Aims. The space experiment CoRoT has recently detected a transiting hot Jupiter in orbit around a moderately active F-type main-sequence star (CoRoT-4a). This planetary system is of particular ...interest because it has an orbital period of 9.202 days, the second longest one among the transiting planets known to date. We study the surface rotation and the activity of the host star during an uninterrupted sequence of optical observations of 58 days. Methods. Our approach is based on a maximum entropy spot modelling technique extensively tested by modelling the variation in the total solar irradiance. It has been successfully applied to model the light curve of another active star with a transiting planet observed by CoRoT, i.e., CoRoT-2a. It assumes that stellar active regions consist of cool spots and bright faculae, analogous to sunspots and solar photospheric faculae, whose visibility is modulated by stellar rotation. Results. The modelling of the light curve of CoRoT-4a reveals three main active longitudes with lifetimes between ${\sim }30$ and ${\sim }60$ days that rotate quasi-synchronously with the orbital motion of the planet. The different rotation rates of the active longitudes are interpreted in terms of surface differential rotation, and a lower limit of $0.057 \pm 0.015$ is derived for its relative amplitude. The enhancement of activity observed close to the subplanetary longitude suggests a magnetic star-planet interaction, although the short duration of the time series prevents us from drawing definite conclusions. Conclusions. The present work confirms the quasi-synchronicity between stellar rotation and planetary orbital motion in the CoRoT-4 system and provides a lower limit for the surface differential rotation of the star. This information can be important in trying to understand the formation and evolution of this highly interesting planetary system. Moreover, there is an indication of a possible star-planet magnetic interaction that needs to be confirmed by future studies.
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HADES RV Programme with HARPS-N at TNG Suárez Mascareño, A.; González Hernández, J. I.; Rebolo, R. ...
Astronomy and astrophysics (Berlin),
09/2017, Volume:
605
Journal Article
Peer reviewed
Open access
We report the discovery of a super-Earth orbiting at the inner edge of the habitable zone of the star GJ 625 based on the analysis of the radial-velocity (RV) time series from the HARPS-N ...spectrograph, consisting of 151 HARPS-N measurements taken over 3.5 yr. GJ 625 b is a planet with a minimum mass Msini of 2.82 ± 0.51 M⊕ with an orbital period of 14.628 ± 0.013 days at a distance of 0.078 AU from its parent star. The host star is the quiet M2 V star GJ 625, located at 6.5 pc from the Sun. We find the presence of a second radial-velocity signal in the range 74–85 days that we relate to stellar rotation after analysing the time series of Ca II H&K and Hα spectroscopic indicators, the variations of the FWHM of the CCF, and the APT2 photometric light curves. We find no evidence linking the short-period radial-velocity signal to any activity proxy.
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Context. The CoRoT satellite has recently discovered a hot Jupiter that transits across the disc of a F9 main-sequence star called CoRoT-6 with a period of 8.886 days. Aims. We model the photospheric ...activity of the star and use the maps of the active regions to study stellar differential rotation and the star-planet interaction. Methods. We apply a maximum entropy spot model to fit the optical modulation as observed by CoRoT during a uninterrupted interval of ~140 days. Photospheric active regions are assumed to consist of spots and faculae in a fixed proportion with solar-like contrasts. Results. Individual active regions have lifetimes up to 30−40 days. Most of them form and decay within five active longitudes whose different migration rates are attributed to the stellar differential rotation for which a lower limit of ΔΩ/Ω = 0.12 ± 0.02 is obtained. Several active regions show a maximum of activity at a longitude lagging the subplanetary point by ~200° with the probability of a chance occurrence being smaller than 1 percent. Conclusions. Our spot modelling indicates that the photospheric activity of CoRoT-6 could be partially modulated by some kind of star-planet magnetic interaction, while an interaction related to tides is highly unlikely because of the weakness of the tidal force.
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For many years an ongoing research program performed at our laboratory has had the aim to investigate the implantation of reactive ions in ices relevant to planetology by using IR spectroscopy. We ...present new results obtained by implanting 200 keV sulfur ions into water ice at 80 K. We have looked at the formation of sulfur-bearing molecules such as sulfuric acid, sulfur dioxide and hydrogen sulfide. We find that hydrated sulfuric acid is formed with high yield (
0.65
±
0.1
molecules
/
ion
). An upper limit to the production yield of SO
2 (
Y
⩽
0.025
molecules
/
ion
) has been estimated; no hydrogen sulfide has been detected. The formation of hydrogen peroxide is confirmed. Ozone is not detected. The results are discussed relevant to the inquiry on the radiolytic sulfur cycle considered responsible for the formation of sulfur-bearing molecules on the surfaces of the Galilean satellites. We demonstrate that sulfur implantation efficiently forms hydrated sulfuric acid whose observed abundance is explained as caused by an exogenic process. It is more difficult to say if the observed sulfur dioxide is quantitatively supported by only sulfur implantation; additional experimental studies are necessary along with direct observations, especially at UV wavelengths such as those that could be performed by instruments on board Hubble Space Telescope or by the forthcoming World Space Observatory (WSO/UV).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The GAPS Programme with HARPS-N at TNG Esposito, M.; Covino, E.; Desidera, S. ...
