The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
François Leblanc - One of the best experts on this subject based on the ideXlab platform.
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Modeling the impact of an X-class solar flare on theExosphere of Mercury
2019Co-Authors: Elisabeth Werner, Jean-yves Chaufray, François Leblanc, Ronan ModoloAbstract:In this first work we simulate the response of Mercury's Exosphere to an X-class solar flare. The momentaneous increase in the extreme ultraviolet (EUV) photon flux during a solar flare functions well as a proxy for modeling the response of the Exosphere to extreme variations in the external plasma conditions. This test will allow us to extend such short-term time variations to model the impact of a CME on the precipitation of sodium and other species in Mercury's coupled Exosphere-magnetosphere system.
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Modeling the impact of an X-class solar flare on the Exosphere of Mercury
2019Co-Authors: Anita Linnéa Elisabeth Werner, Jean-yves Chaufray, François Leblanc, Ronan ModoloAbstract:In this first work we simulate the response of Mercury's Exosphere to an X-class solar flare. The momentaneous increase in the extreme ultraviolet (EUV) photon flux during a solar flare functions well as a proxy for modeling the response of the Exosphere to extreme variations in the external plasma conditions. This test will allow us to extend such short-term time variations to model the impact of a CME on the precipitation of sodium and other species in Mercury's coupled Exosphere-magnetosphere system.
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Europa and Ganymede's Water-Product Exospheres
2017Co-Authors: Apurva Oza, Jean-yves Chaufray, François Leblanc, Carl Schmidt, Lorenz Roth, R. E. Johnson, T. Cassidy, Ludivine Leclercq, Ronan ModoloAbstract:Europa and Ganymede are thought to possess globally similar Exospheres, in spite of the possibility that Europa is currently cryovolcanically active, and Ganymede's intrinsic magnetic field. Ions in Jupiter's magnetosphere bombard the icy surfaces, and produce predominantly O 2 , with slightly less H 2 O and H 2 due to freezing and escape respectively. We investigate and compare the water-product Exospheres of the two satellites under rotation, using our 3-D Exosphere Global Model (EGM). In previous works ([1], [2]), we focused on the near-surface z s , oxidized component of the Exosphere, dominated by thermal-ized O 2 , which undergoes a dusk-over-dawn asymmetry due to diurnal solar insolation of the surface over the satellite's orbit. This was observed by asymmetries in oxygen aurorae. Here, we focus on characterizing the hydrogen-species: H, H 2 , and H 2 O which have been far more elusive as lyman-α auroral emission has multiple production pathways, even in the absence of endogenic sources.
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THEMIS Na Exosphere observations of Mercury and their correlation with in-situ magnetic field measurements by MESSENGER
2015Co-Authors: Valeria Mangano, Anna Milillo, C Plainaki, Rosanna Rispoli, Stefano Massetti, Stefano Orsini, François LeblancAbstract:The Na Exosphere of Mercury is being studied since its discovery in mid ’80s from Earth-based telescopes, and it has revealed a high dynamics and variability. Although the processes and their relationships characterising the Hermean Exosphere generation and dynamics are still not exhaustively understood, there are no doubts on a tight interconnection among the planet's surface, Exosphere, intrinsic magnetic field, the Solar Wind and the Interplanetary Magnetic Field (IMF). Here we analyse an extended dataset of images of the exospheric Na emission, collected from 2009 to 2013, by means of the THEMIS ground- based telescope, and perform a comprehensive statistical study of the recurrent Na emission patterns, and also their potential relationship with the IMF variability. For this purpose, we take advantage of a subset (years 2011-2013) of contemporary in situ measurements of the IMF obtained by the MAG instrument on-board the MESSENGER spacecraft.
