scholarly journals WR 72: a born-again planetary nebula with hydrogen-poor knots

2020 ◽  
Vol 492 (3) ◽  
pp. 3316-3322 ◽  
Author(s):  
V V Gvaramadze ◽  
A Y Kniazev ◽  
G Gräfener ◽  
N Langer
Keyword(s):  
Planetary Nebula ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
Wide Field ◽  
Large Telescope ◽  
Thermal Pulse ◽  
Born Again ◽  
Infrared Survey ◽  
Rare Group

ABSTRACT We report the discovery of a handful of optical hydrogen-poor (H-poor) knots in the central part of an extended infrared nebula centred on the [WO1] star WR 72, obtained by spectroscopic and imaging observations with the Southern African Large Telescope (SALT). Wide-field Infrared Survey Explorer (WISE) images of the nebula show that it is composed of an extended almost circular halo (of ≈6 arcmin or ≈2.4 pc in diameter) and an elongated and apparently bipolar inner shell (of a factor of six smaller size), within which the knots are concentrated. Our findings indicate that WR 72 is a new member of the rare group of H-poor planetary nebulae, which may be explained through a very late thermal pulse of a post-AGB star or by a merger of two white dwarfs.

scholarly journals TYC 8606-2025-1: a mild barium star surrounded by the ejecta of a very late thermal pulse

2019 ◽  
Vol 489 (4) ◽  
pp. 5136-5145 ◽  
Author(s):  
V V Gvaramadze ◽  
Yu V Pakhomov ◽  
A Y Kniazev ◽  
T A Ryabchikova ◽  
N Langer ◽  
...  
Keyword(s):  
Evolutionary Stage ◽  
Wide Field ◽  
Optical Counterpart ◽  
Large Telescope ◽  
Velocity Measurements ◽  
Thermal Pulse ◽  
Orbital Rotation ◽  
Spiral Shape ◽  
Process Elements ◽  
Infrared Survey

ABSTRACT We report the discovery of a spiral-like nebula with the Wide-field Infrared Survey Explorer and the results of optical spectroscopy of its associated star TYC 8606-2025-1 with the Southern African Large Telescope. We find that TYC 8606-2025-1 is a G8 III star of $\approx 3 \, \rm \, M_{\odot }$, showing a carbon depletion by a factor of 2 and a nitrogen enhancement by a factor of 3. We also derived an excess of s-process elements, most strongly for barium, which is a factor of 3 overabundant, indicating that TYC 8606-2025-1 is a mild barium star. We thereby add a new member to the small group of barium stars with circumstellar nebulae. Our radial velocity measurements indicate that TYC 8606-2025-1 has an unseen binary companion. The advanced evolutionary stage of TYC 8606-2025-1, together with the presence of a circumstellar nebula, implies an initial mass of the companion of also about $3 \, \rm \, M_{\odot }$. We conclude that the infrared nebula, due to its spiral shape, and because it has no optical counterpart, was ejected by the companion as a consequence of a very late thermal pulse, during about one orbital rotation.

scholarly journals Abundance Analysis of the J4 Equatorial Knot of the Born-again Planetary Nebula A30

2022 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Jordan Simpson ◽  
David Jones ◽  
Roger Wesson ◽  
Jorge García-Rojas
Keyword(s):  
Binary System ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Upper Limit ◽  
Chemical Segregation ◽  
Born Again ◽  
Physical And Chemical

Abstract A30 belongs to a class of planetary nebulae identified as “born-again”, containing dense, hydrogen-poor ejecta with extreme abundance discrepancy factors (ADFs), likely associated with a central binary system. We present intermediate-dispersion spectroscopy of one such feature—the J4 equatorial knot. We confirm the apparent physical and chemical segregation of the polar and equatorial knots observed in previous studies, and place an upper limit on the ADF for O2+ of 35, significantly lower than that of the polar knots. These findings further reinforce the theory that the equatorial and polar knots originate from different events.

scholarly journals From Planetary Nebulae to White Dwarfs: Constraints from the Asteroseismology of the Pulsating Planetary Nebula Central Star RXJ 2117+3412

2002 ◽  
Vol 185 ◽  
pp. 610-611
Author(s):  
P. Moskalik ◽  
G. Vauclair
Keyword(s):  
Planetary Nebula ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
Central Star

