107 results match your criteria Astronomy and astrophysics[Journal]


Gas phase Elemental abundances in Molecular cloudS (GEMS) II. On the quest for the sulphur reservoir in molecular clouds: the HS case.

Astron Astrophys 2020 May 12;637. Epub 2020 May 12.

Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK.

Context: Sulphur is one of the most abundant elements in the Universe. Surprisingly, sulphuretted molecules are not as abundant as expected in the interstellar medium and the identity of the main sulphur reservoir is still an open question.

Aims: Our goal is to investigate the HS chemistry in dark clouds, as this stable molecule is a potential sulphur reservoir. Read More

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http://dx.doi.org/10.1051/0004-6361/201937180DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7305024PMC

Chemical equilibrium in AGB atmospheres: Successes, failures, and prospects for small molecules, clusters, and condensates.

Astron Astrophys 2020 May 14;637. Epub 2020 May 14.

Instituto de Ciencia de Materiales de Madrid, CSIC, C/ Sor Juana Inés de la Cruz 3, 28049 Cantoblanco, Spain.

Chemical equilibrium has proven extremely useful for predicting the chemical composition of AGB atmospheres. Here we use a recently developed code and an updated thermochemical database that includes gaseous and condensed species involving 34 elements to compute the chemical equilibrium composition of AGB atmospheres of M-, S-, and C-type stars. We include for the first time Ti C clusters, with = 1-4 and = 1-4, and selected larger clusters ranging up to TiC, for which thermochemical data are obtained from quantum-chemical calculations. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7274841PMC

Rotational spectroscopy and astronomical search for glutaronitrile.

Astron Astrophys 2020 Apr 10;636. Epub 2020 Apr 10.

Instituto de Física Fundamental (Iff-CSIC). Group of Molecular Astrophysics, C/ Serrano 123, 28006 Madrid, Spain.

Context: Nitriles constitute almost 15% of the molecules observed in the interstellar medium (ISM), surprisingly only two dinitriles have been detected in the ISM so far. The lack of astronomical detections for dinitriles may be partly explained by the absence of laboratory rotational spectroscopic data.

Aims: Our goal is to investigate the rotational spectrum of glutaronitrile, N≡C-CH-CH-CH-C≡N, in order to allow its possible detection in the ISM. Read More

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http://dx.doi.org/10.1051/0004-6361/202037769DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7250646PMC

ALMA observations of the young protostellar system Barnard 1b: signatures of an incipient hot corino in B1b-S.

Astron Astrophys 2018 Dec 30;620. Epub 2018 Nov 30.

Sorbonne Université, Observatoire de Paris, Université PSL, École normale supérieure, CNRS, LERMA, F-75014, Paris, France.

The Barnard 1b core shows signatures of being at the earliest stages of low-mass star formation, with two extremely young and deeply embedded protostellar objects. Hence, this core is an ideal target to study the structure and chemistry of the first objects formed in the collapse of prestellar cores. We present ALMA Band 6 spectral line observations at ~0. Read More

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http://dx.doi.org/10.1051/0004-6361/201731955DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6914381PMC
December 2018

A rotating fast bipolar wind and disk system around the B[e]-type star MWC 922.

Astron Astrophys 2019 Sep 18;629. Epub 2019 Sep 18.

Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden.

We present interferometric observations with the Atacama Large Millimeter Array (ALMA) of the free-free continuum and recombination line emission at 1 and 3 mm of the "Red Square Nebula" surrounding the B[e]-type star MWC922. The unknown distance to the source is usually taken to be =1.7-3 kpc. Read More

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http://dx.doi.org/10.1051/0004-6361/201936057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6887535PMC
September 2019

Dynamics of cluster-forming hub-filament systems: The case of the high-mass star-forming complex Monoceros R2.

Astron Astrophys 2019 Sep 12;629. Epub 2019 Sep 12.

Zentrum für Astronomie, Institut für Theoretische Astrophysik, Universität Heidelberg, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany.

Context: High-mass stars and star clusters commonly form within hub-filament systems. Monoceros R2 (hereafter Mon R2), at a distance of 830 pc, harbors one of the closest such systems, making it an excellent target for case studies.

Aims: We investigate the morphology, stability and dynamical properties of the Mon R2 hub-filament system. Read More

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http://dx.doi.org/10.1051/0004-6361/201935260DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6823053PMC
September 2019
1 Read

Influence of collisions on ion dynamics in the inner comae of four comets.

Astron Astrophys 2019 Oct;630

Swedish Institute of Space Physics, POB 537, SE-751 21, Uppsala, Sweden.

