Results for "Jes K. Jørgensen"

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Detection of Infall in the Protostar B335 with ALMAOct 12 2015Observations of the isolated globule B335 with ALMA have yielded absorption features against the continuum that are redshifted from the systemic velocity in both HCN and HCO$^+$ lines. These features provide unambiguous evidence for infall toward a central ... More
Normally Regular DigraphsOct 30 2014A normally regular digraph with parameters $(v,k,\lambda,\mu)$ is a directed graph on $v$ vertices whose adjacency matrix $A$ satisfies the equation $AA^t=k I+\lambda (A+A^t)+\mu(J-I-A-A^t)$. This means that every vertex has out-degree $k$, a pair of ... More
Interplay between chemistry and dynamics in embedded protostellar disksSep 25 2013A fundamental part of the study of star formation is to place young stellar objects in an evolutionary sequence. Establishing a robust evolutionary classification scheme allows us not only to understand how the Sun was born but also to predict what kind ... More
Dynamic Optimization of Thermodynamically Rigorous Models of Multiphase Flow in Porous Subsurface Oil ReservoirsJul 24 2018In this paper, we consider dynamic optimization of thermal and isothermal oil recovery processes which involve multicomponent three-phase flow in porous media. We present thermodynamically rigorous models of these processes based on 1) conservation of ... More
Large-scale numerical simulations of star formation put to the test: Comparing synthetic images and actual observations for statistical samples of protostarsOct 27 2015Dec 14 2015(abridged) Context: Both observations and simulations of embedded protostars have progressed rapidly in recent years. Bringing them together is an important step in advancing our knowledge about the earliest phases of star formation. Aims: To compare ... More
Protostellar accretion traced with chemistry: Comparing synthetic C18O maps of embedded protostars to real observationsDec 01 2015Dec 19 2015Context: Understanding how protostars accrete their mass is a central question of star formation. One aspect of this is trying to understand whether the time evolution of accretion rates in deeply embedded objects is best characterised by a smooth decline ... More
Warm water deuterium fractionation in IRAS 16293-2422 - The high-resolution ALMA and SMA viewNov 28 2012Measuring the water deuterium fractionation in the inner warm regions of low-mass protostars has so far been hampered by poor angular resolution obtainable with single-dish ground- and space-based telescopes. Observations of water isotopologues using ... More
Subarcsecond resolution observations of warm water towards three deeply embedded low-mass protostarsMar 22 2012Water is present during all stages of star formation: as ice in the cold outer parts of protostellar envelopes and dense inner regions of circumstellar disks, and as gas in the envelopes close to the protostars, in the upper layers of circumstellar disks ... More
Externally heated protostellar cores in the Ophiuchus star-forming regionNov 21 2016We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H$_2$CO and c-C$_3$H$_2$ rotational temperatures, ... More
Detection of glycolaldehyde towards the solar-type protostar NGC1333 IRAS2AFeb 03 2015Glycolaldehyde is a key molecule in the formation of biologically relevant molecules such as ribose. We report its detection with the Plateau de Bure interferometer towards the Class 0 young stellar object NGC1333 IRAS2A, which is only the second solar-type ... More
Millimeter and Submillimeter Wave Spectroscopy of PropanalJul 07 2017The rotational spectra of the two stable conformers syn- and gauche-propanal (CH3CH2CHO) were studied in the millimeter and submillimeter wave regions from 75 to 500 GHz with the Cologne (Sub-)Millimeter wave Spectrometer. Furthermore, the first excited ... More
Misaligned Disks in the Binary Protostar IRS 43Oct 12 2016Oct 14 2016Recent high angular resolution ($\sim$0.2") ALMA observations of the 1.1 mm continuum and of HCO+ J=3-2 and HCN J=3-2 gas towards the binary protostar IRS 43 reveal multiple Keplerian disks which are significantly misaligned ($\gt$ 60$^\circ$), both in ... More
Complex Molecules in the L1157 Molecular OutflowMay 16 2008We report the detection of complex organic molecules in the young protostellar outflow L1157. We identify lines from HCOOCH3, CH3CN, HCOOH and C2H5OH at the position of the B1 shock in the blueshifted lobe, making it the first time that complex species ... More