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What Do We Know on Mercury’s and Moon Exospheres and Could We Learn from Their Comparison? (invited)
2014Co-Authors: François LeblancAbstract:Mercury’s and the Moon Exospheres have many common characteristics. They are surface bounded Exospheres essentially formed from the interaction of our Sun with their regolith. However, their interaction with their plasma environment and their respective distance to the Sun induce many remarkable discrepancies between these two objects. Mercury’s Exosphere is clearly much denser than the Moon’s but remains much more difficult to observe remotely or in situ. Mercury’s intrinsic magnetic field induces a complex and variable interaction between the solar wind and the surface whereas the Moon regularly interacts with various plasma types (solar wind, magnetospheric…). In terms of observables, they are very complementary. Only few exospheric species have been observed so far on both objects despite many attempts, but observations from the Moon surface or very close to it allowed detecting species not yet observed at Mercury. Many features induced by the solar wind interaction with the Moon surface have been identified: as an example the surface charge, the backscattered population, planetary ions and signatures of the long term space weathering of the regolith. All these features are keys to understand the formation and evolution of these Exospheres. On the other hand, Mercury’s Exosphere is denser and brighter than the Moon’s one. As a consequence, exospheric spatial structures have been identified, in association with the interaction between the solar wind and the magnetosphere or to specific source regions or suggesting some global exospheric dynamic around these objects. It has been also possible to reconstitute their time variations on several time scales, another way to constrain formation and evolution of these objects. In this talk, I will underline what could be common and different on these two objects and will provide few clues how a comparative approach could be helpful to better understand surface bounded Exospheres.
Jean-yves Chaufray - One of the best experts on this subject based on the ideXlab platform.
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Two-dimensional model for the martian Exosphere: Applications to hydrogen and deuterium Lyman α observations
Icarus, 2020Co-Authors: D. Bhattacharyya, Jean-yves Chaufray, J.t. Clarke, Jean-loup Bertaux, M. Mayyasi, S. Stone, R.v. Yelle, W. Pryor, Justin Deighan, S.k. JainAbstract:The analysis of Lyman α observations in the Exosphere of Mars has become limited by the assumption of spherical symmetry in the modeling process, as the models are being used to analyze increasingly detailed measurements. In order to overcome this limitation, a two-dimensional density model is presented, which better emulates the density distribution of deuterium and hydrogen atoms in the Exosphere of Mars. A two-dimensional radiative transfer model developed in order to simulate multiple scattering of solar Lyman α photons by an asymmetric, non-isothermal hydrogen Exosphere, is also presented here. The models incorporate changes in density and temperature structure of the martian atmosphere with radial distance and solar zenith angle. The 2-D models were applied to the MAVEN-IUVS echelle observations of deuterium and hydrogen Lyman α as well as HST Lyman α observations of hydrogen at Mars. The asymmetric 2-D model provided better fits to the data and smaller thermal escape rates in comparison to the symmetric 1-D model for the Exosphere of Mars. However, intensity differences between both models became small above ~2.5 martian radii indicating that the Exosphere of Mars approaches spherical symmetry at higher altitudes, in agreement with earlier studies. In addition, a new cross calibration of the absolute sensitivities of two instruments on the Hubble Space Telescope and the MAVEN-IUVS echelle mode is presented based on near-simultaneous observations of the geocorona and Mars.
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Modeling the impact of an X-class solar flare on theExosphere of Mercury
2019Co-Authors: Elisabeth Werner, Jean-yves Chaufray, François Leblanc, Ronan ModoloAbstract:In this first work we simulate the response of Mercury's Exosphere to an X-class solar flare. The momentaneous increase in the extreme ultraviolet (EUV) photon flux during a solar flare functions well as a proxy for modeling the response of the Exosphere to extreme variations in the external plasma conditions. This test will allow us to extend such short-term time variations to model the impact of a CME on the precipitation of sodium and other species in Mercury's coupled Exosphere-magnetosphere system.
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Modeling the impact of an X-class solar flare on the Exosphere of Mercury
2019Co-Authors: Anita Linnéa Elisabeth Werner, Jean-yves Chaufray, François Leblanc, Ronan ModoloAbstract:In this first work we simulate the response of Mercury's Exosphere to an X-class solar flare. The momentaneous increase in the extreme ultraviolet (EUV) photon flux during a solar flare functions well as a proxy for modeling the response of the Exosphere to extreme variations in the external plasma conditions. This test will allow us to extend such short-term time variations to model the impact of a CME on the precipitation of sodium and other species in Mercury's coupled Exosphere-magnetosphere system.
