Results for "Karl M. Menten"

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The Effect of Far-infrared Radiation on the Hyperfine Anomaly of the OH 18 cm TransitionJan 29 2019We present observations of the four hyperfine structure components of the OH 18 cm transition (1612, 1665, 1667 and 1720 MHz) toward Heiles Cloud 2 (HCL2) in Taurus and the dense cores L183 and L169. Toward the peculiar straight structure in the northern ... More
C II radiative cooling of the Galactic diffuse interstellar medium: Insight about the star formation in Damped Lyman-alpha systemsJun 15 2016The far-infrared [C II] 158 micrometer fine structure transition is considered to be a dominant coolant in the interstellar medium. For this reason, under the assumption of a thermal steady state, it may be used to infer the heating rate and, in turn, ... More
Astro2020: Unlocking the Secrets of Late-Stage Stellar Evolution and Mass Loss through Radio Wavelength ImagingMar 13 2019During the late phases of evolution, low-to-intermediate mass stars like our Sun undergo periods of extensive mass loss, returning up to 80% of their initial mass to the interstellar medium. This mass loss profoundly affects the stellar evolutionary history, ... More
Submillimeter Array Observations of Magnetic Fields in G240.31+0.07: an Hourglass in a Massive Cluster-forming CoreSep 19 2014We report the first detection of an hourglass magnetic field aligned with a well-defined outflow-rotation system in a high-mass star-forming region. The observations were performed with Submillimeter Array toward G240.31+0.07, which harbors a massive, ... More
Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)Aug 23 2013The discovery of amino acids in meteorites and the detection of glycine in samples returned from a comet to Earth suggest that the interstellar chemistry is capable of producing such complex organic molecules. Our goal is to investigate the degree of ... More
Molecular Cloud-scale Star Formation in NGC 300May 09 2014We present the results of a galaxy-wide study of molecular gas and star formation in a sample of 76 HII regions in the nearby spiral galaxy NGC 300. We have measured the molecular gas at 250 pc scales using pointed CO(J=2-1) observations with the APEX ... More
Detections of massive stars in the cluster MCM2005b77, in the star-forming regions GRS G331.34$-$00.36 (S62) and GRS G337.92$-$00.48 (S36)Jun 20 2018Large infrared and millimeter wavelength surveys of the Galactic plane have unveiled more than 600 new bubble HII regions and more than 3000 candidate star clusters. We present a study of the candidate clusters MCM2005b72, DBS2003-157, DBS2003-172, and ... More
Magnetic Fields in High-Mass Infrared Dark CloudsOct 27 2014Oct 29 2014High-mass Stars are cosmic engines known to dominate the energetics in the Milky Way and other galaxies. However, their formation is still not well understood. Massive, cold, dense clouds, often appearing as Infrared Dark Clouds (IRDCs), are the nurseries ... More
Detection of Vibrationally Excited CO in IRC+10216Nov 28 2008Using the Submillimeter Array we have detected the J=3-2 and 2-1 rotational transitions from within the first vibrationally excited state of CO toward the extreme carbon star IRC+10216 (CW Leo). The emission remains spatially unresolved with an angular ... More
From Poloidal to Toroidal: Detection of Well-ordered Magnetic Field in High-mass Proto-cluster G35.2-0.74NNov 04 2013We report on detection of an ordered magnetic field (B field) threading a massive star-forming clump in the molecular cloud G35.2-0.74, using Submillimeter Array observations of polarized dust emission. Thanks to the sensitive and high-angular-resolution ... More
Molecular Line Emission as a Tool for Galaxy Observations (LEGO). I. HCN as a tracer of moderate gas densities in molecular clouds and galaxiesJul 17 2017Trends observed in galaxies, such as the Gao \& Solomon relation, suggest a linear relation between the star formation rate and the mass of dense gas available for star formation. Validation of such relations requires the establishment of reliable methods ... More
Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanideOct 09 2014The largest non-cyclic molecules detected in the interstellar medium (ISM) are organic with a straight-chain carbon backbone. We report an interstellar detection of a branched alkyl molecule, iso-propyl cyanide (i-C3H7CN), with an abundance 0.4 times ... More
