Panoramic Views of the Cygnus Loop

Levenson, N. A.; Graham, James R.; Keller, L. D.; Richter, Matthew J.

doi:10.1086/313136

Cited by 88 publications

(115 citation statements)

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“…It is relatively recently, for instance, that we have come to recognize the Cygnus Loop as the remnant of a core collapse supernova, and that the explosion probably occurred in a cavity evacuated by the progenitor star (Charles, Kahn, & McKee 1985;Hester, Raymond, & Blair 1994;Levenson et al 1997Levenson et al , 1998Bohigas, Sauvageot, & Decourchelle 1999). It is the relatively recent encounter between the SNR blast wave and the cavity wall in its various manifestations (atomic and molecular material distributed in clouds of varying size and density) that is responsible for the dazzling array of structures and phenomena available for study.…”

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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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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“…If we consider that the wall of the cavity at present times must coincide with the edge of the radiative region, at a radius of ∼84 = 13.19 (d/540) pc (Levenson et al 1998), and that after hitting the wall the shock could be ∼30 up to ∼2 further away, we can estimate the position of the wall at the time it was hit by the shock to be < ∼ 13 pc.…”

Section: The 1-d Hd Modelmentioning

confidence: 99%

“…It is believed (see for instance Levenson et al 1998) that the radial position of the optical emission is most successfully explained by a projection effect: it is probably in the far side of the remnant, while the NRFs are in the near side. Falle & Garlick (1982) built a 2-D HD model based on this geometry.…”

Section: Where Will Radiative Cooling Take Place?mentioning

confidence: 99%

“…The Cygnus Loop is a middle-aged supernova remnant (SNR), which is well-studied at radio, optical, UV, and X-ray wavelengths, that is roughly circular with a radius of 1.4 deg (Levenson et al 1998). On the basis of the proper motion measurements of Balmer-dominated filaments in the NE, it is relatively nearby (540 pc according to Blair et al 2005, with an upper limit of ∼580 pc given by Blair et al 2009).…”

Section: Introductionmentioning

confidence: 99%

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The Cygnus Loop: a weak core-collapse SN in our Galaxy

Martinez

2011

A&A

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Context. The Cygnus Loop is thought to be the result of a core-collapse supernova (SN) explosion in the cavity formed by the wind of the progenitor star. Since then the shock has run through the low-density cavity, hit the cavity wall, and it is now running into a denser environment. Aims. We test the consistency of the global parameters of the remnant (as derived at the cavity-cloud interface) with the observational scenario in the north-east (NE) sector of the remnant. Methods. The test is performed with the help of a time-dependent spherically-symmetric hydrodynamical (HD) code using a smooth density distribution at the cavity-cloud interface. Results. When the shock hits the wall of the cavity, the reflected perturbation is found not to be a shock wave but a strong compression wave. The reflected wave heats up the cavity at temperatures higher than those observed in the X-rays. We also find an outwardly decreasing temperature as observed in X-rays, but over a narrower radial interval. After crossing the wall of the cavity, the shock velocity in the cloud is not steady. Nonetheless, we find that the steady-state assumption usually made to fit the line emission of Balmer-dominated non-radiative filaments (NRFs) can be rather accurate (shock velocity variations <3%) if the integration time of the post-shock structure is shorter than ∼200 y, the shock is not too close to the wall and the cloud was not shocked more than ∼1100 yr ago. Conclusions. We propose a revision of the parameters of the cavity-wall scenario, assuming as a constraint the approximate steadiness of the shock velocity in the cloud. With the revised set of parameters, the values of the temperature in the hot cavity are in closer agreement with observations. At the adopted distance of 540 pc, we find an explosion energy E 0 6-8 × 10 49 erg, consistent with previous determinations of E 0 once scaled to the adopted distance. We also determine lower and upper limits of 0.1 and 2.6 × 10 50 erg. This very low value of E 0 suggests an electron-capture explosion of an ∼8-10 M progenitor, and makes the SN of the Cygnus Loop the weakest known core-collapse SN in the Galaxy.

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“…Hester et al further suggest that the region between the Balmer-dominated filaments and the radiative northeastern rim might be one of a more chaotic flow around the edges of the cloud responsible for the radiative rim. Levenson et al (1998) showed that the Cygnus Loop is surrounded by a smooth H i shell and by large interstellar clouds, the morphology of this remnant being dominated by shock-cloud interactions. Miyata & Tsunemi (1999, hereafter MT99) investigated the radial structure of the plasma in the northeastern limb of the Cygnus Loop using Advanced Satellite for Cosmology and Astrophysics (ASCA) data.…”

Section: Introductionmentioning

confidence: 99%

XMM‐NewtonObservation of the Northeastern Limb of the Cygnus Loop

Nemes

Tsunemi

Miyata

2008

ApJ

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In this paper we performed moderate-resolution spectroscopy on the data obtained with XMM-Newton of the northeastern limb of the Cygnus Loop. This observation was proposed as a higher resolution follow-up to that made by ASCA. We investigated the radial variation of the temperature, ionization timescale, elemental abundances, and hydrogen column density across our field of view. We confirmed that on average all the abundances are depleted. However, we could not confirm the jump structure found by Miyata et al. in the physical properties of the plasma at 0.9R S . We also detected what looks like a new line in our spectra which probably comes from C vi. Comparing our results for heavy element abundances with those from Suzaku, we found that they agree to within a factor of 2Y3. The heavy element ratios relative to O were relatively constant across the field of view and a comparison with models shows that the ISM in this part of the remnant was probably created by low-to intermediate-mass stars.

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Panoramic Views of the Cygnus Loop

Cited by 88 publications

References 53 publications

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

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

The Cygnus Loop: a weak core-collapse SN in our Galaxy

XMM‐NewtonObservation of the Northeastern Limb of the Cygnus Loop

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