Alexander E. Thelen
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View article: Zonal Winds in Titan’s Middle Atmosphere from a Stellar Occultation Observed with Keck Adaptive Optics
Zonal Winds in Titan’s Middle Atmosphere from a Stellar Occultation Observed with Keck Adaptive Optics Open
We present spatially resolved Keck/NIRC2 images of a stellar occultation by Titan on 2022 September 5 and compare them to predictions from concurrent Atacama Large Millimeter/submillimeter Array (ALMA) observations and a suite of general c…
View article: Zonal winds in Titan's middle atmosphere from a stellar occultation observed with Keck adaptive optics
Zonal winds in Titan's middle atmosphere from a stellar occultation observed with Keck adaptive optics Open
We present spatially resolved Keck/NIRC2 images of a stellar occultation by Titan on September 5, 2022 and compare them to predictions from concurrent ALMA observations and a suite of General Circulation Model (GCM) simulations. ALMA data …
View article: A Multifrequency Global View of Callisto’s Thermal Properties from ALMA
A Multifrequency Global View of Callisto’s Thermal Properties from ALMA Open
We present thermal observations of Callisto’s leading and trailing hemispheres obtained using the Atacama Large Millimeter/submillimeter Array (ALMA) at 0.87 mm (343 GHz), 1.3 mm (233 GHz), and 3 mm (97 GHz). The angular resolution achieve…
View article: A multi-frequency global view of Callisto's thermal properties from ALMA
A multi-frequency global view of Callisto's thermal properties from ALMA Open
We present thermal observations of Callisto's leading and trailing hemispheres obtained using the Atacama Large Millimeter/submillimeter Array (ALMA) at 0.87 mm (343 GHz), 1.3 mm (233 GHz), and 3 mm (97 GHz). The angular resolution achieve…
View article: ALMA Constraints on the Vertical Temperature Structure of Io’s Atmosphere
ALMA Constraints on the Vertical Temperature Structure of Io’s Atmosphere Open
The vertical temperature profile of Io’s sulfur dioxide (SO2) atmosphere—shaped by volcanic eruptions, surface frost sublimation, and interactions with Jupiter’s magnetospheric environment—remains poorly understood. To date, observational …
View article: Investigating the Vertical Variability of Titan’s 14N/15N in HCN
Investigating the Vertical Variability of Titan’s 14N/15N in HCN Open
Titan’s substantial atmosphere is primarily composed of molecular nitrogen (N2) and methane (CH4), which are dissociated by solar UV photons and subsequently generate a vast chemical network of trace gases. The composition of Titan’s atmos…
View article: Temporal Variability of Titan’s Equatorial Zonal Winds Between 2012-2
Temporal Variability of Titan’s Equatorial Zonal Winds Between 2012-2 Open
Titan, Saturn’s largest satellite, is host to an intricate chemical and dynamical environment. Its atmosphere is composed primarily of molecular nitrogen (N2) and methane (CH4) that form the basis for a complex organic chemistry. But there…
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Resolving the hot and ionized Universe through the Sunyaev-Zeldovich effect
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Resolving the hot and ionized Universe through the Sunyaev-Zeldovich effect Open
An omnipresent feature of the multi-phase “cosmic web” — the large-scale filamentary backbone of the Universe — is that warm/hot (≳ 105 K) ionized gas pervades it. This gas constitutes a relevant contribution to the overall universal matte…
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Gas and dust in nearby galaxies
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Gas and dust in nearby galaxies Open
Understanding the physical processes that regulate star formation and galaxy evolution are major areas of activity in modern astrophysics. Nearby galaxies offer unique opportunities to inspect interstellar medium (ISM), star formation (SF)…
View article: Improved Carbon and Nitrogen Isotopic Ratios for CH<sub>3</sub>CN in Titan’s Atmosphere Using ALMA
Improved Carbon and Nitrogen Isotopic Ratios for CH<sub>3</sub>CN in Titan’s Atmosphere Using ALMA Open
Titan, Saturn’s largest satellite, maintains an atmosphere composed primarily of nitrogen (N 2 ) and methane (CH 4 ) that leads to complex organic chemistry. Some of the nitriles (CN-bearing organics) on Titan are known to have substantial…
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Our Galaxy
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Our Galaxy Open
As we learn more about the multi-scale interstellar medium (ISM) of our Galaxy, we develop a greater understanding for the complex relationships between the large-scale diffuse gas and dust in Giant Molecular Clouds (GMCs), how it moves, h…
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Probing the transient and time-variable sky
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Probing the transient and time-variable sky Open
The study of transient and variable events, including novae, active galactic nuclei, and black hole binaries, has historically been a fruitful path for elucidating the evolutionary mechanisms of our universe. The study of such events in th…
View article: Io’s SO<sub>2</sub> and NaCl Wind Fields from ALMA
Io’s SO<sub>2</sub> and NaCl Wind Fields from ALMA Open
We present spatially resolved measurements of SO 2 and NaCl winds on Io at several unique points in its orbit: before and after eclipse and at maximum eastern and western elongation. The derived wind fields represent a unique case of meteo…
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) Science: Planetary and Cometary Atmospheres
Atacama Large Aperture Submillimeter Telescope (AtLAST) Science: Planetary and Cometary Atmospheres Open
The study of planets and small bodies within our Solar System is fundamental for understanding the formation and evolution of the Earth and other planets. Compositional and meteorological studies of the giant planets provide a foundation f…
View article: Science development study for the Atacama Large Aperture Submillimeter Telescope (AtLAST): Solar and stellar observations
Science development study for the Atacama Large Aperture Submillimeter Telescope (AtLAST): Solar and stellar observations Open
Observations at (sub-)millimeter wavelengths offer a complementary perspective on our Sun and other stars, offering significant insights into both the thermal and magnetic composition of their chromospheres. Despite the fundamental progres…
