Michael E. Ressler
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View article: The Reset Switch Charge Decay Effect in JWST/MIRI Observations
The Reset Switch Charge Decay Effect in JWST/MIRI Observations Open
Blocked impurity band arsenic-doped silicon detectors such as those used in the James Webb Space Telescope’s Mid-Infrared Instrument were invented in the 1980s to overcome many of the unwanted second-order effects found in the photoconduct…
View article: Infrared Synchrotron Emission in the Soft State of GX 339-4 and the Mid-Infrared/X-ray Luminosity Plane of Black Hole X-ray Binaries
Infrared Synchrotron Emission in the Soft State of GX 339-4 and the Mid-Infrared/X-ray Luminosity Plane of Black Hole X-ray Binaries Open
Progress in understanding the growth of accreting black holes remains hampered by a lack of sensitive coordinated multiwavelength observations. In particular, the mid-infrared (MIR) regime remains ill-explored except for jet-dominant state…
View article: A JWST/MIRI view of ąppa,Andromedae b : Refining its mass, age, and physical parameters
A JWST/MIRI view of ąppa,Andromedae b : Refining its mass, age, and physical parameters Open
ąppa,And,b is a substellar companion with a mass near the planet--brown dwarf boundary orbiting a B9IV star at ∼50-$100$,au. Estimates of its age and mass vary, which has fueled a decade-long debate. Additionally, the atmospheric parameter…
View article: Worlds Next Door: A Candidate Giant Planet Imaged in the Habitable Zone of <i>α</i> Centauri A. I. Observations, Orbital and Physical Properties, and Exozodi Upper Limits
Worlds Next Door: A Candidate Giant Planet Imaged in the Habitable Zone of <i>α</i> Centauri A. I. Observations, Orbital and Physical Properties, and Exozodi Upper Limits Open
We report on coronagraphic observations of the nearest solar-type star, α Centauri A ( α Cen A), using the MIRI instrument on the James Webb Space Telescope. The proximity of α Cen (1.33 pc) means that the star’s habitable zone is spatiall…
View article: Worlds Next Door: A Candidate Giant Planet Imaged in the Habitable Zone of <i>α</i> Centauri A. II. Binary Star Modeling, Planet and Exozodi Search, and Sensitivity Analysis
Worlds Next Door: A Candidate Giant Planet Imaged in the Habitable Zone of <i>α</i> Centauri A. II. Binary Star Modeling, Planet and Exozodi Search, and Sensitivity Analysis Open
The James Webb Space Telescope (JWST) observed our closest solar twin, α Centauri A ( α Cen A), with the Mid-Infrared Instrument in the F1550C (15.5 μ m) coronagraphic imaging mode at three distinct epochs between 2024 August and 2025 Apri…
View article: JWST Observations of Segregated <sup>12</sup>CO<sub>2</sub> and <sup>13</sup>CO<sub>2</sub> Ices in Protostellar Envelopes
JWST Observations of Segregated <sup>12</sup>CO<sub>2</sub> and <sup>13</sup>CO<sub>2</sub> Ices in Protostellar Envelopes Open
The evolution of interstellar ices can be studied with thermal tracers such as the vibrational modes of CO2 ice that show great diversity depending on their local chemical and thermal environment. Now with the wide spectral coverage and se…
View article: Expanding the Ice Inventory of NGC 1333 IRAS 2A with INDRA using JWST Observations: Tracing Organic Refractories and Beyond
Expanding the Ice Inventory of NGC 1333 IRAS 2A with INDRA using JWST Observations: Tracing Organic Refractories and Beyond Open
In the era of JWST, with its unprecedented sensitivity and spectral resolution, infrared spectral surveys have revealed a rich inventory of ices, including complex organic molecules (COMs), in young stellar objects (YSOs). However, robust …
View article: JWST Observations of Young protoStars (JOYS)
JWST Observations of Young protoStars (JOYS) Open
Context. The embedded phase of star formation is a crucial period in the development of a young star when the system still accretes matter, emerges from its natal cloud with assistance from powerful jets and outflows, and forms a disk, thu…
View article: JWST observations of segregated $^{12}$CO$_2$ and $^{13}$CO$_2$ ices in protostellar envelopes
JWST observations of segregated $^{12}$CO$_2$ and $^{13}$CO$_2$ ices in protostellar envelopes Open
The evolution of interstellar ices can be studied with thermal tracers such as the vibrational modes of CO$_2$ ice that show great diversity depending on their local chemical and thermal environment. In this work we present JWST observatio…
