Explanipedia

Exploring circumstellar chemistry in X-ray emitting AGB stars Open

J. Alonso-Hernández, C. Sánchez Contreras, M. Agúndez, R. Sahai, J. P. Fonfría , et al. · 2025

Aims . Our goal is to characterise the chemistry and physical conditions of the circumstellar envelopes (CSEs) of Asymptotic Giant Branch (AGB) binary candidate stars with UV-excess and X-ray emission. In particular, our aim is to identify…

Testing the bloated star hypothesis in the massive young stellar object IRAS 19520+2759 through optical and infrared variability Open

R. Pandey, Aina Palau, Javier Serna, R. Kuiper, Á. Sánchez-Monge , et al. · 2025

Using optical time series with Telescopi Joan Oró (TJO), Gaia, TESS, and NEOWISE archival data, we performed a variability study on the candidate bloated massive young stellar object (MYSO) IRAS 19520+2759. This is the first time that a bl…

ALMA observations of CO isotopologues towards six obscured post-asymptotic giant branch stars Open

T. Khouri, Daniel Tafoya, W. H. T. Vlemmings, H. Olofsson, C. Sánchez Contreras , et al. · 2025

Context. Low- and intermediate-mass stars evolve through the asymptotic giant branch (AGB) when an efficient mass-loss process removes a significant fraction of their initial mass. For most sources, this mass-loss process relies on the int…

ALMA observations of CO isotopologues towards six obscured post-AGB stars Open

T. Khouri, Daniel Tafoya, W. H. T. Vlemmings, H. Olofsson, C. Sánchez Contreras , et al. · 2025

Low- and intermediate-mass stars evolve through the asymptotic giant branch (AGB), when an efficient mass-loss process removes a significant fraction of their initial mass. A substantial increase in the mass-loss rate at the end of the AGB…

CO emission survey of asymptotic giant branch stars with ultraviolet excesses <i>(Corrigendum)</i> Open

J. Alonso-Hernández, C. Sánchez Contreras, R. Sahai · 2024

Uncovering the structure and kinematics of the ionized core of M 2-9 with ALMA Open

C. Sánchez Contreras, Daniel Tafoya, J. P. Fonfría, J. Alcolea, A. Castro‐Carrizo , et al. · 2024

We present interferometric observations at 1 and 3 mm with the Atacama Large Millimeter Array (ALMA) of the free-free continuum and millimeter(mm)-wavelength recombination line (mRRL) emission of the ionized core (within ≲130 au) of the yo…

The 17O/18O Ratio of Post-AGB Sources: Canonical and Non-Canonical Populations Open

J. Alcolea, Elisa Masa, T. Khouri, M. Santander-García, I. Gallardo Cava , et al. · 2024

Stellar evolution models serve as tools to derive stellar parameters from elemental and isotopic abundance ratios. For low-to-intermediate mass evolved stars, C/O, 12C/13C, and 17O/18O ratios are proxies of the initial mass, a largely unkn…

Exploring the Ionized Core of the Proto-Planetary Nebula CRL 618 and Its Vicinity with ALMA Open

J. P. Fonfría, C. Sánchez Contreras, Daniel Tafoya, P. Fernández-Ruiz, A. Castro‐Carrizo , et al. · 2024

Proto- and young planetary nebulae comprise dense circumstellar envelopes made of molecular gas and dust, some of which hide compact ionized cores that host stellar systems with hot objects, and show high-velocity bipolar outflows launched…

M 1-92: The Death of an AGB Star Told by Its Isotopic Ratios Open

Elisa Masa, J. Alcolea, M. Santander-García, V. Bujarrabal, C. Sánchez Contreras , et al. · 2024

Ongoing improvements in the sensitivity of sub-mm- and mm-range interferometers and single-dish radio telescopes allow for the increasingly detailed study of AGB and post-AGB objects in molecular species other than CO12 and CO13. With a ne…