Nuclear ashes and outflow in the eruptive star Nova Vul 1670Mar 23 2015CK Vulpeculae was observed in outburst in 1670-16721, but no counterpart was seen until 1982, when a bipolar nebula was found at its location. Historically, CK Vul has been considered to be a nova (Nova Vul 1670), but a similarity to 'red transients', ... More
The Galactic Center Molecular Cloud Survey. II. A Lack of Dense Gas & Cloud Evolution along Galactic Center OrbitsOct 11 2016Jun 08 2017We present the first systematic study of the density structure of clouds found in a complete sample covering all major molecular clouds in the Central Molecular Zone (CMZ; inner $\sim{}200~\rm{}pc$) of the Milky Way. This is made possible by using data ... More
First Detection of HCO+ Emission at High RedshiftMay 17 2006We report the detection of HCO+(1-0) emission towards the Cloverleaf quasar (z=2.56) through observations with the Very Large Array. This is the first detection of ionized molecular gas emission at high redshift (z>2). HCO+ emission is a star formation ... More
Modelling the abundance structure of isocyanic acid (HNCO) toward the low-mass solar type protostar IRAS 16293-2422Nov 02 2018Isocyanic acid (HNCO), the most stable of the simplest molecules containing the four main elements essential for organic chemistry, has been observed in several astrophysical environments such as molecular clouds, star-forming regions, external galaxies ... More
On the Relationship of UC H II Regions and Class II Methanol Masers: I. Source CatalogsSep 12 2016We conducted VLA C-configuration observations to measure positions and luminosities of Galactic Class II 6.7 GHz methanol masers and their associated ultra-compact H II regions. The spectral resolution was 3.90625 kHz and the continuum sensitivity reached ... More
Submillimeter Polarimetry with PolKa, a reflection-type modulator for the APEX telescopeAug 21 2014Aug 29 2014Imaging polarimetry is an important tool for the study of cosmic magnetic fields. In our Galaxy, polarization levels of a few up to $\sim$10\% are measured in the submillimeter dust emission from molecular clouds and in the synchrotron emission from supernova ... More
Fire in the Heart: A Characterization of the High Kinetic Temperatures and Heating Sources in the Nucleus of NGC253Dec 21 2018Jan 18 2019The nuclear starburst within the central $\sim 15^{\prime\prime}$ ($\sim 250$ pc; $1^{\prime\prime} \simeq 17$ pc) of NGC253 has been extensively studied as a prototype for the starburst phase in galactic evolution. Atacama Large Millimeter/submillimeter ... More
The Galactic Center Molecular Cloud Survey. I. A Steep Linewidth-Size Relation & Suppression of Star FormationOct 11 2016Nov 04 2016The Central Molecular Zone (CMZ; inner $\sim{}200~\rm{}pc$) of the Milky Way is a star formation (SF) environment with very extreme physical properties. Exploration of SF in this region is important because (i) this region allows us to test models of ... More
CO multi-line observations of HH 80-81: a two-component molecular outflow associated with the largest protostellar jet in our GalaxyDec 09 2018Stretching a length reaching 10 pc projected in the plane of sky, the radio jet associated with Herbig-Haro objects 80 and 81 (HH 80-81) is known as the largest and best collimated protostellar jet in our Galaxy. The nature of the molecular outflow associated ... More
Unveiling the chemistry of interstellar CH: Spectroscopy of the 2 THz $N=2\leftarrow 1$ ground state lineApr 12 2018The methylidyne radical CH is commonly used as a proxy for H$_2$ in the cold, neutral phase of the interstellar medium. The optical spectroscopy of CH is limited by interstellar extinction, whereas far-infrared observations provide an integral view through ... More
Laboratory spectroscopic study and astronomical detection of vibrationally excited n-propyl cyanideAug 29 2016We performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius~B2(N) between 84.1 and 114.4 GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. We determined line intensities ... More
N131: A dust bubble born from the disruption of a gas filamentOct 21 2015Jan 06 2016OB type stars have strong ionizing radiation, and drive energetic winds. The ultraviolet (UV) radiation from ionizing stars may heat dust and ionize gas to sweep up an expanding bubble shell. This shell may be the result of feedback leading to a new generation ... More
