Far-ultraviolet spectrophotometry of supernova remnants - Observations and astrophysical interpretation

Benvenuti, P.; Dopita, Michael A.; D’Odorico, S.

doi:10.1086/158017

Cited by 22 publications

(19 citation statements)

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“…If the radiative cooling is approximated by a power law in temperature then there is a critical value of the exponent below which the overstability appears. The validity of the use of steady shock models to interpret emission lines from SNRs has been questioned for some time (Benvenuti et al 1980;Raymond 1984), and some observed line intensities are not reproduced with steady shock models.…”

Section: Introductionmentioning

confidence: 99%

Two-fluid models of cosmic ray modified radiative shocks

Wagner

Falle

Hartquist

et al. 2006

A&A

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Aims. We demonstrate that cosmic rays suppress the thermal overstability of radiative shocks for a wide range of upstream parameters and initial conditions. Methods. We perform one-dimensional time-dependent two-fluid simulations, introducing cosmic rays into overstable radiative shocks.Results. When a cosmic ray fluid is introduced, the oscillations of the shock front are damped and a smooth cosmic ray modified shock develops and propagates away from the cold dense layer. A large increase in cosmic ray pressure occurs for lower Mach numbers in radiative cosmic ray modified shocks than in adiabatic cosmic ray modified shocks. The compression ratio is limited to 7 and steady solutions do not exhibit a cold dense layer like those in radiative shocks that are not modified by cosmic rays. If the diffusion length is much larger than the cooling length, the shock is nearly isothermal. The structure of such shocks obtained with the two-fluid code agree well with analytically derived solutions for strictly isothermal flow containing cosmic rays.

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Section: Introductionmentioning

confidence: 99%

Two-fluid models of cosmic ray modified radiative shocks

Wagner

Falle

Hartquist

et al. 2006

A&A

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“…Early studies concentrated on bright optical filaments and characterized the phenomenology of the far-UV spectral region, comparing with steady-flow shock models (Raymond 1979;Shull & McKee 1979) to infer shock conditions (Raymond et al 1980(Raymond et al , 1981Benvenuti, Dopita, & D'Odorico 1980). Subsequent investigations pushed to fainter filaments (Raymond et al 1983;Long et al 1992) and to multiwavelength investigations of small regions (Raymond et al 1988;Hester, Raymond, & Blair 1994;Sankrit et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Far Ultraviolet Spectroscopic Explorer and Hopkins Ultraviolet Telescope Observations of Radiative Shocks in the Cygnus Loop

Blair

Sankrit

Tulin

2002

ASTROPHYS J SUPPL S

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We report a combination of high and low spectral resolution far-ultraviolet spectral data for several groupings of bright radiative shock filaments in the Cygnus Loop supernova remnant. The high-resolution spectra were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite and cover the 905-1187 Å spectral region at 0.1-0.3 Å resolution, depending on observing aperture. The low-resolution data were obtained with the Hopkins Ultraviolet Telescope (HUT) and cover the 850-1850 Å spectral region at $3 Å resolution. These data sets complement each other, with the HUT data providing the broader context of a wider range of emission lines and the FUSE data resolving line profiles from nearby airglow emissions and allowing detailed line profiles to be studied. Relative line intensities and line profiles change on a wide variety of spatial scales. O vi 1032, 1038 emission is much more generally distributed than the optical filaments. The FUSE data provide direct insight into the effects and variability of self-absorption in the strong resonance lines of O vi and C iii 977. Variability of the central reversals in O vi with position indicate a patchy O vi distribution, with self-absorption occurring locally within the remnant. Self-absorption in C iii could be due to the interstellar medium, the local regions of the remnant, or a combination. We also find evidence for overlying molecular hydrogen absorption effects on some lines and suggest an interstellar (foreground) origin. It is likely that these effects have had significant impacts on many previous investigations that based their results on the interpretation of low-resolution spectral data where these effects could not be seen.

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“…Evidence for such fluorescence is well established in solar ultraviolet spectra, particularly of sunspot umbrae (Jordan et al 1977(Jordan et al , 1978Bartoe et al 1978). Furthermore, molecular fluorescence is an important process in comet tails (Feldman et al 1974), planetary atmospheres (e.g., Dur-ranee 1980 and references therein), diffuse interstellar clouds (Duley and Williams 1980), supernova remnants (Benvenuti, Dopita, and D'Odorico 1980), and premain-sequence stars (Brown et al 1981).…”

Section: Introductionmentioning

confidence: 99%

Far-ultraviolet fluorescence of carbon monoxide in the red giant Arcturus

Ayres¹,

Moos²,

Linsky³

1981

ApJ

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We present evidence that many of the weak features observed with the International Ultraviolet Explorer {IUE) in the far-ultraviolet (1150-2000 Á) spectrum of the archetype red giant Arcturus (K2 III) are AX fourth positive bands of carbon monoxide excited by chromospheric emissions of O i, C I, and H i. The appearance of fluorescent CO bands near the wavelengths of commonly used indicators of high-temperature (T>2X 10 4 K) plasma, such as C n X1335 and C iv X1548, introduces a serious ambiguity in diagnosing the presence of hot material in the outer atmospheres of the cool giants by means of low-dispersion IUE spectra.

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Far-ultraviolet spectrophotometry of supernova remnants - Observations and astrophysical interpretation

Cited by 22 publications

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Two-fluid models of cosmic ray modified radiative shocks

Two-fluid models of cosmic ray modified radiative shocks

Far Ultraviolet Spectroscopic Explorer and Hopkins Ultraviolet Telescope Observations of Radiative Shocks in the Cygnus Loop

Far-ultraviolet fluorescence of carbon monoxide in the red giant Arcturus

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