84 results match your criteria Astronomy and astrophysics[Journal]


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

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

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

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

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

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

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

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

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

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

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

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
1 Read

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
12 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-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
4 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
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http://dx.doi.org/10.1051/0004-6361/201832743DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6031296PMC
March 2018
4 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
6 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
2 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
1 Read

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
1 Read

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

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

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

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
1 Read

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
6 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
2 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

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

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

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

The circumstellar envelope around the S-type AGB star W Aql. Effects of an eccentric binary orbit.

Astron Astrophys 2017 Sep;605

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

Context: Recent observations at subarcsecond resolution, now possible also at submillimeter wavelengths, have shown intricate circumstellar structures around asymptotic giant branch (AGB) stars, mostly attributed to binary interaction. The results presented here are part of a larger project aimed at investigating the effects of a binary companion on the morphology of circumstellar envelopes (CSEs) of AGB stars.

Aims: AGB stars are characterized by intense stellar winds that build CSEs around the stars. Read More

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http://dx.doi.org/10.1051/0004-6361/201730934DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5683349PMC
September 2017
6 Reads

Complex organic molecules in strongly UV-irradiated gas.

Astron Astrophys 2017 Jul;603

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

We investigate the presence of complex organic molecules (COMs) in strongly UV-irradiated interstellar molecular gas. We have carried out a complete millimetre (mm) line survey using the IRAM 30 m telescope towards the edge of the Orion Bar photodissociation region (PDR), close to the H dissociation front, a position irradiated by a very intense far-UV (FUV) radiation field. These observations have been complemented with 8. Read More

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http://dx.doi.org/10.1051/0004-6361/201730459DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5683355PMC
July 2017
2 Reads

Chemical segregation in the young protostars Barnard 1b-N and S Evidence of pseudo-disk rotation in Barnard 1b-S.

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

National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA.

The extremely young Class 0 object B1b-S and the first hydrostatic core (FSHC) candidate, B1b-N, provide a unique opportunity to study the chemical changes produced in the elusive transition from the prestellar core to the protostellar phase. We present 40"×70" images of Barnard 1b in the CO 1→0, CO 1→0, NHD 1→1, and SO 3→2 lines obtained with the NOEMA interferometer. The observed chemical segregation allows us to unveil the physical structure of this young protostellar system down to scales of ∼500 au. Read More

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http://www.aanda.org/10.1051/0004-6361/201730963
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http://dx.doi.org/10.1051/0004-6361/201730963DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5662144PMC
October 2017
1 Read

survey and modelling of externally-illuminated photoevaporating protoplanetary disks.

Astron Astrophys 2017 Aug 8;604. Epub 2017 Aug 8.

Grupo de Astrofisica Molecular, Instituto de Ciencia de Materiales de Madrid (CSIC), E-28049, Madrid, Spain.

Context: Protoplanetary disks undergo substantial mass-loss by photoevaporation, a mechanism which is crucial to their dynamical evolution. However, the processes regulating the gas energetics have not been well constrained by observations so far.

Aims: We aim at studying the processes involved in disk photoevaporation when it is driven by far-UV photons (i. Read More

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http://dx.doi.org/10.1051/0004-6361/201629404DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5662148PMC

[Cii] emission from L1630 in the Orion B molecular cloud.

Astron Astrophys 2017 Oct 3;606. Epub 2017 Oct 3.

Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, Netherlands.

Context: L1630 in the Orion B molecular cloud, which includes the iconic Horsehead Nebula, illuminated by the star system Ori, is an example of a photodissociation region (PDR). In PDRs, stellar radiation impinges on the surface of dense material, often a molecular cloud, thereby inducing a complex network of chemical reactions and physical processes.

Aims: Observations toward L1630 allow us to study the interplay between stellar radiation and a molecular cloud under relatively benign conditions, that is, intermediate densities and an intermediate UV radiation field. Read More

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http://dx.doi.org/10.1051/0004-6361/201730881DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5630115PMC
October 2017

Detection of Buckminsterfullerene emission in the diffuse interstellar medium.

Astron Astrophys 2017 Sep;605

Université de Toulouse; UPS-OMP; IRAP; Toulouse, France.

Emission of fullerenes in their infrared vibrational bands has been detected in space near hot stars. The proposed attribution of the diffuse interstellar bands at 9577 and 9632 Å to electronic transitions of the buckminsterfullerene cation (i.e. Read More

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http://dx.doi.org/10.1051/0004-6361/201630325DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5580815PMC
September 2017
1 Read

Spatially resolved images of reactive ions in the Orion Bar.

Astron Astrophys 2017 May 24;601. Epub 2017 May 24.

LERMA, Obs. de Paris, PSL Research University, CNRS, Sorbonne Universiteés, UPMC Univ. Paris 06, ENS, F-75005, France.