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Europa and Ganymede's Water-Product Exospheres
2017Co-Authors: Apurva Oza, Jean-yves Chaufray, François Leblanc, Carl Schmidt, Lorenz Roth, R. E. Johnson, T. Cassidy, Ludivine Leclercq, Ronan ModoloAbstract:Europa and Ganymede are thought to possess globally similar Exospheres, in spite of the possibility that Europa is currently cryovolcanically active, and Ganymede's intrinsic magnetic field. Ions in Jupiter's magnetosphere bombard the icy surfaces, and produce predominantly O 2 , with slightly less H 2 O and H 2 due to freezing and escape respectively. We investigate and compare the water-product Exospheres of the two satellites under rotation, using our 3-D Exosphere Global Model (EGM). In previous works ([1], [2]), we focused on the near-surface z s , oxidized component of the Exosphere, dominated by thermal-ized O 2 , which undergoes a dusk-over-dawn asymmetry due to diurnal solar insolation of the surface over the satellite's orbit. This was observed by asymmetries in oxygen aurorae. Here, we focus on characterizing the hydrogen-species: H, H 2 , and H 2 O which have been far more elusive as lyman-α auroral emission has multiple production pathways, even in the absence of endogenic sources.
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Analysis and modeling of remote observations of the martian hydrogen Exosphere
Icarus, 2017Co-Authors: D. Bhattacharyya, Jean-yves Chaufray, J.t. Clarke, Jean-loup Bertaux, M. MayyasiAbstract:Past observations of the martian Exosphere have given a wide range of values for the mean temperature and number density of the hydrogen population that occupies this uppermost layer. More recently, observations by HST and MEX have found large variations over short timescales exhibited by this layer, which have been attributed to seasonal effects. Here we present an analysis of the modeling techniques used to study the martian Exosphere and their related uncertainties, and discuss the sensitivity of various modeling parameters for any remote observations of the martian hydrogen Exosphere. Degeneracy between the two free parameters in the model, the exobase temperature and density of hydrogen at Mars introduces difficulty in accurately characterizing the properties of the martian Exosphere. An independent measurement of at least one parameter is required in order to positively identify the other. The likely presence of a superthermal component of H adds another uncertainty to the modeling process, with large changes in the resulting escape flux. A study of the latitudinal symmetry of the martian Exosphere found the radial emission profiles to be asymmetric below 2.5 martian radii, and then more uniform at high altitudes. Comparisons between simulated spacecraft and HST intensity profiles with altitude suggest that a larger coverage of intensity profiles is important to better determine the characteristics of the martian Exosphere.
Alain Doressoundiram - One of the best experts on this subject based on the ideXlab platform.
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Mercury Exosphere. III: Energetic characterization of its sodium component
Icarus, 2013Co-Authors: François Leblanc, Jean-yves Chaufray, Valeria Mangano, Alain Doressoundiram, Jean-jacques Berthelier, Arturo López-ariste, Patrizia BorinAbstract:Mercury's sodium Exosphere has been observed only few times with high spectral resolution from ground based observatories enabling the analysis of the emission spectra. These observations highlighted the energetic state of the sodium exospheric atoms relative to the surface temperature. More recently, the Doppler shift of the exospheric Na atoms was measured and interpreted as consistent with an Exosphere moving outwards from the subsolar point (Potter et al. 2009). Using THEMIS Solar telescope, we observed Mercury's sodium Exosphere with very high spectral resolution at two opposite positions of its orbit. Using this very high spectral resolution and the scanning capabilities of THEMIS, we were able to reconstruct the 2D spatial distributions of the Doppler shifts and widths of the sodium atomic Na D2 and D1 lines. These observations revealed surprisingly large Doppler shift as well as spectral width consistent with previous observations. Starting from our 3D model of Mercury Na Exosphere (Mercury Exosphere Global Circulation Model, Leblanc and Johnson 2010), we coupled this model with a 3D radiative transfer model described in a companion paper (Chaufray and Leblanc 2012) which allows us to properly treat the non-maxwellian state of the simulated sodium exospheric population. Comparisons between THEMIS observations and simulations suggest that the previously observed energetic state of the Na Exosphere might be essentially explained by a state of the Na exospheric atoms far from thermal equilibrium along with the Doppler shift dispersion of the Na atoms induced by the solar radiation pressure. However, the Doppler shift of the spectral lines cannot be explained by our modelling, suggesting either an Exosphere spatially structured very differently than in our model or the inaccuracy of the spectral calibration when deriving the Doppler shift.
