ± 0.14 × 105. Conclusions. WASP-12 b becomes the second exoplanet, after WASP-103b, for which the Love number has been measured from the effect of tidal deformation in the light curve. However, constraining the core mass fraction of the planet requires measuring h2 with a higher precision. This can be achieved with high signal-to-noise observations with JWST since the phase curve amplitude, and consequently the induced tidal deformation effect, is higher in the infrared.
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| 8. |
- Cabrera, J., et al.
(author)
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The planetary system around HD 190622 (TOI-1054): Measuring the gas content of low-mass planets orbiting F-stars
- 2023
-
In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 675
-
Journal article (peer-reviewed)abstract
- Context. Giant planets are known to dominate the long-term stability of planetary systems due to their prevailing gravitational interactions, but they are also thought to play an important role in planet formation. Observational constraints improve our understanding of planetary formation processes such as the delivery of volatile-rich planetesimals from beyond the ice line into the inner planetary system. Additional constraints may come from studies of the atmosphere, but almost all such studies of the atmosphere investigate the detection of certain species, and abundances are not routinely quantitatively measured. Aims. Accurate measurements of planetary bulk parameters-that is, mass and density-provide constraints on the inner structure and chemical composition of transiting planets. This information provides insight into properties such as the amounts of volatile species, which in turn can be related to formation and evolution processes. Methods. The Transiting Exoplanet Survey Satellite (TESS) reported a planetary candidate around HD 190622 (TOI-1054), which was subsequently validated and found to merit further characterization with photometric and spectroscopic facilities. The KESPRINT collaboration used data from the High Accuracy Radial Velocity Planet Searcher (HARPS) to independently confirm the planetary candidate, securing its mass, and revealing the presence of an outer giant planet in the system. The CHEOPS consortium invested telescope time in the transiting target in order to reduce the uncertainty on the radius, improving the characterization of the planet. Results. We present the discovery and characterization of the planetary system around HD 190622 (TOI-1054). This system hosts one transiting planet, which is smaller than Neptune (3.087-0.053+0.058REarth, 7.7 ± 1.0 MEarth) but has a similar bulk density (1.43 ± 0.21 g cm-3) and an orbital period of 16 days; and a giant planet, not known to be transiting, with a minimum mass of 227.0 ± 6.7 MEarth in an orbit with a period of 315 days. Conclusions. Our measurements constrain the structure and composition of the transiting planet. HD 190622b has singular properties among the known population of transiting planets, which we discuss in detail. Among the sub-Neptune-sized planets known today, this planet stands out because of its large gas content.
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| 9. |
- Morgado, B. E., et al.
(author)
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A stellar occultation by the transneptunian object (50000) Quaoar observed by CHEOPS
- 2022
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 664
-
Journal article (peer-reviewed)abstract
- Context. Stellar occultation is a powerful technique that allows the determination of some physical parameters of the occulting object. The result depends on the photometric accuracy, the temporal resolution, and the number of chords obtained. Space telescopes can achieve high photometric accuracy as they are not affected by atmospheric scintillation. Aims. Using ESA's CHEOPS space telescope, we observed a stellar occultation by the transneptunian object (50000) Quaoar. We compare the obtained chord with previous occultations by this object and determine its astrometry with sub-milliarcsecond precision. Also, we determine upper limits to the presence of a global methane atmosphere on the occulting body. Methods. We predicted and observed a stellar occultation by Quaoar using the CHEOPS space telescope. We measured the occultation light curve from this dataset and determined the dis- and reappearance of the star behind the occulting body. Furthermore, a ground-based telescope in Australia was used to constrain Quaoar's limb. Combined with results from previous works, these measurements allowed us to obtain a precise position of Quaoar at the occultation time. Results. We present the results obtained from the first stellar occultation by a transneptunian object using a space telescope orbiting Earth; it was the occultation by Quaoar observed on 2020 June 11. We used the CHEOPS light curve to obtain a surface pressure upper limit of 85 nbar for the detection of a global methane atmosphere. Also, combining this observation with a ground-based observation, we fitted Quaoar's limb to determine its astrometric position with an uncertainty below 1.0 mas. Conclusions. This observation is the first of its kind, and it shall be considered as a proof of concept of stellar occultation observations of transneptunian objects with space telescopes orbiting Earth. Moreover, it shows significant prospects for the James Webb Space Telescope.
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| 10. |
- Swayne,, et al.
