TY  - JOUR
A1  - Ramos-Larios, Gerardo
A1  - Toala, Jesús Alberto
A1  - Rodriguez-Gonzalez, Janis B.
A1  - Guerrero, Martin A.
A1  - Gomez-Gonzalez, Víctor Mauricio Alfonso
T1  - Rings and arcs around evolved stars - III. Physical conditions of the ring-like structures in the planetary nebula IC 4406 revealed by MUSE
JF  - Monthly notices of the Royal Astronomical Society
N2  - We present the analysis of Very Large Telescope Multi Unit Spectroscopic Explorer (MUSE) observations of the planetary nebula (PN) IC 4406. MUSE images in key emission lines are used to unveil the presence of at least five ring-like structures north and south of the main nebula of IC4406. MUSE spectra are extracted from the rings to unambiguously assess for the first time in a PN their physical conditions, electron density (n(e)), and temperature (T-e). The rings are found to have similar T-e as the rim of the main nebula, but smaller n(e). Ratios between different ionic species suggest that the rings of IC4406 have a lower ionization state than the main cavity, in contrast to what was suggested for the rings in NGC 6543, the Cat's Eye Nebula.
KW  - stars: evolution
KW  - stars: winds, outflows
KW  - planetary nebulae: general;
KW  - planetary nebulae: individual: IC4406
Y1  - 2022
SN  - 0035-8711
SN  - 1365-2966
VL  - 513
IS  - 2
SP  - 2862
EP  - 2868
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Toalá, Jesús Alberto
A1  - Ramos-Larios, Gerardo
A1  - Guerrero, Martin A.
A1  - Todt, Helge Tobias
T1  - Hidden IR structures in NGC40
BT  - Signpost of an ancient born-again event
JF  - Monthly notices of the Royal Astronomical Society
N2  - We present the analysis of infrared (IR) observations of the planetary nebula NGC40 together with spectral analysis of its [WC]-type central starHD826. Spitzer IRS observations were used to produce spectral maps centred at polycyclic aromatic hydrocarbons (PAH) bands and ionic transitions to compare their spatial distribution. The ionic lines show a clumpy distribution of material around the main cavity of NGC40, with the emission from [Ar II] being the most extended, whilst the PAHs show a rather smooth spatial distribution. Analysis of ratio maps shows the presence of a toroidal structure mainly seen in PAH emission, but also detected in a Herschel PACS 70 mu m image. We argue that the toroidal structure absorbs the UV flux from HD826, preventing the nebula to exhibit lines of high-excitation levels as suggested by previous authors. We discuss the origin of this structure and the results from the spectral analysis of HD826 under the scenario of a late thermal pulse.
KW  - stars: carbon
KW  - stars: evolution
KW  - stars: winds, outflows
KW  - ISM: molecules
KW  - planetary nebulae: individual: NGC40
KW  - infrared: ISM
Y1  - 2019
U6  - https://doi.org/10.1093/mnras/stz624
SN  - 0035-8711
SN  - 1365-2966
VL  - 485
IS  - 3
SP  - 3360
EP  - 3369
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Toala, Jesús Alberto
A1  - Guerrero, Martín A.
A1  - Todt, Helge Tobias
A1  - Hamann, Wolf-Rainer
A1  - Chu, Y.-H.
A1  - Gruendl, R. A.
A1  - Schönberner, Detlef
A1  - Oskinova, Lida
A1  - Marquez-Lugo, R. A.
A1  - Fang, X.
A1  - Ramos-Larios, Gerardo
T1  - The born-again Planetary nebula A78: an X-RAY twin of A30
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We present the XMM-Newton discovery of X-ray emission from the planetary nebula (PN) A78, the second born-again PN detected in X-rays apart from A30. These two PNe share similar spectral and morphological characteristics: they harbor diffuse soft X-ray emission associated with the interaction between the H-poor ejecta and the current fast stellar wind and a point-like source at the position of the central star (CSPN). We present the spectral analysis of the CSPN, using for the first time an NLTE code for expanding atmospheres that takes line blanketing into account for the UV and optical spectra. The wind abundances are used for the X-ray spectral analysis of the CSPN and the diffuse emission. The X-ray emission from the CSPN in A78 can be modeled by a single C VI emission line, while the X-ray emission from its diffuse component is better described by an optically thin plasma emission model with a temperature of kT = 0.088 keV (T approximate to 1.0 x 10(6) K). We estimate X-ray luminosities in the 0.2-2.0 keV energy band of L-X,L-CSPN =(1.2 +/- 0.3) x 10(31) erg s(-1) and L-X,L-DIFF =(9.2 +/- 2.3) x 10(30) erg s(-1) for the CSPN and diffuse components, respectively.
KW  - planetary nebulae: general
KW  - planetary nebulae: individual (A78)
KW  - stars: winds, outflows
KW  - X-rays: ISM
Y1  - 2015
U6  - https://doi.org/10.1088/0004-637X/799/1/67
SN  - 0004-637X
SN  - 1538-4357
VL  - 799
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -