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Ali, A.; El-Nawawy, M. S.; Pfleiderer, J.

doi:10.1023/a:1002442632274

Cited by 9 publications

(10 citation statements)

References 16 publications

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“…4). This result is consistent with that achieved by Ali et al (2000), regardless of the differences between the two samples. Figure 4 shows the increase of IPNe frequency with the inclination angle.…”

Section: The Galactic Orientation Of Ipnesupporting

confidence: 91%

“…A similar work was compiled by Ali et al (2000), and they showed that of an overall sample of 40 one-sided PNe, a third display an orientation roughly parallel to the Galactic plane.…”

Section: Ipne Orientationmentioning

confidence: 80%

“…It provides information about mechanisms capable of explaining the various shapes of PNe such as bipolar and elliptical objects. For IPNe, Ali et al (2000) investigated the spatial orientation and distribution of one-sided PNe. This time we investigate the orientation of IPNe with respect to the Milky Way based on a larger sample.…”

Section: The Galactic Orientation Of Ipnementioning

confidence: 99%

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Interacting planetary nebulae

Ali

Sabin

Snaid

et al. 2012

A&A

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We discuss the classification and orientation of planetary nebulae that interact with the interstellar medium throughout the Milky Way. A sample of 117 confirmed interacting planetary nebulae is used for this purpose. Our results indicate that the majority of interacting objects are located close to the Galactic plane, and ∼77% of them are located inside the Galactic thin disk. One third of the sample is less than 100 parsec from the Galactic plane and thus may interact with molecular and cold neutral clouds. There is a tendency for the planetary nebula interaction region to be parallel to the Galactic plane. We found that ∼73% of interacting planetary nebulae have inclination angles (defined as the angles that join the planetary nebula centroid and the interaction area or bow shock with the Galactic plane) larger than 45 • and ∼38% larger than 70 • , which highlights the possible effect of interstellar magnetic fields. While it is sometime believed that the interaction preferentially occurs in old planetary nebulae, our analysis indicates that the majority of observed planetary nebulae are in the mid stage of their evolution. The mean inclination angle, Galactic height, linear size, and dynamical age are estimated for each stage of interaction. The results indicate strong correlations between the mean inclination angle and the above parameters.

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Section: The Galactic Orientation Of Ipnesupporting

confidence: 91%

“…A similar work was compiled by Ali et al (2000), and they showed that of an overall sample of 40 one-sided PNe, a third display an orientation roughly parallel to the Galactic plane.…”

Section: Ipne Orientationmentioning

confidence: 80%

Section: The Galactic Orientation Of Ipnementioning

confidence: 99%

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Interacting planetary nebulae

Ali

Sabin

Snaid

et al. 2012

A&A

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“…Such features have been seen before in other PNe, e.g. PN G218.9-10.7 (Ali & Pfleiderer 1999) and NGC 6894 (Soker & Zucker 1997), where they are also attributed to the interaction between the PN and its surrounding ISM. In particular, stripes arise due to the stripping of the object's halo by ISM (many examples of such objects were discussed by Ali et al 2012) although Soker & Zucker (1997) speculate that such stripes are shaped by the interstellar magnetic field due to their orientation.…”

Section: Evidence For Interaction With the Ismsupporting

confidence: 70%

The physics and kinematics of the evolved, interacting planetary nebula PN G342.0-01.7

Ali

Amer

Dopita

et al. 2015

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Integral field spectroscopy has been obtained for very few evolved planetary nebulae (PNe). Here we aim to study the physical and kinematical characteristics of the unstudied old planetary nebula PN G342.0-01.7, which shows evidence of interaction with its surrounding interstellar medium. We used integral field spectra from the Wide Field Spectrograph on the ANU 2.3 m telescope to provide spectroscopy across the whole object covering the spectral range 3400−7000 Å. We formed narrow-band images to investigate the excitation structure. The spectral analysis shows that the object is a distant Peimbert Type I planetary nebula (PN) of low excitation, formally of excitation class of 0.5. The low electron density, high dynamical age, and low surface brightness of the object confirm that it is observed fairly late in its evolution. It shows clear evidence for dredge-up of CN-processed material characteristic of its class. In addition, the low peculiar velocity of 7 km s −1 shows it to be a member of the young disk component of our Galaxy. We further determined an average expansion velocity of V exp = 20.2 ± 1.3 km s −1 , a local standard of rest radial velocity RV LSR = −27.7 ± 1.7 km s −1 , and a distance of 2.06±0.6 kpc for the object. We built a self-consistent photoionisation model for the PN matching the observed spectrum, the Hβ luminosity, and the diameter. On the basis of this we derive an effective temperature log T eff ∼ 5.05 and luminosity 1.85 < log L < 2.25. The temperature is much higher than might have been expected using the excitation class, proving that this can be misleading in classifying evolved PNe. PN G342.0-01.7 is in interaction with its surrounding interstellar medium through which the object is moving in the south-west direction. This interaction drives a slow shock into the outer PN ejecta. A shock model suggests that it only accounts for about 10% of the total luminosity, but has an important effect on the global spectrum of the PN.

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“…Several theoretical and observational studies have been realised on the subject (e.g. Borkowski et al 1990;Ali et al 2000) mainly regarding the earliest (and brightest) stages of interaction. However, the study of such interaction processes at more advanced stages has been made difficult due to the low surface brightness usually associated to interacting PNe which has prevented their detection in past surveys.…”

Section: Introductionmentioning

confidence: 99%

New planetary nebulae with ISM interaction discovered with IPHAS

et al. 2011

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Abstract. The low surface brightness usually associated with nebulae mixing with the ISM has long been a substantial obstacle in the observation and statistical study of these interactions. Thanks to the detection capability of the INT Photometric H-alpha Survey (IPHAS), in terms of sensitivity and imaging resolution, we were able to detect and select tens of examples of candidate Planetary Nebulae apparently at different stages of interaction with the interstellar medium (PNe-ISM hereafter) following the Wareing et al. (2007) classification. A spectroscopic investigation was conducted with the San Pedro Martir 2.1m telescope (SPM) in Mexico and we present the first results involving a proper classification and analysis of our candidates. The main difficulty is visually separating PNe-ISM from other faint asymmetric nebulosities such as old HII regions, SNRs and general diffuse H-alpha structures. This investigation is a first step in a more comprehensive study of PNe-ISM as more candidates are uncovered by the IPHAS team.

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Cited by 9 publications

References 16 publications

Interacting planetary nebulae

Interacting planetary nebulae

The physics and kinematics of the evolved, interacting planetary nebula PN G342.0-01.7

New planetary nebulae with ISM interaction discovered with IPHAS

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