Detection of interstellar ortho-D2H+ with SOFIAApr 08 2017We report on the detection of the ground-state rotational line of ortho-D2H+ at 1.477 THz (203 micron) using the German REceiver for Astronomy at Terahertz frequencies (GREAT) onboard the Stratospheric Observatory For Infrared Astronomy (SOFIA). The line ... More
Imaging Atomic and Highly Excited Molecular Gas in a z=6.42 Quasar Host Galaxy: Copious Fuel for an Eddington-Limited Starburst at the End of Cosmic ReionizationJul 31 2009We have imaged CO(J=7-6) and CI(3P2-3P1) emission in the host galaxy of the z=6.42 quasar SDSS J114816.64+525150.3 (hereafter: J1148+5251) through observations with the Plateau de Bure Interferometer. The region showing CO(J=7-6) emission is spatially ... More
Molecular Gas in Redshift 6 Quasar Host GalaxiesFeb 08 2010We report our new observations of redshifted carbon monoxide emission from six z~6 quasars, using the PdBI. CO (6-5) or (5-4) line emission was detected in all six sources. Together with two other previous CO detections, these observations provide unique ... More
Astronomical detection of a radioactive molecule 26AlF in a remnant of an ancient explosionJul 27 2018Decades ago, $\gamma$-ray observatories identified diffuse Galactic emission at 1.809 MeV originating from $\beta^+$ decays of an isotope of aluminium, $^{26}$Al, that has a mean-life time of 1.04 Myr. Objects responsible for the production of this radioactive ... More
ATLASGAL-selected high-mass clumps in the inner Galaxy. VII. Characterisation of mid-J CO emissionDec 19 2018Jan 06 2019High-mass stars are formed within massive molecular clumps, where a large number of stars form close together. The evolution of the clumps with different masses and luminosities is mainly regulated by its high-mass stellar content and the formation of ... More
Molecular Gas in the Host Galaxy of a Quasar at Redshift z=6.42Jul 23 2003Observations of the molecular gas phase in quasar host galaxies provide fundamental constraints on galaxy evolution at the highest redshifts. Molecular gas is the material out of which stars form; it can be traced by spectral line emission of carbon--monoxide ... More
Star Formation in Quasar Host Galaxies at Redshift 6: Millimeter Surveys and New Insights from ALMASep 30 2012Nov 12 2012We have been carrying out a systematic survey of the star formation and ISM properties in the host galaxies of z~6 quasars. Our 250 GHz observations, together with available data from the literature, yield a sample of 14 z~6 quasars that are bright in ... More
Z-machine science other than CO - scientific and technical prospects for very wide band-width radio and (sub)millimeter-wavelength spectroscopyMar 23 2006While clearly the main scientific targets of ''z-machines" will be redshifted lines of carbon monoxide, there also exist other interesting applications. Here scientific and technological aspects of observing lines from CO and other species at high redshift ... More
IAU (Maser) Symposium 287 SummaryApr 26 2012Apr 27 2012I'm trying to summarize the science communicated via oral presentations and by posters at the IAU Symposium 287 "Cosmic Masers - from OH to H_0", which took place from January 29 to February 3, 2012 in Stellenbosch, South Africa.
Exciting Maser Science with New Instruments - the Promise of the EVLAAug 22 2007Aug 28 2007In the near future, the Expanded Very Large Array (EVLA) will allow surveys for maser sources with unprecedented sensitivity, spectral coverage and spectroscopic capabilities. In particular, comprehensive surveys for many maser species with simultaneous ... More
Constraining Dust and Molecular Gas Properties in Lyman Alpha Blobs at z~3Oct 07 2011In order to constrain the bolometric luminosities, dust properties and molecular gas content of giant Lyman alpha nebulae, the so-called Lyman alpha blobs, we have carried out a study of dust continuum and CO line emission in two well-studied representatives ... More
Rotational and high-resolution infrared spectrum of HC$_3$N: global ro-vibrational analysis and improved line catalogue for astrophysical observationsNov 23 2017HC$_3$N is an ubiquitous molecule in interstellar environments, from external galaxies, to Galactic interstellar clouds, star forming regions, and planetary atmospheres. Observations of its rotational and vibrational transitions provide important information ... More
High-resolution absorption spectroscopy of the OH 2Pi 3/2 ground state lineMar 08 2012Apr 12 2012The chemical composition of the interstellar medium is determined by gas phase chemistry, assisted by grain surface reactions, and by shock chemistry. The aim of this study is to measure the abundance of the hydroxyl radical (OH) in diffuse spiral arm ... More
