F. Fontani - INAF-Oss. Astrofisco di Arcetri, Italy

F. Fontani
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Name
F. Fontani
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INAF-Oss. Astrofisco di Arcetri, Italy
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Astrophysics of Galaxies (41)
 
Solar and Stellar Astrophysics (23)
 
Earth and Planetary Astrophysics (2)
 
Instrumentation and Methods for Astrophysics (2)
 
Cosmology and Nongalactic Astrophysics (1)

Publications Authored By F. Fontani

2017May
Affiliations: 1School of Physics and Astronomy, Queen Mary University of London, 2School of Physics and Astronomy, Queen Mary University of London, 3University College London, 4University College London, 5Astrophysics Research Institute, Liverpool John Moores University, 6Astrophysics Research Institute, Liverpool John Moores University, 7Max-Planck Institute for Extraterrestrial Physics, 8INAF-Osservatorio Astrofisico di Arcetri, 9Institut de Plan etologie et d'Astrophysique de Grenoble

Nitrogen is one of the most abundant elements in the Universe and its 14N/15N isotopic ratio has the potential to provide information about the initial environment in which our Sun formed. Recent findings suggest that the Solar System may have formed in a massive cluster since the presence of short-lived radioisotopes in meteorites can only be explained by the influence of a supernova. The aim of this project is to determine the 14N/15N ratio towards a sample of cold, massive dense cores at the initial stages in their evolution. Read More

The formation of deuterated molecules is favoured at low temperatures and high densities. Therefore, the deuteration fraction D$_{frac}$ is expected to be enhanced in cold, dense prestellar cores and to decrease after protostellar birth. Previous studies have shown that the deuterated forms of species such as N2H+ (formed in the gas phase) and CH3OH (formed on grain surfaces) can be used as evolutionary indicators and to constrain their dominant formation processes and time-scales. Read More

The shock L1157-B1 driven by the low-mass protostar L1157-mm is an unique environment to investigate the chemical enrichment due to molecules released from dust grains. IRAM-30m and Plateau de Bure Interferometer observations allow a census of Si-bearing molecules in L1157-B1. We detect SiO and its isotopologues and, for the first time in a shock, SiS. Read More

2017Jan
Affiliations: 1INAF-Osservatorio Astrofisico di Arcetri, 2INAF-Osservatorio Astrofisico di Arcetri, 3Univ. Grenoble Alpes, IPAG, 4INAF-Osservatorio Astrofisico di Arcetri, 5ESO, 6IGN, Observatorio Astronómico Nacional, 7Univ. Grenoble Alpes, IPAG, 8INAF-Osservatorio Astrofisico di Arcetri, 9Leiden Observatory, Leiden University

We present the results of formaldehyde and methanol deuteration measurements towards the Class I low-mass protostar SVS13-A, in the framework of the IRAM 30-m ASAI (Astrochemical Surveys At IRAM) project. We detected emission lines of formaldehyde, methanol, and their deuterated forms (HDCO, D2CO, CHD2OH, CH3OD) with Eup up to 276 K. The formaldehyde analysis indicates Tkin = 15 - 30 K, n (H2) >= 10^6 cm^-3, and a size of about 1200 AU suggesting an origin in the protostellar envelope. Read More

2017Jan
Affiliations: 1Dept. of Astronomy, Yale University, USA, 2Dept. of Astronomy, University of Florida, USA, 3Max-Planck-Institute for Extraterrestrial Physics, 4INAF - Osservatorio Astrofisico di Arcetri, Italy, 5European Southern Observatory, 6Max-Planck-Institute for Astronomy, Germany

We present high resolution (0.2", 1000 AU) ALMA observations of massive infrared dark cloud clump, G028.37+00. Read More

The detection of organic molecules with increasing complexity and potential biological relevance is opening the possibility to understand the formation of the building blocks of life in the interstellar medium. One of the families of molecules with astrobiological interest are the esters, whose simplest member, methyl formate, is rather abundant in star-forming regions. The next step in the chemical complexity of esters is ethyl formate, C$_2$H$_5$OCHO. Read More

2016Sep
Affiliations: 1Dept. of Astronomy, University of Florida, USA, 2Dept. of Astronomy, University of Florida, USA, 3Max-Planck-Institute for Extraterrestrial Physics, 4INAF - Osservatorio Astrofisico di Arcetri, Italy, 5Dept. of Astronomy, University of Florida, USA, 6Max-Planck-Institute for Astronomy, Germany

We carry out an ALMA $\rm N_2D^+$(3-2) and 1.3~mm continuum survey towards 32 high mass surface density regions in seven Infrared Dark Clouds with the aim of finding massive starless cores, which may be the initial conditions for the formation of massive stars. Cores showing strong $\rm N_2D^+$(3-2) emission are expected to be highly deuterated and indicative of early, potentially pre-stellar stages of star formation. Read More