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Mercury Exosphere: II The sodium/potassium ratio
Icarus, 2011Co-Authors: François Leblanc, Alain DoressoundiramAbstract:In Doressoundiram et al. (Icarus, 2010), we presented and discussed two sets of observations of the Na/K ratio in Mercury's Exosphere. These observations suggested that the different spatial distributions of Mercury's Na and K Exospheres could help explain the anomalously large values of Na/K ratio observed at Mercury. In Leblanc and Johnson (Icarus 2010), we simulated the annual cycle of Mercury's sodium Exosphere, emphasizing the importance of the day to night side migration of the sodium and the close relation between the content of the sodium Exosphere and the content of the surface reservoir of adsorbed sodium. In this paper, the potassium Exosphere is modelled using laboratory measurements to constrain the various ejection processes. The annual cycle of the exospheric potassium emission brightness is compared to the few available observations showing that our model provides a reasonable description of this exospheric component. A comparison with the best spatially resolved observation of Doressoundiram et al. (Icarus, 2010) highlights key features of the Na/K spatial distributions. It is essentially differences in global transport, the loss rate and the desorption efficiencies which account for the spatial distribution of the observed ratio. The Na/K ratio in the Exosphere cannot be simply associated with the primary abundances but is closely related to the relative loss rates. Accounting for the transport and loss, the observed Na/K exospheric ratio may be consistent with an initial abundance close to solar or meteoritic ones.
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Mercury Exosphere. II. The sodium/potassium ratio
Icarus, 2011Co-Authors: François Leblanc, Alain DoressoundiramAbstract:Abstract In Doressoundiram et al. (Doressoundiram, A., Leblanc, F., Foellmi, C., Cremonese, G., Donati, F., Veillet, C. [2010]. Icarus 207, 1–8), we presented and discussed two sets of observations of the Na/K ratio in Mercury’s Exosphere. These observations suggested that the different spatial distributions of Mercury’s Na and K Exospheres could help explain the anomalously large values of Na/K ratio observed at Mercury. In Leblanc and Johnson (Leblanc, F., Johnson, R.E. [2010]. Icarus 209, 280–300), we simulated the annual cycle of Mercury’s sodium Exosphere, emphasizing the importance of the day to night side migration of the sodium and the close relation between the content of the sodium Exosphere and the content of the surface reservoir of adsorbed sodium. In this paper, the potassium Exosphere is modeled using laboratory measurements to constrain the various ejection processes. The annual cycle of the exospheric potassium emission brightness is compared to the few available observations showing that our model provides a reasonable description of this exospheric component. A comparison with the best spatially resolved observation of Doressoundiram et al. (Doressoundiram, A., Leblanc, F., Foellmi, C., Cremonese, G., Donati, F., Veillet, C. [2010]. Icarus 207, 1–8) highlights key features of the Na/K spatial distributions. It is essentially differences in global transport, the loss rate and the desorption efficiencies which account for the spatial distribution of the observed ratio. The Na/K ratio in the Exosphere cannot be simply associated with the primary abundances but is closely related to the relative loss rates. Accounting for the transport and loss, the observed Na/K exospheric ratio may be consistent with an initial abundance close to solar or meteoritic ones.
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Metallic Species in Mercury's Exosphere: EMMI/New Technology Telescope Observations
The Astronomical Journal, 2009Co-Authors: Alain Doressoundiram, François Leblanc, C. Foellmi, Stéphane ErardAbstract:We performed high spectral resolution observations of Mercury's Exosphere on 2005 October 30 and 31 using the European Southern Observatory-New Technology Telescope, La Silla, Chile. The large spectral range, 385-855 nm, of the spectrograph, ESO Multi-Mode Instrument, provides a unique opportunity to search for nonidentified species in Hermian's environment. In this paper, we report a tentative detection of atomic aluminum in the Exosphere of Mercury. This detection should be confirmed by further observations and can be used as an upper limit for this element in Mercury's Exosphere. We also estimate the upper limit for the column densities of Fe and Si exospheric atoms. Detection of Al, a refractory element, if confirmed, as well as its high exospheric abundance (between 2 and 18) with respect to Ca would suggest either an unexpected surface composition or a relation between Exosphere and surface composition that is not well understood.
H Lammer - One of the best experts on this subject based on the ideXlab platform.