(author)
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The EBLM project - VIII. First results for M-dwarf mass, radius, and effective temperature measurements using CHEOPS light curves
- 2021
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 506:1, s. 306-322
-
Journal article (peer-reviewed)abstract
- The accuracy of theoretical mass, radius, and effective temperature values for M-dwarf stars is an active topic of debate. Differences between observed and theoretical values have raised the possibility that current theoretical stellar structure and evolution models are inaccurate towards the low-mass end of the main sequence. To explore this issue, we use the CHEOPS satellite to obtain high-precision light curves of eclipsing binaries with low-mass stellar companions. We use these light curves combined with the spectroscopic orbit for the solar-type companion to measure the mass, radius, and effective temperature of the M-dwarf star. Here, we present the analysis of three eclipsing binaries. We use the pycheops data analysis software to fit the observed transit and eclipse events of each system. Two of our systems were also observed by the TESS satellite - we similarly analyse these light curves for comparison. We find consistent results between CHEOPS and TESS, presenting three stellar radii and two stellar effective temperature values of low-mass stellar objects. These initial results from our on-going observing programme with CHEOPS show that we can expect to have similar to 24 new mass, radius, and effective temperature measurements for very low-mass stars within the next few years.
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| 11. |
- Alonso, R., et al.
(author)
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No random transits in CHEOPS observations of HD 139139 *,**
- 2023
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 680
-
Journal article (peer-reviewed)abstract
- Context . The star HD 139139 (a.k.a. ‘the Random Transiter’) is a star that exhibited enigmatic transit-like features with no apparent periodicity in K2 data. The shallow depth of the events (-200 ppm - equivalent to transiting objects with radii of -1.5 R⊕ in front of a Sun-like star) and their non-periodicity constitute a challenge for the photometric follow-up of this star. Aims . The goal of this study is to confirm with independent measurements the presence of shallow, non-periodic transit-like features on this object. Methods . We performed observations with CHEOPS for a total accumulated time of 12.75 days, distributed in visits of roughly 20 h in two observing campaigns in years 2021 and 2022. The precision of the data is sufficient to detect 150 ppm features with durations longer than 1.5 h. We used the duration and times of the events seen in the K2 curve to estimate how many events should have been detected in our campaigns, under the assumption that their behaviour during the CHEOPS observations would be the same as in the K2 data of 2017. Results . We do not detect events with depths larger than 150 ppm in our data set. If the frequency, depth, and duration of the events were the same as in the K2 campaign, we estimate the probability of having missed all events due to our limited observing window would be 4.8%. Conclusions . We suggest three different scenarios to explain our results: 1) Our observing window was not long enough, and the events were missed with the estimated 4.8% probability. 2) The events recorded in the K2 observations were time critical, and the mechanism producing them was either not active in the 2021 and 2022 campaigns or created shallower events under our detectability level. 3) The enigmatic events in the K2 data are the result of an unidentified and infrequent instrumental noise in the original data set or its data treatment.
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| 12. |
- Lam, K. W. F., et al.
(author)
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Discovery of TOI-1260d and the characterization of the multiplanet system
- 2023
-
In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 519:1, s. 1437-1451
-
Journal article (peer-reviewed)abstract
- We report the discovery of a third planet transiting the star TOI-1260, previously known to host two transiting sub-Neptune planets with orbital periods of 3.127 and 7.493 d, respectively. The nature of the third transiting planet with a 16.6-d orbit is supported by ground-based follow-up observations, including time-series photometry, high-angular resolution images, spectroscopy, and archival imagery. Precise photometric monitoring with CHEOPS allows to improve the constraints on the parameters of the system, improving our knowledge on their composition. The improved radii of TOI-1260b and TOI-1260c are 2.36 +/- 0.06R(circle plus), 2.82 +/- 0.08R(circle plus), respectively while the newly discovered third planet has a radius of 3.09 +/- 0.09R(circle plus). The radius uncertainties are in the range of 3 per cent, allowing a precise interpretation of the interior structure of the three planets. Our planet interior composition model suggests that all three planets in the TOI-1260 system contains some fraction of gas. The innermost planet TOI-1260b has most likely lost all of its primordial hydrogen-dominated envelope. Planets c and d were also likely to have experienced significant loss of atmospheric through escape, but to a lesser extent compared to planet b.
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| 13. |
- Meier Valdes, E., et al.
(author)
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Investigating the visible phase-curve variability of 55 Cnc e
- 2023
-
In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 677
-
Journal article (peer-reviewed)abstract
- Context. 55 Cnc e is an ultra-short period super-Earth transiting a Sun-like star. Previous observations in the optical range detected a time-variable flux modulation that is phased with the planetary orbital period, whose amplitude is too large to be explained by reflected light and thermal emission alone. Aims. The goal of the study is to investigate the origin of the variability and timescale of the phase-curve modulation in 55 Cnc e. To this end, we used the CHaracterising ExOPlanet Satellite (CHEOPS), whose exquisite photometric precision provides an opportunity to characterise minute changes in the phase curve from one orbit to the next. Methods. CHEOPS observed 29 individual visits of 55 Cnc e between March 2020 and February 2022. Based on these observations, we investigated the different processes that could be at the origin of the observed modulation. In particular, we built a toy model to assess whether a circumstellar torus of dust driven by radiation pressure and gravity might match the observed flux variability timescale. Results. We find that the phase-curve amplitude and peak offset of 55 Cnc e do vary between visits. The sublimation timescales of selected dust species reveal that silicates expected in an Earth-like mantle would not survive long enough to explain the observed phase-curve modulation. We find that silicon carbide, quartz, and graphite are plausible candidates for the circumstellar torus composition because their sublimation timescales are long. Conclusions. The extensive CHEOPS observations confirm that the phase-curve amplitude and offset vary in time. We find that dust could provide the grey opacity source required to match the observations. However, the data at hand do not provide evidence that circumstellar material with a variable grain mass per unit area causes the observed variability. Future observations with the James Webb Space Telescope (JWST) promise exciting insights into this iconic super-Earth.
