scholarly journals The multi-polar planetary nebula NGC 5189

2011 ◽  
Vol 7 (S283) ◽  
pp. 490-491
Author(s):  
Laurence Sabin ◽  
Roberto Vázquez ◽  
Jose A. Lopéz ◽  
Maria-Teresa García-Diaz
Keyword(s):  
High Resolution ◽  
Mass Loss ◽  
Optical Imaging ◽  
Central Region ◽  
Planetary Nebula ◽  
Spectroscopic Data ◽  
High Nitrogen ◽  
Central Source ◽  
North West ◽  
Nitrogen Levels

AbstractNGC 5189 is a particularly interesting planetary nebula (PN) displaying multiple bipolar structures. This type of morphology is generally attributed to multiple mass loss events believed to originate from a precessing central source. In order to better understand this, once dubbed chaotic PN, we have investigated optical imaging combined with low- and high- resolution spectroscopic data to dissect its components. The imaging reveals three and possibly four well defined bipolar lobes showing a misalignment with respect to the central torus, although sharing the same geometric center. The high nitrogen levels detected in the elongated filaments/condensations surrounding the nebula and at the torus location highlight the presence of low ionization structures as well as the possible occurrence of shocks in the areas perturbed by large dynamical motions. Finally the kinematical study indicates moderate expansion velocities (35 km.s−1 in the western lobe, 33 km.s−1 in the central region and 44 km.s−1 in the eastern lobe). We also notice the asymmetry of the [NII] distribution and the velocities inside NGC 5189 between its North-West and South-East components.

scholarly journals Evidence of Expansion in the Central Region of NGC 2346

1989 ◽  
Vol 131 ◽  
pp. 187-187
Author(s):  
D.P.K. Banerjee ◽  
B. G. Anandarao ◽  
J. N. Desai ◽  
S. K. Jain ◽  
D.C.V. Mallik
Keyword(s):  
High Resolution ◽  
Spectral Range ◽  
Central Region ◽  
Planetary Nebula ◽  
Signal To Noise Ratio ◽  
Emission Lines ◽  
Expansion Velocity ◽  
Signal To Noise ◽  
Central Spot ◽  
Fabry Perot

We present observations of the bipolar planetary nebula NGC 2346 carried out with the 1-m telescope at the Vainu Bappu Observatory in Kavalur, India using (1) a high resolution piezo-electric scanned Fabry-Pérot Spectrometer (with a velocity resolution of 10 km s−1) for line studies in the 6000 A - 7000 A spectral range and (2) a pressure scanned Fabry-Pérot spectrometer (with a velocity-resolution of 5 km s−1) in the green region. The nebula was observed in the H I 6563 A and [N II] 6583 A emission lines using a 15″ aperture and in the [O III] 5007 A line using an 8″ aperture centered on the bright central spot. A number of scans in each of these lines were co-added to improve the signal-to-noise ratio. The [O III] profile shows a well defined split between the blue and the red component, typical of an expanding shell. The [N II] profile does not show a well resolved split, although a pronounced suggestion of a split was observed in all the scans. The Hα profile was broad and asymmetric. The composite [O III] and [N II] profiles were decomposed into two individual Gaussians for obtaining the expansion velocity.

scholarly journals The Central Region of the Planetary Nebula A58

1993 ◽  
Vol 155 ◽  
pp. 387-387
Author(s):  
D.L. Pollacco ◽  
P.W. Hill ◽  
R.E.S. Clegg
Keyword(s):  
High Resolution ◽  
Central Region ◽  
Planetary Nebula ◽  
Emission Lines

We present images and high–resolution spectra of the hydrogen deficient knot at the centre of the old planetary nebula A58. The spectra confirm that this region contains essentially no hydrogen, as previously suspected. Emission lines from the knot are broad (FWHM ∼ 180 and 270 km/s for [NII] and [OIII] lines respectively) and are blue–shifted by ∼100 km/s relative to the systematic velocity.

scholarly journals Hubble Space Telescope and ground-based optical imaging of the Proto-Planetary Nebula M1-92

1997 ◽  
Vol 180 ◽  
pp. 369-370
Author(s):  
Susan R. Trammell ◽  
Robert W. Goodrich
Keyword(s):  
Mass Loss ◽  
Optical Imaging ◽  
Planetary Nebula ◽  
Hubble Space Telescope ◽  
Continuum Emission ◽  
Space Telescope ◽  
Shock Heating ◽  
Optical Line ◽  
The Continuum

We present HST and ground-based images of the bipolar proto-planetary nebula M1-92. Trammell et al. (1993) studied Ml-92 using spectropolarimetry and concluded that the continuum emission is reflected from the inner regions of the object, the forbidden lines are formed locally in the bipolar lobes, and the permitted lines are partially reflected and partially formed in the bipolar lobes. The emission produced in the lobes of Ml-92 is indicative of shock heating, Vs = 60–100 km s–1. Shock emission dominates the optical line spectra of the lobes of M1-92 and is a powerful probe into the properties of the mass loss occurring between the AGB and PN phases of evolution.