Context: Collisions between cometary neutrals in the inner coma of a comet and cometary ions that have been picked up into the solar wind flow and return to the coma lead to the formation of a broad inner boundary known as a collisionopause. This boundary is produced by a combination of charge transfer and chemical reactions, both of which are important at the location of the collisionopause boundary. Four spacecraft measured ion densities and velocities in the inner region of comets, exploring the part of the coma where an ion-neutral collisionopause boundary is expected to form. Read More

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http://dx.doi.org/10.1051/0004-6361/201834828DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6800695PMC
October 2019

Discovery of two new magnesium-bearing species in IRC+10216: MgCN and MgCH.

Astron Astrophys 2019 Oct 23;630. Epub 2019 Sep 23.

Department of Applied Chemistry, Science Building II, National Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 30010, Taiwan.

We report on the detection of two series of harmonically related doublets in IRC +10216. From the observed frequencies, the rotational constant of the first series is = 1380.888 MHz and that of the second series is = 1381. Read More

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http://dx.doi.org/10.1051/0004-6361/201936372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6774763PMC
October 2019

Study of CS, SiO, and SiS abundances in carbon star envelopes: Assessing their role as gas-phase precursors of dust.

Astron Astrophys 2019 Aug 7;628. Epub 2019 Aug 7.

Instituto de Física Fundamental, CSIC, C/Serrano 123, E-28006, Madrid, Spain.

Aims: We aim to determine the abundances of CS, SiO, and SiS in a large sample of carbon star envelopes covering a wide range of mass loss rates to investigate the potential role that these molecules could play in the formation of dust in the surroundings of the central AGB star.

Methods: We surveyed a sample of 25 carbon-rich AGB stars in the 2 mm band, more concretely in the = 3 - 2 line of CS and SiO, and in the = 7 - 6 and = 8 - 7 lines of SiS, using the IRAM 30 m telescope. We performed excitation and radiative transfer calculations based on the large velocity gradient (LVG) method to model the observed lines of the molecules and to derive their fractional abundances in the observed envelopes. Read More

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http://dx.doi.org/10.1051/0004-6361/201935069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6739229PMC

Abundances of sulphur molecules in the Horsehead nebula First NS detection in a photodissociation region.

Astron Astrophys 2019 Aug 29;628. Epub 2019 Jul 29.

LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-75005 Paris, France.

Context: Sulphur is one of the most abundant elements in the Universe (S/H1.310 ) and plays a crucial role in biological systems on Earth. The understanding of its chemistry is therefore of major importance. Read More

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http://dx.doi.org/10.1051/0004-6361/201935354DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6739222PMC

The millimeter-wave spectrum and astronomical search of succinonitrile and its vibrational excited states .

Astron Astrophys 2019 Sep 2;629. Epub 2019 Sep 2.

Instituto de Física Fundamental (IFF-CSIC). Group of Molecular Astrophysics, C/ Serrano 123, 28006 Madrid, Spain.

Context: Dinitriles with a saturated hydrocarbon skeleton and a -C≡N group at each end can have large electric dipole moments. Their formation can be related to highly reactive radicals such as CHCN, CN or CN. Thus, these saturated dinitriles are potential candidates to be observed in the ISM. Read More

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http://dx.doi.org/10.1051/0004-6361/201935899DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6726483PMC
September 2019

Discovery of the first Ca-bearing molecule in space: CaNC.

Astron Astrophys 2019 Jul 3;627. Epub 2019 Jul 3.

Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, F-38406, Saint Martin d'Hères, France.

We report on the detection of calcium isocyanide, CaNC, in the carbon-rich evolved star IRC+10216. We derived a column density for this species of (2±0.5)×10 cm. Read More

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http://dx.doi.org/10.1051/0004-6361/201936040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6640036PMC

A sensitive 3 mm line survey of L483: A broad view of the chemical composition of a core around a Class 0 object.

Astron Astrophys 2019 Jul 29;625. Epub 2019 May 29.

Observatorio Astronómico Nacional, C/ Alfonso XII 3, E-28014 Madrid, Spain.

An exhaustive chemical characterization of dense cores is mandatory to our understanding of chemical composition changes from a starless to a protostellar stage. However, only a few sources have had their molecular composition characterized in detail. Here we present a 3 mm line survey of L483, a dense core around a Class 0 protostar, which was observed with the IRAM 30m telescope in the 80-116 GHz frequency range. Read More

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http://dx.doi.org/10.1051/0004-6361/201935164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6640051PMC

Broad band high resolution rotational spectroscopy for Laboratory Astrophysics.

Astron Astrophys 2019 7;626. Epub 2019 Jun 7.

Instituto de Ciencia de Materiales de Madrid (ICMM. CSIC). Materials Science Factory. Structure of Nanoscopic Systems Group, ESISNA. C/Sor Juana Inés de la Cruz 3, 28049 Cantoblanco, Madrid, Spain.

We present a new experimental setup devoted to the study of gas phase molecules and processes using broad band high spectral resolution rotational spectroscopy. A reactor chamber has been equipped with radio receivers similar to those used by radio astronomers to search for molecular emission in space. The whole Q (31. Read More

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http://dx.doi.org/10.1051/0004-6361/201935197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6557716PMC
June 2019
1 Read

Direct estimation of electron density in the Orion Bar PDR from mm-wave carbon recombination lines.

