Physical Conditions in the Compact Planetary Nebula Sw St 1

Sw St 1 is a compact and possibly young planetary nebula which has been recently observed at infra red (Aitken et al., 1979) and radio (Kwok et al., 1981) wavelengths. In the 8-13 μm region, a silicate emission feature is observed, suggesting that the nebular envelope is oxygen rich. The high emission measure determined from the radio observations implies a large value for the electron density.

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Physical Conditions in the Planetary Nebula Hb 12

Symposium - International Astronomical Union ◽

10.1017/s0074180900094213 ◽

1983 ◽

Vol 103 ◽

pp. 519-520

Author(s):

D.R. Flower ◽

C.J. Penn

Keyword(s):

Planetary Nebula ◽

Emission Measure ◽

Radio Spectrum ◽

Emission Feature ◽

Physical Conditions ◽

High Emission

The planetary nebula Hb 12 has recently been observed at infrared (Aitken et al., 1979) and radio (Purton et al., 1982) wavelengths. The detection of a silicate emission feature in the 8-13 μm region suggests that the nebula is oxygen rich. A high emission measure is derived from the radio spectrum, implying a high intrinsic density.

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Twenty years of observations of PM 1-188: Its chemical abundances and extraordinary kinematics

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab517 ◽

2021 ◽

Author(s):

Miriam Peña ◽

Liliana Hernández-Martínez ◽

Francisco Ruiz-Escobedo

Keyword(s):

Chemical Composition ◽

Planetary Nebula ◽

Central Star ◽

Emission Lines ◽

Type I ◽

Chemical Abundances ◽

Line Intensities ◽

Physical Conditions ◽

The Past ◽

Spectrophotometric Data

Abstract The analysis of 20 years of spectrophotometric data of the double shell planetary nebula PM 1-188 is presented, aiming to determine the time evolution of the emission lines and the physical conditions of the nebula, as a consequence of the systematic fading of its [WC 10] central star whose brightness has declined by about 10 mag in the past 40 years. Our main results include that the [O iii], [O ii], [N ii] line intensities are increasing with time in the inner nebula as a consequence of an increase in electron temperature from 11 000 K in 2005 to more than 14 000 K in 2018, due to shocks. The intensity of the same lines are decreasing in the outer nebula, due to a decrease in temperature, from 13 000 K to 7000 K, in the same period. The chemical composition of the inner and outer shells was derived and they are similar. Both nebulae present subsolar O, S and Ar abundances, while they are He, N and Ne rich. For the outer nebula the values are 12+log He/H = 11.13 ± 0.05, 12+log O/H = 8.04 ± 0.04, 12+log N/H = 7.87 ± 0.06, 12+log S/H = 7.18 ± 0.10 and 12+log Ar = 5.33 ± 0.16. The O, S and Ar abundances are several times lower than the average values found in disc non-Type I PNe, and are reminiscent of some halo PNe. From high resolution spectra, an outflow in the N-S direction was found in the inner zone. Position-velocity diagrams show that the outflow expands at velocities in the −150 to 100 km s−1 range, and both shells have expansion velocities of about 40 km s−1.

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Physical Conditions in the Compact Planetary Nebula Sw St 1

Planetary Nebulae ◽

10.1007/978-94-009-7094-6_74 ◽

1983 ◽

pp. 520-520

Author(s):

M. Cohen ◽

D. R. Flower ◽

A. Goharji

Keyword(s):

Planetary Nebula ◽

Physical Conditions

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Small Galactic Nebulae

Symposium - International Astronomical Union ◽

10.1017/s0074180900095462 ◽

1987 ◽

Vol 115 ◽

pp. 191-192

Author(s):

Yervant Terzian ◽

Kenneth C. Turner

Keyword(s):

High Resolution ◽

Planetary Nebula ◽

Physical Parameters ◽

H Ii Regions ◽

Radio Observations ◽

Cluster Emission ◽

Active Star ◽

Star Forming ◽

Cometary Nebula ◽

Significant Flux

We have performed high resolution VLA radio observations for several small H II regions, including the cluster emission nebulae S258, S255, S257, and S256. The region (PP56) between S255 and S257 at λ2 cm reveals significant flux structure close to OH, H2O and infrared emitting sources as shown in Figure 1. The flux densities and positions are indicated in Table 1. Observations of the cometary nebula PP59 (S269) also reveal similar characteristics as shown in Figure 2. These regions are considered to be active star-forming clouds. The cometary nebula PP40 was also observed and we note that its physical parameters are very similar to those of a typical planetary nebula.