View article: Io's SO2 and NaCl Wind Fields From ALMA
Io's SO2 and NaCl Wind Fields From ALMA Open
We present spatially resolved measurements of SO$_2$ and NaCl winds on Io at several unique points in its orbit: before and after eclipse, and at maximum eastern and western elongation. The derived wind fields represent a unique case of me…
View article: The key science drivers for the Atacama Large Aperture Submillimeter Telescope (AtLAST)
The key science drivers for the Atacama Large Aperture Submillimeter Telescope (AtLAST) Open
Sub-mm and mm wavelengths provide a unique view of the Universe, from the gas and dust that fills and surrounds galaxies to the chromosphere of our own Sun. Current single-dish facilities have presented a tantalising view of the brightest …
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Gas and dust in nearby galaxies
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Gas and dust in nearby galaxies Open
Understanding the physical processes that regulate star formation and galaxy evolution are major areas of activity in modern astrophysics. Nearby galaxies offer unique opportunities to inspect interstellar medium (ISM), star formation (SF…
View article: Science development study for the Atacama Large Aperture Submillimeter Telescope (AtLAST): Solar and stellar observations
Science development study for the Atacama Large Aperture Submillimeter Telescope (AtLAST): Solar and stellar observations Open
Observations at (sub-)millimeter wavelengths offer a complementary perspective on our Sun and other stars, offering significant insights into both the thermal and magnetic composition of their chromospheres. Despite the fundamental progres…
View article: AtLAST Science Overview Report
AtLAST Science Overview Report Open
Submillimeter and millimeter wavelengths provide a unique view of the Universe, from the gas and dust that fills and surrounds galaxies to the chromosphere of our own Sun. Current single-dish facilities have presented a tantalising view of…
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Probing the transient and time-variable sky
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Probing the transient and time-variable sky Open
The study of transient and variable events, including novae, active galactic nuclei, and black hole binaries, has historically been a fruitful path for elucidating the evolutionary mechanisms of our universe. The study of such events in th…
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Surveying the distant Universe
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Surveying the distant Universe Open
During the most active period of star formation in galaxies, which occurs in the redshift range 1 < z < 3, strong bursts of star formation result in significant quantities of dust, which obscures new stars being formed as their UV/optical …
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: The hidden circumgalactic medium
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: The hidden circumgalactic medium Open
Our knowledge of galaxy formation and evolution has incredibly progressed through multi-wavelength observational constraints of the interstellar medium (ISM) of galaxies at all cosmic epochs. However, little is known about the physical pro…
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Resolving the hot and ionized Universe through the Sunyaev-Zeldovich effect
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Resolving the hot and ionized Universe through the Sunyaev-Zeldovich effect Open
An omnipresent feature of the multi-phase “cosmic web” — the large-scale filamentary backbone of the Universe — is that warm/hot (≳ 10 5 K) ionized gas pervades it. This gas constitutes a relevant contribution to the overall universal mat…
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Our Galaxy
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Our Galaxy Open
As we learn more about the multi-scale interstellar medium (ISM) of our Galaxy, we develop a greater understanding for the complex relationships between the large-scale diffuse gas and dust in Giant Molecular Clouds (GMCs), how it moves, h…
View article: Observations of Titan's Stratosphere During Northern Summer: Temperatures, CH3CN and CH3D Abundances
Observations of Titan's Stratosphere During Northern Summer: Temperatures, CH3CN and CH3D Abundances Open
Titan's atmospheric composition and dynamical state have previously been studied over numerous epochs by both ground- and space-based facilities. However, stratospheric measurements remain sparse during Titan's northern summer and fall. Th…
View article: Observations of Titan’s Stratosphere during Northern Summer: Temperatures, CH<sub>3</sub>CN and CH<sub>3</sub>D Abundances
Observations of Titan’s Stratosphere during Northern Summer: Temperatures, CH<sub>3</sub>CN and CH<sub>3</sub>D Abundances Open
Titan’s atmospheric composition and dynamical state have previously been studied over numerous epochs by both ground- and space-based facilities. However, stratospheric measurements remain sparse during Titan’s northern summer and fall. Th…
View article: Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Planetary and cometary atmospheres
Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Planetary and cometary atmospheres Open
The study of planets and small bodies within our Solar System is fundamental for understanding the formation and evolution of the Earth and other planets. Compositional and meteorological studies of the giant planets provide a foundation …
View article: Atacama Large Aperture Submillimeter Telescope \mbox{(AtLAST)} Science: Probing the Transient and Time-variable Sky
Atacama Large Aperture Submillimeter Telescope \mbox{(AtLAST)} Science: Probing the Transient and Time-variable Sky Open
The study of transient and variable events, including novae, active galactic nuclei, and black hole binaries, has historically been a fruitful path for elucidating the evolutionary mechanisms of our universe. The study of such events in th…
View article: ALMA Spectroscopy of Europa: A Search for Active Plumes
ALMA Spectroscopy of Europa: A Search for Active Plumes Open
The subsurface ocean of Europa is a high priority target in the search for extraterrestrial life, but direct investigations are hindered by the presence of a thick, exterior ice shell. Here we present spectral line and continuum maps of Eu…