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Asymmetric Planetary Nebulae 8e
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Asymmetric Planetary Nebulae 8e

A special issue of Galaxies (ISSN 2075-4434).

Deadline for manuscript submissions: closed (31 January 2022) | Viewed by 36585

Special Issue Editors

Dr. Martín Guerrero

E-Mail Website
Guest Editor
Instituto de Astrofísica de Andalucía, Gta. de la Astronomía, 1E-18008 Granada, Spain
Interests: X-ray astronomy; late stage stellar evolution
Prof. Noam Soker

E-Mail Website
Guest Editor
Physics, Technion University, Haifa 32000, Israel
Interests: theory; late stage stellar evolution
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Quentin A. Parker

E-Mail Website
Guest Editor
The Laboratory for Space Research and Department of Physics, The University of Hong Kong, Hong Kong, China
Interests: late stage stellar evolution; wide field surveys; astronomical instrumentation
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Below is a brief summary of the focus, scope and purpose of this Special Issue. We look forward to receiving your submissions for the production of this Special Issue.

  1. Focus: This Special Issue’s focus will be devoted to the shaping effects of stellar outflows from evolved stars in the formation of asymmetrical post-main-sequence nebulae including planetary nebulae, nebulae around massive stars, nova remnants, and symbiotic stars, via the invited and submitted talks.
  2. Scope: The scope of the meeting and, thus, the contents of this Special Issue, include three main topics which will be covered:

        1) Nebular Architecture: morphologies and dynamics across stellar mass and wavelength.

        (1) Multi-wavelength properties of planetary nebulae and related nebulae, including nebulae around evolved massive stars, symbiotic stars, nova remnants, etc.;

        (2) Morphological diversity and statistics;

        (3) Accreting and circumbinary disks: becoming closer to the launching engine of collimated outflows and jets.

        2) Nebular Sequences: time-evolving morphologies and physical structures.

        (1) Nebular evolution from the ejection time to its dilution into the Interstellar Medium(ISM);

        (2) Comparative studies between proto-PNe and Planetary Nebulae(PNe), and between pre-explosion shells and post-explosion remnants in CVs and evolved massive stars;

        (3) Transient nebulae: born-again PNe, nova shells, and other eruptive objects and transients.

        3) The Engine of the Nebular Shaping: mass-loss mechanisms and their effects on the wind’s symmetry.

        (1) Post-MS(Main-Sequence) binary interactions: wide, close, and interacting binaries, common envelopes, planets;

        (2) Magnetic fields: strength, structure, effects, statistics;

        (3) Mass-loss mechanisms: radiation pressure on dust, convection, rotation, non-radial pulsations;

        (4) Collateral effects on stellar evolution, planetary nebulae population, chemistry.

  1. Purpose of the Special Issue:

        (1) This Special Issue will bring together the contents of the meeting and capture the status of the field at this time, in some real sense, and can become an important historical record;

        (2) Special refereed conference proceedings will be well-received and used as decent reference materials by participants and others, and will lead to increased citations in the field, and for the authors;

        (3) The included reviews can be very useful;

        (4) A Special Issue raises the profile of our community, and the research we conduct.

This Special Issue will form an important historical record of a major international conference and will include up-to-date, cutting-edge research that would not normally appear in the literature until 12–18 months later, when full refereed papers are eventually produced. The community will receive a “heads-up” on important advances and thinking in a more timely manner.