Massive stars, multiple stellar systems and clusters are born from the gravitational collapse of massive dense gaseous clumps, and the way these systems form strongly depends on how the parent clump fragments into cores during collapse. Numerical simulations show that magnetic fields may be the key ingredient in regulating fragmentation. Here we present ALMA observations at ~0. Read More

We study the molecular abundance and spatial distribution of the simplest sugar alcohol, ethylene glycol (EG), the simplest sugar glycoladehyde (GA), and other chemically related complex organic species towards the massive star-forming region G31.41+0.31. Read More

Sulfur-bearing molecules are highly reactive in the gas phase of the ISM. However, the form in which most of the sulfur is locked onto interstellar dust grains is unknown. By taking advantage of the short time-scales of shocks in young molecular outflows, one could track back the main form of sulfur in the ices. Read More

High-mass stars shape the interstellar medium in galaxies, and yet, largely because the initial conditions are poorly constrained, we do not know how they form. One possibility is that high-mass stars and star clusters form at the junction of filamentary networks, referred to as 'hubs'. In this letter we present the complex anatomy of a protocluster hub within an Infrared Dark Cloud (IRDC), G035. Read More

In the context of the ASAI (Astrochemical Surveys At IRAM) project, we carried out an unbiased spectral survey in the millimeter window towards the well known low-mass Class I source SVS13-A. The high sensitivity reached (3-12 mK) allowed us to detect at least 6 HDO broad (FWHM ~ 4-5 km/s) emission lines with upper level energies up to Eu = 837 K. A non-LTE LVG analysis implies the presence of very hot (150-260 K) and dense (> 3 10^7 cm-3) gas inside a small radius ($\sim$ 25 AU) around the star, supporting, for the first time, the occurrence of a hot corino around a Class I protostar. Read More

Giant molecular clouds contain supersonic turbulence that can locally heat small fractions of gas to over 100 K. We run shock models for low-velocity, C-type shocks propagating into gas with densities between 10^3 and 10^5 cm^(-3) and find that CO lines are the most important cooling lines. Comparison to photodissociation region (PDR) models indicates that mid-J CO lines (J = 8-7 and higher) should be dominated by emission from shocked gas. Read More

Phosphorus is a crucial element in biochemistry, especially the P-O bond, which is key for the formation of the backbone of the deoxyribonucleic acid. So far, PO has only been detected towards the envelope of evolved stars, and never towards star-forming regions. We report the first detections of PO towards two massive star-forming regions, W51 e1/e2 and W3(OH), using data from the IRAM 30m telescope. Read More

Phosphorus is a crucial element for the development of life, but so far P-bearing molecules have been detected only in a few astrophysical objects, hence its interstellar chemistry is almost totally unknown. Here we show new detections of phosphorus nitride in a sample of dense cores in different evolutionary stages of the intermediate- and high-mass star formation process: starless, with protostellar objects, and with ultracompact HII regions. All detected PN line widths are smaller than ~5 km/s , and they arise from regions associated with kinetic temperatures smaller than 100 K. Read More

Infrared Dark Clouds (IRDCs) are cold, dense regions that are usually found within Giant Molecular Clouds (GMCs). Ongoing star formation within IRDCs is typically still deeply embedded within the surrounding molecular gas. Characterising the properties of relatively quiescent IRDCs may therefore help us to understand the earliest phases of the star formation process. Read More

We present ALMA follow-up observations of two massive, early-stage core candidates, C1-N & C1-S, in Infrared Dark Cloud (IRDC) G028.37+00.07, which were previously identified by their N2D+(3-2) emission and show high levels of deuteration of this species. Read More

Aims: Using the unprecedented combination of high resolution and sensitivity offered by ALMA, we aim to investigate whether and how hot corinos, circumstellar disks, and ejected gas are related in young solar-mass protostars. Methods: We observed CH$_3$CHO and deuterated water (HDO) high-excitation ($E_{\rm u}$ up to 335 K) lines towards the Sun-like protostar HH212--MM1. Results: For the first time, we have obtained images of CH$_3$CHO and HDO emission in the inner $\simeq$ 100 AU of HH212. Read More

Infrared dark clouds are kinematically complex molecular structures in the interstellar medium that can host sites of massive star formation. We present 4 square arcminute maps of the 12CO, 13CO, and C18O J = 3 to 2 lines from selected locations within the C and F (G028.37+00. Read More

2015Nov
Affiliations: 1Dept. of Astronomy, University of Florida, USA, 2Dept. of Astronomy, University of Florida, USA, 3Max-Planck-Institute for Extraterrestrial Physics, 4INAF - Osservatorio Astrofisico di Arcetri, Italy

To understand massive star formation requires study of its initial conditions. Two massive starless core candidates, C1-N & C1-S, have been detected in IRDC G028.37+00. Read More