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| 14. |
- Bruno, G., et al.
(author)
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Detailed cool star flare morphology with CHEOPS and TESS
- 2024
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 686
-
Journal article (peer-reviewed)abstract
- Context. White-light stellar flares are proxies for some of the most energetic types of flares, but their triggering mechanism is still poorly understood. As they are associated with strong X and ultraviolet emission, their study is particularly relevant to estimate the amount of high-energy irradiation onto the atmospheres of exoplanets, especially those in their stars’ habitable zone. Aims. We used the high-cadence, high-photometric capabilities of the CHEOPS and TESS space telescopes to study the detailed morphology of white-light flares occurring in a sample of 130 late-K and M stars, and compared our findings with results obtained at a lower cadence. Methods. We employed dedicated software for the reduction of 3 s cadence CHEOPS data, and adopted the 20 s cadence TESS data reduced by their official processing pipeline. We developed an algorithm to separate multi-peak flare profiles into their components, in order to contrast them to those of single-peak, classical flares. We also exploited this tool to estimate amplitudes and periodicities in a small sample of quasi-periodic pulsation (QPP) candidates. Results. Complex flares represent a significant percentage (≳30%) of the detected outburst events. Our findings suggest that high-impulse flares are more frequent than suspected from lower-cadence data, so that the most impactful flux levels that hit close-in exoplanets might be more time-limited than expected. We found significant differences in the duration distributions of single and complex flare components, but not in their peak luminosity. A statistical analysis of the flare parameter distributions provides marginal support for their description with a log-normal instead of a power-law function, leaving the door open to several flare formation scenarios. We tentatively confirmed previous results about QPPs in high-cadence photometry, report the possible detection of a pre-flare dip, and did not find hints of photometric variability due to an undetected flare background. Conclusions. The high-cadence study of stellar hosts might be crucial to evaluate the impact of their flares on close-in exoplanets, as their impulsive phase emission might otherwise be incorrectly estimated. Future telescopes such as PLATO and Ariel, thanks to their high-cadence capability, will help in this respect. As the details of flare profiles and of the shape of their parameter distributions are made more accessible by continuing to increase the instrument precision and time resolution, the models used to interpret them and their role in star-planet interactions might need to be updated constantly.
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| 15. |
- Ehrenreich, D., et al.
(author)
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A full transit of v 2 Lupi d and the search for an exomoon in its Hill sphere with CHEOPS
- 2023
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 671
-
Journal article (peer-reviewed)abstract
- The planetary system around the naked-eye star v2 Lupi (HD 136352; TOI-2011) is composed of three exoplanets with masses of 4.7, 11.2, and 8.6 Earth masses (M⊕). The TESS and CHEOPS missions revealed that all three planets are transiting and have radii straddling the radius gap separating volatile-rich and volatile-poor super-earths. Only a partial transit of planet d had been covered so we re-observed an inferior conjunction of the long-period 8.6 M⊕ exoplanet v2 Lup d with the CHEOPS space telescope. We confirmed its transiting nature by covering its whole 9.1 h transit for the first time. We refined the planet transit ephemeris to P = 107.13610.0022+0.0019 days and Tc = 2459009.77590.0096+0.0101 BJDTDB, improving by ~40 times on the previously reported transit timing uncertainty. This refined ephemeris will enable further follow-up of this outstanding long-period transiting planet to search for atmospheric signatures or explore the planet s Hill sphere in search for an exomoon. In fact, the CHEOPS observations also cover the transit of a large fraction of the planet s Hill sphere, which is as large as the Earth s, opening the tantalising possibility of catching transiting exomoons. We conducted a search for exomoon signals in this single-epoch light curve but found no conclusive photometric signature of additional transiting bodies larger than Mars. Yet, only a sustained follow-up of v2 Lup d transits will warrant a comprehensive search for a moon around this outstanding exoplanet.
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| 16. |
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| 17. |
- Maxted, P. F. L., et al.