Dr. Martín Guerrero
Prof. Noam Soker
Prof. Dr. Quentin A. Parker
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Galaxies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • planetary nebulae
  • nebulae around massive stars
  • nova remnants
  • symbiotic stars
  • shaping mechanisms
  • binary stars

Published Papers (18 papers)

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Editorial

Jump to: Research

3 pages, 179 KiB  
Editorial
Preface of “Asymmetric Planetary Nebulae 8e”
by Martin A. Guerrero, Quentin A. Parker and Noam Soker
Galaxies 2022, 10(4), 81; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10040081 - 08 Jul 2022
Viewed by 1077
Abstract
Planetary nebulae (PNe) are the progeny of low- and intermediate-mass stars, at the exact time in their late evolution when they eject their hydrogen-rich envelopes and start their transition towards white dwarfs [...] Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)

Research

Jump to: Editorial

10 pages, 1947 KiB  
Article
Understanding High-Energy (UV and X-ray) Emission from AGB Stars—Episodic Accretion in Binary Systems
by Raghvendra Sahai, Jorge Sanz-Forcada, Martin Guerrero, Roberto Ortiz and Carmen Sanchez Contreras
Galaxies 2022, 10(3), 62; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10030062 - 25 Apr 2022
Cited by 2 | Viewed by 1932
Abstract
X-ray surveys of UV-emitting AGB stars show that ∼40% of objects with FUV emission and GALEX FUV/NUV flux ratio Rfuv/nuv ∼> 0.2 (fuvAGB stars) have variable X-ray emission characterized by very high temperatures (Tx∼35–160 [...] Read more.
X-ray surveys of UV-emitting AGB stars show that ∼40% of objects with FUV emission and GALEX FUV/NUV flux ratio Rfuv/nuv ∼> 0.2 (fuvAGB stars) have variable X-ray emission characterized by very high temperatures (Tx∼35–160 MK) and luminosities (Lx∼0.002–0.2 L⊙), indicating the presence of accretion associated with a close binary companion. However, the UV-emitting AGB star population is dominated by objects with Rfuv/nuv ≲ 0.06 (nuvAGB stars), and we do not know whether the UV emission from these is intrinsic to the AGB star or extrinsic (i.e., due to binarity). In order to help distinguish between intrinsic and extrinsic models of the puzzling high-energy emission of cool AGB stars, we report results from two studies—(i) XMM-Newton X-observations of two nuvAGB stars, and (ii) simple chromosphere modeling. In study (i), we detect the one which has the lower FUV/NUV ratio, with a total Lx = 0.00027 L⊙, and a spectrum best fitted with a dominant component at Tx∼10 MK, most likely coronal emission from a main-sequence companion. Therefore, a significant fraction of nuvAGB stars may also be binaries with active, but weak accretion. Study (ii) shows that chromospheres with temperatures of ∼10,000 K can produce Rfuv/nuv≲0.06; higher ratios require hotter gas, implying active accretion. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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11 pages, 664 KiB  
Article
A Study of the Dusty Disks and Shells around Post-RGB Stars in the LMC
by Geetanjali Sarkar and Raghvendra Sahai
Galaxies 2022, 10(2), 56; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10020056 - 02 Apr 2022
Viewed by 1793
Abstract
A new class of dusty post-Red Giant Branch (post-RGB) stars has recently been identified in the Magellanic Clouds. Their spectral energy distributions (SEDs) suggest that their mass-ejecta are similar to dusty post-Asymptotic Giant Branch (post-AGB) stars. We modeled the SEDs of a select [...] Read more.
A new class of dusty post-Red Giant Branch (post-RGB) stars has recently been identified in the Magellanic Clouds. Their spectral energy distributions (SEDs) suggest that their mass-ejecta are similar to dusty post-Asymptotic Giant Branch (post-AGB) stars. We modeled the SEDs of a select sample of post-RGB and post-AGB stars in the Large Magellanic Cloud (LMC), quantified the total dust mass in the disks and shells and set rough constraints on the dust grain compositions and sizes. The shells were significantly more massive than the disks. Our models suggest that circumstellar disks, when present, are geometrically thick with a substantial opening angle, which is consistent with numerical simulations of CE evolution (CEE). Comparison of our model dust mass values with the predictions of dust production during CEE on the RGB suggest that CEE occurred near or at the tip of the RGB for the post-RGB sources in our sample. Amorphous silicate emission features at 10 and 18 μm are seen in the model spectra of several post-RGBs. A surprising result is that the ejected dust in certain post-RGB sources appears to be carbon-rich, thus, providing independent support for the hypothesis of binary interactions leading to the formation of dusty post-RGB objects. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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11 pages, 3591 KiB  
Article
Cylindrical Planetary Nebulae. I. Flow from an Irradiated Ring
by Vincent Icke
Galaxies 2022, 10(2), 53; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10020053 - 24 Mar 2022
Viewed by 1835
Abstract
Many bipolar nebulae with a pronounced cylindrical shape, such as Henize 3-401, show no indication whatsoever of interaction between a disk and a stellar wind, or a jet on the nebular axis. I propose that the disk that is observed at the base [...] Read more.
Many bipolar nebulae with a pronounced cylindrical shape, such as Henize 3-401, show no indication whatsoever of interaction between a disk and a stellar wind, or a jet on the nebular axis. I propose that the disk that is observed at the base of the bipolar is itself the source of the outflow. In particular, I assume that irradiation from the central star causes the disk to evaporate. I have performed numerical hydrodynamical calculations of outflows driven by evaporation of a pseudo-barotropic ring around a hot central star. The first results show that the outflow shapes are cylindrical, and the internal structures are similar to what is observed in some of these nebulae. Since shape is only the first step in the assessment of a model, synthetic observations should be made. For the moment I merely verify that the scalar quantities observed in the archetypical cylindrical nebula Hen 3-401 can be accommodated in my models. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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6 pages, 269 KiB  
Article
Millimetre Observations of Maser-Emitting Planetary Nebulae
by Lucero Uscanga, José R. Rizzo, Miguel Santander-García, José F. Gómez, Luis F. Miranda, Olga Suárez, Panayotis Boumis, Mónica I. Rodríguez, Gerardo Ramos-Larios and Roldán A. Cala
Galaxies 2022, 10(2), 48; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10020048 - 11 Mar 2022
Cited by 1 | Viewed by 1820
Abstract
Observations in the millimetre bands of maser-emitting planetary nebulae (PNe) are crucial to study their circumstellar molecular gas at the beginning of the PN phase. Maser-emitting PNe are in the earliest phases of PN formation; therefore, these sources are key objects to study [...] Read more.
Observations in the millimetre bands of maser-emitting planetary nebulae (PNe) are crucial to study their circumstellar molecular gas at the beginning of the PN phase. Maser-emitting PNe are in the earliest phases of PN formation; therefore, these sources are key objects to study the molecular content during the early evolution of PNe. These circumstellar envelopes are active sites for the formation of molecules. We present preliminary results of millimetre observations with the IRAM 30 m telescope towards one PN (IRAS 17393−2727) of a sample of five maser-emitting PNe, where we detect 12CO and 13CO lines in both J=1→0 and J=2→1 transitions. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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9 pages, 1218 KiB  
Article
M 1–92 Revisited: New Findings and Open Questions: New NOEMA Observations of Minkowski’s Footprint
by Javier Alcolea, Marcelino Agúndez, Valentín Bujarrabal, Arancha Castro-Carrizo, Jean-François Desmurs, John-Eduard Martínez-Fernández, Carmen Sánchez Contreras and Miguel Santander-García
Galaxies 2022, 10(2), 47; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10020047 - 10 Mar 2022
Viewed by 2153
Abstract
PN M 1–92, also known as Minkowski’s Footprint, is a textbook example of a massive pre-planetary nebula. It presents all the characteristics of this type of source: non-spherical symmetry (bipolar cylindrical symmetry in this case), high-velocity gas emission, large amounts of linear momentum [...] Read more.
PN M 1–92, also known as Minkowski’s Footprint, is a textbook example of a massive pre-planetary nebula. It presents all the characteristics of this type of source: non-spherical symmetry (bipolar cylindrical symmetry in this case), high-velocity gas emission, large amounts of linear momentum and kinetic energy (momentum excess), and a self-similar growing structure. We have revisited this object by performing new NOEMA observations (with half arc-second resolution) of a wealth of molecules, including the rare isotopologues of CO, as well as other less abundant species. These maps provide new insights into the origin of this source. Our findings include the discovery of molecular species in the ionised regions of the nebula, confirming its shocked origin; the structure of the massive equatorial component, including the presence of active wind collisions; and the strong evidence that the AGB evolution of the source was terminated prematurely, probably due to the huge mass loss event that resulted in the formation/acceleration of the present nebula. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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11 pages, 997 KiB  
Article
Morphologies of Wolf–Rayet Planetary Nebulae Based on IFU Observations
by Ashkbiz Danehkar
Galaxies 2022, 10(2), 45; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10020045 - 08 Mar 2022
Viewed by 2180
Abstract
Integral field unit (IFU) spectroscopy of planetary nebulae (PNe) provides a plethora of information about their morphologies and ionization structures. An IFU survey of a sample of PNe around hydrogen-deficient stars has been conducted with the Wide Field Spectrograph (WiFeS) on the ANU [...] Read more.
Integral field unit (IFU) spectroscopy of planetary nebulae (PNe) provides a plethora of information about their morphologies and ionization structures. An IFU survey of a sample of PNe around hydrogen-deficient stars has been conducted with the Wide Field Spectrograph (WiFeS) on the ANU 2.3-m telescope. In this paper, we present the Hα kinematic observations of the PN M 2-42 with a weak emission-line star (wels), and the compact PNe Hen 3-1333 and Hen 2-113 around Wolf–Rayet ([WR]) stars from this WiFeS survey. We see that the ring and point-symmetric knots previously identified in the velocity [N ii] channels of M 2-42 are also surrounded by a thin exterior ionized Hα halo, whose polar expansion is apparently faster than the low-ionization knots. The velocity-resolved Hα channel maps of Hen 3-1333 and Hen 2-113 also suggest that the faint multipolar lobes may get to a projected outflow velocity of ∼100 ± 20 km s−1 far from the central stars. Our recent kinematic studies of the WiFeS/IFU survey of other PNe around [WR] and wels mostly hint at elliptical morphologies, while collimated outflows are present in many of them. As the WiFeS does not have adequate resolution for compact (≤6 arcsec) PNe, future high-resolution spatially-resolved observations are necessary to unveil full details of their morpho-kinematic structures. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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9 pages, 3167 KiB  
Article
Further Studies of the Association of Planetary Nebula BMP J16135406 with Galactic Open Cluster NGC 6067
by Vasiliki Fragkou, Quentin A. Parker, Albert A. Zijlstra, Lisa Crause, Laurence Sabin and Roberto Vázquez
Galaxies 2022, 10(2), 44; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10020044 - 07 Mar 2022
Cited by 1 | Viewed by 2073
Abstract
Planetary Nebulae (PNe) that are physical members of Galactic open clusters are powerful probes that allow precise determination of their distance and crucially their initial mass on the main sequence. Here, we revisit the physical association of the PN BMP J1613–5406 with the [...] Read more.
Planetary Nebulae (PNe) that are physical members of Galactic open clusters are powerful probes that allow precise determination of their distance and crucially their initial mass on the main sequence. Here, we revisit the physical association of the PN BMP J1613–5406 with the open cluster NGC 6067 and present our preliminary results based on our new ESO/VLT FORS2 data. Our PN spectral data permit the calculation of a precise radial velocity and reddening to the PN that shows a tight consistency with the literature corresponding cluster parameters including importantly the radial velocity. Our measurements, combined with the agreement between the distances of the two objects and the fact that the PN is located well within the cluster boundaries, confirm that the PN is physically associated with the cluster. The cluster has a turn-off mass of around 5 solar masses that indicates a PN initial mass of around 5.6 solar masses. This is closer to the theoretical lower limit of core-collapse supernova formation than has ever been previously observed, providing a unique opportunity for further stellar and Galactic chemical evolution studies using this system. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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10 pages, 8583 KiB  
Article
Follow-Up of Extended Shells around B[e] Stars
by Tiina Liimets, Michaela Kraus, Alexei Moiseev, Nicolas Duronea, Lydia Sonia Cidale and Cecilia Fariña
Galaxies 2022, 10(2), 41; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10020041 - 01 Mar 2022
Cited by 8 | Viewed by 2325
Abstract
B[e] stars are massive B type emission line stars in different evolutionary stages ranging from pre-main sequence to post-main sequence. Due to their mass loss and ejection events these objects deposit huge amounts of mass and energy into their environment and enrich it [...] Read more.
B[e] stars are massive B type emission line stars in different evolutionary stages ranging from pre-main sequence to post-main sequence. Due to their mass loss and ejection events these objects deposit huge amounts of mass and energy into their environment and enrich it with chemically processed material, contributing significantly to the chemical and dynamical evolution of their host galaxies. However, the large-scale environments of these enigmatic objects have not attracted much attention. The first and so far only catalog reporting the detection of extended shells around a sample of B[e] stars was an Hα imaging survey carried out in the year 2001, and was limited to bright targets in the northern hemisphere. We have recently started a follow-up of those targets to detect possible evolution of their nebulae in the plane of the sky over a baseline of two decades. Furthermore, we extend our survey to southern targets and fainter northern ones to complement and complete our knowledge on large-scale ejecta surrounding B[e] stars. Besides imaging in Hα and selected nebular lines, we utilize long-slit and 3D spectral observations across the nebulae to derive their physical properties. We discovered pronounced nebula structures around 15 more objects, resulting in a total of 27 B[e] stars with a large-scale nebula. Here we present our (preliminary) results for three selected objects: the two massive supergiants MWC137 and MWC 314, and the unclassified B[e] star MWC 819. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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12 pages, 15851 KiB  
Article
Ionization-Gasdynamic Simulations of Wind-Blown Nebulae around Massive Stars
by Vikram V. Dwarkadas
Galaxies 2022, 10(1), 37; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10010037 - 17 Feb 2022
Cited by 6 | Viewed by 2184
Abstract
Using a code that employs a self-consistent method for computing the effects of photo-ionization on circumstellar gas dynamics, we model the formation of wind-driven nebulae around massive stars. We take into account changes in stellar properties and mass-loss over the star’s evolution. Our [...] Read more.
Using a code that employs a self-consistent method for computing the effects of photo-ionization on circumstellar gas dynamics, we model the formation of wind-driven nebulae around massive stars. We take into account changes in stellar properties and mass-loss over the star’s evolution. Our simulations show how various properties, such as the density and ionization fraction, change throughout the evolution of the star. The multi-dimensional simulations reveal the presence of strong ionization front instabilities in the main-sequence phase, similar to those seen in galactic ionization fronts. Hydrodynamic instabilities at the interfaces lead to the formation of filaments and clumps that are continually being stripped off and mixed with the low density interior. Even though the winds start out as completely radial, the spherical symmetry is quickly destroyed, and the shocked wind region is manifestly asymmetrical. The simulations demonstrate that it is important to include the effects of the photoionizing photons from the star, and simulations that do not include this may fail to reproduce the observed density profile and ionization structure of wind-blown bubbles around massive stars. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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9 pages, 1405 KiB  
Article
DEATHSTAR—CO Envelope Size and Asymmetry of Nearby AGB Stars
by Miora Andriantsaralaza, Wouter Vlemmings, Sofia Ramstedt and Elvire De Beck
Galaxies 2022, 10(1), 33; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10010033 - 12 Feb 2022
Viewed by 2284
Abstract
Low- and intermediate-mass stars evolve into asymptotic giant branch (AGB) stars near the end of their lives, losing mass through slow and massive winds. The ejected material creates a chemically-rich expanding envelope around the star, namely the circumstellar envelope (CSE). Investigating the anisotropy [...] Read more.
Low- and intermediate-mass stars evolve into asymptotic giant branch (AGB) stars near the end of their lives, losing mass through slow and massive winds. The ejected material creates a chemically-rich expanding envelope around the star, namely the circumstellar envelope (CSE). Investigating the anisotropy of the mass-loss phenomenon on the AGB is crucial in gaining a better understanding of the shaping of the CSE during the transition from AGB star to planetary nebula (PN). We investigate possible signs of deviation from spherical symmetry in the CO-emitting CSEs of 70 AGB stars by analysing their emission maps in CO J=2−1 and 3−2 observed with the Atacama Compact Array, as part of the DEATHSTAR project. We find that about one third of the sources are likely aspherical, as they exhibit large-scale asymmetries that are unlikely to have been created by a smooth wind. Further high-resolution observations would be necessary to investigate the nature of, and the physical processes behind, these asymmetrical structures. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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7 pages, 3285 KiB  
Article
A Preliminary Investigation of CSPN in the HASH Database
by Quentin A. Parker, Zou Xiang and Andreas Ritter
Galaxies 2022, 10(1), 32; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10010032 - 11 Feb 2022
Cited by 7 | Viewed by 2178
Abstract
We present some preliminary findings on the population of planetary nebula where central stars (CSPN) have been independently identified in the HASH catalogue. Many new discoveries and candidates have been found (416 at the time of this writing), adding significantly to the previously [...] Read more.
We present some preliminary findings on the population of planetary nebula where central stars (CSPN) have been independently identified in the HASH catalogue. Many new discoveries and candidates have been found (416 at the time of this writing), adding significantly to the previously known sample of about 600. We also present results from a comparison between our own HASH measurements of CSPN and those provided in existing CSPN catalogues and those from Gaia. We show the value of a federated, multi-wavelength database of Galactic PNe like HASH in terms of not only uncovering faint, new CSPN but of assisting in correct identifications, removing PN mimics with apparent CSPN, correcting incorrect assignments and providing improved positions. HASH provides the community with a comprehensive and reliable resource for any study of the CSPN population of Galactic PNe. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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8 pages, 365 KiB  
Article
Plasma Diagnostics in the Era of Integral Field Spectroscopy
by Toshiya Ueta
Galaxies 2022, 10(1), 30; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10010030 - 08 Feb 2022
Cited by 2 | Viewed by 1638
Abstract
To understand the physical conditions of various gaseous systems, plasma diagnostics must be performed properly. To that end, it is equally important to have extinction correction performed properly, even before performing plasma diagnostics. This means that the physical conditions of the target sources—the [...] Read more.
To understand the physical conditions of various gaseous systems, plasma diagnostics must be performed properly. To that end, it is equally important to have extinction correction performed properly, even before performing plasma diagnostics. This means that the physical conditions of the target sources—the very quantities to be derived via plasma diagnostics—must be known even before performing extinction correction, because the degree of extinction is determined by comparing the observed spectra of the target sources with their theoretically predicted counterparts. One way to resolve this conundrum is to perform both extinction correction and plasma diagnostics together by iteratively seeking a converged solution. In fact, if these analyses are performed self-consistently, a converged solution can be found based solely on well-calibrated line intensities, given the adopted extinction law and the RV value. However, it is still rare to find these analyses performed numerically rigorously without unnecessary analytical approximations from start to finish. In this contribution for the APN 8e conference, we would like to review this convoluted problem and sort out critical issues based on the results of our recent experiments. It appears that the convoluted theoretical and observational progresses exacerbated by the highly numerical nature of these analyses necessitated a number of analytical simplifications to make the problem analytically tractable in the pre-computer era and that such analytical simplifications still remain rampant in the literature today, even after ample computational resources became readily available. Hence, the community is encouraged to do away with this old habit of sidestepping numerical calculations that was a necessary evil in the past. This is especially true in the context of spatially-resolved 2-D spectroscopy, which obviously conflicts with the uniformity assumption often blindly inherited from 1-D spectroscopy. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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9 pages, 3114 KiB  
Article
SATELLITE: Application to Planetary Nebulae IFU Data
by Stavros Akras, Hektor Monteiro, Jeremy R. Walsh, Isabel Aleman, Denise R. Gonçalves and Panayotis Boumis
Galaxies 2022, 10(1), 27; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10010027 - 01 Feb 2022
Cited by 1 | Viewed by 1886
Abstract
The integral field unit (IFU) spectroscopic view of extended ionized nebulae, such as planetary nebulae (PNe), H II regions, and galaxies, has changed the approach of studying these objects, providing a simultaneous characterization in both spatial directions. However, the spatial spaxel-by-spaxel analysis of [...] Read more.
The integral field unit (IFU) spectroscopic view of extended ionized nebulae, such as planetary nebulae (PNe), H II regions, and galaxies, has changed the approach of studying these objects, providing a simultaneous characterization in both spatial directions. However, the spatial spaxel-by-spaxel analysis of such nebulae through IFUs is not directly comparable with the results obtained from the traditional slit-aperture spectroscopy or the predictions from 1D modelling. The new Python software called “satellite: Spectroscopic Analysis Tool for intEgraL fieLd unIt daTacubEs” is used in the analysis of the VIMOS and MUSE datacubes of four Galactic PNe. The 2D analysis of line ratio maps has shown important variations from one to another nebular component in NGC 7009 and NGC 6778. In particular, the knots in both PNe are characterized by strong emission from neutral gas that is weak or even absent from the main nebula, indicating significant variation in the ionization state and density structure among the nebular components. The far-UV radiation from the central star results in the photo-evaporation of the dense molecular knots resembling the spectrum of photodissociation regions. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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7 pages, 348 KiB  
Article
Lessons from the Ionised and Molecular Mass of Post-CE PNe
by Miguel Santander-García, David Jones, Javier Alcolea, Valentín Bujarrabal and Roger Wesson
Galaxies 2022, 10(1), 26; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10010026 - 01 Feb 2022
Viewed by 1821
Abstract
Close binary evolution is widely invoked to explain the formation of axisymmetric planetary nebulae after a brief common envelope phase. The evolution of the primary would be interrupted abruptly, its still quite massive envelope being fully ejected to form the PN, which should [...] Read more.
Close binary evolution is widely invoked to explain the formation of axisymmetric planetary nebulae after a brief common envelope phase. The evolution of the primary would be interrupted abruptly, its still quite massive envelope being fully ejected to form the PN, which should be more massive than a planetary nebula coming from the same star, were it single. We test this hypothesis by investigating the ionised and molecular masses of a sample consisting of 21 post-common-envelope planetary nebulae, roughly one-fifth of their known total population, and comparing them to a large sample of regular planetary nebulae (not known to host close-binaries). We find that post-common-envelope planetary nebulae arising from single-degenerate systems are, on average, neither more nor less massive than regular planetary nebulae, whereas post-common-envelope planetary nebulae arising from double-degenerate systems are considerably more massive and show substantially larger linear momenta and kinetic energy than the rest. The reconstruction of the common envelope of four objects further suggests that the mass of single-degenerate nebulae actually amounts to a very small fraction of the envelope of their progenitor stars. This leads to the uncomfortable question of where the rest of the envelope is, raising serious doubts on our understanding of these intriguing objects. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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8 pages, 469 KiB  
Article
A Tail of Two Clumps
by Alejandro Cristian Raga, Jorge Cantó, Antonio Castellanos-Ramírez, Jorge Ivan Castorena, Liliana Hernández-Martínez, Ary Rodríguez-González and Pedro Rivera-Ortíz
Galaxies 2022, 10(1), 19; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10010019 - 21 Jan 2022
Cited by 1 | Viewed by 1726
Abstract
We present two axisymmetric simulations of a high velocity clump in a photoionized region: one for the case of a uniform, low density environment and a second one for the case of a clump first traveling within a high density medium and then [...] Read more.
We present two axisymmetric simulations of a high velocity clump in a photoionized region: one for the case of a uniform, low density environment and a second one for the case of a clump first traveling within a high density medium and then emerging into a low density environment. We show that the second scenario results in the production of an axial tail of dense material with a linear velocity vs. position ramp (with zero velocity at the high/low density environment transition). This material comes from a confined bow shock (produced by the clump when it was within the dense cloud) that emerges into the low environmental density region. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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10 pages, 3090 KiB  
Article
Studying Nearby Galactic Planetary Nebulae with MUSE: On the Physical Properties of IC 418
by Ana Monreal-Ibero  and Jeremy R. Walsh
Galaxies 2022, 10(1), 18; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10010018 - 19 Jan 2022
Cited by 1 | Viewed by 2099
Abstract
Spectroscopic mapping of planetary nebulae (PNe) is particularly useful to capture the richness in terms of physical and chemical properties that exist in these objects. The advent of the multi-unit spectroscopic explorer (MUSE), a large integral field unit mounted on the ESO Very [...] Read more.
Spectroscopic mapping of planetary nebulae (PNe) is particularly useful to capture the richness in terms of physical and chemical properties that exist in these objects. The advent of the multi-unit spectroscopic explorer (MUSE), a large integral field unit mounted on the ESO Very Large Telescope, allow us to obtain this information over the whole face of galactic PNe in a reasonable amount of time. This in turn reveals a wealth of information that can bring insight into this structural complexity. Here we discuss new results from commissioning data for the physical properties of IC 418 and succinctly review recently published results on two additional targets (NGC 3132 and NGC 7009). For the newly-analysed PN, electron densities are high with ne([S ii]) displaying a completely different structure than ne([Cl iii]). The electron temperature was relatively uniform, but somewhat higher at the rim as measured by two of the three used diagnostics ([S iii] 6312/9069, and [Ar iii] 5192/7136). The joint results for the three PNe amply illustrate the potential of MUSE for the study of galactic PNe. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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11 pages, 47827 KiB  
Article
Numerical Study of Colliding Winds in Massive Stars
by Amit Kashi and Amir Michaelis
Galaxies 2022, 10(1), 4; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies10010004 - 28 Dec 2021
Cited by 4 | Viewed by 1825
Abstract
We run a numerical experiment ejecting stellar winds in a very massive binary system measuring the properties of the resulting colliding wind structure and accreted mass onto the companion under different conditions. Colliding massive binaries interact and create a colliding wind structure with [...] Read more.
We run a numerical experiment ejecting stellar winds in a very massive binary system measuring the properties of the resulting colliding wind structure and accreted mass onto the companion under different conditions. Colliding massive binaries interact and create a colliding wind structure with a shape that depends on the momentum ratio, orbital motion, distance between the stars, and other factors. We run simulations of a static LBV-WR binary and in each simulation abruptly varying the mass loss rate of the LBV from the fiducial value. The modified wind front propagates and interacts with the previous colliding wind structure, and modifies its shape. We calculate the emitted X-ray from the interaction and investigate the proprieties of the new shape. We derive the mass accretion rate onto the secondary, and find that it depends on the momentum ratio of the winds. We then add orbital velocity that reduces the mass accretion rate, a similar behaviour as the analytical estimates based on modified Bondi–Hoyle–Lyttleton. Creating a large set of simulations like those presented here can allow constraining parameters for specific colliding wind binaries and derive their stellar parameters and orbital solution. Full article
(This article belongs to the Special Issue Asymmetric Planetary Nebulae 8e)
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