IRAS 22134+5834 was observed in the centimeter with (E)VLA, 3~mm with CARMA, 2~mm with PdBI, and 1.3~mm with SMA, to study the continuum emission as well as the molecular lines, that trace different physical conditions of the gas to study the influence of massive YSOs on nearby starless cores, and the possible implications in the clustered star formation process. The multi-wavelength centimeter continuum observations revealed two radio sources within the cluster, VLA1 and VLA2. Read More

2015Sep
Affiliations: 1Dept. of Astronomy, University of Florida, USA, 2Dept. of Astronomy, University of Florida, USA, 3Max-Planck-Institute for Extraterrestrial Physics, 4INAF - Osservatorio Astrofisico di Arcetri, Italy, 5California Institute of Technology, USA, 6Institute for Computational Science, University of Zurich, Switzerland, 7Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/Service d' Astrophysique, France, 8National Astronomical Observatory of Japan, Japan, 9Graduate School of Informatics and Engineering, The University of Electro-Communications, Japan

We study deuterium fractionation in two massive starless/early-stage cores C1-N and C1-S in Infrared Dark Cloud (IRDC) G028.37+00.07, first identified by Tan et al. Read More

2015Sep
Affiliations: 1INAF-Osservatorio Astrofisico di Arcetri, Firenze, 2INAF-Osservatorio Astrofisico di Arcetri, Firenze, 3INAF-Istituto di Radioastronomia, Bologna, 4INAF-Osservatorio Astrofisico di Arcetri, Firenze, 5INAF-Osservatorio Astrofisico di Arcetri, Firenze, 6INAF-Osservatorio Astrofisico di Arcetri, Firenze, 7INAF-Osservatorio Astrofisico di Arcetri, Firenze, 8Universita' di Bologna, Bologna, 9INAF-Osservatorio Astrofisico di Arcetri, Firenze, 10INAF-Osservatorio Astrofisico di Arcetri, Firenze, 11INAF-Istituto di Radioastronomia, Bologna, 12Universita' di Firenze, Firenze, 13INAF-Istituto di Radioastronomia, Bologna, 14INAF-Osservatorio Astrofisico di Arcetri, Firenze, 15INAF-Istituto di Radioastronomia, Bologna, 16INAF-Osservatorio Astrofisico di Arcetri, Firenze, 17INAF-Istituto di Radioastronomia, Bologna, 18INAF-Istituto di Radioastronomia, Bologna, 19INAF-Osservatorio Astrofisico di Arcetri, Firenze, 20INAF-Osservatorio Astrofisico di Arcetri, Firenze, 21INAF-Osservatorio Astrofisico di Arcetri, Firenze

The Premiale Project "Science and Technology in Italy for the upgraded ALMA Observatory - iALMA" has the goal of strengthening the scientific, technological and industrial Italian contribution to the Atacama Large Millimeter/submillimeter Array (ALMA), the largest ground based international infrastructure for the study of the Universe in the microwave. One of the main objectives of the Science Working Group (SWG) inside iALMA, the Work Package 1, is to develop the Italian contribution to the Science Case for the ALMA Band 2 or Band 2+3 receiver. ALMA Band 2 receiver spans from ~67 GHz (bounded by an opaque line complex of ozone lines) up to 90 GHz which overlaps with the lower frequency end of ALMA Band 3. Read More

This booklet contains a collection of contributions to the meeting of the JEts and Disks at INAF (JEDI) group, which took place at the Capodimonte Observatory during 9-10 April 2015. Scope of the meeting was to bring together the JEDI researchers of the Italian Istituto Nazionale di Astrofisica (INAF) working in the field of circumstellar disks and jets in young stars, to discuss together the different agents affecting the structure and the evolution of disks, namely accretion, jets and winds. More information on the JEDI group and its activities can be found at \texttt{http://www. Read More

We report on the first measurements of the isotopic ratio 14N/15N in N2H+ toward a statistically significant sample of high-mass star forming cores. The sources belong to the three main evolutionary categories of the high-mass star formation process: high-mass starless cores, high-mass protostellar objects, and ultracompact HII regions. Simultaneous measurements of 14N/15N in CN have been made. Read More

We combine previously published interferometric and single-dish data of relatively nearby massive dense cores that are actively forming stars to test whether their `fragmentation level' is controlled by turbulent or thermal support. We find no clear correlation between the fragmentation level and velocity dispersion, nor between the observed number of fragments and the number of fragments expected when the gravitationally unstable mass is calculated including various prescriptions for `turbulent support'. On the other hand, the best correlation is found for the case of pure thermal Jeans fragmentation, for which we infer a core formation efficiency around 13 per cent, consistent with previous works. Read More

