Imperial College London

DrMarinaGaland

Faculty of Natural SciencesDepartment of Physics

Reader in Planetary Science
 
 
 
//

Contact

 

m.galand Website

 
 
//

Location

 

Huxley BuildingSouth Kensington Campus

//

Summary

 

Publications

Publication Type
Year
to

117 results found

Carnielli G, Goland M, Leblanc F, Leclercq L, Modolo R, Beth A, Huybrighs HLF, Jia Xet al., 2019, First 3D test particle model of Ganymede's ionosphere, ICARUS, Vol: 330, Pages: 42-59, ISSN: 0019-1035

Journal article

Wedlund CS, Behar E, Nilsson H, Alho M, Kallio E, Gunell H, Bodewits D, Heritier K, Galand M, Beth A, Rubin M, Altwegg K, Volwerk M, Gronoff G, Hoekstra Ret al., 2019, Solar wind charge exchange in cometary atmospheres III. Results from the Rosetta mission to comet 67P/Churyumov-Gerasimenko, Astronomy and Astrophysics, ISSN: 0004-6361

Solar wind charge-changing reactions are of paramount importance to thephysico-chemistry of the atmosphere of a comet. The ESA/Rosetta mission tocomet 67P/Churyumov-Gerasimenko (67P) provides a unique opportunity to studycharge-changing processes in situ. To understand the role of these reactions inthe evolution of the solar wind plasma, and interpret the complex in-situmeasurements made by Rosetta, numerical or analytical models are necessary. Weuse an extended analytical formalism describing solar wind charge-changingprocesses at comets along solar wind streamlines. The model is driven by solarwind ion measurements from the Rosetta Plasma Consortium-Ion CompositionAnalyzer (RPC-ICA) and neutral density observations from the RosettaSpectrometer for Ion and Neutral Analysis-Comet Pressure Sensor (ROSINA-COPS),as well as charge-changing cross sections of hydrogen and helium particles in awater gas. A mission-wide overview of charge-changing efficiencies at comet 67Pis presented. Electron capture cross sections dominate and favor the productionof He and H energetic neutral atoms, with fluxes expected to rival those of H+and He2+ ions. Neutral outgassing rates are retrieved from local RPC-ICA fluxmeasurements, and match ROSINA's estimates very well. From the model, we findthat solar wind charge exchange is unable to fully explain the magnitude of thesharp drop of solar wind ion fluxes observed by Rosetta for heliocentricdistances below 2.5 AU. This is likely because the model does not take intoaccount the relative ion dynamics and, to a lesser extent, ignore the formationof bow shock-like structures upstream of the nucleus. This work also shows thatthe ionization by solar EUV radiation and energetic electrons dominates thesource of cometary ions, although solar wind contributions may be significantduring isolated events.

Journal article

Beth A, Galand M, Heritier K, Comparative study of photo-produced ionosphere in the close environment of comets, Astronomy & Astrophysics, ISSN: 0004-6361