(author)
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Analysis of Early Science observations with the CHaracterising ExOPlanets Satellite (CHEOPS) using pycheops
- 2022
-
In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 514:1, s. 77-104
-
Journal article (peer-reviewed)abstract
- CHEOPS (CHaracterising ExOPlanet Satellite) is an ESA S-class mission that observes bright stars at high cadence from low-Earth orbit. The main aim of the mission is to characterize exoplanets that transit nearby stars using ultrahigh precision photometry. Here, we report the analysis of transits observed by CHEOPS during its Early Science observing programme for four well-known exoplanets: GJ 436 b, HD 106315 b, HD 97658 b, and GJ 1132 b. The analysis is done using pycheops, an open-source software package we have developed to easily and efficiently analyse CHEOPS light-curve data using state-of-the-art techniques that are fully described herein. We show that the precision of the transit parameters measured using CHEOPS is comparable to that from larger space telescopes such as Spitzer Space Telescope and Kepler. We use the updated planet parameters from our analysis to derive new constraints on the internal structure of these four exoplanets.
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| 18. |
- Olofsson, Henrik, 1972, et al.
(author)
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Odin water mapping in the Orion KL region
- 2003
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 402, s. L47-L54
-
Journal article (peer-reviewed)abstract
- New results from water mapping observations of the Orion KL region using the submm/mm wave satellite Odin (2.1\arcmin beam size at 557 GHz), are presented. The ortho-H2O \jkktrans{1}{1}{0}{1}{0}{1} ground state transition was observed in a 7arcminx 7arcmin rectangular grid with a spacing of 1\arcmin, while the same line of H218O was measured in two positions, Orion KL itself and 2\arcmin south of Orion KL. In the main water species, the KL molecular outflow is largely resolved from the ambient cloud and it is found to have an extension of 60\arcsec-110\arcsec. The H2O outflow profile exhibits a rather striking absorption-like asymmetry at the line centre. Self-absorption in the near (or ``blue'') part of the outflow (and possibly in foreground quiescent halo gas) is tentatively suggested to play a role here. We argue that the dominant part of the KL H218O outflow emission emanates from the compact (size ~ 15\arcsec) low-velocity flow and here estimate an H2O abundance of circa 10-5 compared to all H2 in the flow - an order of magnitude below earlier estimates of the H2O abundance in the shocked gas of the high-velocity flow. The narrow ambient cloud lines show weak velocity trends, both in the N-S and E-W directions. H218O is detected for the first time in the southern position at a level of ~ 0.15 K and we here estimate an H2O abundance of (1-8) x 10-8. Odin is a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), and the Centre National d'Études Spatiales (CNES, France). The Swedish Space Corporation (SSC) was the industrial prime contractor and is also responsible for the satellite operation.
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| 19. |
- Pagani, L., et al.
(author)
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Low upper limits on the O2 abundance from the Odin satellite
- 2003
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 402, s. L77-L81
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Journal article (peer-reviewed)abstract
- For the first time, a search has been conducted in our Galaxy for the 119 GHz transition connecting to the ground state of O2, using the Odin satellite. Equipped with a sensitive 3 mm receiver (Tsys(SSB) = 600 K), Odin has reached unprecedented upper limits on the abundance of O2, especially in cold dark clouds where the excited state levels involved in the 487 GHz transition are not expected to be significantly populated. Here we report upper limits for a dozen sources. In cold dark clouds we improve upon the published SWAS upper limits by more than an order of magnitude, reaching N(O2)/N(H2) <= 10-7 in half of the sources. While standard chemical models are definitively ruled out by these new limits, our results are compatible with several recent studies that derive lower O2 abundances. Goldsmith et al. (\cite{SWAS2002}) recently reported a SWAS tentative detection of the 487 GHz transition of O2 in an outflow wing towards rho Oph A in a combination of 7 beams covering approximately 10arcmin x 14arcmin . In a brief (1.3 hour integration time) and partial covering of the SWAS region (~65% if we exclude their central position), we did not detect the corresponding 119 GHz line. Our 3 sigma upper limit on the O2 column density is 7.3x 1015 cm-2. We presently cannot exclude the possibility that the SWAS signal lies mostly outside of the 9\arcmin Odin beam and has escaped our sensitive detector. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation was the industrial prime contractor and is operating Odin.
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| 20. |
- Sandqvist, Aa., et al.
(author)
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Odin observations of H2O in the Galactic Centre
- 2003
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 402, s. L63-L67
-
Journal article (peer-reviewed)abstract
- The Odin satellite has been used to detect emission and absorption in the 557-GHz H216O line in the Galactic Centre towards the Sgr Astar Circumnuclear Disk (CND), and the Sgr A +20 km s-1 and +50 km s-1 molecular clouds. Strong broad H2O emission lines have been detected in all three objects. Narrow H2O absorption lines are present at all three positions and originate along the lines of sight in the 3-kpc Spiral Arm, the -30 km s-1 Spiral Arm and the Local Sgr Spiral Arm. Broad H2O absorption lines near -130 km s-1 are also observed, originating in the Expanding Molecular Ring. A new molecular feature (the ``High Positive Velocity Gas'' - HPVG) has been identified in the positive velocity range of ~+120 to +220 km s-1, seen definitely in absorption against the stronger dust continuum emission from the +20 km s-1 and +50 km s-1 clouds and possibly in emission towards the position of Sgr Astar CND. The 548-GHz H218O isotope line towards the CND is not detected at the 0.02 K (rms) level. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation was the industrial prime contractor and is also responsible for the satellite operation.