Astronomy and astrophysics (Berlin),
05/2017, Volume:
601
Journal Article
Peer reviewed
Open access
Context. The orbital obliquity of planets with respect to the rotational axis of their host stars is a relevant parameter for the characterization of the global architecture of planetary systems and ...a key observational constraint to discriminate between different scenarios proposed to explain the existence of close-in giant planets. Aims. In the framework of the GAPS project, we conduct an observational programme aimed at determinating the orbital obliquity of known transiting exoplanets. The targets are selected to probe the obliquity against a wide range of stellar and planetary physical parameters. Methods. We exploit high-precision radial velocity (RV) measurements, delivered by the HARPS-N spectrograph at the 3.6 m Telescopio Nazionale Galileo, to measure the Rossiter-McLaughlin (RM) effect in RV time-series bracketing planet transits, and to refine the orbital parameters determinations with out-of-transit RV data. We also analyse new transit light curves obtained with several 1−2 m class telescopes to better constrain the physical fundamental parameters of the planets and parent stars. Results. We report here on new transit spectroscopic observations for three very massive close-in giant planets: WASP-43 b, HAT-P-20 b and Qatar-2 b (Mp = 2.00, 7.22, 2.62 MJ; a = 0.015, 0.036, 0.022 AU, respectively) orbiting dwarf K-type stars with effective temperature well below 5000 K (Teff = 4500 ± 100, 4595 ± 45, 4640 ± 65 K respectively). These are the coolest stars (except for WASP-80) for which the RM effect has been observed so far. We find λ = 3.5 ± 6.8 deg for WASP-43 b and λ = −8.0 ± 6.9 deg for HAT-P-20 b, while for Qatar-2, our faintest target, the RM effect is only marginally detected, though our best-fit value λ = 15 ± 20 deg is in agreement with a previous determination. In combination with stellar rotational periods derived photometrically, we estimate the true spin-orbit angle, finding that WASP-43 b is aligned while the orbit of HAT-P-20 b presents a small but significant obliquity (Ψ = 36-12+10 deg). By analyzing the CaII H&K chromospheric emission lines for HAT-P-20 and WASP-43, we find evidence for an enhanced level of stellar activity that is possibly induced by star-planet interactions.
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In this paper we present the results of new experiments on ion irradiation of water ice performed on thin films to study the synthesis of the hydrogen peroxide molecule and discuss the possibility of ...detecting it in icy mantles on interstellar grains. The used experimental technique has been in situ infrared spectroscopy. We have irradiated thin films (i.e. the ice thickness was smaller than the penetration depth of the used ion) with three different ions, namely 200 keV of H+ and He+ and 400 keV of Ar++. The experiments were carried out at temperatures of 16 and 77 K. We have found that hydrogen peroxide is produced by all of the different ions at both temperatures. The detection of such a molecule has been possible from the study of its infrared feature centered at about 2850 cm-1 (3.5 μm). The obtained results also show that the produced H2O2/H2O(%) ratio is greater for the heaviest ion (~6% for the case of Ar++) and that H+ is the ion that produces the smallest quantity (~1%). These upper limits in the production of hydrogen peroxide constrain the quantity of H2O2 that can be formed after bombardment by cosmic particles on icy mantles of grains in the interstellar medium.
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Purpose
To evaluate a novel surgical combination of ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) and sutureless scleral fixation for Carlevale intraocular lens ...(SSF-Carlevale IOL) implantation to manage corneal endothelial decompensation when there is a concomitant need for secondary IOL fixation.
Methods
Clinical data collected from 10 eyes of 9 patients with bullous keratopathy (BK) who underwent combined UT-DSAEK and SSF-Carlevale IOL implantation in a single procedure were retrospectively analyzed. Anterior chamber IOL (4 cases), aphakia (4 cases, 1 of which associated with PEX), and previous trauma (2 cases) were the conditions responsible for BK. Corrected distance visual acuity (CDVA), intraocular pressure (IOP), endothelial cell density (ECD), central corneal thickness (CCT), graft thickness (GT) and complications were recorded over a 12-month follow-up period.
