Identification

Title

Mercuryâ€™s exospheric He I 58.4 nm emission: Dependence on the orbital phase

Abstract

Aims. Emission from helium atoms in Mercury's exosphere at 58.4 nm was observed by the Mariner 10 spacecraft in the 1970s. This emission is due to resonant scattering of solar radiation. Since Mercury's orbit is ellipsoidal, solar radiation and wind fluxes on Mercury vary along its orbit. Furthermore, the flux of the solar He I 58.4 nm emission observed on Mercury varies with Mercury's radial velocity with the Sun. Using model simulations, we demonstrate how Mercury's exospheric He I 58.4 nm emission varies due to the periodic changes in solar radiation and wind. Methods. The simulation is based on our Monte-Carlo model that accounts for changes in fluxes of the solar wind and radiation. Results. The model results indicate that the He I 58.4 nm brightness varies by between one and three orders of magnitude along the planet's orbit. These findings are strongly dependent on the intrinsic line width of the solar He I 58.4 nm emission. Conclusions. Although this variation has never been observed because Mariner 10 only sampled emission near Mercury's aphelion, we expect this variation to be observable by new missions, such as BepiColombo and Hisaki. Our results are also important for the characterization of exoplanets with ultraviolet space missions.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7wh2tgb

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

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Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2021-10-14T00:00:00Z

Frequency of update

Quality and validity

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Conformity

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name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact