scholarly journals The Classification of M 1-78

1995 ◽  
Vol 12 (1) ◽  
pp. 31-36 ◽  
Author(s):  
G. T. Gussie
Keyword(s):  
Planetary Nebula ◽  
Main Sequence ◽  
Central Star ◽  
Expansion Velocity ◽  
Sequence Evolution ◽  
High Luminosity ◽  
Hii Region ◽  
Transient Phenomena ◽  
Ultracompact Hii

AbstractThe published properties of M1-78 are discussed with the purpose of resolving the object’s classification as either a planetary nebula or an ultracompact HII region. A classification as a planetary nebula is rejected primarily because of the high luminosity of the object, but because of the chemical composition and expansion velocity of the nebula, a novel classification is proposed instead: that of an ultracompact HII region with a post-main sequence central star (possibly a WN star). It must therefore follow that observable ultracompact HII regions persist beyond the main sequence lifetimes of at least some massive stars, and so cannot be transient phenomena that are seen only during pre-main sequence or early main sequence evolution.

scholarly journals Spectrophotometry and Multicolour Imagery of the Planetary Nebula Around the P Cygni Star AG Carinae

1993 ◽  
Vol 155 ◽  
pp. 217-217
Author(s):  
C. Rossi ◽  
A. Altamore ◽  
R.D.D. Costa ◽  
A. Damineli Neto ◽  
J.A. De Freitas Pacheco ◽  
...  
Keyword(s):  
Stellar Wind ◽  
Planetary Nebula ◽  
Central Star ◽  
Interesting Case ◽  
Circumstellar Dust ◽  
High Luminosity ◽  
Peak Separation ◽  
Dust Temperature ◽  
Ring Nebula ◽  
H Ii Region

Some of the high luminosity stars in our Galaxy are surrounded by planetary-like nebulae formed by material ejected from the central star. The most interesting case is that of the ring nebula PK 289-0° 1 around the P Cygni star AG Car. Long slit spectroscopy shows that nitrogen is overabundant and oxygen underabundant in the nebula. The Hα/[NII] ratio is lower in the nebula with respect to the surrounding H II region, possibly as a result of the N overabundance in the stellar wind. The emission line peak separation confirms a model of a distorted spherical shell expanding at 66 km s−1. The scattered star's spectrum is observable near the star, suggesting the presence of circumstellar dust grains. A nebular mass of at least 2.7 M⊙ is derived. While the nebula in the Hα imagery reveals the ring-like shape with many structures, in the blue it is much fainter and smoother. No nebular emission was detected in the JHK bands, suggesting a low dust temperature.

scholarly journals The post-common-envelope binary central star of the planetary nebula PN G283.7−05.1

2020 ◽  
Vol 642 ◽  
pp. A108 ◽  
Author(s):  
D. Jones ◽  
H. M. J. Boffin ◽  
J. Hibbert ◽  
T. Steinmetz ◽  
R. Wesson ◽  
...  
Keyword(s):  
Planetary Nebula ◽  
Main Sequence ◽  
Planetary Nebulae ◽  
Central Star ◽  
Radial Velocity Curve ◽  
Common Envelope ◽  
Low Mass ◽  
Red Giant ◽  
Model Temperature ◽  
Temperature Surface

We present the discovery and characterisation of the post-common-envelope central star system in the planetary nebula PN G283.7−05.1. Deep images taken as part of the POPIPlaN survey indicate that the nebula may possess a bipolar morphology similar to other post-common-envelope planetary nebulae. Simultaneous light and radial velocity curve modelling reveals that the newly discovered binary system comprises a highly irradiated M-type main-sequence star in a 5.9-hour orbit with a hot pre-white dwarf. The nebular progenitor is found to have a particularly low mass of around 0.4 M⊙, making PN G283.7−05.1 one of only a handful of candidate planetary nebulae that is the product of a common-envelope event while still on the red giant branch. In addition to its low mass, the model temperature, surface gravity, and luminosity are all found to be consistent with the observed stellar and nebular spectra through comparison with model atmospheres and photoionisation modelling. However, the high temperature (Teff ∼ 95 kK) and high luminosity of the central star of the nebula are not consistent with post-RGB evolutionary tracks.

scholarly journals The Distribution of Planetary Nebula Nuclei in the log L-log T Plane: Inferences from Theory

1989 ◽  
Vol 131 ◽  
pp. 473-480
Author(s):  
R. A. Shaw
Keyword(s):  
Planetary Nebula ◽  
Main Sequence ◽  
Galactic Disk ◽  
Mass Function ◽  
Initial Mass Function ◽  
Sequence Evolution ◽  
Selection Effects ◽  
Core Mass ◽  
Star Forming ◽  
History Of