Misaligned Disks in the Binary Protostar IRS 43Oct 12 2016Recent high angular resolution ($\sim$0.2") ALMA observations of the 1.1 mm continuum and of HCO+ J=3-2 and HCN J=3-2 gas towards the binary protostar IRS 43 reveal multiple Keplerian disks which are significantly misaligned ($\gt$ 60$^\circ$), both in ... More
Exploring the Origins of Earth's Nitrogen: Astronomical Observations of Nitrogen-bearing Organics in Protostellar EnvironmentsSep 20 2018It is not known whether the original carriers of Earth's nitrogen were molecular ices or refractory dust. To investigate this question, we have used data and results of Herschel observations towards two protostellar sources: the high-mass hot core of ... More
The Class 0 Protostar BHR71: Herschel Observations and Dust Continuum ModelsJan 03 2017We use Herschel spectrophotometry of BHR71, an embedded Class 0 protostar, to provide new constraints on its physical properties. We detect 645 (non-unique) spectral lines amongst all spatial pixels. At least 61 different spectral lines originate from ... More
Externally heated protostellar cores in the Ophiuchus star-forming regionNov 21 2016Nov 22 2016We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H$_2$CO and c-C$_3$H$_2$ rotational temperatures, ... More
An Unbiased Spectral Line Survey toward R CrA IRS7B in the 345 GHz Window with ASTEOct 10 2011We have conducted a spectral line survey in the 332 - 364 GHz region with the ASTE 10 m telescope toward R CrA IRS7B, a low-mass protostar in the Class 0 or Class 0/I transitional stage. We have also performed some supplementary observations in the 450 ... More
c2d Spitzer IRS spectra of embedded low-mass young stars: gas-phase emission linesMay 17 2010A survey of mid-IR gas-phase emission lines of H2, H2O and various atoms toward a sample of 43 embedded low-mass young stars in nearby star-forming regions is presented. The sources are selected from the Spitzer "Cores to Disks" (c2d) legacy program. ... More
Resolved images of a protostellar outflow launched by an extended disk windDec 15 2016Young stars are associated with prominent outflows of molecular gas. The ejection of gas via these outflows is believed to remove angular momentum from the protostellar system, thus permitting young stars to grow by accretion of material from the protostellar ... More
Millimeter and Submillimeter Wave Spectroscopy of PropanalJul 07 2017Mar 13 2019The rotational spectra of the two stable conformers syn- and gauche-propanal (CH$_3$CH$_2$CHO) were studied in the millimeter and submillimeter wave regions from 75 to 500 GHz with the Cologne (Sub-)Millimeter wave Spectrometer. Furthermore, the first ... More
Tentative detection of ethylene glycol toward W51/e2 and G34.3+0.2Jul 13 2015How complex organic - and potentially prebiotic - molecules are formed in regions of low- and high-mass star-formation remains a central question in astrochemistry. In particular, with just a few sources studied in detail, it is unclear what role environment ... More
Probing the effects of external irradiation on low-mass protostars through unbiased line surveysSep 08 2015Sep 29 2015(abridged) Context: The envelopes of molecular gas around embedded low-mass protostars show different chemistries, which can be used to trace their formation history and physical conditions. The excitation of some molecular species can also be used to ... More
Efficient and Robust Estimation for a Class of Generalized Linear Longitudinal Mixed ModelsAug 17 2010We propose a versatile and computationally efficient estimating equation method for a class of hierarchical multiplicative generalized linear mixed models with additive dispersion components, based on explicit modelling of the covariance structure. The ... More
The organic chemistry in the innermost, infalling envelope of the Class 0 protostar L483Sep 02 2018Context. Observations of the innermost regions of deeply embedded protostellar cores have shown complicated physical structures as well as a rich chemistry with the existence of complex organic molecules. The protostellar envelopes, outflow and large-scale ... More