An Interferometric Spectral-line Survey of IRC+10216 in the 345 GHz BandDec 27 2010We report a spectral-line survey of the extreme carbon star IRC+10216 carried out between 293.9 and 354.8 GHz with the Submillimeter Array. A total of 442 lines were detected, more than 200 for the first time; 149 are unassigned. Maps at an angular resolution ... More
Gas dynamics of a luminous $z$ = 6.13 quasar ULAS J1319$+$0950 revealed by ALMA high resolution observationsJul 10 2017Jul 12 2017We present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the dust continuum and [C II] 158 $\mu$m fine structure line emission towards a far-infrared-luminous quasar, ULAS J131911.29$+$095051.4 at $z=6.13$, and combine the new ... More
On the nature of the compact sources in IRAS 16293-2422 seen in at centimeter to sub-millimeter wavelengthsMar 06 2019We present multi-epoch continuum observations of the Class 0 protostellar system IRAS 16293-2422 taken with the Very Large Array (VLA) at multiple wavelengths between 7 mm and 15 cm (41 GHz down to 2 GHz), as well as single-epoch Atacama Large Millimeter/submillimeter ... More
Submillimeter narrow emission lines from the inner envelope of IRC+10216Nov 13 2008A spectral-line survey of IRC+10216 in the 345 GHz band has been undertaken with the Submillimeter Array. Although not yet completed, it has already yielded a fairly large sample of narrow molecular emission lines with line-widths indicating expansion ... More
Star Formation and Gas Kinematics of Quasar Host Galaxies at z~6: New insights from ALMAFeb 18 2013Jul 08 2013We present ALMA observations of the [C II] 158 micron fine structure line and dust continuum emission from the host galaxies of five redshift 6 quasars. We also report complementary observations of 250 GHz dust continuum and CO (6-5) line emission from ... More
Star Formation and ISM Properties in Host Galaxies of Three Far-infrared Luminous Quasars at $z\sim6$Mar 04 2019We present Karl G. Jansky Very Large Array (VLA) observations of the CO (2$-$1) line emission towards three far-infrared luminous quasars at $z\sim6$: SDSS J231038.88$+$185519.7 and SDSS J012958.51$-$003539.7 with $\sim0\farcs6$ resolution and SDSS J205406.42$-$000514.8 ... More
Submillimeter spectroscopy and astronomical searches of vinyl mercaptan, C$_2$H$_3$SHFeb 15 2019We have extended the pure rotational investigation of the two isomers syn and anti vinyl mercaptan to the millimeter domain using a frequency-multiplication spectrometer. The species were produced by a radiofrequency discharge in 1,2-ethanedithiol. Additional ... More
A Reverse Shock in GRB 160509AJun 28 2016We present the second multi-frequency radio detection of a reverse shock in a $\gamma$-ray burst. By combining our extensive radio observations of the Fermi-LAT GRB 160509A at $z = 1.17$ up to $20$ days after the burst with Swift X-ray observations and ... More
The ionised, radical and molecular Milky Way: spectroscopic surveys with the SKADec 17 2014The bandwith, sensitivity and sheer survey speed of the SKA offers unique potential for deep spectroscopic surveys of the Milky Way. Within the frequency bands available to the SKA lie many transitions that trace the ionised, radical and molecular components ... More
The local spiral structure of the Milky WayOct 02 2016Oct 04 2016The nature of the spiral structure of the Milky Way has long been debated. Only in the last decade have astronomers been able to accurately measure distances to a substantial number of high-mass star-forming regions, the classic tracers of spiral structure ... More
Aluminium oxide in the optical spectrum of VY Canis MajorisNov 17 2012We report the first identification of the optical bands of the B-X system of AlO in the red supergiant VY CMa. In addition to TiO, VO, ScO, and YO, which were recognized in the optical spectrum of the star long time ago, AlO is another refractory molecule ... More
An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South: Near-infrared morphologies and stellar sizesDec 01 2014We analyse HST WFC3/$H_{160}$-band observations of a sample of 48 ALMA-detected submillimeter galaxies (SMGs) in the Extended Chandra Deep Field South field, to study their stellar morphologies and sizes. We detect 79$\pm$17% of the SMGs in the $H_{160}$-band ... More
