Lee Hartmann
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View article: The ODYSSEUS Survey. Spatial Correlation of Magnetospheric Inclinations Points to Parsec-scale Star–Cloud Connection
The ODYSSEUS Survey. Spatial Correlation of Magnetospheric Inclinations Points to Parsec-scale Star–Cloud Connection Open
The properties of stars and planets are shaped by the initial conditions of their natal clouds. However, the spatial scales over which the initial conditions can exert a significant influence are not well constrained. We report the first e…
Observational signatures of outside-in accretion bursts in embedded protostars Open
Optical and infrared surveys have detected increasing numbers of disc accretion outbursts in young stars. Some models of these FU Ori-type events predict that the outburst should start at near- to mid-infrared wavelengths before an optical…
On the protostellar mass–luminosity relation Open
We present a preliminary view of the protostellar mass–luminosity relation using current samples of protostars with dynamical mass estimates. To provide a lower limit to the expected luminosities, we adopt an empirical estimate for the int…
On the protostellar mass-luminosity relation Open
We present a preliminary view of the protostellar mass-luminosity relation using current samples of protostars with dynamical mass estimates. To provide a lower limit to the expected luminosities, we adopt an empirical estimate for the int…
View article: Complex Organics Surrounding the FU Ori–type Object V1057 Cyg Indicative of Sublimated Ices
Complex Organics Surrounding the FU Ori–type Object V1057 Cyg Indicative of Sublimated Ices Open
FU Ori– and EX Lup–type objects present natural experiments for understanding a critical stage in the star and planet formation process. These objects offer insight into the diversity of molecules available to forming planetary systems due…
View article: IPA: Class 0 Protostars Viewed in CO Emission Using JWST
IPA: Class 0 Protostars Viewed in CO Emission Using JWST Open
We investigate the bright CO fundamental emission in the central regions of five protostars in their primary mass assembly phase using new observations from JWST’s Near-Infrared Spectrograph and Mid-Infrared Instrument. CO line emission im…
View article: High Mass Inner Regions Found in Five Outbursting Sources
High Mass Inner Regions Found in Five Outbursting Sources Open
Young stellar objects are thought to commonly undergo sudden accretion events that result in a rise in bolometric luminosity. These outbursts likely coincide with the onset of planet formation, and could impact the formation of planets. Th…
View article: Complex Organics Surrounding the FU Ori-Type Object V1057 Cyg Indicative of Sublimated Ices
Complex Organics Surrounding the FU Ori-Type Object V1057 Cyg Indicative of Sublimated Ices Open
FU Ori and EX Lup type objects present natural experiments for understanding a critical stage in the star and planet formation process. These objects offer insight into the diversity of molecules available to forming planetary systems due …
High Mass Inner Regions Found in Five Outbursting Sources Open
Young stellar objects are thought to commonly undergo sudden accretion events that result in a rise in bolometric luminosity. These outbursts likely coincide with the onset of planet formation and could impact the formation of planets. The…
View article: Investigating Protostellar Accretion-driven Outflows across the Mass Spectrum: JWST NIRSpec Integral Field Unit 3–5 μm Spectral Mapping of Five Young Protostars
Investigating Protostellar Accretion-driven Outflows across the Mass Spectrum: JWST NIRSpec Integral Field Unit 3–5 μm Spectral Mapping of Five Young Protostars Open
Investigating Protostellar Accretion is a Cycle 1 JWST program using the NIRSpec+MIRI integral field units to obtain 2.9–28 μ m spectral cubes of five young protostars with luminosities of 0.2–10,000 L ⊙ in their primary accretion phase. T…
View article: JWST observations of <sup>13</sup>CO<sub>2</sub> ice
JWST observations of <sup>13</sup>CO<sub>2</sub> ice Open
The structure and composition of simple ices can be severely modified during stellar evolution by protostellar heating. Key to understanding the involved processes are thermal and chemical tracers that can be used to diagnose the history a…
Mechanistic insights into silver-gold nanoalloy formation by two-dimensional population balance modeling Open
The large-scale synthesis of nanoparticles (NPs) with defined properties requires detailed understanding of the underlying formation mechanisms and kinetics. The formation mechanisms of bimetallic NPs are still not sufficiently understood …
View article: Discovery of a Collimated Jet from the Low-luminosity Protostar IRAS 16253−2429 in a Quiescent Accretion Phase with the JWST
Discovery of a Collimated Jet from the Low-luminosity Protostar IRAS 16253−2429 in a Quiescent Accretion Phase with the JWST Open
Investigating Protostellar Accretion (IPA) is a JWST Cycle 1 GO program that uses NIRSpec integral field units and MIRI Medium Resolution Spectrograph to obtain 2.9–28 μ m spectral cubes of young, deeply embedded protostars with luminositi…
Tailoring the reaction pathway for control of size and composition of silver-gold alloy nanoparticles Open
This is the raw data for the manuscript: Tailoring the reaction pathway for control of size and composition of silver-gold alloy nanoparticlesAbstract:In this work, we focus on tuning both the particle size and chemical composition of bime…
Tailoring the reaction pathway for control of size and composition of silver-gold alloy nanoparticles Open
This is the raw data for the manuscript: Tailoring the reaction pathway for control of size and composition of silver-gold alloy nanoparticlesAbstract:In this work, we focus on tuning both the particle size and chemical composition of bime…