2015Apr
Authors: ALMA Partnership1, E. B. Fomalont2, C. Vlahakis3, S. Corder4, A. Remijan5, D. Barkats6, R. Lucas7, T. R. Hunter8, C. L. Brogan9, Y. Asaki10, S. Matsushita11, W. R. F. Dent12, R. E. Hills13, N. Phillips14, A. M. S. Richards15, P. Cox16, R. Amestica17, D. Broguiere18, W. Cotton19, A. S. Hales20, R. Hiriart21, A. Hirota22, J. A. Hodge23, C. M. V. Impellizzeri24, J. Kern25, R. Kneissl26, E. Liuzzo27, N. Marcelino28, R. Marson29, A. Mignano30, K. Nakanishi31, B. Nikolic32, J. E. Perez33, L. M. Pérez34, I. Toledo35, R. Aladro36, B. Butler37, J. Cortes38, P. Cortes39, V. Dhawan40, J. Di Francesco41, D. Espada42, F. Galarza43, D. Garcia-Appadoo44, L. Guzman-Ramirez45, E. M. Humphreys46, T. Jung47, S. Kameno48, R. A. Laing49, S. Leon50, J. Mangum51, G. Marconi52, H. Nagai53, L. -A. Nyman54, M. Radiszcz55, J. A. Rodón56, T. Sawada57, S. Takahashi58, R. P. J. Tilanus59, T. van Kempen60, B. Vila Vilaro61, L. C. Watson62, T. Wiklind63, F. Gueth64, K. Tatematsu65, A. Wootten66, A. Castro-Carrizo67, E. Chapillon68, G. Dumas69, I. de Gregorio-Monsalvo70, H. Francke71, J. Gallardo72, J. Garcia73, S. Gonzalez74, J. E. Hibbard75, T. Hill76, T. Kaminski77, A. Karim78, M. Krips79, Y. Kurono80, C. Lopez81, S. Martin82, L. Maud83, F. Morales84, V. Pietu85, K. Plarre86, G. Schieven87, L. Testi88, L. Videla89, E. Villard90, N. Whyborn91, M. A. Zwaan92, F. Alves93, P. Andreani94, A. Avison95, M. Barta96, F. Bedosti97, G. J. Bendo98, F. Bertoldi99, M. Bethermin100, A. Biggs101, J. Boissier102, J. Brand103, S. Burkutean104, V. Casasola105, J. Conway106, L. Cortese107, B. Dabrowski108, T. A. Davis109, M. Diaz Trigo110, F. Fontani111, R. Franco-Hernandez112, G. Fuller113, R. Galvan Madrid114, A. Giannetti115, A. Ginsburg116, S. F. Graves117, E. Hatziminaoglou118, M. Hogerheijde119, P. Jachym120, I. Jimenez Serra121, M. Karlicky122, P. Klaasen123, M. Kraus124, D. Kunneriath125, C. Lagos126, S. Longmore127, S. Leurini128, M. Maercker129, B. Magnelli130, I. Marti Vidal131, M. Massardi132, A. Maury133, S. Muehle134, S. Muller135, T. Muxlow136, E. O'Gorman137, R. Paladino138, D. Petry139, J. Pineda140, S. Randall141, J. S. Richer142, A. Rossetti143, A. Rushton144, K. Rygl145, A. Sanchez Monge146, R. Schaaf147, P. Schilke148, T. Stanke149, M. Schmalzl150, F. Stoehr151, S. Urban152, E. van Kampen153, W. Vlemmings154, K. Wang155, W. Wild156, Y. Yang157, S. Iguchi158, T. Hasegawa159, M. Saito160, J. Inatani161, N. Mizuno162, S. Asayama163, G. Kosugi164, K. -I. Morita165, K. Chiba166, S. Kawashima167, S. K. Okumura168, N. Ohashi169, R. Ogasawara170, S. Sakamoto171, T. Noguchi172, Y. -D. Huang173, S. -Y. Liu174, F. Kemper175, P. M. Koch176, M. -T. Chen177, Y. Chikada178, M. Hiramatsu179, D. Iono180, M. Shimojo181, S. Komugi182, J. Kim183, A. -R. Lyo184, E. Muller185, C. Herrera186, R. E. Miura187, J. Ueda188, J. Chibueze189, Y. -N. Su190, A. Trejo-Cruz191, K. -S. Wang192, H. Kiuchi193, N. Ukita194, M. Sugimoto195, R. Kawabe196, M. Hayashi197, S. Miyama198, P. T. P. Ho199, N. Kaifu200, M. Ishiguro201, A. J. Beasley202, S. Bhatnagar203, J. A. Braatz III204, D. G. Brisbin205, N. Brunetti206, C. Carilli207, J. H. Crossley208, L. D'Addario209, J. L. Donovan Meyer210, D. T. Emerson211, A. S. Evans212, P. Fisher213, K. Golap214, D. M. Griffith215, A. E. Hale216, D. Halstead217, E. J. Hardy218, M. C. Hatz219, M. Holdaway220, R. Indebetouw221, P. R. Jewell222, A. A. Kepley223, D. -C. Kim224, M. D. Lacy225, A. K. Leroy226, H. S. Liszt227, C. J. Lonsdale228, B. Matthews229, M. McKinnon230, B. S. Mason231, G. Moellenbrock232, A. Moullet233, S. T. Myers234, J. Ott235, A. B. Peck236, J. Pisano237, S. J. E. Radford238, W. T. Randolph239, U. Rao Venkata240, M. G. Rawlings241, R. Rosen242, S. L. Schnee243, K. S. Scott244, N. K. Sharp245, K. Sheth246, R. S. Simon247, T. Tsutsumi248, S. J. Wood249
Affiliations: 1Joint ALMA Observatory, Chile, 2Joint ALMA Observatory, Chile, 3Joint ALMA Observatory, Chile, 4Joint ALMA Observatory, Chile, 5Joint ALMA Observatory, Chile, 6Joint ALMA Observatory, Chile, 7Institut de Planetologie et d'Astrophysique de Grenoble, France, 8National Radio Astronomy Observatory, Charlottesville, USA, 9National Radio Astronomy Observatory, Charlottesville, USA, 10National Astronomical Observatory of Japan, Japan, 11Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 12Joint ALMA Observatory, Chile, 13Astrophysics Group, Cavendish Laboratory, UK, 14Joint ALMA Observatory, Chile, 15Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, UK, 16Joint ALMA Observatory, Chile, 17National Radio Astronomy Observatory, Charlottesville, USA, 18IRAM, France, 19National Radio Astronomy Observatory, Charlottesville, USA, 20Joint ALMA Observatory, Chile, 21National Radio Astronomy Observatory, Socorro, USA, 22Joint ALMA Observatory, Chile, 23National Radio Astronomy Observatory, Charlottesville, USA, 24Joint ALMA Observatory, Chile, 25National Radio Astronomy Observatory, Socorro, USA, 26Joint ALMA Observatory, Chile, 27INAF, Bologna, Italy, 28INAF, Bologna, Italy, 29National Radio Astronomy Observatory, Socorro, USA, 30INAF, Bologna, Italy, 31Joint ALMA Observatory, Chile, 32Astrophysics Group, Cavendish Laboratory, UK, 33National Radio Astronomy Observatory, Charlottesville, USA, 34National Radio Astronomy Observatory, Socorro, USA, 35Joint ALMA Observatory, Chile, 36European Southern Observatory, Chile, 37National Radio Astronomy Observatory, Charlottesville, USA, 38Joint ALMA Observatory, Chile, 39Joint ALMA Observatory, Chile, 40National Radio Astronomy Observatory, Socorro, USA, 41National Research Council Herzberg Astronomy & Astrophysics, Canada, 42Joint ALMA Observatory, Chile, 43Joint ALMA Observatory, Chile, 44Joint ALMA Observatory, Chile, 45European Southern Observatory, Chile, 46European Southern Observatory, Garching bei Munchen, Germany, 47Korea Astronomy and Space Science Institute, Korea, 48Joint ALMA Observatory, Chile, 49European Southern Observatory, Garching bei Munchen, Germany, 50Joint ALMA Observatory, Chile, 51National Radio Astronomy Observatory, Charlottesville, USA, 52Joint ALMA Observatory, Chile, 53National Astronomical Observatory of Japan, Japan, 54Joint ALMA Observatory, Chile, 55Joint ALMA Observatory, Chile, 56European Southern Observatory, Chile, 57Joint ALMA Observatory, Chile, 58Joint ALMA Observatory, Chile, 59Leiden Observatory, The Netherlands, 60Leiden Observatory, The Netherlands, 61Joint ALMA Observatory, Chile, 62European Southern Observatory, Chile, 63Joint ALMA Observatory, Chile, 64IRAM, France, 65National Astronomical Observatory of Japan, Japan, 66National Radio Astronomy Observatory, Charlottesville, USA, 67IRAM, France, 68IRAM, France, 69IRAM, France, 70Joint ALMA Observatory, Chile, 71Joint ALMA Observatory, Chile, 72Joint ALMA Observatory, Chile, 73Joint ALMA Observatory, Chile, 74Joint ALMA Observatory, Chile, 75National Radio Astronomy Observatory, Charlottesville, USA, 76Joint ALMA Observatory, Chile, 77European Southern Observatory, Chile, 78Argelander-Institut fur Astronomie, Bonn, Germany, 79IRAM, France, 80Joint ALMA Observatory, Chile, 81Joint ALMA Observatory, Chile, 82IRAM, France, 83Leiden Observatory, The Netherlands, 84Joint ALMA Observatory, Chile, 85IRAM, France, 86Joint ALMA Observatory, Chile, 87National Research Council Herzberg Astronomy & Astrophysics, Canada, 88European Southern Observatory, Garching bei Munchen, Germany, 89Joint ALMA Observatory, Chile, 90Joint ALMA Observatory, Chile, 91Joint ALMA Observatory, Chile, 92European Southern Observatory, Garching bei Munchen, Germany, 93Max Planck Institute for Extraterrestial Physics, Garching, Germany, 94European Southern Observatory, Garching bei Munchen, Germany, 95Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, UK, 96Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 97INAF, Bologna, Italy, 98Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, UK, 99Argelander-Institut fur Astronomie, Bonn, Germany, 100European Southern Observatory, Garching bei Munchen, Germany, 101European Southern Observatory, Garching bei Munchen, Germany, 102IRAM, France, 103INAF, Bologna, Italy, 104Argelander-Institut fur Astronomie, Bonn, Germany, 105INAF-Oss. Astrofisco di Arcetri, Italy, 106Department of Earth and Space Sciences, Chalmers University of Technology, Sweden, 107Centre for Astrophysics & Supercomputing, Swinburne University of