A multi-wavelength view of the Galactic center dust ridge reveals little star formationNov 02 2012The Galactic center dust ridge consists of a narrow string of massive condensations identified in submillimeter dust continuum emission. To determine whether new high-mass stars are forming in this region, we performed new observations at 870 $\mu$m with ... More
Widespread HCN maser emission in carbon-rich evolved starsMar 02 2018Context. HCN is a major constituent of the circumstellar envelopes of carbon-rich evolved stars, and rotational lines from within its vibrationally excited states probe parts of these regions closest to the stellar surface. A number of such lines are ... More
High-mass star-forming cloud G0.38+0.04 in the Galactic Center Dust Ridge contains H2CO and SiO masersOct 21 2015Nov 16 2015We have discovered a new H$_2$CO (formaldehyde) $1_{1,0}-1_{1,1}$ 4.82966 GHz maser in Galactic Center Cloud C, G0.38+0.04. At the time of acceptance, this is the eighth region containing an H$_2$CO maser detected in the Galaxy. Cloud C is one of only ... More
Dense gas in the Galactic central molecular zone is warm and heated by turbulenceSep 04 2015The Galactic center is the closest region in which we can study star formation under extreme physical conditions like those in high-redshift galaxies. We measure the temperature of the dense gas in the central molecular zone (CMZ) and examine what drives ... More
Imaging the Radio Photospheres of Mira VariablesAug 16 2007We have used the VLA at 43 GHz to image the radio continuum emission from o Ceti, R Leo, and W Hya and to precisely locate their SiO maser emission with respect to the star. The radio continuum emission region for all three stars has a diameter close ... More
Radio and X-ray variability of Young Stellar Objects in the Coronet ClusterSep 15 2005The Coronet Cluster in the nearby R CrA dark cloud offers the rare opportunity to study at least four "class I" protostellar sources as well as one candidate "class 0" source, a Herbig Ae star, and a candidate brown dwarf within a few square arcminutes ... More
Outflows, Accretion, and Clustered Protostellar Cores around a Forming O StarNov 27 2010We present a Submillimeter Array study in the 1.3 mm waveband of the NGC 7538 IRS 1--3 massive star-forming region. The brightest core in the mm continuum map, MM1, harbors the IRS 1 young O star. The core has a gas temperature of about 245 K and shows ... More
Atlas of Cosmic ray-induced astrochemistryNov 07 2018Nov 13 2018Cosmic-rays are the primary initiators of interstellar chemistry, and getting a better understanding of the varying impact they have on the chemistry of interstellar clouds throughout the Milky Way will not only expand our understanding of interstellar ... More
Ubiquitous argonium (ArH$^+$) in the diffuse interstellar medium -- a molecular tracer of almost purely atomic gasMar 31 2014Apr 14 2014We describe the assignment of a previously unidentified interstellar absorption line to ArH$^+$ and discuss its relevance in the context of hydride absorption in diffuse gas with a low H$_2$ fraction. The column densities along several lines of sight ... More
Imaging the cold molecular gas in SDSS J1148 + 5251 at z = 6.4May 28 2015We present Karl G. Jansky Very Large Array (VLA) observations of the CO ($J = 2 \rightarrow 1$) line emission towards the $z = 6.419$ quasar SDSS J$114816.64+525150.3$ (J$1148+5251$). The molecular gas is found to be marginally resolved with a major axis ... More
The Middle Pleistocene Transition by frequency locking and slow ramping of internal periodJan 06 2019The increase in glacial cycle length from approximately $41$ to on average $100$ thousand years around $1$ million years ago, called the Middle Pleistocene Transition (MPT), lacks a conclusive explanation. We describe a dynamical mechanism which we call ... More
6.7 GHz methanol absorption toward the Seyfert 2 galaxy NGC 3079May 07 2008The detection of the 6.7 GHz line of methanol (CH3OH) is reported for the first time toward an object beyond the Magellanic Clouds. Using the Effelsberg 100 m telescope, two absorption features were identified toward the Seyfert 2 galaxy NGC 3079. Both ... More
86 GHz SiO maser survey of late-type stars in the Inner Galaxy. IV. SiO emission and infrared data for sources in the Scutum and Sagittarius-Carina arms, 20 deg < l < 50 degJun 06 2018We present an 86 GHz SiO (v = 1, J = 2 ---> 1) maser search toward late-type stars located within |b|<0.5 deg and 20 deg < l < 50 deg. This search is an extension at longer longitudes of a previously published work. We selected 135 stars from the MSX ... More