VIS-NIR LED Illumination in Backside Circuit Edit and Optical Probing Applications

2012 ◽  
Author(s):  
Shida Tan ◽  
Richard H. Livengood ◽  
Dane Scott ◽  
Roy Hallstein ◽  
Pat Pardy ◽  
...  
Keyword(s):  
High Resolution ◽  
Image Quality ◽  
Optical Imaging ◽  
Narrow Band ◽  
Light Emitting Diode ◽  
Air Gap ◽  
Optical Image ◽  
Proof Of Concept ◽  
Light Emitting ◽  
Optical Probing

Abstract High resolution optical imaging is critical in assisting backside circuit edit (CE) and optical probing navigation. In this paper, we demonstrated improved optical image quality using VIS-NIR narrow band light emitting diode (LED) illumination in various FIB and optical probing platforms. The proof of concept was demonstrated with both common non-contact air gap lenses and solid immersion lenses (SIL).

High‐Resolution X‐Ray Image of the Hydrogen‐deficient Planetary Nebula Abell 30

1997 ◽  
Vol 482 (2) ◽  
pp. 891-896 ◽  
Author(s):  
You‐Hua Chu ◽  
Thomas H. Chang ◽  
Gail M. Conway
Keyword(s):  
High Resolution ◽  
Planetary Nebula ◽  
X Ray

scholarly journals Responses of Root Characteristic Parameters and Plant Dry Matter Accumulation, Distribution and Transportation to Nitrogen Levels for Spring Maize in Northeast China

Agriculture ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 308
Author(s):  
Yang Yu ◽  
Chunrong Qian ◽  
Wanrong Gu ◽  
Caifeng Li
Keyword(s):  
Surface Area ◽  
Nitrogen Fertilizer ◽  
Root Length ◽  
Dry Matter ◽  
Projection Area ◽  
Dry Matter Accumulation ◽  
Characteristic Parameters ◽  
High Nitrogen ◽  
Nitrogen Levels ◽  
Matter Transport

Improving nitrogen use efficiency is a significant scientific problem to be solved. Two maize hybrids JD27 (Jidan 27) and SD19 (Sidan 19) were selected to study the effects of nitrogen levels on root characteristic parameters and plant dry matter accumulation, distribution and transportation. We set five different nitrogen levels, which were nitrogen deficiency (000N), low nitrogen (075N), medium nitrogen (150N), high nitrogen (225N) and excessive nitrogen (300N). The results showed that the root length and root surface area of JD27 were significantly higher than those of SD19 under 075N. With the increase of nitrogen levels, the root difference among varieties gradually decreased. The root length, projection area, total surface area and total volume reached the maximum values at silking stage. The average root diameter kept stable or decreased slowly with the growth stage. The dry matter accumulation of JD27 was higher than that of SD19 at all growth stages. Increasing the amount of nitrogen fertilizer can promote the transport of dry matter to grain and improve dry matter transport efficiency after anthesis. Under the treatment of medium and high nitrogen fertilizer, maize was easy to obtain a higher yield, but excessive nitrogen fertilizer inhibited the increase of yield. This study provides theoretical and practical guidance for maize production techniques.

scholarly journals New models for the rapid evolution of the central star of the Stingray Nebula

2021 ◽  
Author(s):  
T M Lawlor
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Planetary Nebula ◽  
Rapid Evolution ◽  
Central Star ◽  
Asymptotic Giant Branch ◽  
Initial Mass ◽  
Thermal Pulse ◽  
The Past ◽  
New Models

Abstract We present stellar evolution calculations from the Asymptotic Giant Branch (AGB) to the Planetary Nebula (PN) phase for models of initial mass 1.2 M⊙ and 2.0 M⊙ that experience a Late Thermal Pulse (LTP), a helium shell flash that occurs following the AGB and causes a rapid looping evolution between the AGB and PN phase. We use these models to make comparisons to the central star of the Stingray Nebula, V839 Ara (SAO 244567). The central star has been observed to be rapidly evolving (heating) over the last 50 to 60 years and rapidly dimming over the past 20–30 years. It has been reported to belong to the youngest known planetary nebula, now rapidly fading in brightness. In this paper we show that the observed timescales, sudden dimming, and increasing Log(g), can all be explained by LTP models of a specific variety. We provide a possible explanation for the nebular ionization, the 1980’s sudden mass loss episode, the sudden decline in mass loss, and the nebular recombination and fading.

scholarly journals Radiation-Driven Stellar Eruptions

Galaxies ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 10 ◽  
Author(s):  
Kris Davidson
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Central Region ◽  
Massive Stars ◽  
Variable Stars ◽  
Blast Waves ◽  
Subsequent Evolution ◽  
Fundamental Causes ◽  
Radiative Output ◽  
Luminous Blue Variable

Very massive stars occasionally expel material in colossal eruptions, driven by continuum radiation pressure rather than blast waves. Some of them rival supernovae in total radiative output, and the mass loss is crucial for subsequent evolution. Some are supernova impostors, including SN precursor outbursts, while others are true SN events shrouded by material that was ejected earlier. Luminous Blue Variable stars (LBV’s) are traditionally cited in relation with giant eruptions, though this connection is not well established. After four decades of research, the fundamental causes of giant eruptions and LBV events remain elusive. This review outlines the basic relevant physics, with a brief summary of essential observational facts. Reasons are described for the spectrum and emergent radiation temperature of an opaque outflow. Proposed mechanisms are noted for instabilities in the star’s photosphere, in its iron opacity peak zones, and in its central region. Various remarks and conjectures are mentioned, some of them relatively unfamiliar in the published literature.

Sign in / Sign up

Export Citation Format

Share Document