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Discovery of a 30-degree-long ultraviolet arc in Ursa Major

Bracco, Andrea; Benjamin, R. A.; Alves, M. I. R.; Lehmann, A.; Boulanger, F.; Montier, L.; Mittelman, D.; di Cicco, D.; Walker, S. (2020) Discovery of a 30-degree-long ultraviolet arc in Ursa Major. Astronomy & Astrophysics, 636 . ISSN 0004-6361

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Our view of the interstellar medium of the Milky Way and the universe beyond is affected by the structure of the local environment in the solar neighborhood. We present the discovery of a 30-degree-long arc of ultraviolet emission with a thickness of only a few arcminutes: the Ursa Major arc. This consists of several arclets seen in the near- and far-ultraviolet bands of the GALEX satellite. A two degree section of the arc was first detected in the Hα optical spectral line in 1997 ; additional sections were seen in the optical by the team of amateur astronomers included in this work. This direction of the sky is known for very low hydrogen column density and dust extinction ; many deep fields for extragalactic and cosmological investigations lie in this direction. Diffuse ultraviolet and optical interstellar emission are often attributed to scattering of light by interstellar dust. The lack of correlation between the Ursa Major arc and thermal dust emission observed with the Planck satellite, however, suggests that other emission mechanisms must be at play. We discuss the origin of the Ursa Major arc as the result of an interstellar shock in the solar neighborhood.

Item Type: Article
Uncontrolled Keywords: ultraviolet: ISM ; ISM: structure ; shock waves ; ISM: supernova remnants ; solar neighborhood ; local insterstellar matte
Subjects: NATURAL SCIENCES > Physics
NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Divisions: Division of Experimental Physics
Project titleProject leaderProject codeProject type
Origin of Magnetic strUctureS in the ISM obscuring the Cosmic DAwnJelić, Vibor; Braco, Andrea843008EK
Depositing User: Vibor Jelić
Date Deposited: 17 Nov 2021 08:48
DOI: 10.1051/0004-6361/202037975

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