Follow-up observations toward Planck cold clumps with ground-based radio telescopesOct 26 2014Oct 30 2014The physical and chemical properties of prestellar cores, especially massive ones, are still far from being well understood due to the lack of a large sample. The low dust temperature ($<$14 K) of Planck cold clumps makes them promising candidates for ... More
First redshift determination of an optically/UV faint submillimeter galaxy using CO emission linesSep 17 2009We report the redshift of a distant, highly obscured submm galaxy (SMG), based entirely on the detection of its CO line emission. We have used the newly commissioned Eight-MIxer Receiver (EMIR) at the IRAM 30m telescope, with its 8 GHz of instantaneous ... More
Distance and Kinematics of the Red Hypergiant VY CMa: VLBA and VLA AstrometrySep 14 2011We report astrometric results of phase-referencing VLBI observations of 43 GHz SiO maser emission toward the red hypergiant VY Canis Majoris (\vycma) using the Very Long Baseline Array (VLBA). We measured a trigonometric parallax of 0.83 $\pm$ 0.08 mas, ... More
The Distance to the Perseus Spiral Arm in the Milky WayDec 08 2005We have measured the distance to the massive star-forming region W3OH in the Perseus spiral arm of the Milky Way to be 1.95 $\pm$ 0.04 kilo-parsecs ($5.86\times10^{16}$ km). This distance was determined by triangulation, with the Earth's orbit as one ... More
A Submillimeter HCN Laser in IRC+10216Nov 19 1999We report the detection of a strong submillimeter wavelength HCN laser line at a frequency near 805 GHz toward the carbon star IRC+10216. This line, the J=9-8 rotational transition within the (04(0)0) vibrationally excited state, is one of a series of ... More
ATLASGAL-selected massive clumps in the inner Galaxy IV. Millimeter hydrogen recombination lines from associated HII regionsFeb 07 2017Observations of millimeter wavelength radio recombination lines (mm-RRLs) are used to search for HII regions in an unbiased way that is complementary to many of the more traditional methods previously used. We carried out targeted mm-RRL observations ... More
A study of three southern high-mass star-forming regionsOct 19 2010Based on color-selected IRAS point sources, we have started to conduct a survey of 47 high-mass star-forming regions in the southern hemisphere in 870um dust continuum and molecular line emission in several frequency ranges between 290 GHz and 806 GHz. ... More
Submillimeter-wave emission of three Galactic red novae: cool molecular outflows produced by stellar mergersApr 04 2018May 23 2018Red novae are optical transients erupting at luminosities typically higher than those of classical novae. Their outbursts are believed to be caused by stellar mergers. We present millimeter/submillimeter-wave observations with ALMA and SMA of the three ... More
Molecular gas in high redshift QSOsFeb 24 2004We review cm and mm observations of thermal molecular line emission from high redshift QSOs. These observations reveal the massive gas reservoirs (10^{10} to 10^{11} M_sun) required to fuel star formation at high rates. We discuss evidence for active ... More
A high-sensitivity 6.7 GHz methanol maser survey toward H2O sourcesMar 16 2008We present the results of a high sensitivity survey for 6.7 GHz methanol masers towards 22 GHz water maser using the 100 m Efflesberg telescope. A total of 89 sources were observed and 10 new methanol masers were detected. The new detections are relatively ... More
The inhomogeneous ISM toward PKS1830-211 SW - A detailed view on molecular gas at a look-back time of 7.5 GyrDec 17 2014Based on measurements with the Effelsberg 100-m telescope, a multi-line study of molecular species is presented toward the south-western source of the gravitational lens system PKS 1830-211, which is by far the best known target to study molecular gas ... More
Fundamental Vibrational Transitions of HCl Detected in CRL 2136Oct 15 2013We would like to understand the chemistry of dense clouds and their hot cores more quantitatively by obtaining more complete knowledge of the chemical species present in them. We have obtained high-resolution infrared absorption spectroscopy at 3-4 um ... More
On the Variations of Fundamental Constants and AGN feedback in the QSO host galaxy RXJ0911.4+0551 at z=2.79Apr 25 2012We report on sensitive observations of the CO(7-6) and CI(2-1) transitions in the z=2.79 QSO host galaxy RXJ0911.4+0551 using the IRAM Plateau de Bure interferometer (PdBI). Our extremely high signal to noise spectra combined with the narrow CO line width ... More
Water Maser Emission from the Active Nucleus in M51Sep 10 200122 GHz water vapor `kilomaser' emission is reported from the central region of the Whirlpool galaxy M 51 (NGC 5194). The red-shifted spectral features (Vlsr ~ 560 km/s), flaring during most of the year 2000, originate from a spatially unresolved maser ... More
Detection of CO (2-1) and Radio Continuum Emission from the z = 4.4 QSO BRI 1335-0417Jun 08 1999We have detected redshifted CO (2-1) emission at 43 GHz and radio continuum emission at 1.47 and 4.86 GHz from the z = 4.4 QSO BRI 1335-0417 using the Very Large Array. The CO data imply optically thick emission from warm (>30 K) molecular gas with a ... More
Volume Density Thresholds for Overall Star Formation imply Mass-Size Thresholds for Massive Star FormationJun 06 2011We aim at understanding the massive star formation (MSF) limit $m(r) = 870 M_{\odot} (r/pc)^{1.33}$ in the mass-size space of molecular structures recently proposed by Kauffmann & Pillai (2010). As a first step, we build on the hypothesis of a volume ... More
Interferometric Observations of Redshifted Molecular Absorption toward Gravitational LensesDec 09 1998We have made radio- and millimeter-wavelength interferometric observations of a variety of molecular absorption lines toward the gravitational lens systems B0218+357 and PKS1830-211. The absorption occurs in the lensing galaxies at redshifts of 0.685 ... More
Magnetic Field Clumping in Massive Star-Forming Regions as Determined from Excited-State OH Absorption and Maser EmissionJan 10 2005We have observed six high-mass star-forming regions in the 2 Pi 3/2, J = 7/2 lines of OH using the GBT in order to investigate whether the magnetic field, and hence the density, measured in absorption differs from that implied by maser Zeeman splitting. ... More
Molecules in G1.6-0.025 - 'Hot' Chemistry in the Absence of Star Formation at the Periphery of the Galactic Center RegionOct 15 2008Feb 13 2009We present molecular line mapping of the Giant Molecular Cloud G1.6-0.025, which is located at the high longitude end of the Central Molecular Zone of our Galaxy. We assess the degree of star formation activity in that region using several tracers and ... More
Formaldehyde Densitometry of Starburst Galaxies: Density-Independent Global Star FormationFeb 14 2013Mar 05 2013Accurate techniques which allow for the derivation of the spatial density in star formation regions are rare. A technique which has found application for the derivation of spatial densities in Galactic star formation regions utilizes the density-sensitive ... More
A 1.3 cm wavelength radio flare from a deeply embedded source in the Orion BN/KL regionNov 13 2007Aims: Our aim was to measure and characterize the short-wavelength radio emission from young stellar objects (YSOs) in the Orion Nebula Cluster and the BN/KL star-forming region. Methods: We used the NRAO Very Large Array at a wavelength of 1.3 cm and ... More
Ammonia in Infrared Dark CloudsJan 04 2006Infrared Dark Clouds appear to be the long sought population of cold and dense aggregations with the potential of harbouring the earliest stages of massive star formation. Up to now there has been no systematic study on the temperature distribution, velocity ... More
Circumstellar molecular composition of the oxygen-rich AGB star IK Tau: I. Observations and LTE chemical abundance analysisApr 12 2010Apr 20 2010The aim of this paper is to study the molecular composition in the circumstellar envelope around the oxygen-rich star IK Tau. We observed IK Tau in several (sub)millimeter bands using the APEX telescope during three observing periods. To determine the ... More
High mass star formation in the infrared dark cloud G11.11-0.12Oct 20 2005We report detection of moderate to high-mass star formation in an infrared dark cloud (G11.11-0.12) where we discovered class II methanol and water maser emissions at 6.7 GHz and 22.2 GHz, respectively. We also observed the object in ammonia inversion ... More
High Redshift HI 21cm Absorption toward Red QuasarsDec 09 1998We have searched for redshifted absorption in the 21 cm line of neutral hydrogen toward `red quasars', which are extragalactic radio sources with a steep spectral drop between optical and infrared wavelengths. The success rate for detecting HI 21cm absorption ... More