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3d modeling of mercury s solar wind sputtered surface Exosphere environment
Planetary and Space Science, 2015Co-Authors: M Pfleger, H Lammer, Herbert Lichtenegger, A Mura, Peter Wurz, Esa Kallio, Markku Alho, S Mckennalawlor, J A MartinfernandezAbstract:The efficiency of sputtered refractory elements by H+ and He++ solar wind ions from Mercury's surface and their contribution to the Exosphere are studied for various solar wind conditions. A 3D solar wind-planetary interaction hybrid model is used for the evaluation of precipitation maps of the sputter agents on Mercury's surface. By assuming a global mineralogical surface composition, the related sputter yields are calculated by means of the 2013 SRIM code and are coupled with a 3D Exosphere model. Because of Mercury's magnetic field, for quiet and nominal solar wind conditions the plasma can only precipitate around the polar areas, while for extreme solar events (fast solar wind, coronal mass ejections, interplanetary magnetic clouds) the solar wind plasma has access to the entire dayside. In that case the release of particles form the planet's surface can result in an Exosphere density increase of more than one order of magnitude. The corresponding escape rates are also about an order of magnitude higher. Moreover, the amount of He++ ions in the precipitating solar plasma flow enhances also the release of sputtered elements from the surface in the Exosphere. A comparison of our model results with MESSENGER observations of sputtered Mg and Ca elements in the Exosphere shows a reasonable quantitative agreement. (C) 2015 Elsevier Ltd. All rights reserved.
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self consistent modelling of mercury s Exosphere by sputtering micro meteorite impact and photon stimulated desorption
Planetary and Space Science, 2010Co-Authors: Peter Wurz, H Lammer, Urs Rohner, James A. Whitby, J A Martinfernandez, C. KolbAbstract:Abstract A Monte-Carlo model of Exospheres ( Wurz and Lammer, 2003 ) was extended by treating the ion-induced sputtering process, photon-stimulated desorption, and micro-meteorite impact vaporisation quantitatively in a self-consistent way starting with the actual release of particles from the mineral surface of Mercury. Based on available literature data we established a global model for the surface mineralogy of Mercury and from that derived the average elemental composition of the surface. This model serves as a tool to estimate densities of species in the Exosphere depending on the release mechanism and the associated physical parameters quantitatively describing the particle release from the surface. Our calculation shows that the total contribution to the exospheric density at the Hermean surface by solar wind sputtering is about 4×10 7 m –3 , which is much less than the experimental upper limit of the exospheric density of 10 12 m –3 . The total calculated exospheric density from micro-meteorite impact vaporisation is about 1.6×10 8 m –3 , also much less than the observed value. We conclude that solar wind sputtering and micro-meteorite impact vaporisation contribute only a small fraction of Mercury’s Exosphere, at least close to the surface. Because of the considerably larger scale height of atoms released via sputtering into the Exosphere, sputtered atoms start to dominate the Exosphere at altitudes exceeding around 1000 km, with the exception of some light and abundant species released thermally, e.g. H 2 and He. Because of Mercury’s strong gravitational field not all particles released by sputtering and micro-meteorite impact escape. Over extended time scales this will lead to an alteration of the surface composition.
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Titan's atomic hydrogen corona
Icarus, 2010Co-Authors: P. Hedelt, H Lammer, P. Wurz, Y. Ito, H.u. Keller, R. Reulke, H. Rauer, L. EspositoAbstract:Based on measurements performed by the Hydrogen Deuterium Absorption Cell (HDAC) aboard the Cassini orbiter, Titan's atomic hydrogen Exosphere is investigated. Data obtained during the T9 encounter are used to infer the distribution of atomic hydrogen throughout Titan's Exosphere, as well as the exospheric temperature.
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Titan's atomic hydrogen corona
Icarus, 2010Co-Authors: P. Hedelt, H Lammer, P. Wurz, Y. Ito, H.u. Keller, R. Reulke, H. Rauer, L. EspositoAbstract:Based on measurements performed by the Hydrogen Deuterium Absorption Cell (HDAC) aboard the Cas- sini orbiter, Titan's atomic hydrogen Exosphere is investigated. Data obtained during the T9 encounter are used to infer the distribution of atomic hydrogen throughout Titan's Exosphere, as well as the exospheric temperature. The measurements performed during the flyby are modeled by performing Monte Carlo radiative trans- fer calculations of solar Lyman-a radiation, which is resonantly scattered on atomic hydrogen in Titan's Exosphere. Two different atomic hydrogen distribution models are applied to determine the best fitting density profile. One model is a static model that uses the Chamberlain formalism to calculate the distri- bution of atomic hydrogen throughout the Exosphere, whereas the second model is a Particle model, which can also be applied to non-Maxwellian velocity distributions. The density distributions provided by both models are able to fit the measurements although both models differ at the exobase: best fitting exobase atomic hydrogen densities of nH = (1.5 ± 0.5)
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Energetic neutral atoms as the explanation for the high velocity hydrogen around HD 209458b
Nature, 2008Co-Authors: M. Holmström, T Penz, H Lammer, F. Selsis, A. Ekenbäck, P. WurzAbstract:Absorption in the stellar Lyman-$\alpha$ (Ly-$\alpha$) line observed during the transit of the extrasolar planet HD 209458b reveals high velocity atomic hydrogen at great distances from the planet. This has been interpreted as hydrogen atoms escaping from the Exosphere of the planet, possibly undergoing hydrodynamic blow-off, being accelerated by stellar radiation pressure. However, around solar system planets the production of energetic neutral atoms from charge exchange between solar wind protons and neutral hydrogen from the Exospheres has been observed, and should also occur at extrasolar planets. Here we show that the measured transit-associated Ly-$\alpha$ absorption can be explained by the interaction between the Exosphere of HD 209458b and the stellar wind, and that radiation pressure alone cannot explain the observation. This is the first observation of energetic neutral atoms outside the solar system. Since the stellar wind protons are the source of the observed energetic neutral atoms, this provides a completely new method of probing stellar wind conditions, and our model suggests a slow and hot stellar wind near HD 209458b at the time of the observation.
Malcolm Fridlund - One of the best experts on this subject based on the ideXlab platform.
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search for an Exosphere in sodium and calcium in the transmission spectrum of exoplanet 55 cancri e
Astronomy and Astrophysics, 2016Co-Authors: A R Riddenharper, I A G Snellen, C U Keller, R De Kok, E Di Gloria, H J Hoeijmakers, M Brogi, Malcolm FridlundAbstract:Context. The atmospheric and surface characterization of rocky planets is a key goal of exoplanet science. Unfortunately, the measurements required for this are generally out of reach of present-day instrumentation. However, the planet Mercury in our own solar system exhibits a large Exosphere composed of atomic species that have been ejected from the planetary surface by the process of sputtering. Since the hottest rocky exoplanets known so far are more than an order of magnitude closer to their parent star than Mercury is to the Sun, the sputtering process and the resulting Exospheres could be orders of magnitude larger and potentially detectable using transmission spectroscopy, indirectly probing their surface compositions. Aims. The aim of this work is to search for an absorption signal from exospheric sodium (Na) and singly ionized calcium (Ca+) in the optical transmission spectrum of the hot rocky super-Earth 55 Cancri e. Although the current best-fitting models to the planet mass and radius require a possible atmospheric component, uncertainties in the radius exist, making it possible that 55 Cancri e could be a hot rocky planet without an atmosphere. Methods. High resolution (R similar to 110 000) time-series spectra of five transits of 55 Cancri e, obtained with three different telescopes (UVES/VLT, HARPS/ESO 3.6 m and HARPS-N/TNG) were analysed. Targeting the sodium D lines and the calcium H and K lines, the potential planet exospheric signal was filtered out from the much stronger stellar and telluric signals, making use of the change of the radial component of the orbital velocity of the planet over the transit from -57 to +57 km s(-1). Results. Combining all five transit data sets, we detect a signal potentially associated with sodium in the planet Exosphere at a statistical significance level of 3 sigma. Combining the four HARPS transits that cover the calcium H and K lines, we also find a potential signal from ionized calcium (4.1 sigma). Interestingly, this latter signal originates from just one of the transit measurements with a 4.9 sigma detection at this epoch. Unfortunately, due to the low significance of the measured sodium signal and the potentially variable Ca+ signal, we estimate the p-values of these signals to be too high (corresponding to <4 sigma) to claim unambiguous exospheric detections. By comparing the observed signals with artificial signals injected early in the analysis, the absorption by Na and Ca+ are estimated to be at a level of similar to 2.3 x 10(-3) and similar to 7.0 x 10(-2) respectively, relative to the stellar spectrum. Conclusions. If confirmed, the 3 sigma signal would correspond to an optically thick sodium Exosphere with a radius of 5 R-circle plus, which is comparable to the Roche lobe radius of the planet. The 4.9 sigma detection of Ca+ in a single HARPS data set would correspond to an optically thick Ca+ Exosphere approximately five times larger than the Roche lobe radius. If this were a real detection, it would imply that the Exosphere exhibits extreme variability. Although no formal detection has been made, we advocate that probing the Exospheres of hot super-Earths in this way has great potential, also knowing that Mercury's Exosphere varies significantly over time. It may be a fast route towards the first characterization of the surface properties of this enigmatic class of planets.