Journal article

Tinetti G, Drossart P, Eccleston P, Hartogh P, Heske A, Leconte J, Micela G, Ollivier M, Pilbratt G, Puig L, Turrini D, Vandenbussche B, Wolkenberg P, Beaulieu J-P, Buchave LA, Ferus M, Griffin M, Guedel M, Justtanont K, Lagage P-O, Machado P, Malaguti G, Min M, Norgaard-Nielsen HU, Rataj M, Ray T, Ribas I, Swain M, Szabo R, Werner S, Barstow J, Burleigh M, Cho J, du Foresto VC, Coustenis A, Decin L, Encrenaz T, Galand M, Gillon M, Helled R, Carlos Morales J, Munoz AG, Moneti A, Pagano I, Pascale E, Piccioni G, Pinfield D, Sarkar S, Selsis F, Tennyson J, Triaud A, Venot O, Waldmann I, Waltham D, Wright G, Amiaux J, Augueres J-L, Berthe M, Bezawada N, Bishop G, Bowles N, Coffey D, Colome J, Crook M, Crouzet P-E, Da Peppo V, Sanz IE, Focardi M, Frericks M, Hunt T, Kohley R, Middleton K, Morgante G, Ottensamer R, Pace E, Pearson C, Stamper R, Symonds K, Rengel M, Renotte E, Ade P, Affer L, Alard C, Allard N, Altieri F, Andre Y, Arena C, Argyriou I, Aylward A, Baccani C, Bakos G, Banaszkiewicz M, Barlow M, Batista V, Bellucci G, Benatti S, Bernardi P, Bezard B, Blecka M, Bolmont E, Bonfond B, Bonito R, Bonomo AS, Brucato JR, Brun AS, Bryson I, Bujwan W, Casewell S, Charnay B, Pestellini CC, Chen G, Ciaravella A, Claudi R, Cledassou R, Damasso M, Damiano M, Danielski C, Deroo P, Di Giorgio AM, Dominik C, Doublier V, Doyle S, Doyon R, Drummond B, Duong B, Eales S, Edwards B, Farina M, Flaccomio E, Fletcher L, Forget F, Fossey S, Fraenz M, Fujii Y, Garcia-Piquer A, Gear W, Geoffray H, Gerard JC, Gesa L, Gomez H, Graczyk R, Griffith C, Grodent D, Guarcello MG, Gustin J, Hamano K, Hargrave P, Hello Y, Heng K, Herrero E, Hornstrup A, Hubert B, Ida S, Ikoma M, Iro N, Irwin P, Jarchow C, Jaubert J, Jones H, Julien Q, Kameda S, Kerschbaum F, Kervella P, Koskinen T, Krijger M, Krupp N, Lafarga M, Landini F, Lellouch E, Leto G, Luntzer A, Rank-Luftinger T, Maggio A, Maldonado J, Maillard J-P, Mall U, Marquette J-B, Mathis S, Maxted P, Matsuo T, Medvedev A, Miguel Y, Minier V, Moreet al., 2018, A chemical survey of exoplanets with ARIEL, Experimental Astronomy, Vol: 46, Pages: 135-209, ISSN: 0922-6435

Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using know

Journal article

Hajra R, Henri P, Myllys M, Heritier KL, Galand M, Wedlund CS, Breuillard H, Behar E, Edberg NJT, Goetz C, Nilsson H, Eriksson AI, Goldstein R, Tsurutani BT, More J, Vallieres X, Wattieauxu Get al., 2018, Cometary plasma response to interplanetary corotating interaction regions during 2016 June-September: a quantitative study by the Rosetta Plasma Consortium, Monthly Notices of the Royal Astronomical Society, Vol: 480, Pages: 4544-4556, ISSN: 0035-8711

Four interplanetary corotating interaction regions (CIRs) were identified during 2016 June–September by the Rosetta Plasma Consortium (RPC) monitoring in situ the plasma environment of the comet 67P/Churyumov–Gerasimenko (67P) at heliocentric distances of ∼3–3.8 au. The CIRs, formed in the interface region between low- and high-speed solar wind streams with speeds of ∼320–400 km s−1 and ∼580–640 km s−1, respectively, are characterized by relative increases in solar wind proton density by factors of ∼13–29, in proton temperature by ∼7–29, and in magnetic field by ∼1–4 with respect to the pre-CIR values. The CIR boundaries are well defined with interplanetary discontinuities. Out of 10 discontinuities, four are determined to be forward waves and five are reverse waves, propagating at ∼5–92 per cent of the magnetosonic speed at angles of ∼20°–87° relative to ambient magnetic field. Only one is identified to be a quasi-parallel forward shock with magnetosonic Mach number of ∼1.48 and shock normal angle of ∼41°. The cometary ionosphere response was monitored by Rosetta from cometocentric distances of ∼4–30 km. A quiet time plasma density map was developed by considering dependences on cometary latitude, longitude, and cometocentric distance of Rosetta observations before and after each of the CIR intervals. The CIRs lead to plasma density enhancements of ∼500–1000 per cent with respect to the quiet time reference level. Ionospheric modelling shows that increased ionization rate due to enhanced ionizing (>12–200 eV) electron impact is the prime cause of the large cometary plasma density enhancements during the CIRs. Plausible origin mechanisms of the cometary ionizing electron enhancements are discussed.

Journal article

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://wlsprd.imperial.ac.uk:80/respub/WEB-INF/jsp/search-html.jsp Request URI: /respub/WEB-INF/jsp/search-html.jsp Query String: limit=5&amp%3bid=00422628&amp%3brespub-action=search.html&amp%3bperson=true&amp%3bpage=8&respub-action=search.html&id=00422628&person=true