The EUV emission from sun-grazing comets

Abstract

The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) has observed two sun-grazing comets as they passed through the solar atmosphere. Both passages resulted in a measurable enhancement of Extreme Ultraviolet (EUV) radiance in several of the AIA bandpasses. We explain this EUV emission by considering the evolution of the cometary atmosphere as it interacts with the ambient solar atmosphere. Molecules in the comet rapidly sublimate as it approaches the Sun. They are then photodissociated by the solar radiation field to create atomic species. Subsequent ionization of these atoms produces a higher abundance of ions than normally present in the corona and results in EUV emission in the wavelength ranges of the AIA telescope passbands.

Accepted to ApJ

References in corpus (1)

• Comet C/2011 W3 (Lovejoy): Orbit Determination, Outbursts, Disintegration of Nucleus, Dust-Tail Morphology, and Relationship to New Cluster of Bright Sungrazers

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• Non-equilibrium ionization effects on solar EUV and X-ray imaging observations
• Destruction and Observational Signatures of Sun-Impacting Comets
• Turning up the heat on `Oumuamua
• Probing Coronal Magnetic Fields with Sungrazing Comets: \hi\ Ly$\alpha$ from Pickup Ions
• Probing the Density Fine Structuring of the Solar Corona with Comet Lovejoy
• Predictions for Dusty Mass Loss from Asteroids during Close Encounters with Solar Probe Plus