Roldán A. Cala
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View article: Low- and high-velocity “water fountains”: Different evolutionary stages
Low- and high-velocity “water fountains”: Different evolutionary stages Open
“Water fountains” (WFs) are optically obscured evolved stars. Most of them are thought to be in the post-asymptotic giant branch (post-AGB) phase, and they are characterized by H 2 O maser emission tracing molecular jets. Interestingly, fo…
View article: Identification and characterization of nascent planetary nebulae with OH and H <sub>2</sub> O masers
Identification and characterization of nascent planetary nebulae with OH and H <sub>2</sub> O masers Open
Stars such as the Sun expel their outer layers and form planetary nebulae (PNe) as they evolve into white dwarfs. PNe exhibit diverse morphologies, the origins of which are not fully understood. PNe with OH (OHPNe) and H 2 O (H 2 OPNe) mas…
View article: Low- and high-velocity `water fountains': different evolutionary stages
Low- and high-velocity `water fountains': different evolutionary stages Open
`Water fountains' (WFs) are optically obscured evolved stars, most of them thought to be in the post-asymptotic giant branch (post-AGB) phase, characterized by H$_{2}$O maser emission tracing molecular jets. Interestingly, four WFs (IRAS 1…
View article: Identification and characterization of nascent planetary nebulae with OH and H$_2$O masers
Identification and characterization of nascent planetary nebulae with OH and H$_2$O masers Open
Stars like the Sun expel their outer layers and form planetary nebulae (PNe) as they evolve into white dwarfs. PNe exhibit diverse morphologies, the origins of which are not fully understood. PNe with OH (OHPNe) and H$_{2}$O (H$_{2}$OPNe) …
View article: An interferometric search for SiO maser emission in planetary nebulae
An interferometric search for SiO maser emission in planetary nebulae Open
Maser emission of SiO, H$_2$O and, OH is widespread in Asymptotic Giant Branch (AGB) stars with oxygen(O)-rich envelopes. This emission quickly disappear during the post-AGB phase and is extremely rare in planetary nebulae (PN). So far, on…
View article: An interferometric search for SiO maser emission in planetary nebulae
An interferometric search for SiO maser emission in planetary nebulae Open
Context. Maser emission of SiO, H 2 O, and OH is widespread in asymptotic giant branch (AGB) stars with oxygen- (O-) rich envelopes. This emission quickly disappears during the post-AGB phase and is extremely rare in planetary nebulae (PNe…
View article: Long- and short-term variability of the possible nascent planetary nebula IRAS 22568+6141: A late thermal pulse?
Long- and short-term variability of the possible nascent planetary nebula IRAS 22568+6141: A late thermal pulse? Open
IRAS 22568+6141 has been classified as a low-excitation planetary nebula (PN) and presents non-thermal radio continuum emission, which could be a signature of a nascent PNe. We present intermediate-resolution long-slit spectra obtained in …
View article: Long and short term variability of the possible nascent planetary nebula IRAS 22568+6141: A late thermal pulse?
Long and short term variability of the possible nascent planetary nebula IRAS 22568+6141: A late thermal pulse? Open
IRAS 22568+6141 has been classified as a low-ionisation planetary nebula (PN) and presents non-thermal radio continuum emission, which could be a signature of nascent PNe. We present intermediate-resolution long-slit spectra obtained in 20…
View article: Dual chemistry, high ADF and internal kinematics of the planetary nebula Vy 2-2
Dual chemistry, high ADF and internal kinematics of the planetary nebula Vy 2-2 Open
OH masers are signpost of planetary nebulae (PNe) at a very young stage. In particular, Vy 2-2 was the first OH maser-emitting PN ever identified. It consists of a bright compact shell and a faint bipolar structure. The reported values for…
View article: A sensitive search for SiO maser emission in planetary nebulae
A sensitive search for SiO maser emission in planetary nebulae Open
Eight planetary nebulae (PNe) are known to emit OH and/or H 2 O masers, but there is no report of an SiO maser in this type of objects. We present a search for SiO masers in 16 confirmed and candidate PNe, carried out with the Australia Te…
View article: Nascent planetary nebulae: new identifications and extraordinary evolution
Nascent planetary nebulae: new identifications and extraordinary evolution Open
Planetary nebulae (PNe) harbouring masers of H 2 O (H 2 OPNe) and/or OH (OHPNe) are thought to be nascent PNe. They are extremely scarce, and so far only eight members are know to date. Here we explain our current effort to identify new H …
View article: Searching for nascent planetary nebulae: OHPNe candidates in the SPLASH survey
Searching for nascent planetary nebulae: OHPNe candidates in the SPLASH survey Open
The evolution of asymptotic giant branch stars from the spherical symmetry into the diverse shapes of planetary nebulae (PNe) is a topic of intensive research. Young PNe provide a unique opportunity to characterize the onset of this transi…
View article: Searching for nascent planetary nebulae: OHPNe candidates in the SPLASH survey
Searching for nascent planetary nebulae: OHPNe candidates in the SPLASH survey Open
The evolution of asymptotic giant branch stars from the spherical symmetry into the diverse shapes of planetary nebulae (PNe) is a topic of intensive research. Young PNe provide a unique opportunity to characterize the onset of this transi…
View article: Millimetre Observations of Maser-Emitting Planetary Nebulae
Millimetre Observations of Maser-Emitting Planetary Nebulae Open
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; therefor…