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| 21. |
- Bonfanti, A., et al.
(author)
-
TOI-1055 b: Neptunian planet characterised with HARPS, TESS, and CHEOPS
- 2023
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 671
-
Journal article (peer-reviewed)abstract
- Context. TOI-1055 is a Sun-like star known to host a transiting Neptune-sized planet on a 17.5-day orbit (TOI-1055 b). Radial velocity (RV) analyses carried out by two independent groups using nearly the same set of HARPS spectra have provided measurements of planetary masses that differ by ∼2σ. Aims. Our aim in this work is to solve the inconsistency in the published planetary masses by significantly extending the set of HARPS RV measurements and employing a new analysis tool that is able to account and correct for stellar activity. Our further aim was to improve the precision on measurements of the planetary radius by observing two transits of the planet with the CHEOPS space telescope. Methods. We fit a skew normal function to each cross correlation function extracted from the HARPS spectra to obtain RV measurements and hyperparameters to be used for the detrending. We evaluated the correlation changes of the hyperparameters along the RV time series using the breakpoint technique. We performed a joint photometric and RV analysis using a Markov chain Monte Carlo scheme to simultaneously detrend the light curves and the RV time series. Results. We firmly detected the Keplerian signal of TOI-1055 b, deriving a planetary mass of Mb = 20.4-2.5+2.6 MO (∼12%). This value is in agreement with one of the two estimates in the literature, but it is significantly more precise. Thanks to the TESS transit light curves combined with exquisite CHEOPS photometry, we also derived a planetary radius of Rb = 3.490-0.064+0.070 RO (∼1.9%). Our mass and radius measurements imply a mean density of ρb = 2.65-0.35+0.37 g cm-3 (∼14%). We further inferred the planetary structure and found that TOI-1055 b is very likely to host a substantial gas envelope with a mass of 0.41-0.20+0.34 MO and a thickness of 1.05-0.29+0.30 RO. Conclusions. Our RV extraction combined with the breakpoint technique has played a key role in the optimal removal of stellar activity from the HARPS time series, enabling us to solve the tension in the planetary mass values published so far for TOI-1055 b.
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| 22. |
- Bourrier, V., et al.
(author)
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A CHEOPS-enhanced view of the HD 3167 system
- 2022
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 668
-
Journal article (peer-reviewed)abstract
- Much remains to be understood about the nature of exoplanets smaller than Neptune, most of which have been discovered in compact multi-planet systems. With its inner ultra-short period planet b aligned with the star and two larger outer planets d-c on polar orbits, the multi-planet system HD 3167 features a peculiar architecture and offers the possibility to investigate both dynamical and atmospheric evolution processes. To this purpose we combined multiple datasets of transit photometry and radial velocimetry (RV) to revise the properties of the system and inform models of its planets. This effort was spearheaded by CHEOPS observations of HD 3167b, which appear inconsistent with a purely rocky composition despite its extreme irradiation. Overall the precision on the planetary orbital periods are improved by an order of magnitude, and the uncertainties on the densities of the transiting planets b and c are decreased by a factor of 3. Internal structure and atmospheric simulations draw a contrasting picture between HD 3167d, likely a rocky super-Earth that lost its atmosphere through photo-evaporation, and HD 3167c, a mini-Neptune that kept a substantial primordial gaseous envelope. We detect a fourth, more massive planet on a larger orbit, likely coplanar with HD 3167d-c. Dynamical simulations indeed show that the outer planetary system d-c-e was tilted, as a whole, early in the system history, when HD 3167b was still dominated by the star influence and maintained its aligned orbit. RV data and direct imaging rule out that the companion that could be responsible for the present-day architecture is still bound to the HD 3167 system. Similar global studies of multi-planet systems will tell how many share the peculiar properties of the HD 3167 system, which remains a target of choice for follow-up observations and simulations.
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| 23. |
- Harre, J. V., et al.
(author)
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Examining the orbital decay targets KELT-9 b, KELT-16 b, and WASP-4 b, and the transit-timing variations of HD 97658 b
- 2023
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 669
-
Journal article (peer-reviewed)abstract
- Context. Tidal orbital decay is suspected to occur for hot Jupiters in particular, with the only observationally confirmed case of this being WASP-12 b. By examining this effect, information on the properties of the host star can be obtained using the so-called stellar modified tidal quality factor Q′∗, which describes the efficiency with which the kinetic energy of the planet is dissipated within the star. This can provide information about the interior of the star. Aims. In this study, we aim to improve constraints on the tidal decay of the KELT-9, KELT-16, and WASP-4 systems in order to find evidence for or against the presence of tidal orbital decay. With this, we want to constrain the Q′∗ value for each star. In addition, we aim to test the existence of the transit timing variations (TTVs) in the HD 97658 system, which previously favoured a quadratic trend with increasing orbital period. Methods. Making use of newly acquired photometric observations from CHEOPS (CHaracterising ExOplanet Satellite) and TESS (Transiting Exoplanet Survey Satellite), combined with archival transit and occultation data, we use Markov chain Monte Carlo (MCMC) algorithms to fit three models to the data, namely a constant-period model, an orbital-decay model, and an apsidal-precession model. Results. We find that the KELT-9 system is best described by an apsidal-precession model for now, with an orbital decay trend at over 2 σ being a possible solution as well. A Keplerian orbit model with a constant orbital period provides the best fit to the transit timings of KELT-16 b because of the scatter and scale of their error bars. The WASP-4 system is best represented by an orbital decay model at a 5 σ significance, although apsidal precession cannot be ruled out with the present data. For HD 97658 b, using recently acquired transit observations, we find no conclusive evidence for a previously suspected strong quadratic trend in the data.