High-Speed Outflows and Dusty Disks during the AGB to PN Transition: The PANORAMA survey Open

Raghvendra Sahai, J. Alcolea, Bruce Balick, Eric G. Blackman, V. Bujarrabal , et al. · 2024

As mass-losing asymptotic giant branch (AGB) stars evolve to planetary nebulae (PNe), the mass outflow geometries transform from nearly spherical to extreme aspherical. The physical mechanisms governing this transformation are widely belie…

CO emission survey of asymptotic giant branch stars with ultraviolet excesses Open

J. Alonso-Hernández, C. Sánchez Contreras, R. Sahai · 2024

Context . The transition from the spherically symmetric envelopes around asymptotic giant branch (AGB) stars to the asymmetric morphologies observed in planetary nebulae is still not well understood, and the shaping mechanisms are a subjec…

CO emission survey of asymptotic giant branch stars with ultraviolet excesses Open

Jaime Alonso-Hernández, C. Sánchez Contreras, R. Sahai · 2024

Context. The transition from the spherically symmetric envelopes around asymptotic giant branch (AGB) stars to the asymmetric morphologies observed in planetary nebulae is still not well understood, and the shaping mechanisms are a subject…

Zooming on the emerging ionized regions of pPNe with ALMA Open

C. Sánchez Contreras, Daniel Tafoya, J. P. Fonfría, J. Alcolea, A. Castro‐Carrizo , et al. · 2023

We report on recent results from our successful and pioneering observational program with ALMA to study emerging ultracom pact HII regions of pre-Planetary Nebulae (pPNe) using mm-wavelength recombination lines (mRRLs) as new optimal trace…

High-Speed Outflows and Dusty Disks during the AGB to PN Transition: The PANORAMA survey Open

R. Sahai, J. Alcolea, Bruce Balick, Eric G. Blackman, V. Bujarrabal , et al. · 2023

As AGB stars evolve to planetary nebulae (PNe), the geometry of the ejected mass transforms from nearly spherical to extremely aspherical. The mechanisms governing this transformation are plausibly linked to binarity and the associated pro…

The Red Rectangle: a thin disk with big grains Open

J. Alcolea, V. Bujarrabal, A. Castro‐Carrizo, J. Kluska, C. Sánchez Contreras , et al. · 2023

The Red Rectangle is a nebula surrounding the post-AGB star HD 44179. It is the prototype of a particular class of nebulae associated with post-AGB binaries characterised by the presence of stable circumbinary disks in (quasi-)Keplerian ro…

The very compact dust disk in the Red Rectangle Open

V. Bujarrabal, J. Alcolea, A. Castro‐Carrizo, J. Kluska, C. Sánchez Contreras , et al. · 2023

We aim to study the dust distribution in the central regions of the Keplerian disk of the Red Rectangle, the prototype of binary post-AGB stars with rotating circumbinary disks, and to compare it with the distribution of relevant molecular…

The very compact dust disk in the Red Rectangle Open

V. Bujarrabal, J. Alcolea, A. Castro‐Carrizo, J. Kluska, C. Sánchez Contreras , et al. · 2023

Aims. We aim to study the dust distribution in the central regions of the Keplerian disk of the Red Rectangle, the prototype of binary post-AGB stars with rotating circumbinary disks, and to compare it with the distribution of relevant mol…

The Binary and the Disk: The Beauty is Found within NGC3132 with JWST Open

R. Sahai, V. Bujarrabal, G. Quintana-Lacaci, Nicole Reindl, G. C. Van de Steene , et al. · 2023

The planetary nebula (PN) NGC 3132 is a striking example of the dramatic but poorly understood mass-loss phenomena that (1–8) M ⊙ stars undergo during their death throes as they evolve into white dwarfs (WDs). From an analysis of JWST mult…

The messy death of a multiple star system and the resulting planetary nebula as observed by JWST Open

