Radiative shock-wave theory. I - Chemical abundance diagnostics and galactic abundance gradients

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

doi:10.1086/161653

Cited by 70 publications

(101 citation statements)

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“…These spectra clearly indicate that the nebula consists of shocked material. The relative strength of [S II]/Hα at all six locations is greater than the 0.4 criteria for identifying optical shocked material (Mathewson & Clarke 1972;Raymond 1979;Shull & McKee 1979;Dodorico et al 1980;Dopita et al 1984). Moreover, the absence of appreciable [O III] 4959, 5007 emission in the nebula (see Fig.…”

Section: Resultsmentioning

confidence: 74%

A distance estimate to the Cygnus Loop based on the distances to two stars located within the remnant

Fesen

Neustadt

Black

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Underlying nearly every quantitative discussion of the Cygnus Loop supernova remnant is uncertainty about its distance. Here we present optical images and spectra of nebulosities around two stars whose mass-loss material appears to have interacted with the remnant's expanding shock front and thus can be used to estimate the Cygnus Loop's distance. Narrow passband images reveal a small emission-line nebula surrounding an M4 red giant near the remnant's eastern nebula NGC 6992. Optical spectra of the nebula show it to be shock-heated with significantly higher electron densities than seen in the remnant's filaments. This along with a bow-shaped morphology suggests it is likely red giant mass-loss material shocked and accelerated by passage of the Cygnus Loop's blast wave. We also identify a B7 V star located along the remnant's northwestern limb which also appears to have interacted with the remnant's shock wave. It lies within a small arc of nebulosity in an unusually complex region of highly curved and distorted filaments along the remnant's northern shock front suggestive of a localized disturbance of the shock front due to the B star's stellar winds. Based on the assumption that these two stars lie inside the remnant, combined with an estimated distance to a molecular cloud situated along the remnant's western limb, we propose a distance to the Cygnus Loop of 1.0 ± 0.2 kpc. Although larger than several recent estimates of 500 − 800 pc, a distance 1 kpc helps resolve difficulties with the remnant's postshock cosmic ray and gas pressure ratio and estimated supernova explosion energy.

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Section: Resultsmentioning

confidence: 74%

A distance estimate to the Cygnus Loop based on the distances to two stars located within the remnant

Fesen

Neustadt

Black

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…In our case, [OIII]λ5007/Hβ emission line ratios for SNR2, SNR3, and SNR5 were found as 0.27, 1.22, and 1.6, respectively, corresponding to nebular propagation velocities of <85 km s −1 (see Fig. 5 of Dopita et al 1984). There are many SNRs that have low shock velocity values in a number of nearby galaxies Blair & Long 2004 We adopted the method by Blair & Long (2004) based on their Fig.…”

Section: The Follow-up Optical Spectroscopymentioning

confidence: 71%

“…With the same reasoning, although the line ratio values of [S II]λ6716/[S II]λ6731 > 1.46 are considered to correspond to a low density limit with N e ≤ 10 cm −3 (Osterbrock 1989), we can only quote an electron density for both SNR2 and SNR5 of simply <100 cm −3 . Using the shock abundance models by Dopita et al (1984), the elemental abundances can be determined from the SNR spectra. Their models assume a shock velocity around or less than 100 km s −1 which is considered a low shock velocity.…”

Section: The Follow-up Optical Spectroscopymentioning

confidence: 99%

A search for supernova remnants in the nearby spiral galaxy M 74 (NGC 628)

Сонбас¹,

Akyüz

Balman

et al. 2010

A&A

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An optical search was carried out for supernova remnants (SNRs) in the Sc type nearby spiral galaxy M 74, using ground-based observations at the TUBITAK National Observatory (TUG, Antalya/Turkey) and the Special Astrophysics Observatory (SAO, Russia). Observations were supplemented by the spectral analysis of archived X-ray data from XMM-Newton and Chandra. We also present spectral follow-up observations of these SNR candidates, however, we are able to spectrally confirm only three of them (SNR2, SNR3, and SNR5). The lack of confirmation for the rest might come from contamination by the nearby H II emission regions, as well as from the inaccurate positioning of the long slit on these objects. In addition, we searched the XMM-Newton and Chandra Observatory archival data for the X-ray counterparts to the optically identified candidates. We find positional coincidence with only three SNR candidates, SNR1, SNR2, and SNR8. The spectrum of SNR2 yields a shock temperature of 10.8 keV with an ionization timescale of 1.6 × 10 10 s cm −3 , indicating a relatively young remnant in an early Sedov phase, which is not supported by our optical wavelength analysis. Given the high luminosity of 10 39 erg s −1 and the characteristics of the X-ray spectrum, we favor an ultra luminous X-ray source interpretation for this source associated with an SNR. We calculated an X-ray flux upper limit of 9.0 × 10 −15 erg cm −2 s −1 for the rest of the SNRs, including spectroscopically identified SNR3 and SNR5.

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“…In particular, there is no evidence of shock-excited gas, which would reveal itself by very large [ N ii]/ H or [O ii]/ H ratios (Dopita et al 1984). Nor does the [O i]/ H ratio become sufficiently large to put it in the shockexcited classification (Dopita & Sutherland 1995).…”

Section: Keck Lris Spectroscopymentioning

confidence: 99%

Minkowski’s Object: A Starburst Triggered by a Radio Jet, Revisited

Croft

Breugel

Vries

et al. 2006

ApJ

167

166

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We present neutral hydrogen, ultraviolet, optical, and near-infrared imaging, and optical spectroscopy, of Minkowski's Object ( MO), a star-forming peculiar galaxy near NGC 541. The observations strengthen evidence that star formation in MO was triggered by the radio jet from NGC 541. Key new results are the discovery of a 4:9 ; 10 8 M double H i cloud straddling the radio jet downstream from MO, where the jet changes direction and decollimates; strong detections of MO, also showing double structure, in UVand H; and numerous H ii regions and associated clusters in MO. In UV, MO resembles the radio-aligned, rest-frame UV morphologies in many high-redshift radio galaxies (HzRGs), also thought to be caused by jet-induced star formation. MO's stellar population is dominated by a 7.5 Myr old, 1:9 ; 10 7 M instantaneous burst, with a current star formation rate of 0.52 M yr À1 (concentrated upstream from where the H i column density is high). This is unlike the jet-induced star formation in Centaurus A, where the jet interacts with preexisting cold gas; in MO, the H i may have cooled out of a warmer, clumpy intergalactic or interstellar medium as a result of jet interaction, followed by the collapse of the cooling clouds and subsequent star formation (consistent with numerical simulations). Since the radio source that triggered star formation in MO is much less luminous, and therefore more common than powerful HzRGs, and because the environment around MO is not particularly special in terms of abundant dense, cold gas, jet-induced star formation in the early universe might be even more prevalent than previously thought.

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Radiative shock-wave theory. I - Chemical abundance diagnostics and galactic abundance gradients

Cited by 70 publications

References 0 publications

A distance estimate to the Cygnus Loop based on the distances to two stars located within the remnant

A distance estimate to the Cygnus Loop based on the distances to two stars located within the remnant

A search for supernova remnants in the nearby spiral galaxy M 74 (NGC 628)

Minkowski’s Object: A Starburst Triggered by a Radio Jet, Revisited

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