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| 24. |
- Larsson, B., et al.
(author)
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First NH3 detection of the Orion Bar
- 2003
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 402, s. L69-L72
-
Journal article (peer-reviewed)abstract
- Odin has successfully observed three regions in the Orion A cloud, i.e. Ori KL, Ori S and the Orion Bar, in the 572.5 GHz rotational ground state line of ammonia, ortho-NH3 (J,K) = (1,0) -> (0,0), and the result for the Orion Bar represents the first detection in an ammonia line. Several velocity components are present in the data. Specifically, the observed line profile from the Orion Bar can be decomposed into two components, which are in agreement with observations in high-J CO lines by Wilson et al. (\cite{wilson01}). Using the source model for the Orion Bar by these authors, our Odin observation implies a total ammonia abundance of NH3/H2 = 5x 10-9. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation has been the industrial prime contractor.
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| 25. |
- Morris, B. M., et al.
(author)
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CHEOPS precision phase curve of the Super-Earth 55 Cancri e
- 2021
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 653
-
Journal article (peer-reviewed)abstract
- Context. 55 Cnc e is a transiting super-Earth (radius 1.88 R-circle plus and mass 8 M-circle plus) orbiting a G8V host star on a 17-h orbit. Spitzer observations of the planet's phase curve at 4.5 mu m revealed a time-varying occultation depth, and MOST optical observations are consistent with a time-varying phase curve amplitude and phase offset of maximum light. Both broadband and high-resolution spectroscopic analyses are consistent with either a high mean molecular weight atmosphere or no atmosphere for planet e. A long-term photometric monitoring campaign on an independent optical telescope is needed to probe the variability in this system. Aims. We seek to measure the phase variations of 55 Cnc e with a broadband optical filter with the 30 cm effective aperture space telescope CHEOPS and explore how the precision photometry narrows down the range of possible scenarios. Methods. We observed 55 Cnc for 1.6 orbital phases in March of 2020. We designed a phase curve detrending toolkit for CHEOPS photometry which allowed us to study the underlying flux variations in the 55 Cnc system. Results. We detected a phase variation with a full-amplitude of 72 +/- 7 ppm, but did not detect a significant secondary eclipse of the planet. The shape of the phase variation resembles that of a piecewise-Lambertian; however, the non-detection of the planetary secondary eclipse, and the large amplitude of the variations exclude reflection from the planetary surface as a possible origin of the observed phase variations. They are also likely incompatible with magnetospheric interactions between the star and planet, but may imply that circumplanetary or circumstellar material modulate the flux of the system. Conclusions. This year, further precision photometry of 55 Cnc from CHEOPS will measure variations in the phase curve amplitude and shape over time.
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| 26. |
- Osborn, H. P., et al.
(author)
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Two warm Neptunes transiting HIP 9618 revealed by TESS and Cheops
- 2023
-
In: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 523:2, s. 3069-3089
-
Journal article (peer-reviewed)abstract
- HIP 9618 (HD 12572, TOI-1471, TIC 306263608) is a bright (G = 9.0 mag) solar analogue. TESS photometry revealed the star to have two candidate planets with radii of 3.9 ± 0.044 R (HIP 9618 b) and 3.343 ± 0.039 R (HIP 9618 c). While the 20.77291 d period of HIP 9618 b was measured unambiguously, HIP 9618 c showed only two transits separated by a 680-d gap in the time series, leaving many possibilities for the period. To solve this issue, CHEOPS performed targeted photometry of period aliases to attempt to recover the true period of planet c, and successfully determined the true period to be 52.56349 d. High-resolution spectroscopy with HARPS-N, SOPHIE, and CAFE revealed a mass of 10.0 ± 3.1M for HIP 9618 b, which, according to our interior structure models, corresponds to a 6.8 ± 1.4 per cent gas fraction. HIP 9618 c appears to have a lower mass than HIP 9618 b, with a 3-sigma upper limit of <18M. Follow-up and archival RV measurements also reveal a clear long-term trend which, when combined with imaging and astrometric information, reveal a low-mass companion (0.08+−000512M☉) orbiting at 26.0+−111900 au. This detection makes HIP 9618 one of only five bright (K < 8 mag) transiting multiplanet systems known to host a planet with P > 50 d, opening the door for the atmospheric characterization of warm (Teq < 750 K) sub-Neptunes.