AbstractWe summarize the results of an asteroseismological study of the pulsating planetary nebula central star RXJ 2117+3412.

scholarly journals Degenerates with Dusty Disks: White Dwarfs and Cataclysmic Variables in the Infrared

2012 ◽  
Vol 8 (S290) ◽  
pp. 121-124
Author(s):  
D. W. Hoard
Keyword(s):  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Wide Field ◽  
Spitzer Space Telescope ◽  
Space Telescope ◽  
Infrared Observations ◽  
Compact Binaries ◽  
Dusty Disks ◽  
Infrared Survey

AbstractRecent infrared observations, particularly from the Spitzer Space Telescope and Wide-field Infrared Survey Explorer, of white dwarfs, cataclysmic variables and other interacting compact binaries, have revealed the presence of dust in many systems. I briefly review the discovery and observational properties of dust around white dwarfs and cataclysmic variables.

scholarly journals Ablation and Wind Mass-Loading in the Born-Again Planetary Nebula A 30

2011 ◽  
Vol 7 (S283) ◽  
pp. 378-379
Author(s):  
Martín A. Guerrero ◽  
You-Hua Chu ◽  
Wolf-Rainer Hamann ◽  
Lidia Oskinova ◽  
Detlef Schönberner ◽  
...  
Keyword(s):  
Stellar Wind ◽  
Planetary Nebula ◽  
Central Star ◽  
Mass Loading ◽  
Diffuse Emission ◽  
X Ray ◽  
Thermal Pulse ◽  
Born Again

AbstractWe present XMM-Newton and Chandra observations of the born-again planetary nebula A 30. These X-ray observations reveal a bright unresolved source at the position of the central star whose X-ray luminosity exceeds by far the model expectations for photospheric emission and for shocks within the stellar wind. We suggest that a “born-again hot bubble” may be responsible for this X-ray emission. Diffuse X-ray emission associated with the petal-like features and one of the H-poor knots seen in the optical is also found. The weakened emission of carbon lines in the spectrum of the diffuse emission can be interpreted as the dilution of stellar wind by mass-loading or as the detection of material ejected during a very late thermal pulse.

scholarly journals The initial/final mass relation for stellar evolution with mass loss

1981 ◽  
Vol 59 ◽  
pp. 339-344
Author(s):  
Volker Weidemann
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
White Dwarf ◽  
Empirical Data ◽  
Planetary Nebula ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
Universal Relation ◽  
Mass Relation ◽  
Theoretical Concepts

The relation between initial and final masses is discussed under consideration of changing theoretical concepts and new empirical data on masses of white dwarfs and nuclei of planetary nebulae. It is concluded that presently adopted schemes of evolution need revision, and that no universal relation exists.The strongest evidence for large amounts of mass loss during stellar evolution has been provided by the existence of white dwarfs – with masses typically of 0.6 m (m = M/Mʘ), much below the galactic turn-off masses – and by the phenomenon of planetary nebula production before a star descends into the white dwarf region.

scholarly journals Proto-Planetary Nebulae

1978 ◽  
Vol 76 ◽  
pp. 305-313 ◽  
Author(s):  
B. Zuckerman
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebula ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
Red Giants ◽  
Intermediate Mass ◽  
Gaseous Nebulae ◽  
First Time

Although rare, planetary nebulae have been extensively studied by astronomers. This affection is certainly due in part to the beauty of the gaseous nebulae but it is also due to the belief that many, probably most, stars of intermediate mass (1–4 M) become planetary nebulae at least once during their lifetimes. If the planetary nebula is an (almost) inevitable stage in stellar evolution, it is important to determine its evolutionary precursors and followers. The latter are likely to be the white dwarfs and the former are generally believed to be red giants. With the advent of infrared and radio techniques it now appears possible, for the first time, to specify the immediate progenitors of planetary nebulae.

scholarly journals Recalibrating the Wide-field Infrared Survey Explorer (WISE) W4 Filter

2014 ◽  
Vol 31 ◽  
Author(s):  
M. J. I. Brown ◽  
T. H. Jarrett ◽  
M. E. Cluver
Keyword(s):  
Response Curve ◽  
Reasonable Agreement ◽  
Planetary Nebulae ◽  
System Response ◽  
Wide Field ◽  
Effective Wavelength ◽  
Photometric Calibration ◽  
The Difference ◽  
Infrared Survey