Technology, Australia, 108Space Radio-diagnostics Research Center, Geodesy and Land Management, University of Warmia and Mazury, Poland, 109Centre for Astrophysics Research, Science & Technology Research Institute, University of Hertfordshire, UK, 110European Southern Observatory, Garching bei Munchen, Germany, 111INAF-Oss. Astrofisco di Arcetri, Italy, 112Departamento de Astronomia, Universidad de Chile, Chile, 113Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, UK, 114Centro de Radiostronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Mexico, 115Argelander-Institut fur Astronomie, Bonn, Germany, 116European Southern Observatory, Garching bei Munchen, Germany, 117Astrophysics Group, Cavendish Laboratory, UK, 118European Southern Observatory, Garching bei Munchen, Germany, 119Leiden Observatory, The Netherlands, 120Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 121European Southern Observatory, Garching bei Munchen, Germany, 122Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 123Leiden Observatory, The Netherlands, 124Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 125Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 126European Southern Observatory, Garching bei Munchen, Germany, 127European Southern Observatory, Garching bei Munchen, Germany, 128Max-Planck-Institut fur Radioastronomie, Bonn, Germany, 129Department of Earth and Space Sciences, Chalmers University of Technology, Sweden, 130Argelander-Institut fur Astronomie, Bonn, Germany, 131Department of Earth and Space Sciences, Chalmers University of Technology, Sweden, 132INAF, Bologna, Italy, 133Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/Service dAstrophysique, France, 134Argelander-Institut fur Astronomie, Bonn, Germany, 135Max-Planck-Institut fur Radioastronomie, Bonn, Germany, 136Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, UK, 137Max-Planck-Institut fur Radioastronomie, Bonn, Germany, 138INAF, Bologna, Italy, 139European Southern Observatory, Garching bei Munchen, Germany, 140Max Planck Institute for Extraterrestial Physics, Garching, Germany, 141European Southern Observatory, Garching bei Munchen, Germany, 142Astrophysics Group, Cavendish Laboratory, UK, 143INAF, Bologna, Italy, 144Department of Physics, Astrophysics, University of Oxford, UK, 145INAF, Bologna, Italy, 146I. Physikalisches Institut, Universitaet zu Koeln, Germany, 147Argelander-Institut fur Astronomie, Bonn, Germany, 148I. Physikalisches Institut, Universitaet zu Koeln, Germany, 149European Southern Observatory, Garching bei Munchen, Germany, 150Leiden Observatory, The Netherlands, 151European Southern Observatory, Garching bei Munchen, Germany, 152Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 153European Southern Observatory, Garching bei Munchen, Germany, 154Department of Earth and Space Sciences, Chalmers University of Technology, Sweden, 155European Southern Observatory, Garching bei Munchen, Germany, 156European Southern Observatory, Garching bei Munchen, Germany, 157Korea Astronomy and Space Science Institute, Korea, 158National Astronomical Observatory of Japan, Japan, 159National Astronomical Observatory of Japan, Japan, 160National Astronomical Observatory of Japan, Japan, 161National Astronomical Observatory of Japan, Japan, 162Joint ALMA Observatory, Chile, 163National Astronomical Observatory of Japan, Japan, 164National Astronomical Observatory of Japan, Japan, 165Joint ALMA Observatory, Chile, 166National Astronomical Observatory of Japan, Japan, 167National Astronomical Observatory of Japan, Japan, 168Faculty of Science, Japan Women's University, Japan, 169National Astronomical Observatory of Japan, Japan, 170National Astronomical Observatory of Japan, Japan, 171National Astronomical Observatory of Japan, Japan, 172National Astronomical Observatory of Japan, Japan, 173Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 174Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 175Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 176Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 177Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 178National Astronomical Observatory of Japan, Japan, 179National Astronomical