Revisiting the magnetization of comet 67P/Churyumov-Gerasimenko

Heinisch, Philip; Auster, H. U.; Richter, Ingo; Glaßmeier, Karl‐Heinz

doi:10.1051/0004-6361/201834278

Cited by 5 publications

(7 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The magnetic field measurements measured by the Rosetta lander Philae at the Jupiter family comet 67P Churyumov-Gerasimenko offer a unique constraint on nebular magnetism. Other than being the only near-field measurements at a comet, the 67P measurements are also distinguished by the fact that they were taken as part of a near-surface >1-km-long transect with four separate landings during which the magnetometer sensor reached within 5 cm of the surface ( 168 ). Philae constrained the magnetization of the comet to <5 × 10 −6 emu g −1 for spatial scales of >10 cm ( 171 ).…”

Section: Paleomagnetismmentioning

confidence: 99%

See 1 more Smart Citation

History of the solar nebula from meteorite paleomagnetism

Weiss

Bai

2021

Sci. Adv.

View full text Add to dashboard Cite

We review recent advances in our understanding of magnetism in the solar nebula and protoplanetary disks (PPDs). We discuss the implications of theory, meteorite measurements, and astronomical observations for planetary formation and nebular evolution. Paleomagnetic measurements indicate the presence of fields of 0.54 ± 0.21 G at ~1 to 3 astronomical units (AU) from the Sun and ≳0.06 G at 3 to 7 AU until >1.22 and >2.51 million years (Ma) after solar system formation, respectively. These intensities are consistent with those predicted to enable typical astronomically observed protostellar accretion rates of ~10−8M⊙year−1, suggesting that magnetism played a central role in mass transport in PPDs. Paleomagnetic studies also indicate fields <0.006 G and <0.003 G in the inner and outer solar system by 3.94 and 4.89 Ma, respectively, consistent with the nebular gas having dispersed by this time. This is similar to the observed lifetimes of extrasolar protoplanetary disks.

show abstract

Section: Paleomagnetismmentioning

confidence: 99%

“…Spacecraft have measured the magnetic field at the surface of two asteroids, during flybys of five other asteroids, and at the surface of a comet (166)(167)(168). Although two of the asteroid flybys have tentatively identified remanent magnetic fields, these detections are ambiguous.…”

Section: Spacecraft Measurementsmentioning

confidence: 99%

History of the solar nebula from meteorite paleomagnetism

Weiss

Bai

2021

Sci. Adv.

View full text Add to dashboard Cite

show abstract

“…Preceding MASCOT, there was only one direct magnetic measurement from the surface of Eros (S‐type) by a magnetometer on the NEAR spacecraft during its final crash landing (Acuña et al, ). Other magnetic observations were conducted by the Philae lander on a comet 67P/Churyumov‐Gerasimenko (Heinisch et al, ). Both measurements found no detectable signal related to the surface fields and provided therefore only an upper limit on the material specific magnetic moment.…”

Section: Introductionmentioning

confidence: 99%

“…Specific magnetic moment given either directly in the relevant paper or derived from therein provided magnetic moment. The references for the respective properties are for Gaspra (Kivelson et al, ), Braille (Richter et al, ), Šteins (Auster et al, ), Lutetia (Coradini et al, ; Richter et al, ), Eros (Acuña et al, ; McCoy et al, ), and 67P (Heinisch et al, ). The magnetization values for simplicity show orders of magnitude only.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties of Asteroid (162173) Ryugu