Astron Astrophys 2019 May 7;625. Epub 2019 May 7.

Centro de Astrobiología (CSIC-INTA), Ctra. de Torrejón a Ajalvir, km 4, E28850 Torrejón de Ardoz, Madrid, Spain.

Context: A significant fraction of the molecular gas in star-forming regions is irradiated by stellar UV photons. In these environments, the electron density () plays a critical role in the gas dynamics, chemistry, and collisional excitation of certain molecules.

Aims: We determine in the prototypical strongly irradiated photodissociation region (PDR), the Orion Bar, from the detection of new millimeter-wave carbon recombination lines (mmCRLs) and existing far-IR [Cii] hyperfine line observations. Read More

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http://dx.doi.org/10.1051/0004-6361/201935556DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6558286PMC
May 2019
1 Read

Interferometric observations of SiO thermal emission in the inner wind of M-type AGB stars IK Tauri and IRC+10011.

Astron Astrophys 2019 May 19;624. Epub 2019 Apr 19.

Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, 38406, Saint Martin d'Hères, France.

Context: Asymptotic giant branch (AGB) stars go through a process of strong mass loss that involves pulsations of the atmosphere, which extends to a region in which the conditions are adequate for dust grains to form. Radiation pressure acts on these grains which, coupled to the gas, drive a massive outflow. The details of this process are not clear, including which molecules are involved in the condensation of dust grains. Read More

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http://dx.doi.org/10.1051/0004-6361/201834864DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6542683PMC
May 2019
9 Reads

Gas phase Elemental abundances in Molecular cloudS (GEMS): I. The prototypical dark cloud TMC 1.

Astron Astrophys 2019 May 19;624. Epub 2019 Apr 19.

Departamento de Física, Universidade Federal de Juiz de Fora-UFJF, Juiz de Fora, MG 36036-330, Brazil.

GEMS is an IRAM 30m Large Program whose aim is determining the elemental depletions and the ionization fraction in a set of prototypical star-forming regions. This paper presents the first results from the prototypical dark cloud TMC 1. Extensive millimeter observations have been carried out with the IRAM 30m telescope (3 mm and 2 mm) and the 40m Yebes telescope (1. Read More

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http://dx.doi.org/10.1051/0004-6361/201834654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6542666PMC
May 2019
7 Reads

Chemical segregation of complex organic O-bearing species in Orion KL.

Astron Astrophys 2018 Dec 30;620. Epub 2018 Nov 30.

Instituto de Física Fundamental (IFF-CSIC). Calle Serrano 123, E-28006 Madrid, Spain.

We investigate the chemical segregation of complex O-bearing species (including the largest and most complex ones detected to date in space) towards Orion KL, the closest high-mass star-forming region. The molecular line images obtained using the ALMA science verification data reveal a clear segregation of chemically related species depending on their different functional groups. We map the emission of CHOH, HCOOCH, CHOCH, CHOCH, CHCOOCH, HCOOCHCH, CHCHOCH, HCOOH, OHCHCHOH, CHCOOH, CHCHOH, CHOCHOH, OHCHCHO, and CHCOCH with ~1. Read More

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http://dx.doi.org/10.1051/0004-6361/201834417DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6485672PMC
December 2018
1 Read

Molecular tracers of radiative feedback in Orion (OMC-1) Widespread CH ( = 1-0), CO (10-9), HCN (6-5), and HCO (6-5) emission.

Astron Astrophys 2019 Feb;622

Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain.

Young massive stars regulate the physical conditions, ionization, and fate of their natal molecular cloud and surroundings. It is important to find tracers that help quantifying the stellar feedback processes that take place at different spatial scales. We present ~85 arcmin (~1. Read More

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http://dx.doi.org/10.1051/0004-6361/201834409DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6390943PMC
February 2019
2 Reads

Gas infall and possible circumstellar rotation in R Leo.

Astron Astrophys 2019 Feb;622

Molecular Astrophysics Group, Instituto de Física Fundamental, CSIC, C/ Serrano, 123, 28006, Madrid (Spain).

We present new interferometer molecular observations of R Leo taken at 1.2 mm with the Atacama Large Millimeter Array with an angular resolution up to These observations permit us to resolve the innermost envelope of this star revealing the existence of a complex structure that involves extended continuum emission and molecular emission showing a non-radial gas velocity distribution. This molecular emission displays prominent red-shifted absorptions located right in front to the star typical of material infall and lateral gas motions compatible with the presence of a torus-like structure. Read More

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http://dx.doi.org/10.1051/0004-6361/201834840DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6390941PMC
February 2019
1 Read

The millimeter-wave spectrum of methyl ketene and the astronomical search for it.