The organic chemistry in the innermost, infalling envelope of the Class 0 protostar L483Sep 02 2018May 06 2019Context: The protostellar envelopes, outflow and large-scale chemistry of Class~0 and Class~I objects have been well-studied, but while previous works have hinted at or found a few Keplerian disks at the Class~0 stage, it remains to be seen if their presence ... More
ALMA detections of the youngest protostars in OphiuchusNov 09 2018We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of 1.1 mm dust continuum and CO 2-1 emission toward six dense cores within the Ophiuchus molecular cloud. We detect compact, sub-arcsecond continuum structures toward three targets, ... More
Viewpoint: Opportunities and challenges of two-dimensional magnetic van der Waals materials: magnetic graphene?Apr 29 2016There has been a huge increase of interests in two-dimensional van der Waals materials over the past ten years or so with the conspicuous absence of one particular class of materials: magnetic van der Waals systems. In this Viewpoint, we point it out ... More
The Co-evolution of Disk and Star in Embedded Stages: The Case of the Very Low-mass ProtostarSep 03 2018We have observed the CCH (N=3-2, J=7/2-5/2, F=4-3 and 3-2) and SO (6_7-5_6) emission at a 0"2 angular resolution toward the low-mass Class 0 protostellar source IRAS 15398-3359 with ALMA. The CCH emission traces the infalling-rotating envelope near the ... More
Deuterated methyl mercaptan (CH$_3$SD): Laboratory rotational spectroscopy and search toward IRAS 16293-2422 BDec 06 2018Methyl mercaptan (also known as methanethiol), CH3SH, has been found in the warm and dense parts of high -- as well as low -- mass star-forming regions. The aim of the present study is to obtain accurate spectroscopic parameters of the S-deuterated methyl ... More
The Star Formation Rate of Molecular CloudsDec 18 2013We review recent advances in the analytical and numerical modeling of the star formation rate in molecular clouds and discuss the available observational constraints. We focus on molecular clouds as the fundamental star formation sites, rather than on ... More
The Earliest Stages of Star and Planet Formation: Core Collapse, and the Formation of Disks and OutflowsJan 10 2014(Abridged) In this review we focus on the observations and theory of the formation of early disks and outflows, and their connections with the first phases of planet formation. Large rotationally supported circumstellar disks, although common around more ... More
Deuterated methyl mercaptan (CH$_3$SD): Laboratory rotational spectroscopy and search toward IRAS 16293-2422 BDec 06 2018Mar 12 2019Methyl mercaptan (also known as methanethiol), CH3SH, has been found in the warm and dense parts of high -- as well as low -- mass star-forming regions. The aim of the present study is to obtain accurate spectroscopic parameters of the S-deuterated methyl ... More
Discrete Dispersion Models and Their Tweedie AsymptoticsSep 26 2014We introduce a class of two-parameter discrete dispersion models, obtained by combining convolution with a factorial tilting operation, similar to exponential dispersion models which combine convolution and exponential tilting. The equidispersed Poisson ... More
Physical and chemical fingerprint of protostellar disc formationApr 30 2019(Abridged) The purpose of this paper is to explore and compare the physical and chemical structure of Class I low-mass protostellar sources on protoplanetary disc scales. We present a study of the dust and gas emission towards a representative sample ... More
Adaptable Radiative Transfer Innovations for Submillimeter Telescopes (ARTIST)Feb 23 2011Submillimeter observations are a key for answering many of the big questions in modern-day astrophysics, such as how stars and planets form, how galaxies evolve, and how material cycles through stars and the interstellar medium. With the upcoming large ... More
Dynamical structure of the inner 100 AU of the deeply embedded protostar IRAS 16293-2422Jun 03 2014A fundamental question about the early evolution of low-mass protostars is when circumstellar disks may form. High angular resolution observations of molecular transitions in the (sub)millimeter wavelength windows make it possible to investigate the kinematics ... More
Warm gas towards young stellar objects in Corona Australis - Herschel/PACS observations from the DIGIT key programmeNov 29 2013The effects of external irradiation on the chemistry and physics in the protostellar envelope around low-mass young stellar objects are poorly understood. The Corona Australis star-forming region contains the R CrA dark cloud, comprising several low-mass ... More