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| 27. |
- Hoyer, S., et al.
(author)
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Characterization of the HD 108236 system with CHEOPS and TESS Confirmation of a fifth transiting planet
- 2022
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 668
-
Journal article (peer-reviewed)abstract
- Context. The HD 108236 system was first announced with the detection of four small planets based on TESS data. Shortly after, the transit of an additional planet with a period of 29.54 d was serendipitously detected by CHEOPS. In this way, HD 108236 (V = 9.2) became one of the brightest stars known to host five small transiting planets (Rp < 3 Ro˙). Aims. We characterize the planetary system by using all the data available from CHEOPS and TESS space missions. We use the flexible pointing capabilities of CHEOPS to follow up the transits of all the planets in the system, including the fifth transiting body. Methods. After updating the host star parameters by using the results from Gaia eDR3, we analyzed 16 and 43 transits observed by CHEOPS and TESS, respectively, to derive the planets' physical and orbital parameters. We carried out a timing analysis of the transits of each of the planets of HD 108236 to search for the presence of transit timing variations. Results. We derived improved values for the radius and mass of the host star (R∗ = 0.876 ± 0.007 R0 and M∗ = 0.867-0.046+0.047M). We confirm the presence of the fifth transiting planet f in a 29.54 d orbit. Thus, the HD 108236 system consists of five planets of Rb = 1.587±0.028, Rc = 2.122±0.025, Rd = 2.629 ± 0.031, Re = 3.008 ± 0.032, and Rf = 1.89 ± 0.04 [Ro˙]. We refine the transit ephemeris for each planet and find no significant transit timing variations for planets c, d, and e. For planets b and f, instead, we measure significant deviations on their transit times (up to 22 and 28 min, respectively) with a non-negligible dispersion of 9.6 and 12.6 min in their time residuals. Conclusions. We confirm the presence of planet f and find no significant evidence for a potential transiting planet in a 10.9 d orbital period, as previously suggested. Further monitoring of the transits, particularly for planets b and f, would confirm the presence of the observed transit time variations. HD 108236 thus becomes a key multi-planetary system for the study of formation and evolution processes. The reported precise results on the planetary radii - together with a profuse RV monitoring - will allow for an accurate characterization of the internal structure of these planets.
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| 28. |
- Kiss, Mózsi, et al.
(author)
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The PoGOLite balloon-borne soft gamma-ray polarimeter
- 2008
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In: COOL DISCS, HOT FLOWS. - : AIP. ; , s. 225-232
-
Conference paper (peer-reviewed)abstract
- Linearly polarized radiation in the hard X-ray/soft gamma-ray band is expected from a large variety of astronomical sources. We discuss the importance of polarimetric studies for several classes of sources - pulsars, accreting black holes. magnetic neutron stars and jets from active galaxies - and then describe PoGOLite, a balloon-borne instrument which is currently under construction and will be able to measure the polarization of electromagnetic radiation from such extra-solar objects in the energy range 25-80 keV.
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| 29. |
- Takahashi, H., et al.
(author)
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A thermal-neutron detector with a phoswich system of LiCaAlF6 and BGO crystal scintillators onboard PoGOLite
- 2010
-
In: 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, NSS/MIC 2010 and 17th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, RTSD 2010. ; , s. 32-37
-
Conference paper (peer-reviewed)abstract
- To measure the flux of atmospheric neutrons and study the neutron contribution to the background of the main detector of the PoGOLite (Polarized Gamma-ray Observer) balloon-borne experiment, a thermal-neutron detector with a phoswich system of LiCaAlF6 (Eu) and BGO crystal scintillators is developed. The performance to separate thermal-neutron events from those of gamma-rays and charged particles is validated with 252Cf on ground. The detector is attached to the PoGOLite instrument and is launched in 2011 from the Esrange facility in the North of Sweden. Although the emission wavelength of the LiCaAlF6 (Ce) is 300 nm and overlaps with the absorption wavelength of the BGO, the phoswich capability of the LiCaAlF6 (Ce) with the BGO is also confirmed with installing a waveform shifter.
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| 30. |
- Wilson, C. D., et al.
(author)
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Submillimeter emission from water in the W3 region
- 2003
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 402, s. L59-L62
-
Journal article (peer-reviewed)abstract
- Using the Odin satellite, we have mapped the submillimeter emission from the 110-101 transition of ortho-water in the W3 star-forming region. A 5arcminx 5arcmin map of the W3 IRS4 and W3 IRS5 region reveals strong water lines at half the positions in the map. The relative strength of the Odin lines compared to previous observations by SWAS suggests that we are seeing water emission from an extended region. Across much of the map the lines are double-peaked, with an absorption feature at -39 km s-1; however, some positions in the map show a single strong line at -43 km s-1. We interpret the double-peaked lines as arising from optically thick, self-absorbed water emission near the W3 IRS5, while the narrower blue-shifted lines originate in emission near W3 IRS4. In this model, the unusual appearance of the spectral lines across the map results from a coincidental agreement in velocity between the emission near W3 IRS4 and the blue peak of the more complex lines near W3 IRS5. The strength of the water lines near W3 IRS4 suggests we may be seeing water emission enhanced in a photon-dominated region. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation was the industrial prime contractor and is also responsible for the satellite operation.