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Variable Spectra of IC 4997 and NGC 6572

Symposium - International Astronomical Union ◽

10.1017/s0074180900172213 ◽

1993 ◽

Vol 155 ◽

pp. 488-488

Author(s):

Siek Hyung ◽

Lawrence H. Aller ◽

Walter A. Feibelman

Keyword(s):

Emission Line ◽

Electron Density ◽

Line Intensity ◽

Planetary Nebula ◽

Radiative Flux ◽

Gradual Decrease ◽

High Dispersion ◽

Echelle Spectrograph

Variability of the [OIII]4363/4340 H γ ratio in IC 4007 was established in 1956 by William Liller and L.H. Aller who attributed the changes to a gradual decrease of electron density with time. Subsequent 4363/4340 ratio fluctuations negated this explanation. Ferland pointed out that small changes in the radiative flux of the Planetary nebula nucleus (PNN) could explains the variations. Our pervious study emphasized IUE observations, here we compare high dispersion spectra obtained with the Hamilton Echelle Spectrograph with previous measurements to asses line intensity variations. Emission line variability in PNN spectra as noted by Mendez et al. (1988) and by other for HeII 4686 in NGC 6572 may offer significant clues. PNN 4686 appeared by 1990 in IC 4997. Possibly both of these PNN may be evolving into Wolf-Rayet objects, but this development does not necessarily imply that the nebular excitation will increase with time.

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A CO Search for Molecular Gas in High Mass Post-Main-Sequence Nebulae

International Astronomical Union Colloquium ◽

10.1017/s0252921100023873 ◽

1989 ◽

Vol 120 ◽

pp. 295-299

Author(s):

J.P. Phillips ◽

A. Mampaso ◽

N. Ukita ◽

P.G. Williams

Keyword(s):

Main Sequence ◽

Emission Measure ◽

Rapid Evolution ◽

Central Star ◽

Physical Characteristics ◽

High Mass ◽

Molecular Gas ◽

High Incidence ◽

High Emission ◽

Stellar Temperatures

High mass post-main-sequence nebulae are characterised by a set of unusual, and in certain cases extreme physical characteristics, including large outflow velocities (cf. Phillips and Mampaso, 1988a), extremely compact high emission measure cores (Phillips and Mampaso, 1988b), a high incidence of bipolar morphology (Peimbert and Torres Peimbert, 1982), and evidence for anomalously high levels of shock excited H2 S(l) emission towards both the source cores (Phillips et al 1983, 1985) and nebular peripheries (Zuckerman and Gatley, 1988). The large central star masses also predispose these sources to rapid evolution within the H-R plane (perhaps one or two orders of magnitude more rapid than for typical PN (Schonberner 1981, 1983), and the acquisition of stellar temperatures T* > 105 K, giving rise to correspondingly high levels of nebular excitation.

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Magnetic Field in the Proto-Planetary Nebula OH17.7–2.0

Symposium - International Astronomical Union ◽

10.1017/s0074180900208383 ◽

2003 ◽

Vol 209 ◽

pp. 143-144

Author(s):

Indra Bains ◽

Tim Gledhill ◽

Jeremy Yates ◽

Anita Richards

Keyword(s):

Magnetic Field ◽

Planetary Nebula ◽

Field Structure ◽

Radio Observations ◽

Magnetic Field Structure ◽

First Results ◽

The Magnetic Field

We have used radio observations of OH masers in proto-planetary nebula (PPN) candidates to probe the magnetic field structure of these objects. Here we present the first results of our study, concerning the PPN OH17.7–2.0.

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Physical conditions in H II galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900213211 ◽

2003 ◽

Vol 212 ◽

pp. 722-723

Author(s):

Carolina Kehrig ◽

Eduardo Telles ◽

François Cuisinier

Keyword(s):

Electron Temperature ◽

Electron Density ◽

Statistical Properties ◽

Chemical Abundances ◽

Physical Conditions ◽

Temperature Electron

We present a spectrophotometric survey of 111 H ii galaxies. Observations were made at the ESO 1.52m telescope, with the b&c spectrograph. Our sample presents a great overlap with Terlevich et al. 1991. Additional targets come from the Calan-Tololo an Marseille catalogues. All objects have been observed and analysed homogeneously. We analyse their statistical properties and derive physical conditions (reddening, electron temperature, electron density), as well as chemical abundances.

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