View article: A Preliminary Search for Planets and Exozodiacal Emission Around <i>α</i> Centauri A with JWST/MIRI
A Preliminary Search for Planets and Exozodiacal Emission Around <i>α</i> Centauri A with JWST/MIRI Open
We present F1550C (15.5 μ m) coronagraphic imaging observations of the nearest solar-type star α Cen A using the James Webb Space Telescope (JWST) Mid-InfraRed Instrument (MIRI). The observations, executed in 2025 February, were compromise…
View article: Revealing a Main-sequence Star that Consumed a Planet with JWST
Revealing a Main-sequence Star that Consumed a Planet with JWST Open
The subluminous red nova (SLRN) Zwicky Transient Facility (ZTF) SLRN-2020 is the most compelling direct detection of a planet being consumed by its host star, a scenario known as a planetary engulfment event. We present JWST spectroscopy o…
View article: JWST/MIRI Study of the Enigmatic Mid-infrared Rings in the Planetary Nebula NGC 1514
JWST/MIRI Study of the Enigmatic Mid-infrared Rings in the Planetary Nebula NGC 1514 Open
While NGC 1514 is an elliptical, but complex, planetary nebula at optical wavelengths, it was discovered to have a pair of infrared-bright, axisymmetric rings contained within its faint outer shell during the course of the Wide-field Infra…
View article: Investigating the Electron-capture Supernova Candidate AT 2019abn with JWST Spectroscopy
Investigating the Electron-capture Supernova Candidate AT 2019abn with JWST Spectroscopy Open
The James Webb Space Telescope (JWST) has opened up a new window to study highly reddened explosive transients. We present results from late-time JWST follow-up spectroscopic observations with NIRSpec and MIRI-LRS of the intermediate-lumin…
View article: Rapid Mid-Infrared Spectral-Timing with <i>JWST</i>: I. GRS 1915+105 during a MIR–bright and X-ray–obscured state
Rapid Mid-Infrared Spectral-Timing with <i>JWST</i>: I. GRS 1915+105 during a MIR–bright and X-ray–obscured state Open
We present mid-infrared (MIR) spectral-timing measurements of the prototypical Galactic microquasar GRS 1915+105. The source was observed with the Mid-Infrared Instrument (MIRI) onboard JWST in June 2023 at a MIR luminosity LMIR ≈ 1036 erg…
View article: Calibrating the Clock of JWST
Calibrating the Clock of JWST Open
JWST, despite not being designed to observe astrophysical phenomena that vary on rapid timescales, can be an unparalleled tool for such studies. If timing systematics can be controlled, JWST will be able to open up the subsecond infrared t…
View article: JOYS+ study of solid-state <sup>12</sup>C/<sup>13</sup>C isotope ratios in protostellar envelopes
JOYS+ study of solid-state <sup>12</sup>C/<sup>13</sup>C isotope ratios in protostellar envelopes Open
Context . The carbon isotope ratio is a powerful tool for studying the evolution of stellar systems due to its sensitivity to the local chemical environment. Recent detections of CO isotopologs in disks and exoplanet atmospheres revealed a…
View article: Calibrating the clock of JWST
Calibrating the clock of JWST Open
JWST, despite not being designed to observe astrophysical phenomena that vary on rapid time scales, can be an unparalleled tool for such studies. If timing systematics can be controlled, JWST will be able to open up the sub-second infrared…
View article: Revealing Potential Initial Mass Function Variations with Metallicity: JWST Observations of Young Open Clusters in a Low-metallicity Environment
Revealing Potential Initial Mass Function Variations with Metallicity: JWST Observations of Young Open Clusters in a Low-metallicity Environment Open
We present the substellar mass function of star-forming clusters (≃0.1 Myr old) in a low-metallicity environment (≃−0.7 dex). We performed deep JWST/NIRCam and MIRI imaging of two star-forming clusters in Digel Cloud 2, a star-forming regi…
View article: A new atmospheric characterization of the sub-stellar companion HR\,2562\,B with JWST/MIRI observations
A new atmospheric characterization of the sub-stellar companion HR\,2562\,B with JWST/MIRI observations Open
Context: HR2562B is a planetary-mass companion located 0.56arcsec (19au) from its host star. It is one of a few L/T transitional objects orbiting a young star. This companion provides insight into the evolution of young objects in the L/T …
View article: Resolving Twin Jets and Twin Disks with JWST and ALMA: The Young WL 20 Multiple System
Resolving Twin Jets and Twin Disks with JWST and ALMA: The Young WL 20 Multiple System Open