Tracing the cold and warm physico-chemical structure of deeply embedded protostars: IRAS 16293-2422 versus VLA 1623-2417May 14 2018Much attention has been placed on the dust distribution in protostellar envelopes, but there are still many unanswered questions regarding the structure of the gas. We aim to start identifying the factors that determine the chemical structure of protostellar ... More
A Substellar-Mass Protostar and its Outflow of IRAS 15398-3359 Revealed by Subarcsecond-Resolution Observations of H$_2$CO and CCHOct 22 2014Sub-arcsecond ($0.^{\prime\prime}5$) images of H$_2$CO and CCH line emission have been obtained in the $0.8$ mm band toward the low-mass protostar IRAS 15398-3359 in the Lupus 1 cloud as one of the Cycle 0 projects of the Atacama Large Millimeter/Submillimeter ... More
Early formation of planetary building blocks inferred from Pb isotopic ages of chondrulesAug 08 2017The most abundant components of primitive meteorites (chondrites) are millimeter-sized glassy spherical chondrules formed by transient melting events in the solar protoplanetary disk. Using Pb-Pb dates of 22 individual chondrules, we show that primary ... More
Evidence for the start of planet formation in a young circumstellar diskJun 25 2018The growth of dust grains in protoplanetary disks is a necessary first step towards planet formation. This growth has been inferred via observations of thermal dust emission towards mature protoplanetary systems (age >2 million years) with masses that ... More
Protostellar accretion traced with chemistry. High resolution C18O and continuum observations towards deeply embedded protostars in PerseusMar 29 2017Context: Understanding how accretion proceeds is a key question of star formation, with important implications for both the physical and chemical evolution of young stellar objects. In particular, very little is known about the accretion variability in ... More
Imaging the water snowline in a protostellar envelope with H$^{13}$CO$^+$Jan 08 2018Snowlines are key ingredients for planet formation. Providing observational constraints on the locations of the major snowlines is therefore crucial for fully connecting planet compositions to their formation mechanism. Unfortunately, the most important ... More
ALMA observations of the kinematics and chemistry of disc formationMay 06 2014May 12 2014Context: The R CrA cloud hosts a handful of Class 0/I low-mass young stellar objects. The chemistry and physics at scales $>500$ AU in this cloud are dominated by the irradiation from the nearby Herbig Be star R CrA. The luminous large-scale emission ... More
L1448-MM observations by the Herschel Key program, "Dust, Ice, and Gas In Time" (DIGIT)Sep 09 2013We present Herschel/PACS observations of L1448-MM, a Class 0 protostar with a prominent outflow. Numerous emission lines are detected at 55 < lambda < 210 micrometer including CO, OH, H2O, and [O I]. We investigate the spatial distribution of each transition ... More
Imaging chemical differentiation around the low-mass protostar L483-mmMay 20 2004This paper presents a millimeter wavelength aperture-synthesis study of the spatial variations of the chemistry in the envelope around the deeply embedded low-mass protostar L483-mm on 1000 AU (5") scales. Lines of 8 molecular species including CN, C18O, ... More
Stellar escapers from M67 can reach solar-like Galactic orbitsMay 23 2019We investigate the possibility that the Sun could have been born in M67 by carrying out $N$-body simulations of M67-like clusters in a time-varying Galactic environment, and following the galactic orbits of stars that escape from them. We find that model ... More
The ALMA-PILS survey: First detection of nitrous acid (HONO) in the interstellar mediumMar 08 2019Nitrogen oxides are thought to play a significant role as a nitrogen reservoir and to potentially participate in the formation of more complex species. Until now, only NO, N$_2$O and HNO have been detected in the interstellar medium. We report the first ... More
The young population of the Chamaeleon II dark cloudFeb 29 2008We discuss the results of the optical spectroscopic follow-up of pre-main sequence (PMS) objects and candidates selected in the Chamaeleon II dark cloud based on data from the Spitzer Legacy survey "From Molecular Cores to Planet Forming Disks" (c2d) ... More