Observatory of Japan, Japan, 180National Astronomical Observatory of Japan, Japan, 181National Astronomical Observatory of Japan, Japan, 182National Astronomical Observatory of Japan, Japan, 183Korea Astronomy and Space Science Institute, Korea, 184Korea Astronomy and Space Science Institute, Korea, 185National Astronomical Observatory of Japan, Japan, 186National Astronomical Observatory of Japan, Japan, 187National Astronomical Observatory of Japan, Japan, 188National Astronomical Observatory of Japan, Japan, 189National Astronomical Observatory of Japan, Japan, 190Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 191Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 192Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 193National Astronomical Observatory of Japan, Japan, 194National Astronomical Observatory of Japan, Japan, 195Joint ALMA Observatory, Chile, 196National Astronomical Observatory of Japan, Japan, 197National Astronomical Observatory of Japan, Japan, 198National Institutes of Natural Sciences, 199Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 200National Astronomical Observatory of Japan, Japan, 201National Astronomical Observatory of Japan, Japan, 202National Radio Astronomy Observatory, Charlottesville, USA, 203National Radio Astronomy Observatory, Socorro, USA, 204National Radio Astronomy Observatory, Charlottesville, USA, 205National Radio Astronomy Observatory, Charlottesville, USA, 206National Radio Astronomy Observatory, Charlottesville, USA, 207National Radio Astronomy Observatory, Socorro, USA, 208National Radio Astronomy Observatory, Charlottesville, USA, 209Jet Propulsion Laboratory, California Institute of Technology, USA, 210National Radio Astronomy Observatory, Charlottesville, USA, 211National Radio Astronomy Observatory, Charlottesville, USA, 212National Radio Astronomy Observatory, Charlottesville, USA, 213National Radio Astronomy Observatory, Charlottesville, USA, 214National Radio Astronomy Observatory, Socorro, USA, 215National Radio Astronomy Observatory, Charlottesville, USA, 216National Radio Astronomy Observatory, Charlottesville, USA, 217National Radio Astronomy Observatory, Charlottesville, USA, 218National Radio Astronomy Observatory, Chile, 219National Radio Astronomy Observatory, Charlottesville, USA, 220National Radio Astronomy Observatory, Charlottesville, USA, 221National Radio Astronomy Observatory, Charlottesville, USA, 222National Radio Astronomy Observatory, Charlottesville, USA, 223National Radio Astronomy Observatory, Charlottesville, USA, 224National Radio Astronomy Observatory, Charlottesville, USA, 225National Radio Astronomy Observatory, Charlottesville, USA, 226National Radio Astronomy Observatory, Charlottesville, USA, 227National Radio Astronomy Observatory, Charlottesville, USA, 228National Radio Astronomy Observatory, Charlottesville, USA, 229National Research Council Herzberg Astronomy & Astrophysics, Canada, 230National Radio Astronomy Observatory, Charlottesville, USA, 231National Radio Astronomy Observatory, Charlottesville, USA, 232National Radio Astronomy Observatory, Socorro, USA, 233National Radio Astronomy Observatory, Charlottesville, USA, 234National Radio Astronomy Observatory, Socorro, USA, 235National Radio Astronomy Observatory, Socorro, USA, 236National Radio Astronomy Observatory, Charlottesville, USA, 237National Radio Astronomy Observatory, Charlottesville, USA, 238Cahill Center for Astronomy and Astrophysics, California Institute of Technology, USA, 239National Radio Astronomy Observatory, Charlottesville, USA, 240National Radio Astronomy Observatory, Socorro, USA, 241National Radio Astronomy Observatory, Charlottesville, USA, 242National Radio Astronomy Observatory, Charlottesville, USA, 243National Radio Astronomy Observatory, Charlottesville, USA, 244National Radio Astronomy Observatory, Charlottesville, USA, 245National Radio Astronomy Observatory, Charlottesville, USA, 246National Radio Astronomy Observatory, Charlottesville, USA, 247National Radio Astronomy Observatory, Charlottesville, USA, 248National Radio Astronomy Observatory, Socorro, USA, 249National Radio Astronomy Observatory, Charlottesville, USA