The expected distribution of planetary nebula nuclei (PNNs) on the log L-log T plane is calculated based upon modern stellar evolutionary theory, the initial mass function (IMF), and various assumptions concerning mass loss during post-main sequence evolution. The distribution is found to be insensitive to the assumed range of main-sequence progenitor mass, and to reasonable variations in the age and the star forming history of the galactic disk. Rather, the distribution is determined primarily by the heavy dependence of the evolution rate upon core mass, and secondarily upon the steepness of the IMF and other factors. The distribution is rather different than any found from observations, and probably reveals strong observational selection effects.

scholarly journals The post-common-envelope binary central star of the planetary nebula ETHOS 1

2020 ◽  
Vol 498 (4) ◽  
pp. 6005-6012
Author(s):  
James Munday ◽  
David Jones ◽  
Jorge García-Rojas ◽  
Henri M J Boffin ◽  
Brent Miszalski ◽  
...  
Keyword(s):  
Planetary Nebula ◽  
Main Sequence ◽  
Orbital Plane ◽  
Central Star ◽  
Low Mass Stars ◽  
Common Envelope ◽  
First Case ◽  
Kinematic Modelling ◽  
Low Mass ◽  
The Common

ABSTRACT We present a detailed study of the binary central star of the planetary nebula ETHOS 1 (PN G068.1+11.0). Simultaneous modelling of light and radial velocity curves reveals the binary to comprise a hot and massive pre-white dwarf with an M-type main-sequence companion. A good fit to the observations was found with a companion that follows expected mass–temperature–radius relationships for low-mass stars, indicating that despite being highly irradiated, it is consistent with not being significantly hotter or larger than a typical star of the same mass. Previous modelling indicated that ETHOS 1 may comprise the first case where the orbital plane of the central binary does not lie perpendicular to the nebular symmetry axis, at odds with the expectation that the common envelope is ejected in the orbital plane. We find no evidence for such a discrepancy, deriving a binary inclination in agreement with that of the nebula as determined by spatio-kinematic modelling. This makes ETHOS 1 the ninth post-common-envelope planetary nebula in which the binary orbital and nebular symmetry axes have been shown to be aligned, with as yet no known counter-examples. The probability of finding such a correlation by chance is now less than 0.000 02 per cent.

scholarly journals A Very Rapid-Evolving Young Planetary Nebula

1993 ◽  
Vol 155 ◽  
pp. 357-357
Author(s):  
A. Manchado ◽  
P. García-Lario ◽  
K.C. Sahu ◽  
S.R. Pottasch
Keyword(s):  
Planetary Nebula ◽  
Sudden Change ◽  
Central Star ◽  
Time Interval ◽  
Expansion Velocity ◽  
Electronic Density ◽  
Infrared Excess ◽  
La Palma ◽  
Balmer Lines ◽  
Emission Line Spectrum

During a time interval of only 2 years, a sudden change has been detected in the emission line spectrum of a young planetary nebula IRAS 0656 2-0337, whose nature has been recently discussed by several authors, was firstly observed in December 1987 at La Silla (Chile) and in October 1988 at La Palma (Spain), showing only the Balmer lines in emission. A third spectrum, obtained at La Silla during February 1990, shows a quite different appearance, with forbidden emission lines typical of a planetary nebula. The electronic density is very high, and there is a high infrared excess too. An expansion velocity of 45 km s−1 has been estimated. It is shown that the effective temperature of the central star has significantly increased over this period of time. This is consistent with the evolution of a massive progenitor in the post-AGB phase, with L = 7000L⊙ at D = 4 kpc, in which the ionization of the neutral envelope, detected in CO, is now taking place.

scholarly journals High Velocity Outflows in Post-Main Sequence Nebulae

1989 ◽  
Vol 131 ◽  
pp. 194-194 ◽  
Author(s):  
J. P. Phillips ◽  
A. Mampaso
Keyword(s):  
High Velocity ◽  
Main Sequence ◽  
Major Axis ◽  
Central Star ◽  
Expansion Velocity ◽  
Type I ◽  
Isaac Newton ◽  
La Palma ◽  
Binary Evolution ◽  
Strong Winds

We have observed a broad range of post-main-sequence, type I and irregular nebulae using the intermediate dispersion spectrograph of the Isaac Newton Telescope (La Palma, Spain). Many of these show evidence for high velocity mass outflow, and in particular we find: (i) High velocity (∼ 500 km s−1), and appreciable mass loss outflows within ≅ 10 arcsecs of M2-9 and SH 2-71; (ii) Substantial shell expansion velocities in NGC 7026 (∼ 102 km s−1) with evidence for an appreciable driving wind at the central star, velocity ≅ 103 km s−1; (iii) Jet outflows extending over a range 260 km s−1 in Hb 5, with a distinctly tilted line structure suggestive of shock compression at the edges of an outflow cavity; and finally (iv) similarly strong winds (2 × 10 km s−1) from each member of a WC binary in the nucleus of NGC 6905. The binary separation is approximately 3.6 arcseconds, and the core is further enveloped by two, apparently co-spatial shells, expansion velocity 90 km s−1, and separation ΔV ≅ 130 km s−1. The [N II] emission for the shells is extraordinarily weak, although ansae located outside of the shells, and perpendicular to the binary major axis, possess I([N II]λ6584) > I(HIλ6563). We propose that the two shells were ejected at differing phases of binary evolution.