The ALMA-PILS survey: The sulphur connection between protostars and comets: IRAS 16293-2422 B and 67P/Churyumov-GerasimenkoFeb 08 2018The evolutionary past of our Solar System can be pieced together by comparing analogous low-mass protostars with remnants of our Protosolar Nebula - comets. Sulphur-bearing molecules may be unique tracers of the joint evolution of the volatile and refractory ... More
Water in star-forming regions with Herschel: highly excited molecular emission from the NGC 1333 IRAS 4B outflowNov 03 2011Jan 18 2012During the embedded phase of pre-main sequence stellar evolution, a disk forms from the dense envelope while an accretion-driven outflow carves out a cavity within the envelope. Highly excited H2O emission in spatially unresolved Spitzer/IRS spectra of ... More
Dimethyl ether in its ground state, v=0, and lowest two torsionally excited states, v11=1 and v15=1, in the high-mass star-forming region G327.3-0.6Feb 25 2013The goal of this paper is to determine the respective importance of solid state vs. gas phase reactions for the formation of dimethyl ether. This is done by a detailed analysis of the excitation properties of the ground state and the torsionally excited ... More
The Mass Evolution of Protostellar Disks and Envelopes in the Perseus Molecular CloudFeb 15 2019In the standard picture for low-mass star formation, a dense molecular cloud undergoes gravitational collapse to form a protostellar system consisting of a new central star, a circumstellar disk, and a surrounding envelope of remaining material. The mass ... More
High D$_2$O/HDO ratio in the inner regions of the low-mass protostar NGC1333 IRAS2AJul 25 2014Aug 16 2014Water plays a crucial role both in the interstellar medium and on Earth. To constrain its formation mechanisms and its evolution through the star formation process, the determination of the water deuterium fractionation ratios is particularly suitable. ... More
The ALMA-PILS survey: The sulphur connection between protostars and comets: IRAS 16293-2422 B and 67P/Churyumov-GerasimenkoFeb 08 2018Feb 21 2018The evolutionary past of our Solar System can be pieced together by comparing analogous low-mass protostars with remnants of our Protosolar Nebula - comets. Sulphur-bearing molecules may be unique tracers of the joint evolution of the volatile and refractory ... More
High-J CO survey of low-mass protostars observed with Herschel-HIFIJun 17 2013The evolution of deeply embedded young stellar objects (YSOs) has traditionally been traced through dust continuum spectral energy distributions (SEDs), but the use of CO excitation as an evolutionary probe has not yet been explored due to lack of high-J ... More
The chemical connection between 67P/C-G and IRAS 16293-2422Feb 08 2018The chemical evolution of a star- and planet-forming system begins in the prestellar phase and proceeds across the subsequent evolutionary phases. The chemical trail from cores to protoplanetary disks to planetary embryos can be studied by comparing distant ... More
Size Dependence of Metal-Insulator Transition in Stoichiometric Fe3O4 NanocrystalsJun 17 2015Magnetite (Fe3O4) is one of the most actively studied materials with a famous metal-insulator transition (MIT), so-called the Verwey transition at around 123 K. Despite the recent progress in synthesis and characterization of Fe3O4 nanocrystals (NCs), ... More
On the Formal Model for IEC 61499 Composite Function BlocksMay 23 2018The applications for IEC 61499 that is standard architecture for developing the applications of distributed control and measurement in factory automation, have the connected structure of the graphical elements called BFB(basic function block), SIFB(service ... More
The HDO/H2O ratio in gas in the inner regions of a low-mass protostarNov 12 2010The HDO/H2O abundance ratio is thought to be a key diagnostic on the evolution of water during the star- and planet-formation process and thus on its origin on Earth. We here present millimeter-wavelength high angular resolution observations of the deeply ... More
Strong irradiation of protostellar cores in Corona AustralisSep 21 2012Sep 24 2012The importance of the physical environment in the evolution of newly formed low-mass stars remains an open question. In particular, radiation from nearby more massive stars may affect both the physical and chemical structure of these kinds of young stars. ... More