Astron Astrophys 2018 Nov;619

Univ. Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR - UMR6226, F-35000 Rennes, France.

Context: The analysis of isomeric species of a compound observed in the interstellar medium (ISM) is a useful tool to understand the chemistry of complex organic molecules. It could, likewise, assist in the detection of new species.

Aims: Our goal consists in analyzing one of the two most stable species of the CHO family, methyl ketene, whose actual rotational parameters are not precise enough to allow its detection in the ISM. Read More

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http://dx.doi.org/10.1051/0004-6361/201833267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6309256PMC
November 2018
2 Reads

Laboratory rotational spectrum and astronomical search for methoxyacetaldehyde.

Astron Astrophys 2018 Nov;619

Grupo de Espectroscopia Molecular (GEM), Edificio Quifima, Área de Química-Física, Laboratorios de Espectroscopia y Bioespectroscopia, Parque Científico UVa, Unidad Asociada CSIC, Universidad de Valladolid, 47011 Valladolid, Spain.

Context: Methoxyacetaldehyde belongs to a group of structural isomers with the general formula CHO, of which methyl acetate and ethyl formate are known interstellar molecules. Rotational data available for methoxyacetaldehyde are limited to 40 GHz, which makes predictions at higher frequencies rather uncertain.

Aims: The aim of this work is to provide accurate experimental frequencies of methoxyacetaldehyde in the millimeter-wave region to support its detection in the interstellar medium. Read More

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http://dx.doi.org/10.1051/0004-6361/201833773DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6290985PMC
November 2018
2 Reads

Through the magnifying glass: ALMA acute viewing of the intricate nebular architecture of OH231.8+4.2.

Astron Astrophys 2018 Oct;618

Instituto de Fisica Fundamental (CSIC), C/ Serrano, 123, E-28006, Madrid, Spain.

We present continuum and molecular line emission ALMA observations of OH 231.8+4.2, a well studied bipolar nebula around an asymptotic giant branch (AGB) star. Read More

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https://www.aanda.org/10.1051/0004-6361/201833632
Publisher Site
http://dx.doi.org/10.1051/0004-6361/201833632DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6251484PMC
October 2018
1 Read

Revisiting the case of R Monocerotis: Is CO removed at R < 20 au?.

Astron Astrophys 2018 Sep;617

Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC). E-28049, Cantoblanco, Madrid, Spain.

Context: To our knowledge, R Mon is the only B0 star in which a gaseous Keplerian disk has been detected. However, there is some controversy about the spectral type of R Mon. Some authors propose that it could be a later B8e star, where disks are more common. Read More

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http://dx.doi.org/10.1051/0004-6361/201731658DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6251485PMC
September 2018
1 Read

High-speed molecular cloudlets around the Galactic center's supermassive black hole.

Astron Astrophys 2018 Oct;618

Instituto de Física Fundamental (CSIC). Calle Serrano 121, 28006, Madrid, Spain.

We present 1″-resolution ALMA observations of the circumnuclear disk (CND) and the interstellar environment around Sgr A*. The images unveil the presence of small spatial scale CO (=3-2) molecular "cloudlets" (≲20,000 AU size) within the central parsec of the Milky Way, in other words, inside the cavity of the CND, and moving at high speeds, up to 300 km s along the line-of-sight. The CO-emitting structures show intricate morphologies: extended and filamentary at high negative-velocities (v ≲-150 km s), more localized and clumpy at extreme positive-velocities (v ≳+200 km s). Read More

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http://dx.doi.org/10.1051/0004-6361/201833558DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6231548PMC
October 2018
1 Read

IRC +10216 as a spectroscopic laboratory: improved rotational constants for SiC, its isotopologues, and SiC.

Astron Astrophys 2018 Oct 3;618. Epub 2018 Oct 3.

Instituto de Radioastronomía Milimétrica, Avenida Divina Pastora 7, E-18012, Granada, Spain.

This work presents a detailed analysis of the laboratory and astrophysical spectral data available for SiC, SiC,SiC, SiCC, and SiC. New data on the rotational lines of these species between 70 and 350 GHz have been obtained with high spectral resolution (195 kHz) with the IRAM 30m telescope in the direction of the circumstellar envelope IRC +10216. Frequency measurements can reach an accuracy of 50 kHz for features observed with a good signal to noise ratio. Read More

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http://dx.doi.org/10.1051/0004-6361/201833335DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6231541PMC
October 2018
1 Read

Diagnostic value of far-IR water ice features in T Tauri disks.

Astron Astrophys 2018 Sep;617

Department of Surfaces, Coatings, and Molecular Astrophysics, Spanish National Research Council, Madrid, Spain.

Aims: This paper investigates how the far-IR water ice features can be used to infer properties of disks around T Tauri stars and the water ice thermal history. We explore the power of future observations with SOFIA/HIRMES and SPICA's proposed far-IR instrument SAFARI.

