39 citations · 127 across the 23 of their papers we have counts for
24 papers
The energetic atmosphere of the Sun
Sven Wedemeyer, Mats Kirkaune, Miroslav Barta +16
Understanding the mechanisms that heat the Sun's chromosphere and corona to temperatures far exceeding those of the solar photosphere below remains one of the central challenges in…
Detection of C Combination Bands in the Near-IR Spectrum of Tc 1
Morgan M. Giese, Vincent J. Esposito, Simon Van Schuylenbergh +26
We report the detection of a set of new near-infrared emission features between 3.5 and 5.2 m in JWST/NIRSpec observations of Tc 1, the planetary nebula known for displaying the…
ATOMIUM: Inner circumstellar envelopes of oxygen-rich AGB stars as revealed by highly excited SiO lines
B. Pimpanuwat, S. Etoka, M. D. Gray +14
Silicon monoxide (SiO) traces the physical conditions and dynamics in the circumstellar envelopes (CSEs) of AGB stars. We present high-resolution ALMA Band 6 observations of highly…
Current Unsolved Problems in Planetary Nebulae Research
Sun Kwok, Bruce Balick, You-Hua Chu +5
While there has been significant progress in our understanding of the origin and evolu-tion of planetary nebulae in the last 50 years, there remain several unsolved problems. These…
The dusty envelopes of asymptotic giant branch stars with ultraviolet excesses
Jaime Alonso-Hernández, Carmen Sánchez Contreras, Raghvendra Sahai +1
Aims. In a first study, we characterised the properties of the gas component in the circumstellar envelopes surrounding a sample of 29 AGB stars with UV excesses. Now we intend to…
Detection of CO ice in the planetary nebula NGC 6302
Charmi Bhatt, Simon W. Cao, Jan Cami +20
Using JWST/MIRI observations, we report the detection of CO ice in the dusty torus of the planetary nebula NGC 6302, an environment generally considered hostile to fragile mole…
Unveiling the First O-Type Bloated Star Candidate through ALMA and EVLA Observations
Rakesh Pandey, Aina Palau, Alvaro Sánchez-Monge +5
We investigate the circumstellar environment of the O-type bloated star candidate IRAS 19520+2759 (I19520) using high-resolution observations from the Atacama Large Millimeter/subm…
The JWST/MIRI view of the planetary nebula NGC 6302 I.: a UV irradiated torus and a hot bubble triggering PAH formation
Mikako Matsuura, Kevin Volk, Patrick Kavanagh +34
NGC 6302 is a spectacular bipolar planetary nebula (PN) whose spectrum exhibits fast outflows and highly ionized emission lines, indicating the presence of a very hot central star…
JWST observations of the Ring Nebula (NGC 6720): III. A dusty disk around its Central Star
Raghvendra Sahai, Griet Van de Steene, Peter van Hoof +16
The planetary nebula NGC 6720, also known as the ``Ring Nebula", is one of the most iconic examples of nearby planetary nebulae whose morphologies present a challenge to our theore…
Testing the bloated star hypothesis in the massive young stellar object IRAS 19520+2759 through optical and infrared variability
Rakesh Pandey, Aina Palau, Javier Serna +8
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 obje…
The Structure of the Molecular Envelope of the Ring Nebula (NGC 6720)
Joel H. Kastner, David Wilner, Diana Ryder +5
We present the first interferometric imaging of molecular line emission from the Ring Nebula, NGC~6720, in the form of Submillimeter Array (SMA) observations of CO $J=2\rightarrow…
ALMA detection of Masers and Dasars in the Hydrogen Recombination Lines of the Planetary Nebula Mz3
Z. Abraham, P. P. B. Beaklini, I. Aleman +5
The hydrogen recombination lines H30, H40, H42, H50 and H57 and the underlying bremsstrahlung continuum emission were detected with ALMA in the bipolar nebula Mz3. T…