Results
In 90% (9/10) of eyes graft clarity was maintained during follow-up. The mean CDVA improved significantly (p < 0.0001) from 1.78 ± 0.76 logMAR preoperatively to 0.53 ± 0.3 logMAR at 12 months. ECD on average decreased from 2575 ± 125.3 cells/mm2 (donor tissue) to 1697 ± 133.3 cells/mm2 in 12 months. The mean CCT decreased from 870 ± 200 µm to 650 µm ± 9 at 12 months (ANOVA, p = 0.0005).
Conclusions
Combined UT-DSAEK and SSF-Carlevale IOL implantation was associated with good corneal graft survival and IOP control, with few complications. These findings suggest that this surgical approach is a practical option for patients requiring both treatment for corneal endothelial dysfunction and secondary IOL implantation.
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NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
ABSTRACT
Considering the model of the initial disc of planetesimals consisting of 10 038 test particles, we simulated the formation of the distant comet reservoirs up to 2 Gyr. The result concerning ...the outer part of the Oort cloud (OC) was described in our previous paper. Here, we deal with the evolution of the population and structure at 2 Gyr of the complementary inner part of the OC. The dynamical evolution of the massless test particles was followed via the numerical integration of their orbits. We considered the perturbations produced by four giant planets assuming they have their current orbits and masses, as well as the perturbations caused by the Galactic tide and passing stars. The efficiency of the formation of inner OC is found to be very low: only about 1.1 per cent of all considered particles ended in this part of the comet cloud. In particular, the particles originated from Uranus (35.5 per cent), Neptune (35.4 per cent) and Edgeworth–Kuiper belt (18.4 per cent) regions of the initial protoplanetary disc. At 2 Gyr, the dynamics of the inner cloud is mainly governed by the dominant z‐term of the Galactic tide. The number density of the bodies is proportional to the heliocentric distance, r, as ∝r−3.53. The directional distribution of orbits is still strongly inhomogeneous. There are, for example, large empty regions in the space angles around the Galactic Equator points with the galactic longitude 90° and 270° (non‐rotating frame), or there are only few bodies having the ecliptical latitude higher than +60° or lower than −60°. A strong concentration of objects at the ecliptic is apparent up to ≈1000 au (with a possible, but not exactly proved extension to ≈1500 au). Beyond r≈ 6000 au, the bodies directly above and below the Sun, with respect to the ecliptic, are absent.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Aims. A possible transit of HAT-P-13c had been predicted to occur on 2010 April 28. Here we report on the results of our multi-site campaign organised to detect the event. Methods. CCD photometric ...observations were carried out at five observatories in five countries. We reached 30% time coverage in a 5-day interval centered on the suspected transit of HAT-P-13c. Two transits of HAT-P-13b were also observed. Results. No transit of HAT-P-13c was detected during the campaign. By a numerical experiment with 105 model systems, we conclude that HAT-P-13c is not a transiting exoplanet with a significance level from 65% to 72%, depending on the planet parameters and the prior assumptions. We present two times of transit of HAT-P-13b ocurring at BJD 2455141.5522 ± 0.0010 and BJD 2455249.4508 ± 0.0020. The TTV of HAT-P-13b is consistent with zero within 0.001 days. The refined orbital period of HAT-P-13b is 2.916293 ± 0.000010 days.
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PURPOSE:This study aimed to present the efficacy and safety of cenegermin eye drop (Oxervate; Dompè Farmaceutici, Milan, Italy) treatment in a pediatric patient affected by neurotrophic keratopathy ...(NK) with Goldenhar syndrome.
METHODS:This case reports an infant presenting ulceration and a small central opacity in the cornea of the right and left eyes, respectively. The NK bilaterally worsened despite the use of therapeutic contact lenses and temporary partial tarsorrhaphy. Magnetic resonance imaging showed absence and hypoplasia of the right and left trigeminal nerves, respectively. Cenegermin eye drops were administered 1 drop/each eye, 6 times daily for 8 weeks to promote corneal healing.
RESULTS:Complete healing was achieved in both eyes after treatment. During the 16-month follow-up period, no epithelial defect, recurrence, or complications were noticed, whereas corneal opacities progressively became clearer, although insignificant improvements in corneal sensitivity or in the reflex tearing were observed.
CONCLUSIONS:Cenegermin was effective in treating NK in an infant with Goldenhar syndrome.
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