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 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.

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.

REBIRTH OF X-RAY EMISSION FROM THE BORN-AGAIN PLANETARY NEBULA A30

2012 ◽  
Vol 755 (2) ◽  
pp. 129 ◽  
Author(s):  
M. A. Guerrero ◽  
N. Ruiz ◽  
W.-R. Hamann ◽  
Y.-H. Chu ◽  
H. Todt ◽  
...  
Keyword(s):  
Planetary Nebula ◽  
X Ray ◽  
Born Again

scholarly journals Sakurai's object: spectroscopic monitoring and nebula observations

1997 ◽  
Vol 180 ◽  
pp. 392-392
Author(s):  
D. L. Pollacco ◽  
N.A. Walton ◽  
H. G. Schwarz ◽  
S. A. Bell
Keyword(s):  
Planetary Nebula ◽  
Theoretical Models ◽  
Central Star ◽  
Thermal Pulse ◽  
Spectroscopic Monitoring ◽  
Transient Events ◽  
Modern Instrumentation

Sakurai's object is thought to be undergoing a final thermal pulse or shell flash. It is the first example of this type of object to be studied using modern instrumentation and will be useful and unique for the time being for placing theoretical models of these transient events on a firm observational footing. The only other definite candidate is V605 Aql – now the WC central star of the planetary nebula Abell 58 – which is thought to have undergone a final thermal pulse around 1918.

scholarly journals The very fast evolution of Sakurai's object

2016 ◽  
Vol 12 (S323) ◽  
pp. 380-381 ◽  
Author(s):  
G. C. Van de Steene ◽  
P. A. M. van Hoof ◽  
S. Kimeswenger ◽  
A. A. Zijlstra ◽  
A. Avison ◽  
...  
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Planetary Nebula ◽  
Temporal Evolution ◽  
Optical Emission ◽  
Central Star ◽  
Evolutionary Models ◽  
Thermal Pulse ◽  
Emission Line Spectrum ◽  
Fast Evolution

AbstractV4334 Sgr (a.k.a. Sakurai's object) is the central star of an old planetary nebula that underwent a very late thermal pulse a few years before its discovery in 1996. We have been monitoring the evolution of the optical emission line spectrum since 2001. The goal is to improve the evolutionary models by constraining them with the temporal evolution of the central star temperature. In addition the high resolution spectral observations obtained by X-shooter and ALMA show the temporal evolution of the different morphological components.

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 XMM-Newton Detection of Extended X-ray Emission from the Saturn Nebula

2003 ◽  
Vol 209 ◽  
pp. 427-428
Author(s):  
Martín A. Guerrero ◽  
Robert A. Gruendl ◽  
You-Hua Chu
Keyword(s):  
Stellar Wind ◽  
Planetary Nebula ◽  
Emission Measure ◽  
Evolutionary Stage ◽  
Dynamic Effects ◽  
Central Cavity ◽  
Spectral Analyses ◽  
X Ray ◽  
Hot Gas ◽  
Volume Emission

XMM-Newton EPIC observations of the planetary nebula NGC 7009, the Saturn Nebula, have detected extended X-ray emission from its central cavity. The diffuse X-ray emission must originate in the shocked fast stellar wind. Spectral analyses show that the temperature of the hot gas is 1.7 x 106 K. The RMS density derived from the volume emission measure is a few tens H-atom cm-3. The hot gas does not appear over-pressurized with respect to the nebular shell. The Saturn Nebula may represent an evolutionary stage at which the dynamic effects of the hot gas in the central cavity on the cold nebular shell starts to decline due to the diminishing strength of the fast stellar wind and the expansion of the central cavity.

scholarly journals Chandra observations of the planetary nebula IC 4593

2020 ◽  
Vol 494 (3) ◽  
pp. 3784-3789
Author(s):  
J A Toalá ◽  
M A Guerrero ◽  
L Bianchi ◽  
Y-H Chu ◽  
O De Marco
Keyword(s):  
Planetary Nebula ◽  
Careful Analysis ◽  
Central Star ◽  
Stellar Atmosphere ◽  
Hot Stars ◽  
Imaging Spectrometer ◽  
Ccd Imaging ◽  
X Ray ◽  
High Ionization ◽  
Thin Plasma

ABSTRACT The Advanced CCD Imaging Spectrometer (ACIS-S) camera on board the Chandra X-ray Observatory has been used to discover a hot bubble in the planetary nebula (PN) IC 4593, the most distant PN detected by Chandra so far. The data are used to study the distribution of the X-ray-emitting gas in IC 4593 and to estimate its physical properties. The hot bubble has a radius of ∼2 arcsec and is found to be confined inside the optically bright innermost cavity of IC 4593. The X-ray emission is mostly consistent with that of an optically thin plasma with temperature kT ≈ 0.15 keV (or TX ≈ 1.7 × 106 K), electron density ne ≈ 15 cm−3, and intrinsic X-ray luminosity in the 0.3–1.5 keV energy range LX = 3.4 × 1030 erg s−1. A careful analysis of the distribution of hard (E >0.8 keV) photons in IC 4593 suggests the presence of X-ray emission from a point source likely associated with its central star (CSPN). If this was the case, its estimated X-ray luminosity would be LX, CSPN = 7 × 1029 erg s−1, fulfilling the log(LX, CSPN/Lbol) ≈ −7 relation for self-shocking winds in hot stars. The X-ray detection of the CSPN helps explain the presence of high-ionization species detected in the ultraviolet spectra as predicted by stellar atmosphere models.

Spectral manifestations of the stellar wind of the central star of a planetary nebula

Astrophysics ◽  
1989 ◽  
Vol 30 (1) ◽  
pp. 90-93
Author(s):  
A. A. Nikitin ◽  
T. Kh. Feklistova ◽  
A. F. Kholtygin
Keyword(s):  
Stellar Wind ◽  
Planetary Nebula ◽  
Central Star
Sign in / Sign up

Export Citation Format

Share Document