High-Speed Outflows and Dusty Disks during the AGB to PN Transition: The PANORAMA survey
Raghvendra Sahai, Javier Alcolea, Bruce Balick +15
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 physica…
A Dust-Scattering Model for M1-92: A Revised Estimate of the Mass Distribution and Inclination
Yun Qi Li, Mark R. Morris, Raghvendra Sahai
Preplanetary nebulae (PPNe) are formed from mass-ejecting late-stage AGB stars. Much of the light from the star gets scattered or absorbed by dust particles, giving rise to the obs…
Chemical tracers of a highly eccentric AGB-main sequence star binary
T. Danilovich, J. Malfait, M. Van de Sande +32
Binary interactions have been proposed to explain a variety of circumstellar structures seen around evolved stars, including asymptotic giant branch (AGB) stars and planetary nebul…
The Molecular Exoskeleton of the Ring-like Planetary Nebula NGC 3132
Joel H. Kastner, David Wilner, Paula Moraga Baez +4
We present Submillimeter Array (SMA) mapping of CO , CO , and CN emission from the Ring-like planetary nebula (…
CO emission survey of asymptotic giant branch stars with ultraviolet excesses
Jaime Alonso-Hernández, Carmen Sánchez Contreras, Raghvendra Sahai
Context. The transition from the spherically symmetric envelopes around asymptotic giant branch (AGB) stars to the asymmetric morphologies observed in planetary nebulae is still no…
ATOMIUM: Halide molecules around the S-type AGB star W Aquilae
T. Danilovich, M. Van de Sande, J. M. C. Plane +36
S-type asymptotic giant branch (AGB) stars are thought to be intermediates in the evolution of oxygen- to carbon-rich AGB stars. The chemical compositions of their circumstellar en…
DEATHSTAR: Nearby AGB stars with the Atacama Compact Array II. CO envelope sizes and asymmetries: The S-type stars
M. Andriantsaralaza, S. Ramstedt, W. H. T. Vlemmings +13
We aim to constrain the sizes of the CO circumstellar envelopes (CSEs) of 16 S-type stars, along with an additional 7 and 4 CSEs of C-type and M-type AGB stars, respectively. We ma…
DEATHSTAR: Nearby AGB stars with the Atacama Compact Array I. CO envelope sizes and asymmetries: A new hope for accurate mass-loss-rate estimates
S. Ramstedt, W. H. T. Vlemmings, L. Doan +16
This is the first publication of the DEATHSTAR project. The goal of the project is to reduce the uncertainties of observational estimates of mass-loss rates from Asymptotic Giant B…
Binarity and Accretion in AGB Stars: HST/STIS Observations of UV Flickering in Y Gem
R. Sahai, C. Sánchez Contreras, A. Mangan +3
Binarity is believed to dramatically affect the history and geometry of mass loss in AGB and post-AGB stars, but observational evidence of binarity is sorely lacking. As part of a…
ALMA Observations of the Water Fountain Pre-Planetary Nebula IRAS 16342-3814: High-velocity bipolar jets and an Expanding Torus
R. Sahai, W. H. T. Vlemmings, T. Gledhill +4
We have mapped 12CO J=3-2 and other molecular lines from the "water-fountain" bipolar pre-planetary nebula (PPN) IRAS 16342-3814 with ~0."35 resolution using ALMA. We find (i) two…
An Extreme High-Velocity Bipolar Outflow in the Pre-Planetary Nebula IRAS 08005-2356
R. Sahai, N. A. Patel
We report interferometric mapping of the bipolar pre-planetary nebula IRAS 08005-2356 with an angular-resolution of ~1"-5", using the Submillimeter Array (SMA), in the 12CO J=2-1,…
Galactic bulge giants: probing stellar and galactic evolution I. Catalogue of Spitzer IRAC and MIPS sources
Stefan Uttenthaler, Matthias Stute, Raghvendra Sahai +5
Aims: We aim at measuring mass-loss rates and the luminosities of a statistically large sample of Galactic bulge stars at several galactocentric radii. The sensitivity of previous…