We report high angular resolution (4.9″×3.0″) images of reactive ions SH, HOC, and SO toward the Orion Bar photodissociation region (PDR). Read More

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http://dx.doi.org/10.1051/0004-6361/201730716DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5500010PMC
May 2017
2 Reads

The growth of carbon chains in IRC +10216 mapped with ALMA.

Astron Astrophys 2017 May;601

Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.

Linear carbon chains are common in various types of astronomical molecular sources. Possible formation mechanisms involve both bottom-up and top-down routes. We have carried out a combined observational and modeling study of the formation of carbon chains in the C-star envelope IRC +10216, where the polymerization of acetylene and hydrogen cyanide induced by ultraviolet photons can drive the formation of linear carbon chains of increasing length. Read More

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http://dx.doi.org/10.1051/0004-6361/201630274DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5405872PMC
May 2017
17 Reads

Spatial distribution of FIR rotationally excited CH and OH emission lines in the Orion Bar PDR.

Astron Astrophys 2017 Mar 21;599. Epub 2017 Feb 21.

LERMA, Observatoire de Paris, PSL Research University, Ecole Normale Supérieure, CNRS, 75014 Paris; Sorbonne Universités, UPMC Paris 06, CNRS, LERMA, 75005 Paris.

Context: The methylidyne cation (CH) and hydroxyl (OH) are key molecules in the warm interstellar chemistry, but their formation and excitation mechanisms are not well understood. Their abundance and excitation are predicted to be enhanced by the presence of vibrationally excited H or hot gas (~500-1000 K) in photodissociation regions with high incident FUV radiation field. The excitation may also originate in dense gas (> 10 cm) followed by nonreactive collisions with H, H, and electrons. Read More

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http://dx.doi.org/10.1051/0004-6361/201629445DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5334792PMC

ALMA Compact Array observations of the Fried Egg nebula: Evidence for large-scale asymmetric mass-loss from the yellow hypergiant IRAS 17163-3907.

Astron Astrophys 2017 Jan;597

Jodrell Bank Centre for Astrophysics, Alan Turing Building, Manchester M13 9PL, UK.

Yellow hypergiants are rare and represent a fast evolutionary stage of massive evolved stars. That evolutionary phase is characterised by a very intense mass loss, the understanding of which is still very limited. Here we report ALMA Compact Array observations of a 50″-mosaic toward the Fried Egg nebula, around one of the few Galactic yellow hypergiants IRAS 17163-3907. Read More

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http://dx.doi.org/10.1051/0004-6361/201628416DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5300097PMC
January 2017
1 Read

/HIFI observations of the circumstellar ammonia lines in IRC+10216.

Astron Astrophys 2016 08 12;592. Epub 2016 Aug 12.

Chalmers University of Technology, Department of Earth and Space Sciences, Onsala Space Observatory, S-439 92 Onsala, Sweden.

Context: A discrepancy exists between the abundance of ammonia (NH) derived previously for the circumstellar envelope (CSE) of IRC+10216 from far-IR submillimeter rotational lines and that inferred from radio inversion or mid-infrared (MIR) absorption transitions.

Aims: To address the discrepancy described above, new high-resolution far-infrared (FIR) observations of both ortho- and para-NH transitions toward IRC+10216 were obtained with , with the goal of determining the ammonia abundance and constraining the distribution of NH in the envelope of IRC+10216.

Methods: We used the Heterodyne Instrument for the Far Infrared (HIFI) on board to observe all rotational transitions up to the = 3 level (three ortho- and six para-NH lines). Read More

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http://dx.doi.org/10.1051/0004-6361/201527290DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5217166PMC
August 2016
2 Reads

Helioseismic Holography of Simulated Sunspots: dependence of the travel time on magnetic field strength and Wilson depression.

Astron Astrophys 2017 25;604. Epub 2017 Aug 25.

Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.

Improving methods for determining the subsurface structure of sunspots from their seismic signature requires a better understanding of the interaction of waves with magnetic field concentrations. We aim to quantify the impact of changes in the internal structure of sunspots on local helioseismic signals. We have numerically simulated the propagation of a stochastic wave field through sunspot models with different properties, accounting for changes in the Wilson depression between 250 and 550 km and in the photospheric umbral magnetic field between 1500 and 3500 G. Read More

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http://dx.doi.org/10.1051/0004-6361/201730798DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5901911PMC
August 2017
1 Read

ALMA high spatial resolution observations of the dense molecular region of NGC 6302.

Astron Astrophys 2017 Jan 19;597. Epub 2016 Dec 19.

Institut de Radioastronomie Millimétrique, 38406, Saint Martin d'Hères, France.

Context: The mechanism behind the shaping of bipolar planetary nebulae is still poorly understood. It is becoming increasingly clear that the main agents must operate at their innermost regions, where a significant equatorial density enhancement should be present and related to the collimation of light and jet launching from the central star preferentially towards the polar directions. Most of the material in this equatorial condensation must be lost during the asymptotic giant branch as stellar wind and later released from the surface of dust grains to the gas phase in molecular form. Read More

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http://dx.doi.org/10.1051/0004-6361/201629288DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5166980PMC
January 2017

The millimeter IRAM-30 m line survey toward IK Tau.

Astron Astrophys 2017 Jan 19;597. Epub 2016 Dec 19.

Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany.

Aims: We aim to investigate the physical and chemical properties of the molecular envelope of the oxygen-rich AGB star IK Tau.

Methods: We carried out a millimeter wavelength line survey between ~79 and 356 GHz with the IRAM-30 m telescope. We analysed the molecular lines detected in IK Tau using the population diagram technique to derive rotational temperatures and column densities. Read More

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http://dx.doi.org/10.1051/0004-6361/201628776DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5166976PMC
January 2017

molecular photoswitching in interstellar Space.

Astron Astrophys 2016 Dec 22;596. Epub 2016 Nov 22.

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

As many organic molecules, formic acid (HCOOH) has two conformers ( and ). The energy barrier to internal conversion from to is much higher than the thermal energy available in molecular clouds. Thus, only the most stable conformer () is expected to exist in detectable amounts. Read More

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http://dx.doi.org/10.1051/0004-6361/201629913DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5166968PMC
December 2016

Further ALMA observations and detailed modeling of the Red Rectangle.

Astron Astrophys 2016 Sep 29;593. Epub 2016 Sep 29.

Centro de Astrobiología (CSIC-INTA), ESAC Campus, E-28691 Villanueva de la Cañada, Madrid, Spain.

Aims: We aim to study the rotating and expanding gas in the Red Rectangle, which is a well known object that recently left the asymptotic giant branch (AGB) phase. We analyze the properties of both components and the relation between them. Rotating disks have been very elusive in post-AGB nebulae, in which gas is almost always found to be in expansion. Read More

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http://dx.doi.org/10.1051/0004-6361/201628546DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5166967PMC
September 2016
11 Reads

Millimeter wave spectra of carbonyl cyanide.

Astron Astrophys 2016 08 19;592. Epub 2016 Jul 19.

Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837, 35708 Rennes Cedex 7, France.

Context: More than 30 cyanide derivatives of simple organic molecules have been detected in the interstellar medium, but only one dicarbonitrile has been found and that very recently. There is still a lack of high-resolution spectroscopic data particularly for dinitriles derivatives. The carbonyl cyanide molecule is a new and interesting candidate for astrophysical detection. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5058435PMC
http://dx.doi.org/10.1051/0004-6361/201628379DOI Listing
August 2016
1 Read

The first CO image: I. Probing the HI/H layer around the ultracompact HII region Mon R2.

Astron Astrophys 2016 09;593

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

The CO reactive ion is thought to be a tracer of the boundary between a HII region and the hot molecular gas. In this study, we present the spatial distribution of the CO rotational emission toward the Mon R2 star-forming region. The CO emission presents a clumpy ring-like morphology, arising from a narrow dense layer around the HII region. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5055094PMC
http://dx.doi.org/10.1051/0004-6361/201628899DOI Listing
September 2016

The millimeter wave spectrum of methyl cyanate: a laboratory study and astronomical search in space.

Astron Astrophys 2016 07;591

Institut des Sciences Chimiques de Rennes, École Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837, 35708 Rennes Cedex 7, France.

Aims: The recent discovery of methyl isocyanate (CHNCO) in Sgr B2(N) and Orion KL makes methyl cyanate (CHOCN) a potential molecule in the interstellar medium. The aim of this work is to fulfill the first requirement for its unequivocal identification in space, i.e. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5055117PMC
http://dx.doi.org/10.1051/0004-6361/201628140DOI Listing

Laboratory measurements and astronomical search for the HSO radical.

Astron Astrophys 2016 07;591

Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via Selmi 2, I-40126 Bologna, Italy.

Context: Despite the fact that many sulfur-bearing molecules, ranging from simple diatomic species up to astronomical complex molecules, have been detected in the interstellar medium, the sulfur chemistry in space is largely unknown and a depletion in the abundance of S-containing species has been observed in the cold, dense interstellar medium (ISM). The chemical form of the missing sulfur has yet to be identified.

Aims: For these reasons, in view of the fact that there is a large abundance of triatomic species harbouring sulfur, oxygen, and hydrogen, we decided to investigate the HSO radical in the laboratory to try its astronomical detection. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5055096PMC
http://dx.doi.org/10.1051/0004-6361/201628745DOI Listing
July 2016
2 Reads