We report the discovery of jets emanating from pre-main-sequence objects exclusively at mid-infrared wavelengths, enabled by the superb sensitivity of JWST's Mid-InfraRed Medium-Resolution Spectrometer (MIRI MRS) instrument. These jets are…
View article: JOYS+: The link between the ice and gas of complex organic molecules
JOYS+: The link between the ice and gas of complex organic molecules Open
Context. A rich inventory of complex organic molecules (COMs) has been observed in high abundances in the gas phase toward Class 0 protostars. It has been suggested that these molecules are formed in ices and sublimate in the warm inner en…
View article: Resolving Twin Jets and Twin Disks with JWST and ALMA: The Young WL 20 Multiple System
Resolving Twin Jets and Twin Disks with JWST and ALMA: The Young WL 20 Multiple System Open
We report the discovery of jets emanating from pre-main-sequence objects exclusively at mid-infrared wavelengths, enabled by the superb sensitivity of JWST’s Mid-Infrared Instrument Medium-Resolution Spectrometer. These jets are observed o…
View article: Revealing Potential Initial Mass Function variations with metallicity: JWST observations of young open clusters in a low-metallicity environment
Revealing Potential Initial Mass Function variations with metallicity: JWST observations of young open clusters in a low-metallicity environment Open
We present the substellar mass function of star-forming clusters ($\simeq$0.1 Myr old) in a low-metallicity environment ($\simeq$$-$0.7 dex). We performed deep JWST/NIRCam and MIRI imaging of two star-forming clusters in Digel Cloud 2, a s…
View article: JOYS+: link between ice and gas of complex organic molecules. Comparing JWST and ALMA data of two low-mass protostars
JOYS+: link between ice and gas of complex organic molecules. Comparing JWST and ALMA data of two low-mass protostars Open
A rich inventory of complex organic molecules (COMs) has been observed in high abundances in the gas phase toward Class 0 protostars. These molecules are suggested to be formed in ices and sublimate in the warm inner envelope close to the …
View article: Investigating the Electron Capture Supernova Candidate AT 2019abn with JWST Spectroscopy
Investigating the Electron Capture Supernova Candidate AT 2019abn with JWST Spectroscopy Open
The James Webb Space Telescope (JWST) has opened up a new window to study highly reddened explosive transients. We present results from late-time (1421 days post-explosion) JWST follow-up spectroscopic observations with NIRSpec and MIRI LR…
View article: A new atmospheric characterization of the sub-stellar companion HR 2562 B with JWST/MIRI observations
A new atmospheric characterization of the sub-stellar companion HR 2562 B with JWST/MIRI observations Open
Context. HR 2562 B is a planetary-mass companion at an angular separation of 0.56″ (19 au) from the host star, which is also a member of a select number of L/T transitional objects orbiting a young star. This companion gives us a great opp…
View article: Overview Results of JWST Observations of Star-forming Clusters in the Extreme Outer Galaxy
Overview Results of JWST Observations of Star-forming Clusters in the Extreme Outer Galaxy Open
The extreme outer Galaxy (EOG), which we define as the region of the Milky Way with a galactocentric radius of more than 18 kpc, provides an excellent opportunity to study star formation in an environment significantly different from that …
View article: Rapid Mid-Infrared Spectral-Timing with JWST. I. The prototypical black hole X-ray Binary GRS 1915+105 during a MIR-bright and X-ray-obscured state
Rapid Mid-Infrared Spectral-Timing with JWST. I. The prototypical black hole X-ray Binary GRS 1915+105 during a MIR-bright and X-ray-obscured state Open
We present mid-infrared (MIR) spectral-timing measurements of the prototypical Galactic microquasar GRS 1915+105. The source was observed with the Mid-Infrared Instrument (MIRI) onboard JWST in June 2023 at a MIR luminosity L(MIR)~10^{36} …
View article: Mid-infrared Fine Structure Lines from the Galactic Warm Ionized Medium
Mid-infrared Fine Structure Lines from the Galactic Warm Ionized Medium Open
The Warm Ionized Medium (WIM) hosts most of the ionized gas in the Galaxy and occupies perhaps a quarter of the volume of the Galactic disk. Decoding the spectrum of the Galactic diffuse ionizing field is of fundamental interest. This can …