SPEAR Far Ultraviolet Spectral Images of the Cygnus Loop

Abstract

We present far-ultraviolet (FUV) spectral images, measured at C IV 1550, He II 1640, Si IV+O IV] 1400, and O III] 1664, of the entire Cygnus Loop, observed with the Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR) instrument, also known as FIMS. The spatial distribution of FUV emission generally corresponds with a limb-brightened shell, and is similar to optical, radio and X-ray images. The features found in the present work include a ``carrot'', diffuse interior, and breakout features, which have not been seen in previous FUV studies. Shock velocities of 140-160 km/s is found from a line ratio of O IV] to O III], which is insensitive not only to resonance scattering but also to elemental abundance. The estimated velocity indicates that the fast shocks are widespread across the remnant. By comparing various line ratios with steady-state shock models, it is also shown that the resonance scattering is widespread.

arXiv comment13 pages, 3 figures, 1 table, accepted for publication in ApJL

References in corpus (11)

• ASMOOTH: A simple and efficient algorithm for adaptive kernel smoothing of two-dimensional imaging data
• Panoramic Views of the Cygnus Loop
• The ROSAT-HRI X-Ray Survey of the Cygnus Loop
• The Distance to the Cygnus Loop from Hubble Space Telescope Imaging of the Primary Shock Front
• The SPEAR Instrument and On-Orbit Performance
• The Spectroscopy of Plasma Evolution from Astrophysical Radiation Mission
• A Detailed Analysis of a Cygnus Loop Shock-Cloud Interaction
• Optical and Far-UV Spectroscopy of Knot D in the Vela Supernova Remnant
• HST-STIS Observations of the Cygnus Loop: Spatial Structure of a Non-radiative Shock
• A Comparison of Ultraviolet, Optical, and X-Ray Imagery of Selected Fields in the Cygnus Loop
• FUSE Observations of the Cygnus Loop: OVI Emission from a Nonradiative Shock

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• Far-UV Observations of a Thermal Interface in the Orion-Eridanus Superbubble
• Far-Ultraviolet Observations of the Spica Nebula and the Interaction Zone
• Global Far-Ultraviolet Properties of the Cygnus Loop
• Far-Ultraviolet Cooling Features of the Antlia Supernova Remnant
• C IV Emission-line Detection of the Supernova Remnant RCW 114
• Far-Ultraviolet Spectral Images of the Vela Supernova Remnant: Supplements and Comparisons with other Wavelength Images
• Global distribution of far-ultraviolet emissions from highly ionized gas in the Milky Way
• Unbiased Spectroscopic Study of the Cygnus Loop with LAMOST. I. Optical Properties of Emission Lines and the Global Spectrum
• Far-ultraviolet Emission-line Morphologies of the Supernova Remnant G65.3+5.7
• Space Missions for Astronomy and Astrophysics in Korea: Past, Present, and Future