View article: IPA: Class 0 Protostars Viewed in CO Emission Using JWST
IPA: Class 0 Protostars Viewed in CO Emission Using JWST Open
We investigate the bright CO fundamental emission in the central regions of five protostars in their primary mass assembly phase using new observations from JWST's Near-Infrared Spectrograph (NIRSpec) and Mid-Infrared Instrument (MIRI). CO…
Mechanistic insights into silver-gold nanoalloy formation by two-dimensional population balance modeling Open
This is the raw data for the manuscript: Mechanistic insights into silver-gold nanoalloy formation by two-dimensional population balance modelingAbstract:The large-scale synthesis of nanoparticles (NPs) with defined properties requires det…
Mechanistic insights into silver-gold nanoalloy formation by two-dimensional population balance modeling Open
This is the raw data for the manuscript: Mechanistic insights into silver-gold nanoalloy formation by two-dimensional population balance modelingAbstract:The large-scale synthesis of nanoparticles (NPs) with defined properties requires det…
View article: Pathways to Discovery in Astronomy and Astrophysics for the 2020s
Pathways to Discovery in Astronomy and Astrophysics for the 2020s Open
We live in an extraordinary period of discovery in astronomy and astrophysics. Six Nobel Prizes have been awarded over the past decade alone for discoveries based on astronomical data (dark energy, gravitational waves, neutrino oscillation…
View article: Discovery of a collimated jet from the low luminosity protostar IRAS 16253$-$2429 in a quiescent accretion phase with the JWST
Discovery of a collimated jet from the low luminosity protostar IRAS 16253$-$2429 in a quiescent accretion phase with the JWST Open
Investigating Protostellar Accretion (IPA) is a JWST Cycle~1 GO program that uses NIRSpec IFU and MIRI MRS to obtain 2.9--28~$μ$m spectral cubes of young, deeply embedded protostars with luminosities of 0.2 to 10,000~L$_{\odot}$ and centra…
View article: Investigating Protostellar Accretion-Driven Outflows Across the Mass Spectrum: JWST NIRSpec IFU 3-5~$μ$m Spectral Mapping of Five Young Protostars
Investigating Protostellar Accretion-Driven Outflows Across the Mass Spectrum: JWST NIRSpec IFU 3-5~$μ$m Spectral Mapping of Five Young Protostars Open
Investigating Protostellar Accretion is a Cycle 1 JWST program using the NIRSpec+MIRI integral field units to obtain 2.9--28 $μ$m spectral cubes of five young protostars with luminosities of 0.2-10,000 L$_{\odot}$ in their primary accretio…
Can envelope backwarming of discs explain mm-bright, extended protostellar structures? Open
We construct simple models to explore in principle whether the backwarming by radiation from infalling envelopes can significantly heat and change the structure of protoplanetary discs. The motivation for this investigation is the recent s…
Magnetically activated accretion outbursts of pre-main-sequence discs Open
We investigate whether triggering of the magnetorotational instability (MRI) in protoplanetary discs can account for the wide diversity of observed accretion outbursts. We show that short-lived, relatively low accretion rate events probabl…
View article: Extension of HOPS out to 500 pc (eHOPS). I. Identification and Modeling of Protostars in the Aquila Molecular Clouds*
Extension of HOPS out to 500 pc (eHOPS). I. Identification and Modeling of Protostars in the Aquila Molecular Clouds* Open
We present a Spitzer/Herschel focused survey of the Aquila molecular clouds ( d ∼ 436 pc) as part of the eHOPS (extension of the Herschel orion protostar survey, or HOPS, Out to 500 ParSecs) census of nearby protostars. For every source de…
View article: Constraints on star formation in Orion A from Gaia
Constraints on star formation in Orion A from Gaia Open
We develop statistical methods within a Bayesian framework to infer the star formation history from photometric surveys of pre-main sequence populations. Our procedures include correcting for biases due to extinction in magnitude-limited s…
View article: Constraints on star formation in Orion A from <i>Gaia</i>
Constraints on star formation in Orion A from <i>Gaia</i> Open
We develop statistical methods within a Bayesian framework to infer the star formation history from photometric surveys of pre-main-sequence populations. Our procedures include correcting for biases due to extinction in magnitude-limited s…
View article: 300: An ACA 870 μm Continuum Survey of Orion Protostars and Their Evolution
300: An ACA 870 μm Continuum Survey of Orion Protostars and Their Evolution Open
We present an 870 μ m continuum survey of 300 protostars from the Herschel Orion Protostar Survey using the Atacama Compact Array (ACA). These data measure protostellar flux densities on envelope scales ≤8000 au (20″) and resolve the struc…
View article: 300: An ACA 870 $μ$m Continuum Survey of Orion Protostars and their Evolution
300: An ACA 870 $μ$m Continuum Survey of Orion Protostars and their Evolution Open
We present an 870 $μ$m continuum survey of 300 protostars from the Herschel Orion Protostar Survey using the Atacama Compact Array (ACA). These data measure protostellar flux densities on envelope scales $\leq$8000 au (20") and resolve the…
View article: Extension of HOPS Out to 500 ParSecs (eHOPS). I. Identification and Modeling of Protostars in the Aquila Molecular Clouds
Extension of HOPS Out to 500 ParSecs (eHOPS). I. Identification and Modeling of Protostars in the Aquila Molecular Clouds Open
We present a Spitzer/Herschel focused survey of the Aquila molecular clouds ($d \sim 436$~pc) as part of the eHOPS (extension of HOPS Out to 500 ParSecs) census of nearby protostars. For every source detected in the Herschel/PACS bands, th…