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| 31. |
- Liseau, R., et al.
(author)
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First detection of NH3 (10 -> 00) from a low mass cloud core. On the low ammonia abundance of the rho Oph A core
- 2003
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 402, s. L73-L76
-
Journal article (peer-reviewed)abstract
- Odin has successfully observed the molecular core rho Oph A in the 572.5 GHz rotational ground state line of ammonia, NH3 (JK = 10 -> 00). The interpretation of this result makes use of complementary molecular line data obtained from the ground (C17O and CH3OH) as part of the Odin preparatory work. Comparison of these observations with theoretical model calculations of line excitation and transfer yields a quite ordinary abundance of methanol, X(CH3OH)= 3 x 10-9. Unless NH3 is not entirely segregated from C17O and CH3OH, ammonia is found to be significantly underabundant with respect to typical dense core values, viz. X(NH3) = 8 x 10-10. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation has been the industrial prime contractor. and based on observations collected with the Swedish ESO Submillimeter Telescope, SEST, in La Silla, Chile.
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| 32. |
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| 33. |
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| 34. |
- Pearce, Mark, et al.
(author)
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Balloon-borne hard X-ray polarimetry with PoGOLite
- 2012
-
In: 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC). - : IEEE. - 9781467320306 ; , s. 1885-1892
-
Conference paper (peer-reviewed)abstract
- PoGOLite is a hard X-ray polarimeter operating in the 25-100 keV energy band. The instrument design is optimised for the observation of compact astrophysical sources. Observations are conducted from a stabilised stratospheric balloon platform at an altitude of approximately 40 km. The primary targets for first balloon flights of a reduced effective area instrument are the Crab and Cygnus-X1. The polarisation of incoming photons is determined using coincident Compton scattering and photo-absorption events reconstructed in an array of plastic scintillator detector cells surrounded by a bismuth germanate oxide (BGO) side anticoincidence shield and a polyethylene neutron shield. A custom attitude control system keeps the polarimeter field-of-view aligned to targets of interest, compensating for sidereal motion and perturbations such as torsional forces in the balloon rigging. An overview of the PoGOLite project is presented and the outcome of the ill-fated maiden balloon flight is discussed.
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| 35. |
- Crovisier, J., et al.
(author)
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The chemical composition of 9P/tempel 1 from radio observations
- 2009
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In: ESO Astrophysics Symposia. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1431-2433 .- 1611-6143. - 9783540769583 ; 2009, s. 243-248
-
Conference paper (peer-reviewed)abstract
- In 2005, as part of a world-wide multi-wavelength investigation of comet 9P/Tempel 1 in support to the Deep Impact mission, we conducted radio spectroscopic observations with the Nançay radio telescope, the Odin satellite, the CSO 10-m and the IRAM 30-m telescopes. We report here our results concerning the chemical composition of the comet. The relative abundances of the detected species (H2O, CH3OH, H2S, HCN) or their upper limits (CO, H2CO, CS) are comparable to the mean values observed in other comets. No significant changes of the outgassing rates (except possibly for CH3OH) or of the molecular abundances were observed following the impact.
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| 36. |
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| 37. |
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| 38. |
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| 39. |
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| 40. |
- Hjalmarson, Åke, et al.
(author)
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Recent astronomy highlights from the Odin satellite
- 2005
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In: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 36, s. 1031-1047
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Journal article (peer-reviewed)abstract
- Astronomy highlights, mainly from the third year of Odin observations time shared 50/50% with aeronomy are presented: the very low O2 abundance limits achieved, the highly pressure broadened absorption lines of H2O, H218O, and CO (5 → 4) in the atmosphere of Mars, the high precision H2O and H218O observations of comets, the detections of NH3 and H2O around the C-rich star IRC+10216 (CW Leo) and of H2O around the O-rich star W Hya, NH3 and H2O observations of infall/outflow interactions, observations of H2O, H218O, H217O as well as NH3 and 15NH3 in multiple absorptions towards Sgr B2, and in emission towards Orion KL, the H2O detection of several new outflows in the DR21 W75S region. We also discuss the results of deconvolution of high S/N H2O, CO and 13CO (5 → 4) maps of the Orion KL region to 40″ resolution (the beam size of the Herschel telescope) and the first results from our ongoing “spectral scan” of Orion KL in bands around 555 and 570 GHz. Finally, a search for primordial molecules is presented.
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| 41. |
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| 42. |
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