Methods: A series of detailed radiative transfer disk models around a representative T Tauri star are used to investigate how the far-IR water ice features at 45 and 63 m change with key disk properties: disk size, grain sizes, disk dust mass, dust settling, and ice thickness. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6203324PMC
September 2018
1 Read

Millimeter wave spectra of ethyl isocyanate and searches for it in Orion KL and Sgr B2.

Astron Astrophys 2018 Aug 7;616. Epub 2018 Sep 7.

Grupo de Espectroscopia Molecular (GEM), Edificio Quifima, Área de Química-Física, Laboratorios de Espectroscopia y Bioespectroscopia, Parque Científico UVa, Unidad Asociada CSIC, Universidad de Valladolid, E-47011 Valladolid, Spain.

Context: Relatively high abundances of methyl isocyanate (CHNCO), a methyl derivative of isocyanic acid (HNCO), found in the Orion KL and Sgr B2 molecular clouds suggest that its ethyl derivative, ethyl isocyanate (CHCHNCO), may also be present.

Aims: The aim of this work is to provide accurate experimental frequencies of ethyl isocyanate in its ground and excited vibrational states in the millimeter wave region to support searches for it in the interstellar medium.

Methods: The rotational spectrum of ethyl isocyanate was recorded at room temperature from 80 to 340 GHz using the millimeter wave spectrometer in Valladolid. Read More

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http://dx.doi.org/10.1051/0004-6361/201833223DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6203308PMC
August 2018
1 Read

The chemistry of disks around T Tauri and Herbig Ae/Be stars.

Astron Astrophys 2018 Aug;616

Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-92190 Meudon, France.

Context: Infrared and (sub-)mm observations of disks around T Tauri and Herbig Ae/Be stars point to a chemical differentiation between both types of disks, with a lower detection rate of molecules in disks around hotter stars.

Aims: To investigate the underlying causes of the chemical differentiation indicated by observations we perform a comparative study of the chemistry of T Tauri and Herbig Ae/Be disks. This is one of the first studies to compare chemistry in the outer regions of these two types of disks. Read More

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http://dx.doi.org/10.1051/0004-6361/201732518DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6120683PMC
August 2018
2 Reads

Structure of photodissociation fronts in star-forming regions revealed by observations of high-J CO emission lines with Herschel.

Astron Astrophys 2018 Jul 27;615. Epub 2018 Jul 27.

Department of Astronomy, University of Michigan, 311 West Hall, 1085 S. University Avenue, Ann Arbor, MI 48109, USA.

Context: In bright photodissociation regions (PDRs) associated to massive star formation, the presence of dense "clumps" that are immersed in a less dense interclump medium is often proposed to explain the difficulty of models to account for the observed gas emission in high-excitation lines.

Aims: We aim at presenting a comprehensive view of the modeling of the CO rotational ladder in PDRs, including the high-J lines that trace warm molecular gas at PDR interfaces.

Methods: We observed the CO and CO ladders in two prototypical PDRs, the Orion Bar and NGC 7023 NW using the instruments onboard . Read More

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https://www.aanda.org/10.1051/0004-6361/201832611
Publisher Site
http://dx.doi.org/10.1051/0004-6361/201832611DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6120684PMC
July 2018
2 Reads

Time-dependent molecular emission in IRC+10216.

Astron Astrophys 2018 Jul 13;615. Epub 2018 Jul 13.

Department of Physics and Astronomy, John Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.

Context: The variability in IRC+10216, the envelope of the asymptotic giant branch (AGB) star CW Leo, has attracted increasing attention in recent years. Studying the details of this variability in the molecular emission required a systematic observation program.

Aims: We aim to reveal and characterize the periodical variability of the rotational lines from several molecules and radicals in IRC+10216, and to compare it with previously reported IR variability. Read More

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http://dx.doi.org/10.1051/0004-6361/201833303DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6120678PMC
July 2018
13 Reads

Laboratory measurements and astronomical search for cyanomethanimine.

Astron Astrophys 2018 Jan 2;609. Epub 2018 Feb 2.

Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy.

Context: C-cyanomethanimine (HNCHCN), existing in the two and isomeric forms, is a key prebiotic molecule, but, so far, only the isomer has been detected toward the massive star-forming region. Sagittarius B2(N) using transitions in the radio wavelength domain.

Aims: With the aim of detecting HNCHCN in Sun-like-star forming regions, the laboratory investigation of its rotational spectrum has been extended to the millimeter-/submillimeter-wave (mm-/submm-) spectral window in which several unbiased spectral surveys have been already carried out. Read More

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http://dx.doi.org/10.1051/0004-6361/201731972DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6071866PMC
January 2018

High-velocity hot CO emission close to Sgr A*: /HIFI submillimeter spectral survey toward Sgr A.

Astron Astrophys 2018 Aug 13;616. Epub 2018 Aug 13.