The VLA Nascent Disk And Multiplicity (VANDAM) Survey of Perseus Protostars. Resolving the Sub-Arcsecond Binary System in NGC 1333 IRAS2AOct 29 2014We are conducting a Jansky VLA Ka-band (8 mm and 1 cm) and C-band (4 cm and 6.4 cm) survey of all known protostars in the Perseus Molecular Cloud, providing resolution down to $\sim$0.06'' and $\sim$0.35" in Ka-band and C-band, respectively. Here we present ... More
A young bipolar outflow from IRAS 15398-3359Jan 26 2016Changing physical conditions in the vicinity of protostars allow for a rich and interesting chemistry to occur. Heating and cooling of the gas allows molecules to be released from and frozen out on dust grains. These changes in physics, traced by chemistry, ... More
Water Vapor in the Inner 25 AU of a Young Disk around a Low-Mass ProtostarJan 10 2010Water is one of the key molecules in the physical and chemical evolution of star- and planet-forming regions. We here report the first spatially resolved observation of thermal emission of (an isotopologue of) water with the Plateau de Bure Interferometer ... More
Star and Planet Formation with ALMA: an OverviewAug 22 2007Submillimeter observations with ALMA will be the essential next step in our understanding of how stars and planets form. Key projects range from detailed imaging of the collapse of pre-stellar cores and measuring the accretion rate of matter onto deeply ... More
The Spitzer survey of interstellar clouds in the Gould Belt. II. The Cepheus Flare observed with IRAC and MIPSMar 24 2009We present Spitzer IRAC (~2 deg^2) and MIPS (~8 deg^2) observations of the Cepheus Flare which is associated with the Gould Belt, at an approximate distance of ~300 pc. Around 6500 sources are detected in all four IRAC bands, of which ~900 have MIPS 24 ... More
Embedded Protostars in the Dust, Ice, and Gas In Time (DIGIT) Key Program: Continuum SEDs, and an Inventory of Characteristic Far-Infrared Lines from PACS SpectroscopyApr 27 2013May 09 2013We present 50-210 um spectral scans of 30 Class 0/I protostellar sources, obtained with Herschel-PACS, and 0.5-1000 um SEDs, as part of the Dust, Ice, and Gas in Time (DIGIT) Key Program. Some sources exhibit up to 75 H2O lines ranging in excitation energy ... More
The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and LifetimesNov 06 2008(Abridged) The c2d Spitzer Legacy project obtained images and photometry with both IRAC and MIPS instruments for five large, nearby molecular clouds. This paper combines information drawn from studies of individual clouds into a combined and updated statistical ... More
The Spitzer Survey of Interstellar Clouds in the Gould Belt. IV. Lupus V and VI Observed with IRAC and MIPSJan 24 2011We present Gould's Belt (GB) Spitzer IRAC and MIPS observations of the Lupus V and VI clouds and discuss them in combination with near-infrared (2MASS) data. Our observations complement those obtained for other Lupus clouds within the frame of the Spitzer ... More
Linking interstellar and cometary O$_2$: a deep search for $^{16}$O$^{18}$O in the solar-type protostar IRAS 16293--2422May 31 2018Recent measurements carried out at comet 67P/C-G with the ${\it Rosetta}$ probe revealed that molecular oxygen, O$_2$, is the fourth most abundant molecule in comets. Models show that O$_2$ is likely of primordial nature, coming from the interstellar ... More
The Spitzer c2d survey of Large, Nearby, Interstellar Clouds. V. Chamaeleon II Observed with IRACOct 27 2006We present IRAC (3.6, 4.5, 5.8, and 8.0 micron) observations of the Chamaeleon II molecular cloud. The observed area covers about 1 square degree defined by $A_V >2$. Analysis of the data in the 2005 c2d catalogs reveals a small number of sources (40) ... More
Mass Assembly of Stellar Systems and their Evolution with the SMA - 1.3 mm Subcompact Data ReleaseJun 19 2018We present the Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey, which uses the Submillimeter Array (SMA) interferometer to map the continuum and molecular lines for all 74 known Class 0/I protostellar systems in the Perseus ... More
The Spitzer Survey of Interstellar Clouds in the Gould Belt. VI. The Auriga-California Molecular Cloud observed with IRAC and MIPSFeb 25 2014We present observations of the Auriga-California Molecular Cloud (AMC) at 3.6, 4.5, 5.8, 8.0, 24, 70 and 160 micron observed with the IRAC and MIPS detectors as part of the Spitzer Gould Belt Legacy Survey. The total mapped areas are 2.5 sq-deg with IRAC ... More