AbstractWe present a revised effective wavelength and photometric calibration for the Wide-field Infrared Survey Explorer W4 band, including tests of empirically motivated modifications to its pre-launch laboratory-measured relative system response curve. We derived these by comparing measured W4 photometry with photometry synthesised from spectra of galaxies and planetary nebulae. The difference between measured and synthesised photometry using the pre-launch laboratory-measured W4 relative system response can be as large as 0.3 mag for galaxies and 1 mag for planetary nebulae. We find the W4 effective wavelength should be revised upward by 3.3%, from 22.1 to 22.8 μm, and the W4 AB magnitude of Vega should be revised from mW4 = 6.59 to mW4 = 6.66. In an attempt to reproduce the observed W4 photometry, we tested three modifications to the pre-launch laboratory-measured W4 relative system response curve, all of which have an effective wavelength of 22.8 μm. Of the three relative system response curve models tested, a model that matches the laboratory-measured relative system response curve, but has the wavelengths increased by 3.3% (or ≃ 0.73 μm) achieves reasonable agreement between the measured and synthesised photometry.

scholarly journals Are the Dyson rings around pulsars detectable?

2017 ◽  
Vol 17 (2) ◽  
pp. 112-115 ◽  
Author(s):  
Z. Osmanov
Keyword(s):  
Neutron Star ◽  
Solar System ◽  
Spherical Shell ◽  
Angular Resolution ◽  
Wide Field ◽  
Large Telescope ◽  
Very Large Telescope ◽  
Freeman Dyson ◽  
Infrared Survey

AbstractIn the previous paper ring (Osmanov 2016) (henceforth Paper-I) we have extended the idea of Freeman Dyson and have shown that a supercivilization has to use ring-like megastructures around pulsars instead of a spherical shell. In this work we reexamine the same problem in the observational context and we show that facilities of modern infrared (IR) telescopes (Very Large Telescope Interferometer and Wide-field Infrared Survey Explorer (WISE)) might efficiently monitor the nearby zone of the solar system and search for the IR Dyson-rings up to distances of the order of 0.2 kpc, corresponding to the current highest achievable angular resolution, 0.001 mas. In this case the total number of pulsars in the observationally reachable area is about 64 ± 21. We show that pulsars from the distance of the order of ~ 1 kpc are still visible for WISE as point-like sources but in order to confirm that the object is the neutron star, one has to use the ultraviolet telescopes, which at this moment cannot provide enough sensitivity.

scholarly journals The cooling-down central star of the planetary nebula SwSt 1: a late thermal pulse in a massive post-AGB star?

2020 ◽  
Vol 498 (1) ◽  
pp. 1205-1220
Author(s):  
Marcin Hajduk ◽  
Helge Todt ◽  
Wolf-Rainer Hamann ◽  
Karolina Borek ◽  
Peter A M van Hoof ◽  
...  
Keyword(s):  
Planetary Nebula ◽  
Central Star ◽  
Line Flux ◽  
Stellar Spectrum ◽  
Thermal Pulse ◽  
Ultraviolet Spectra ◽  
Stellar Temperature ◽  
Released Energy ◽  
Red Giant ◽  
Born Again

ABSTRACT SwSt 1 (PN G001.5-06.7) is a bright and compact planetary nebula containing a late [WC]-type central star. Previous studies suggested that the nebular and stellar lines are slowly changing with time. We studied new and archival optical and ultraviolet spectra of the object. The [O iii] 4959 and 5007 Å to H β line flux ratios decreased between about 1976 and 1997/2015. The stellar spectrum also shows changes between these epochs. We modelled the stellar and nebular spectra observed at different epochs. The analyses indicate a drop of the stellar temperature from about 42 kK to 40.5 kK between 1976 and 1993. We do not detect significant changes between 1993 and 2015. The observations show that the star performed a loop in the H–R diagram. This is possible when a shell source is activated during its post-AGB evolution. We infer that a late thermal pulse (LTP) experienced by a massive post-AGB star can explain the evolution of the central star. Such a star does not expand significantly as the result of the LTP and does not became a born-again red giant. However, the released energy can remove the tiny H envelope of the star.

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