Imperial College London

DrMarinaGaland

Faculty of Natural SciencesDepartment of Physics

Reader in Planetary Science
 
 
 
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Contact

 

m.galand Website

 
 
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Location

 

Huxley BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Hajra:2017:0004-6361/2017305s91,
author = {Hajra, R and Henri, P and Vallières, X and Galand, M and Héritier, K and Eriksson, AI and Odelstad, E and Edberg, NJT and Burch, JL and Broiles, T and Goldstein, R and Glassmeier, KH and Richter, I and Goetz, C and Tsurutani, BT and Nilsson, H and Altwegg, K and Rubin, M},
doi = {0004-6361/2017305s91},
journal = {Astronomy and Astrophysics},
title = {Impact of a cometary outburst on its ionosphere: Rosetta Plasma Consortium observations of the outburst exhibited by comet 67P/Churyumov-Gerasimenko on 19 February 2016},
url = {http://dx.doi.org/10.1051/0004-6361/2017305s91},
volume = {607},
year = {2017}
}

RIS format (EndNote, RefMan)

TY  - JOUR
AB - © ESO, 2017. We present a detailed study of the cometary ionospheric response to a cometary brightness outburst using in situ measurements for the first time. The comet 67P/Churyumov-Gerasimenko (67P) at a heliocentric distance of 2.4 AU from the Sun, exhibited an outburst at ∼1000 UT on 19 February 2016, characterized by an increase in the coma surface brightness of two orders of magnitude. The Rosetta spacecraft monitored the plasma environment of 67P from a distance of 30 km, orbiting with a relative speed of ∼0.2 m s-1. The onset of the outburst was preceded by pre-outburst decreases in neutral gas density at Rosetta, in local plasma density, and in negative spacecraft potential at ∼0950 UT. In response to the outburst, the neutral density increased by a factor of ∼1.8 and the local plasma density increased by a factor of ∼3, driving the spacecraft potential more negative. The energetic electrons (tens of eV) exhibited decreases in the flux of factors of ∼2 to 9, depending on the energy of the electrons. The local magnetic field exhibited a slight increase in amplitude (~5 nT) and an abrupt rotation (∼36.4°) in response to the outburst. A weakening of 10-100 mHz magnetic field fluctuations was also noted during the outburst, suggesting alteration of the origin of the wave activity by the outburst. The plasma and magnetic field effects lasted for about 4 h, from ∼1000 UT to 1400 UT. The plasma densities are compared with an ionospheric model. This shows that while photoionization is the main source of electrons, electron-impact ionization and a reduction in the ion outflow velocity need to be accounted for in order to explain the plasma density enhancement near the outburst peak.
AU - Hajra,R
AU - Henri,P
AU - Vallières,X
AU - Galand,M
AU - Héritier,K
AU - Eriksson,AI
AU - Odelstad,E
AU - Edberg,NJT
AU - Burch,JL
AU - Broiles,T
AU - Goldstein,R
AU - Glassmeier,KH
AU - Richter,I
AU - Goetz,C
AU - Tsurutani,BT
AU - Nilsson,H
AU - Altwegg,K
AU - Rubin,M
DO - 0004-6361/2017305s91
PY - 2017///
SN - 0004-6361
TI - Impact of a cometary outburst on its ionosphere: Rosetta Plasma Consortium observations of the outburst exhibited by comet 67P/Churyumov-Gerasimenko on 19 February 2016
T2 - Astronomy and Astrophysics
UR - http://dx.doi.org/10.1051/0004-6361/2017305s91
VL - 607
ER -