Alignment Between Protostellar Outflows and Filamentary StructureJul 25 2017We present new Submillimeter Array (SMA) observations of CO(2-1) outflows toward young, embedded protostars in the Perseus molecular cloud as part of the Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey. For 57 Perseus ... More
Experimental percolation studies of two-dimensional honeycomb lattice: Li2Mn1-xTixO3Jun 27 2014Li2MnO3 with a S=3/2 two-dimensional Mn honeycomb lattice has a Neel-type antiferromagnetic transition at TN=36 K with a broad maximum in the magnetic susceptibility at TM=48 K. We have investigated site percolation effects by replacing Mn with nonmagnetic ... More
Empirical average-case relation between undersampling and sparsity in x-ray CTNov 24 2012Aug 04 2014In x-ray computed tomography (CT) it is generally acknowledged that reconstruction methods exploiting image sparsity allow reconstruction from a significantly reduced number of projections. The use of such reconstruction methods is motivated by recent ... More
The Multivariate Generalised von Mises: Inference and applicationsFeb 16 2016May 23 2016Circular variables arise in a multitude of data-modelling contexts ranging from robotics to the social sciences, but they have been largely overlooked by the machine learning community. This paper partially redresses this imbalance by extending some standard ... More
Chemical tracers of episodic accretion in low-mass protostarsMar 17 2015Aims: Accretion rates in low-mass protostars can be highly variable in time. Each accretion burst is accompanied by a temporary increase in luminosity, heating up the circumstellar envelope and altering the chemical composition of the gas and dust. This ... More
Fabry-Perot interference, Kondo effect and Coulomb blockade in carbon nanotubesNov 13 2007High quality single wall carbon nanotube quantum dots have been made showing both metallic and semiconducting behavior. Some of the devices are identified as small band gap semiconducting nanotubes with relatively high broad conductance oscillations for ... More
Kondo resonance enhanced supercurrent in single wall carbon nanotube Josephson junctionsJan 17 2006May 10 2007We have contacted single wall carbon nanotubes grown by chemical vapor deposition to superconducting Ti/Al/Ti electrodes. The device, we here report on is in the Kondo regime exhibiting a four-fold shell structure, where a clear signature of the superconducting ... More
The kinematics of NGC1333-IRAS2A - a true Class 0 protostarMay 28 2009Low-mass star formation is described by gravitational collapse of dense cores of gas and dust. At some point during the collapse, a disk is formed around the protostar and the disk will spin up and grow in size as the core contracts because of angular ... More
A latent variable model with mixed binary and continuous response variablesJul 05 2015We propose a method for obtaining maximum likelihood estimates in a model with continuous and binary outcomes. Combinations of left and right censored observations are also naturally modeled in this framework. The model and estimation procedure has been ... More
Spin-orbit torque induced dipole skyrmion motion at room temperatureMay 31 2018We demonstrate deterministic control of dipole-field-stabilized skyrmions by means of spin-orbit torques arising from heavy transition-metal seed layers. Experiments are performed on amorphous Fe/Gd multilayers that are patterned into wires and exhibit ... More
Current Star Formation in the Perseus Molecular Cloud: Constraints from Unbiased Submillimeter and Mid-Infrared SurveysOct 12 2006We present a census of the population of deeply embedded young stellar objects (YSOs) in the Perseus molecular cloud complex based on a combination of Spitzer Space Telescope mid-IR data from the c2d legacy team and JCMT/SCUBA submillimeter maps from ... More
Physical structure and CO abundance of low-mass protostellar envelopesMay 05 2002We present 1D radiative transfer modelling of the envelopes of a sample of 18 low-mass protostars and pre-stellar cores with the aim of setting up realistic physical models, for use in a chemical description of the sources. The density and temperature ... More
Molecular abundances in low-mass protostellar envelopesNov 24 2002A study of the chemical structure of the envelopes around a sample protostars is introduced. Physical models for the envelopes derived using 1D radiative transfer modeling of their dust continuum emission are used as input for Monte Carlo modeling of ... More