Sorbonne Université, Observatoire de Paris, Université PSL, École Normale Supérieure, CNRS, LERMA, F-75014, Paris, France.

The properties of molecular gas, the fuel that forms stars, inside the cavity of the circumnuclear disk (CND) are not well constrained. We present results of a velocity-resolved submillimeter scan (~480 to 1250 GHz) and [C ii] 158 m line observations carried out with /HIFI toward Sgr A*; these results are complemented by a ~2'×2' CO (=3-2) map taken with the IRAM 30 m telescope at ~7″ resolution. We report the presence of high positive-velocity emission (up to about +300 km s) detected in the wings of CO =5-4 to 10-9 lines. Read More

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http://dx.doi.org/10.1051/0004-6361/201833684DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6914365PMC

High-resolution observations of IRAS 08544-4431: Detection of a disk orbiting a post-AGB star and of a slow disk wind.

Astron Astrophys 2017 Jun;614

Instituut voor Sterrenkunde, K.U.Leuven, Celestijnenlaan 200B, 3001 Leuven, Belgium.

Aims: In order to study the effects of rotating disks in the post-asymptotic giant branch (post-AGB) evolution, we observe a class of binary post-AGB stars that seem to be systematically surrounded by equatorial disks and slow outflows. Although the rotating dynamics had only been well identified in three cases, the study of such structures is thought to be fundamental to the understanding of the formation of disks in various phases of the late evolution of binary stars and the ejection of planetary nebulae from evolved stars.

Methods: We present ALMA maps of CO and CO =3-2 lines in the source IRAS 08544-4431, which belongs to the above mentioned class of objects. Read More

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http://dx.doi.org/10.1051/0004-6361/201732422DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6031302PMC
June 2017
21 Reads

Detection of interstellar HCS and its metastable isomer HSC: new pieces in the puzzle of sulfur chemistry.

Astron Astrophys 2018 Mar;611

Observatorio Astronómico Nacional (OAN), C/ Alfonso XII 3, 28014 Madrid, Spain.

We present the first identification in interstellar space of the thioformyl radical (HCS) and its metastable isomer HSC. These species were detected toward the molecular cloud L483 thanks to observations carried out with the IRAM 30m telescope in the 3 mm band. We derive beam-averaged column densities of 7 × 10 cm for HCS and 1. Read More

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https://www.aanda.org/10.1051/0004-6361/201832743
Publisher Site
http://dx.doi.org/10.1051/0004-6361/201832743DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6031296PMC
March 2018
5 Reads

Rotational spectrum of methoxyamine up to 480 GHz: a laboratory study and astronomical search.

Astron Astrophys 2018 Jan 22;609. Epub 2017 Dec 22.

Grupo de Espectroscopia Molecular (GEM), Edificio Quifima, Área de Química-Física, Laboratorios de Espectroscopia y Bioespectroscopia, Parque Científico UVa, Unidad Asociada CSIC, Universidad de Valladolid, 47011 Valladolid, Spain.

Aims: Methoxyamine is a potential interstellar amine that has been predicted by gas-grain chemical models for the formation of complex molecules. The aim of this work is to provide direct experimental frequencies of its ground-vibrational state in the millimeter- and submillimeter-wave regions to achieve its detection in the interstellar medium.

Methods: Methoxyamine was chemically liberated from its hydrochloride salt, and its rotational spectrum was recorded at room temperature from 75 to 480 GHz using the millimeter-wave spectrometer in Valladolid. Read More

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https://www.aanda.org/10.1051/0004-6361/201730744
Publisher Site
http://dx.doi.org/10.1051/0004-6361/201730744DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6031297PMC
January 2018
9 Reads

Discovery of the elusive radical NCO and confirmation of HNCO in space.

Astron Astrophys 2018 Apr 10;612. Epub 2018 May 10.

Observatorio Astronómico Nacional (OAN), C/ Alfonso XII 3, 28014 Madrid, Spain.

The isocyanate radical (NCO) is the simplest molecule containing the backbone of the peptide bond, C(=O)-N. This bond has a prebiotic interest since is the one linking two amino acids to form large chains of proteins. It is also present in some organic molecules observed in space such as HNCO, NHCHO and CHNCO. Read More

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https://www.aanda.org/10.1051/0004-6361/201833074
Publisher Site
http://dx.doi.org/10.1051/0004-6361/201833074DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6027991PMC
April 2018
3 Reads

The Abundance of SiC in Carbon Star Envelopes: Evidence that SiC is a gas-phase precursor of SiC dust.

Astron Astrophys 2018 Mar 20;611. Epub 2018 Mar 20.

Observatorio Astronómico Nacional (IGN), Apartado de Correos 112, 28803, Alcalá de Henares, Madrid, Spain.