Orsola De Marco, Muhammad Akashi, S. Akras, J. Alcolea, Isabel Aleman , et al. · 2023

Planetary nebulae (PNe), the ejected envelopes of red giant stars, provide us with a history of the last, mass-losing phases of 90 percent of stars initially more massive than the Sun. Here, we analyse James Webb Space Telescope (JWST) Ear…

Author Correction: The messy death of a multiple star system and the resulting planetary nebula as observed by JWST Open

Orsola De Marco, Muhammad Akashi, S. Akras, J. Alcolea, Isabel Aleman , et al. · 2023

The messy death of a multiple star system and the resulting planetary nebula as observed by JWST Open

Orsola De Marco, Muhammad Akashi, S. Akras, J. Alcolea, Isabel Aleman , et al. · 2022

The binary and the disk: the beauty is found within NGC3132 with JWST Open

R. Sahai, V. Bujarrabal, G. Quintana-Lacaci, Nicole Reindl, G. C. Van de Steene , et al. · 2022

The planetary nebula (PN) NGC3132 is a striking example of the dramatic but poorly understood, mass-loss phenomena that (1-8) Msun stars undergo during their death throes as they evolve into white dwarfs (WDs). From an analysis of JWST mul…

Dissecting the central regions of OH 231.8+4.2 with ALMA: A salty rotating disk at the base of a young bipolar outflow Open

C. Sánchez Contreras, J. Alcolea, Ramón Rodríguez-Cardoso, V. Bujarrabal, A. Castro‐Carrizo , et al. · 2022

We present a set of Atacama Large Millimeter/submillimeter Array (ALMA) continuum and molecular line emission maps at ~1 mm wavelengths of OH 231.8+4.2. This is a well studied bipolar nebula around an asymptotic giant branch (AGB) star tha…

Understanding High-Energy (UV and X-ray) Emission from AGB Stars—Episodic Accretion in Binary Systems Open

R. Sahai, J. Sanz‐Forcada, M. A. Guerrero, R. Ortiz, C. Sánchez Contreras · 2022

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 luminosi…

M 1–92 Revisited: New Findings and Open Questions: New NOEMA Observations of Minkowski’s Footprint Open

J. Alcolea, M. Agúndez, V. Bujarrabal, A. Castro‐Carrizo, J. F. Desmurs , et al. · 2022

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-v…

Observational identification of a sample of likely recent common-envelope events Open

T. Khouri, W. H. T. Vlemmings, Daniel Tafoya, A. F. Pérez-Sánchez, C. Sánchez Contreras , et al. · 2021

Formation and Evolution of Circumstellar and Interstellar PAHs: A Laboratory Study Open

C. Sánchez Contreras, C. L. Ricketts, F. Salama · 2020

Formation and Evolution of Circumstellar and Interstellar PAHs: A Laboratory Study Open

C. Sánchez Contreras, C. L. Ricketts, F. Salama · 2020

Studies of dust analogs formed from hydrocarbon (CH4, C2H2, C2H4, C2H6) and PAH precursors have been performed using a new facility that we have developed to simulate interstellar and circumstellar processes.The species formed in a plasma …

Accretion-powered Outflows in AGB Stars Open

R. Sahai, J. Sanz‐Forcada, C. Sánchez Contreras · 2020

One of the big challenges for 21st century stellar astrophysics is the impact of binary interactions on stellar evolution. Such interactions are believed to play a key role in the death throes of 1-8 M ⊙ stars, as they evolve from the AGB …

ALMA (finally!) discloses a rotating disk+bipolar wind system at the centre of the wind-prominent pPN OH 231.8+4.2 Open

C. Sánchez Contreras, J. Alcolea, Ramón Rodríguez-Cardoso, V. Bujarrabal, A. Castro‐Carrizo , et al. · 2020

We present interferometric continuum and molecular line emission maps obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) of OH231.8+4.2, a well studied bipolar nebula around an asymptotic giant branch (AGB) star that is …

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