The Multivariate Generalised von Mises distribution: Inference and applicationsFeb 16 2016Aug 08 2017Circular variables arise in a multitude of data-modelling contexts ranging from robotics to the social sciences, but they have been largely overlooked by the machine learning community. This paper partially redresses this imbalance by extending some standard ... More
The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. IV. Lupus Observed with MIPSJun 13 2007We present maps of 7.78 square degrees of the Lupus molecular cloud complex at 24, 70, and $160\:\mu$m. They were made with the Spitzer Space Telescope's Multiband Imaging Photometer for Spitzer (MIPS) instrument as part of the Spitzer Legacy Program, ... More
Antihydrogen formation dynamics in a multipolar neutral anti-atom trapFeb 16 2010Antihydrogen production in a neutral atom trap formed by an octupole-based magnetic field minimum is demonstrated using field-ionization of weakly bound anti-atoms. Using our unique annihilation imaging detector, we correlate antihydrogen detection by ... More
Rapidity dependence of deuteron production in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeVMay 29 2010Apr 04 2011We have measured the distributions of protons and deuterons produced in high energy heavy ion Au+Au collisions at RHIC over a very wide range of transverse and longitudinal momentum. Near mid-rapidity we have also measured the distribution of anti-protons ... More
Lasing on a narrow transition in a cold thermal strontium ensembleMar 29 2019Highly stable laser sources based on narrow atomic transitions provide a promising platform for direct generation of stable and accurate optical frequencies. Here we investigate a simple system operating in the high-temperature regime of cold atoms. The ... More
Cosmic ray strangeletsNov 22 2004Searching for strangelets in cosmic rays may be the best way to test the possible stability of strange quark matter. I review calculations of the astrophysical strangelet flux in the GV--TV rigidity range, which will be investigated from the Alpha Magnetic ... More
Color-flavor locked strangelets and their detectionDec 11 2001Strange quark matter in a color-flavor locked state is significantly more bound than ``ordinary'' strange quark matter. This increases the likelihood of strangelet metastability or even absolute stability. Properties of color-flavor locked strangelets ... More
Physical Properties of StrangeletsFeb 07 1995Low-baryon number lumps of strange quark matter, strangelets, are presently searched for in ultra-relativistic heavy-ion experiments at CERN and Brookhaven. This paper gives an overview of the physical properties of strangelets with emphasis on experimental ... More
Strangelets in Cosmic RaysDec 29 2006The properties of strangelets are reviewed and two experiments searching for them in cosmic rays are described. The prospects for strangelets as ultra-high energy cosmic rays beyond the classical GZK-cutoff are discussed.
Stable quark matter in cosmic rays?Dec 20 2005Stable lumps of quark matter may be present in cosmic rays at a flux level, which can be detected by high precision cosmic ray experiments sensitive to anomalous "nuclei" with high mass-to-charge ratio. The properties of these lumps, called strangelets, ... More
Color-flavor locking in strange stars, strangelets, and cosmic raysNov 29 2001Three topics with relation to color superconductivity in strange quark matter are discussed. 1) The r-mode instability in strange stars, which is consistent with the existence of ``ordinary'' strange quark matter stars but inconsistent with strange stars ... More
Shell model versus liquid drop model for strangeletsJul 18 1994An ansatz for the curvature contribution to the density of states for massive quarks in a bag is given and shown to reproduce exact mode-filling calculations. A mass-formula for spherical lumps of 3-flavor quark matter is derived self-consistently from ... More
Cavitation from bulk viscosity in neutron stars and quark starsSep 21 2009Sep 30 2009The bulk viscosity in quark matter is sufficiently high to reduce the effective pressure below the corresponding vapor pressure during density perturbations in neutron stars and strange stars. This leads to mechanical instability where the quark matter ... More