Context: Silicon carbide dust is ubiquitous in circumstellar envelopes around C-rich AGB stars. However, the main gas-phase precursors leading to the formation of SiC dust have not yet been identified. The most obvious candidates among the molecules containing an Si-C bond detected in C-rich AGB stars are SiC, SiC, and SiC. Read More

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http://dx.doi.org/10.1051/0004-6361/201732038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5884425PMC
March 2018
2 Reads

IRC +10 216 in 3-D: morphology of a TP-AGB star envelope.

Astron Astrophys 2018 Feb 7;610. Epub 2018 Feb 7.

Center for Astrophysics, 60 Garden street, Cambridge, MA USA.

During their late pulsating phase, AGB stars expel most of their mass in the form of massive dusty envelopes, an event that largely controls the composition of interstellar matter. The envelopes, however, are distant and opaque to visible and NIR radiation: their structure remains poorly known and the mass-loss process poorly understood. Millimeter-wave interferometry, which combines the advantages of longer wavelength, high angular resolution and very high spectral resolution is the optimal investigative tool for this purpose. Read More

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http://dx.doi.org/10.1051/0004-6361/201731619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5815495PMC
February 2018
2 Reads

Clustering the Orion B giant molecular cloud based on its molecular emission.

Astron Astrophys 2018 Feb 12;610. Epub 2018 Feb 12.

Maison de la Simulation, CEA-CNRS-INRIA-UPS-UVSQ, USR 3441, Centre d'étude de Saclay, F-91191 Gif-Sur-Yvette, France.

Context: Previous attempts at segmenting molecular line maps of molecular clouds have focused on using position-position-velocity data cubes of a single molecular line to separate the spatial components of the cloud. In contrast, wide field spectral imaging over a large spectral bandwidth in the (sub)mm domain now allows one to combine multiple molecular tracers to understand the different physical and chemical phases that constitute giant molecular clouds (GMCs).

Aims: We aim at using multiple tracers (sensitive to different physical processes and conditions) to segment a molecular cloud into physically/chemically similar regions (rather than spatially connected components), thus disentangling the different physical/chemical phases present in the cloud. Read More

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http://dx.doi.org/10.1051/0004-6361/201731833DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5813791PMC
February 2018
2 Reads

A model for straight and helical solar jets: II. Parametric study of the plasma beta.

Astron Astrophys Suppl Ser 2016 12 25;596. Epub 2016 Nov 25.

Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.

Context: Jets are dynamic, impulsive, well-collimated plasma events that develop at many different scales and in different layers of the solar atmosphere.

Aims: Jets are believed to be induced by magnetic reconnection, a process central to many astrophysical phenomena. Within the solar atmosphere, jet-like events develop in many different environments, e. Read More

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http://dx.doi.org/10.1051/0004-6361/201629109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779865PMC
December 2016
1 Read

Metal abundances in hot white dwarfs with signatures of a superionized wind.

Astron Astrophys 2018 Jan;609

NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.

About a dozen hot white dwarfs with effective temperatures = 65 000 K - 120 000 K exhibit unusual absorption features in their optical spectra. These objects were tentatively identified as Rydberg lines of ultra-high excited metals in ionization stages v-x, indicating line formation in a dense environment with temperatures near 10 K. Since some features show blueward extensions, it was argued that they stem from a superionized wind. Read More

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http://dx.doi.org/10.1051/0004-6361/201731740DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6999747PMC
January 2018

Using radio astronomical receivers for molecular spectroscopic characterization in astrochemical laboratory simulations: A proof of concept.

Astron Astrophys 2018 Jan 22;609. Epub 2017 Dec 22.

ICMM. CSIC. Molecular Astrophysics Group. C/ Sor Juana Inés de la Cruz 3. Cantoblanco, 28049 Madrid. Spain.

We present a proof of concept on the coupling of radio astronomical receivers and spectrometers with chemical reactors and the performances of the resulting setup for spectroscopy and chemical simulations in laboratory astrophysics. Several experiments including cold plasma generation and UV photochemistry were performed in a 40 cm long gas cell placed in the beam path of the Aries 40 m radio telescope receivers operating in the 41-49 GHz frequency range interfaced with fast Fourier transform spectrometers providing 2 GHz bandwidth and 38 kHz resolution. The impedance matching of the cell windows has been studied using different materials. Read More

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http://dx.doi.org/10.1051/0004-6361/201730969DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5741178PMC
January 2018
1 Read

Clues to NaCN formation.

Astron Astrophys 2017 Nov 9;607. Epub 2017 Nov 9.

Instituto de Ciencia de Materiales de Madrid, Sor Juana Inés de la Cruz, 3, Cantoblanco, 28049 Madrid, Spain.

Context: ALMA is providing us essential information on where certain molecules form. Observing where these molecules emission arises from, the physical conditions of the gas, and how this relates with the presence of other species allows us to understand the formation of many species, and to significantly improve our knowledge of the chemistry that occurs in the space.

Aims: We studied the molecular distribution of NaCN around IRC +10216, a molecule detected previously, but whose origin is not clear. Read More

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http://dx.doi.org/10.1051/0004-6361/201732015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5687569PMC
November 2017
2 Reads

The ESO Diffuse Interstellar Bands Large Exploration Survey: EDIBLES I. Project description, survey sample and quality assessment.

Astron Astrophys 2017 Oct 16;606. Epub 2017 Oct 16.

Kapteyn Institute, University of Groningen, Groningen, The Netherlands.

The carriers of the diffuse interstellar bands (DIBs) are largely unidentified molecules ubiquitously present in the interstellar medium (ISM). After decades of study, two strong and possibly three weak near-infrared DIBs have recently been attributed to the [Formula: see text] fullerene based on observational and laboratory measurements. There is great promise for the identification of the over 400 other known DIBs, as this result could provide chemical hints towards other possible carriers. Read More

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http://dx.doi.org/10.1051/0004-6361/201730912DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5693340PMC
October 2017
17 Reads
4.380 Impact Factor

Zeeman effect in sulfur monoxide: A tool to probe magnetic fields in star forming regions.

Astron Astrophys 2017 Sep 1;605. Epub 2017 Sep 1.

Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, via Selmi 2, 40126 Bologna, Italy.

Context: Magnetic fields play a fundamental role in star formation processes and the best method to evaluate their intensity is to measure the Zeeman effect of atomic and molecular lines. However, a direct measurement of the Zeeman spectral pattern from interstellar molecular species is challenging due to the high sensitivity and high spectral resolution required. So far, the Zeeman effect has been detected unambiguously in star forming regions for very few non-masing species, such as OH and CN. Read More

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http://dx.doi.org/10.1051/0004-6361/201730858DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5693346PMC
September 2017
4 Reads

A spectroscopic survey of Orion KL between 41.5 and 50 GHz.

Astron Astrophys 2017 Sep 14;605. Epub 2017 Sep 14.

Grupo de Astrofísica Molecular. Instituto de Ciencia de Materiales de Madrid (CSIC). Calle Sor Juana Inés de la Cruz 3, Cantoblanco, E-28049 Madrid, Spain.

Context: The nearby massive star-forming region Orion KL is one of the richest molecular reservoirs known in our Galaxy. The region hosts newly formed protostars, and the strong interaction between their radiation and their outflows with the environment results in a series of complex chemical processes leading to a high diversity of interstellar tracers. The region is therefore one of the most frequently observed sources, and the site where many molecular species have been discovered for the first time. Read More

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http://dx.doi.org/10.1051/0004-6361/201629936DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5693341PMC
September 2017
1 Read

Sub-arcsecond imaging of the water emission in Arp 220.

Astron Astrophys 2017 Jun 2;602. Epub 2017 Jun 2.

Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, Domaine Universitaire, 38406, Saint Martin d'Hères, France.

Aims: Extragalactic observations of water emission can provide valuable insights into the excitation of the interstellar medium. In particular they allow us to investigate the excitation mechanisms in obscured nuclei, i.e. Read More

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http://dx.doi.org/10.1051/0004-6361/201630331DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5687566PMC
June 2017
1 Read

Evidence for disks at an early stage in class 0 protostars?

Astron Astrophys 2017 Oct 4;606. Epub 2017 Oct 4.

LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-92190 Meudon, France.

Aims: The formation epoch of protostellar disks is debated because of the competing roles of rotation, turbulence, and magnetic fields in the early stages of low-mass star formation. Magnetohydrodynamics simulations of collapsing cores predict that rotationally supported disks may form in strongly magnetized cores through ambipolar diffusion or misalignment between the rotation axis and the magnetic field orientation. Detailed studies of individual sources are needed to cross check the theoretical predictions. Read More

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http://dx.doi.org/10.1051/0004-6361/201630187DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5683350PMC
October 2017
1 Read

Discovery of methyl silane and confirmation of silyl cyanide in IRC +10216.

Astron Astrophys 2017 Oct 9;606. Epub 2017 Oct 9.

Grupo de Espectroscopía Molecular (GEM), Edificio Quifima, Área de Química-Física, Laboratorios de Espectroscopía y Bioespectroscopía, Parque Científico UVa, Unidad Asociada CSIC, Universidad de Valladolid, 47011 Valladolid, Spain.

We report the discovery in space of methyl silane, CHSiH, from observations of ten rotational transitions between 80 and 350 GHz ( from 4 to 16) with the IRAM 30 m radio telescope. The molecule was observed in the envelope of the C-star IRC +10216. The observed profiles and our models for the expected emission of methyl silane suggest that the it is formed in the inner zones of the circumstellar envelope, 1-40 , with an abundance of (0. Read More

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http://dx.doi.org/10.1051/0004-6361/201731672DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5683346PMC
October 2017
1 Read