The Infancy of Solar-Type Stars and its Relevance for the Origin of Life

1997 ◽  
Vol 161 ◽  
pp. 267-282 ◽  
Author(s):  
Thierry Montmerle
Keyword(s):  
Main Sequence ◽  
Solar Nebula ◽  
Circumstellar Disks ◽  
T Tauri Stars ◽  
Necessary Condition ◽  
Sequence Evolution ◽  
T Tauri ◽  
Solar Type ◽  
Optical Domain ◽  
The Origin Of Life

AbstractFor life to develop, planets are a necessary condition. Likewise, for planets to form, stars must be surrounded by circumstellar disks, at least some time during their pre-main sequence evolution. Much progress has been made recently in the study of young solar-like stars. In the optical domain, these stars are known as «T Tauri stars». A significant number show IR excess, and other phenomena indirectly suggesting the presence of circumstellar disks. The current wisdom is that there is an evolutionary sequence from protostars to T Tauri stars. This sequence is characterized by the initial presence of disks, with lifetimes ~ 1-10 Myr after the intial collapse of a dense envelope having given birth to a star. While they are present, about 30% of the disks have masses larger than the minimum solar nebula. Their disappearance may correspond to the growth of dust grains, followed by planetesimal and planet formation, but this is not yet demonstrated.

scholarly journals Planetary Nebula Evolution Traced by Distance-Independent Parameters

1993 ◽  
Vol 155 ◽  
pp. 480-480
Author(s):  
C.Y. Zhang ◽  
S. Kwok
Keyword(s):  
Physical Properties ◽  
Mass Distribution ◽  
Planetary Nebula ◽  
Strong Support ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolution Model ◽  
The Core ◽  
Independent Parameters ◽  
Central Stars

Making use of the results from recent infrared and radio surveys of planetary nebulae, we have selected 431 nebulae to form a sample where a number of distance-independent parameters (e.g., Tb, Td, I60μm and IRE) can be constructed. In addition, we also made use of other distance-independent parameters ne and T∗ where recent measurements are available. We have investigated the relationships among these parameters in the context of a coupled evolution model of the nebula and the central star. We find that most of the observed data in fact lie within the area covered by the model tracks, therefore lending strong support to the correctness of the model. Most interestingly, we find that the evolutionary tracks for nebulae with central stars of different core masses can be separated in a Tb-T∗ plane. This implies that the core masses and ages of the central stars can be determined completely independent of distance assumptions. The core masses and ages have been obtained for 302 central stars with previously determined central-star temperatures. We find that the mass distribution of the central stars strongly peaks at 0.6 M⊙, with 66% of the sample having masses <0.64 MM⊙. The luminosities of the central stars are then derived from their positions in the HR diagram according to their core masses and central star temperatures. If this method of mass (and luminosity) determination turns out to be accurate, we can bypass the extremely unreliable estimates for distances, and will be able to derive other physical properties of planetary nebulae.

scholarly journals The Remarkable Evolution of the Post-Agb Star FG SGE

1998 ◽  
Vol 11 (1) ◽  
pp. 363-363
Author(s):  
Johanna Jurcsik ◽  
Benjamin Montesinos
Keyword(s):  
Time Scales ◽  
Effective Temperature ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolutionary Models ◽  
Single Star ◽  
Line Intensities ◽  
Evolutionary Changes ◽  
Evolutionary Studies

FG Sagittae is one of the most important key objects of post-AGB stellar evolutionary studies. As a consequence of a final helium shell flash, this unique variable has shown real evolutionary changes on human time scales during this century. The observational history was reviewed in comparison with predictions from evolutionary models. The central star of the old planetary nebula (Hel-5) evolved from left to right in the HR diagram, going in just hundred years from the hot region of exciting sources of planetary nebulae to the cool red supergiant domain just before our eyes becoming a newly-born post-AGB star. The effective temperature of the star was around 50,000 K at the beginning of this century, and the last estimates in the late 1980s give 5,000-6,500 K. Recent spectroscopic observations obtained by Ingemar Lundström show definite changes in the nebular line intensities. This fact undoubtedly rules out the possibility that, instead of FG Sge, a hidden hot object would be the true central star of the nebula. Consequently, the observed evolutionary changes are connected with the evolution of a single star.

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