CN Zeeman and dust polarization in a high-mass cold clumpApr 25 2016We report on the young massive clump (G35.20w) in W48 that previous molecular line and dust observations have revealed to be in the very early stages of star formation. Based on virial analysis, we find that a strong field of ~1640 microG is required ... More
Near- and Mid-Infrared colors of evolved stars in the Galactic plane. The Q1 and Q2 parametersOct 31 2011Mass-loss from evolved stars chemically enriches the ISM. Stellar winds from massive stars and their explosions as SNs shape the ISM and trigger star formation. Studying evolved stars is fundamental for understanding galaxy formation and evolution, at ... More
Hot gas and dust in a protostellar cluster near W3(OHJan 20 1999We used the IRAM Interferometer to obtain sub-arcsecond resolution observations of the high-mass star-forming region W3(OH) and its surroundings at a frequency of 220 GHz. With the improved angular resolution, we distinguish 3 peaks in the thermal dust ... More
Orion KL: The hot core that is not a "Hot Core"Sep 07 2010We present sensitive high angular resolution submillimeter and millimeter observations of torsionally/vibrationally highly excited lines of the CH$_3$OH, HC$_3$N, SO$_2$, and CH$_3$CN molecules and of the continuum emission at 870 and 1300 $\mu$m from ... More
Formaldehyde Densitometry of Starburst GalaxiesOct 10 2007With a goal toward deriving the physical conditions in external galaxies, we present a survey of the formaldehyde emission in a sample of starburst systems. By extending a technique used to derive the spatial density in star formation regions in our own ... More
The CO line SED and atomic carbon in IRAS F10214+4724Oct 15 2008Using the IRAM 30m telescope and the Plateau de Bure interferometer we have detected the \ctwo and the CO 3$-$2, 4$-$3, 6$-$5, 7$-$6 transitions as well as the dust continuum at 3 and 1.2 mm towards the distant luminous infrared galaxy IRAS F10214+4724 ... More
Extended emission of D2H+ in a prestellar coreSep 14 2010Context: In the last years, the H2D+ and D2H+ molecules have gained great attention as probes of cold and depleted dense molecular cloud cores. These ions are at the basis of molecular deuterium fractionation, a common characteristic observed in star ... More
An Interferometric Spectral-Line and Imaging Survey of VY Canis Majoris in the 345 GHz BandSep 27 2013A spectral line survey of the oxygen-rich red supergiant VY Canis Majoris was made between 279 and 355 GHz with the Submillimeter Array. Two hundred twenty three spectral features from 19 molecules (not counting isotopic species of some of them) were ... More
Organic molecules, ions, and rare isotopologues in the remnant of the stellar-merger candidate, CK Vulpeculae (Nova 1670)Aug 07 2017Aug 18 2017CK Vul is a star whose outburst was observed in 1670-72. A stellar-merger event was proposed to explain its ancient eruption. Aims: We aim to investigate the composition of the molecular gas recently discovered in the remnant of CK Vul. Methods: We observed ... More
The Serpens filament: at the onset of slightly supercritical collapseSep 20 2018The Serpens filament, as one of the nearest infrared dark clouds, is regarded as a pristine filament at a very early evolutionary stage of star formation. In order to study its molecular content and dynamical state, we mapped this filament in seven species. ... More
Trigonometric Parallaxes of Massive Star-Forming Regions: VII. G9.62+0.20 and the Expanding 3 KPC-ARMSep 21 2009We report a trigonometric parallax of 12 GHz methanol masers associated with the massive star forming region G9.62+0.20, corresponding to a distance of 5.2+-0.6 kpc. With a local standard of rest velocity of about 2 km/s, the region's kinematic distances ... More
Parallaxes for W49N and G048.60+0.02: Distant Star Forming Regions in the Perseus Spiral ArmDec 13 2013We report trigonometric parallax measurements of 22 GHz H$_2$O masers in two massive star-forming regions from VLBA observations as part of the BeSSeL Survey. The distances of $11.11^{+0.79}_{-0.69}$ kpc to W49N (G043.16+0.01) and $10.75^{+0.61}_{-0.55}$ ... More
High-resolution radio continuum survey of M33 II. Thermal and nonthermal emissionAug 20 2007We determine the variation in the nonthermal radio spectral index in the nearby spiral galaxy M33 at a linear resolution of 360 pc. We separate the thermal and nonthermal components of the radio continuum emission without the assumption of a constant ... More