Distance to the Cygnus Loop from [ITAL]HUBBLE SPACE TELESCOPE[/ITAL][ITAL]Hubble Space Telescope[/ITAL] Imaging of the Primary Shock Front

Blair, William P.; Sankrit, Ravi; Raymond, J. C.; Long, Knox S.

doi:10.1086/300994

Cited by 67 publications

(72 citation statements)

References 14 publications

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“…This does not mean that the shock is steady, because the steadiness of the shock velocity is obtained at the expense of a variable pre-shock ambient density. In the revised model, we have found that: (i) the shock velocity is consistent with the value derived with the steady-state analysis of L92, HRB94, and Blair et al (1999), and this over a much longer evolutionary time; (ii) the temperature distribution of the hot matter close to the wall of the cavity is well within the range observed in the X-ray, although not over the same radial extent. Additional work is needed to clarify this point, both for the X-ray derived temperature distribution and the parameters of the cavity-wall scenario.…”

Section: Discussionsupporting

confidence: 82%

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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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Section: Discussionsupporting

confidence: 82%

“…Other authors (L92; Blair et al 1999;Sankrit et al 2000) use, for the same filament, t i ≤ 200 yr. They also suggest that the shock might have recently decelerated.…”

Section: The Time Evolution Of V Smentioning

confidence: 99%

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

Martinez

2011

A&A

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“…For our target cloud with r = 0.053 pc, and assuming a nominal distance R = 5 pc (e.g., the radius of the Cygnus loop SNR, Blair et al 1999), D g ≈ 3 × 10 −5 . D g is the maximum fraction of the total amount of SN-ejected material that can be injected into the target cloud, assuming 100% injection efficiency.…”

Section: Dilution Factorsmentioning

confidence: 99%

Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-lived Radioisotopes with a Shock Wave. V. Nonisothermal Collapse Regime

Boss

2017

ApJ

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Recent meteoritical analyses support an initial abundance of the short-lived radioisotope 60 Fe that may be high enough to require nucleosynthesis in a core collapse supernova, followed by rapid incorporation into primitive meteoritical components, rather than a scenario where such isotopes were inherited from a well-mixed region of a giant molecular cloud polluted by a variety of supernovae remnants and massive star winds. This paper continues to explore the former scenario, by calculating three dimensional, adaptive mesh refinement, hydrodynamical code (FLASH 2.5) models of the self-gravitational, dynamical collapse of a molecular cloud core that has been struck by a thin shock front with a speed of 40 km/sec, leading to the injection of shock front matter into the collapsing cloud through the formation of Rayleigh-Taylor fingers at the shock-cloud intersection. These models extend the previous work into the nonisothermal collapse regime using a polytropic approximation to represent compressional heating in the optically thick protostar. The models show that the injection efficiencies of shock front material are enhanced compared to previous models, which were not carried into the nonisothermal regime and so did not reach such high densities. The new models, combined with the recent estimates of initial 60 Fe abundances, imply that the supernova triggering and injection scenario remains as a plausible explanation for the origin of the short-lived radioisotopes involved in the formation of our solar system.

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“…Excessive thermal material should also significantly enhance rotation measure (RM) values; such RMs, however, are not observed (Uyanıker et al 2002, the mean value of the rotation measure is about −20 rad m −2 ). At a distance of 440 pc (Blair et al 1999), the linear size of the Cygnus Loop complex would be about 25 pc. The inferred thermal electron densities, with B = 3 µG, are then of the order of 0.33 cm −3 .…”

Section: Remarks On Spectral Variationsmentioning

confidence: 99%

Radio emission from the Cygnus Loop and its spectral characteristics

Uyanıker

Reich

Yar

et al. 2004

A&A

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Abstract. We present a new sensitive 2675 MHz radio continuum map of the Cygnus Loop, which is used in conjunction with 408 MHz, 863 MHz and 1420 MHz maps from both the Effelsberg 100-m telescope and the DRAO Synthesis Telescope for a spectral analysis. Between 408 MHz and 2675 MHz we find an overall integrated spectral index of α = −0.42 ± 0.06 (S ∼ ν α ), close to previous results. There is no indication of a spectral break in the integrated spectrum. Spatially highly varying and rather strong spectral curvature was previously reported, but is not confirmed on the basis of new, higher sensitivity observations. We found spectral variations across the Cygnus Loop reaching up to ∆α = 0.2 from a TT-plot analysis. The flattest spectra are seen towards enhanced emission areas. Spectral index maps produced between different frequency pairs, as well as all four maps, revealed that there are at least three flat spectrum regions. In regions interior to the high emission filaments, we have detected at least two spectral components across the whole object with α = −0.4 and α = −0.6 towards northern and southern parts of the object, respectively.

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Distance to the Cygnus Loop from [ITAL]HUBBLE SPACE TELESCOPE[/ITAL][ITAL]Hubble Space Telescope[/ITAL] Imaging of the Primary Shock Front

Cited by 67 publications

References 14 publications

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

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

Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-lived Radioisotopes with a Shock Wave. V. Nonisothermal Collapse Regime

Radio emission from the Cygnus Loop and its spectral characteristics

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