et al. 2020

View full text Add to dashboard Cite

Observations of the magnetization state of asteroids indicate diverse properties. Values between 1.9 × 10 −6 Am 2 /kg (Eros) and 10 −2 Am 2 /kg (Braille) have been reported. A more detailed understanding of asteroidal magnetic properties allows far-reaching conclusions of the magnetization mechanism as well as the strength of the magnetic field of the solar system regions the asteroid formed in. The Hayabusa2 mission with its lander Mobile Asteroid Surface Scout is equipped with a magnetometer experiment, MasMag. MasMag is a state-of-the-art three-axis fluxgate magnetometer, successfully operated also on Philae, the Rosetta mission lander. MasMag has enabled, after Eros for the second time ever, to determine the magnetic field of an asteroid during descent and on-surface operations. The new observations show that Ryugu, a low-albedo C-type asteroid, has no detectable global magnetization, and any local magnetization is either small (< 10 −6 Am 2 /kg) or on very small (subcentimeter) scales. This implies, for example, that energetic solar wind particles could reach and alter the surface unimpeded by strong asteroidal magnetic fields, such as minimagnetospheres in case of the Moon.Plain Language Summary Magnetic measurements in space near and on solar system bodies such as asteroids can provide important information about their formation history and their material properties. Hayabusa2, a Japanese mission, visited asteroid Ryugu, a type of asteroid (carbon rich) not visited before. Ryugu is a rubble pile, that is, an agglomeration of rocks and boulders. It is not expected to have any global magnetic field, but it can be magnetized on smaller scales (boulders or pebbles). Hayabusa2 carried therefore a small lander called Mobile Asteroid Surface Scout equipped also with an instrument for magnetic field measurement (magnetometer). In this study, we present observations from the magnetometer that were collected during Mobile Asteroid Surface Scout's descent and landing on the surface of Ryugu. The magnetic measurements show that Ryugu is not magnetized on boulder (greater than centimeter) scales. This gives us indication on its origin and evolution. In particular, it shows that Ryugu and the bodies it was created from did not possess any magnetic field generation mechanism and that they were not created in an environment with strong background magnetic field. The results are important inputs for theories about the solar system evolution that work with magnetic field as one of the drivers for dust accretion and planetary formation.

show abstract

“…At Earth, other magnetised planets, and the Jovian moon Ganymede, the magnetospheric structure restricts entry of these extra-atmospheric particles into the atmosphere, confining auroras to regions with open field lines. However, comets are unmagnetised (Heinisch et al 2019), so they exhibit more similarities to regions of Mars with no crustal magnetisation, where diffuse auroras have been seen (Schneider et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Multi-instrument analysis of far-ultraviolet aurora in the southern hemisphere of comet 67P/Churyumov-Gerasimenko

Stephenson

Galand

Feldman

et al. 2021

A&A

View full text Add to dashboard Cite

Aims. We aim to determine whether dissociative excitation of cometary neutrals by electron impact is the major source of far-ultraviolet (FUV) emissions at comet 67P/Churyumov-Gerasimenko in the southern hemisphere at large heliocentric distances, both during quiet conditions and impacts of corotating interaction regions observed in the summer of 2016. Methods. We combined multiple datasets from the Rosetta mission through a multi-instrument analysis to complete the first forward modelling of FUV emissions in the southern hemisphere of comet 67P and compared modelled brightnesses to observations with the Alice FUV imaging spectrograph. We modelled the brightness of OI1356, OI1304, Lyman-β, CI1657, and CII1335 emissions, which are associated with the dissociation products of the four major neutral species in the coma: CO2, H2O, CO, and O2. The suprathermal electron population was probed by the Ion and Electron Sensor of the Rosetta Plasma Consortium and the neutral column density was constrained by several instruments: the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA), the Microwave Instrument for the Rosetta Orbiter and the Visual InfraRed Thermal Imaging Spectrometer. Results. The modelled and observed brightnesses of the FUV emission lines agree closely when viewing nadir and dissociative excitation by electron impact is shown to be the dominant source of emissions away from perihelion. The CII1335 emissions are shown to be consistent with the volume mixing ratio of CO derived from ROSINA. When viewing the limb during the impacts of corotating interaction regions, the model reproduces brightnesses of OI1356 and CI1657 well, but resonance scattering in the extended coma may contribute significantly to the observed Lyman-β and OI1304 emissions. The correlation between variations in the suprathermal electron flux and the observed FUV line brightnesses when viewing the comet’s limb suggests electrons are accelerated on large scales and that they originate in the solar wind. This means that the FUV emissions are auroral in nature.

show abstract

Revisiting the magnetization of comet 67P/Churyumov-Gerasimenko

Cited by 5 publications

References 34 publications

History of the solar nebula from meteorite paleomagnetism

History of the solar nebula from meteorite paleomagnetism

Magnetic Properties of Asteroid (162173) Ryugu

Multi-instrument analysis of far-ultraviolet aurora in the southern hemisphere of comet 67P/Churyumov-Gerasimenko

Contact Info

Product

Resources

About