A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to ~15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from September to late November 2014, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Read More

Infrared dark clouds (IRDCs) are dense, molecular structures in the interstellar medium that can harbour sites of high-mass star formation. IRDCs contain supersonic turbulence, which is expected to generate shocks that locally heat pockets of gas within the clouds. We present observations of the CO J = 8-7, 9-8, and 10-9 transitions, taken with the Herschel Space Observatory, towards four dense, starless clumps within IRDCs (C1 in G028. Read More

Molecular complexity builds up at each step of the Sun-like star formation process, starting from simple molecules and ending up in large polyatomic species. Complex organic molecules (COMs; such as methyl formate, HCOOCH$_3$, dymethyl ether, CH$_3$OCH$_3$, formamide, NH$_2$CHO, or glycoaldehyde, HCOCH$_2$OH) are formed in all the components of the star formation recipe (e.g. Read More

The formation of complex organic molecules (COMs) in protostellar environments is a hotly debated topic. In particular, the relative importance of the gas phase processes as compared to a direct formation of COMs on the dust grain surfaces is so far unknown. We report here the first high-resolution images of acetaldehyde (CH$_3$CHO) emission towards the chemically rich protostellar shock L1157-B1, obtained at 2 mm with the IRAM Plateau de Bure interferometer. Read More

An ever growing number of observational and theoretical evidence suggests that the deuterated fraction (column density ratio between a species containing D and its hydrogenated counterpart, Dfrac) is an evolutionary indicator both in the low- and the high-mass star formation process. However, the role of surface chemistry in these studies has not been quantified from an observational point of view. In order to compare how the deuterated fractions of species formed only in the gas and partially or uniquely on grain surfaces evolve with time, we observed rotational transitions of CH3OH, 13CH3OH, CH2DOH, CH3OD at 3 and 1. Read More

In the low-mass regime, it is found that the gas-phase abundances of C-bearing molecules in cold starless cores rapidly decrease with increasing density, as the molecules form mantles on dust grains. We study CO depletion in 102 massive clumps selected from the ATLASGAL 870 micron survey, and investigate its correlation with evolutionary stage and with the physical parameters of the sources. Moreover, we study the gradients in [12C]/[13C] and [18O]/[17O] isotopic ratios across the inner Galaxy, and the virial stability of the clumps. Read More

We present the results of a line identification analysis using data from the IRAM Plateau de Bure Inferferometer, focusing on six massive star-forming hot cores: G31.41+0.31, G29. Read More

Infrared Dark Clouds (IRDCs) are unique laboratories to study the initial conditions of high-mass star and star cluster formation. We present high-sensitivity and high-angular resolution IRAM PdBI observations of N2H+ (1-0) towards IRDC G035.39-00. Read More

Chemical models predict that the deuterated fraction (the column density ratio between a molecule containing D and its counterpart containing H) of N2H+, Dfrac(N2H+), is high in massive pre-protostellar cores and rapidly drops of an order of magnitude after the protostar birth, while that of HNC, Dfrac(HNC), remains constant for much longer. We tested these predictions by deriving Dfrac(HNC) in 22 high-mass star forming cores divided in three different evolutionary stages, from high-mass starless core candidates (HMSCs, 8) to high-mass protostellar objects (HMPOs, 7) to Ultracompact HII regions (UCHIIs, 7). For all of them, Dfrac (N2H+) was already determined through IRAM-30m Telescope observations, which confirmed the theoretical rapid decrease of Dfrac(N2H+) after protostar birth (Fontani et al. Read More

The enormous radiative and mechanical luminosities of massive stars impact a vast range of scales and processes, from the reionization of the universe, to the evolution of galaxies, to the regulation of the interstellar medium, to the formation of star clusters, and even to the formation of planets around stars in such clusters. Two main classes of massive star formation theory are under active study, Core Accretion and Competitive Accretion. In Core Accretion, the initial conditions are self-gravitating, centrally concentrated cores that condense with a range of masses from the surrounding, fragmenting clump environment. Read More

In order to shed light on the main physical processes controlling fragmentation of massive dense cores, we present a uniform study of the density structure of 19 massive dense cores, selected to be at similar evolutionary stages, for which their relative fragmentation level was assessed in a previous work. We inferred the density structure of the 19 cores through a simultaneous fit of the radial intensity profiles at 450 and 850 micron (or 1.2 mm in two cases) and the Spectral Energy Distribution, assuming spherical symmetry and that the density and temperature of the cores decrease with radius following power-laws. Read More

2014Jan
Affiliations: 1European Southern Observatory, Germany, 2University of Leeds, UK, 3Osservatorio Astrofisico di Arcetri, Italy, 4University of Florida, USA, 5University of Leeds, UK, 6Max-Planck-Institute for Astronomy, Germany, 7University of Wisconsin-Madison, USA

Some theories of dense molecular cloud formation involve dynamical environments driven by converging atomic flows or collisions between preexisting molecular clouds. The determination of the dynamics and physical conditions of the gas in clouds at the early stages of their evolution is essential to establish the dynamical imprints of such collisions, and to infer the processes involved in their formation. We present multi-transition 13CO and C18O maps toward the IRDC G035. Read More

We present the first detection of N2H+ towards a low-mass protostellar outflow, namely the L1157-B1 shock, at about 0.1 pc from the protostellar cocoon. The detection was obtained with the IRAM 30-m antenna. Read More

(Abridged) Aims. To investigate the first stages of the process of high-mass star formation, we selected a sample of massive clumps previously observed with the SEST at 1.2 mm and with the ATNF ATCA at 1. Read More

2013Jul
Affiliations: 1INAF-IRA and Italian ARC, 2INAF-OAA, 3Obs. de Paris, 4INAF-IRA and Italian ARC, 5INAF-OAA, 6University of Bologna, 7INAF-OAA

The formation of the first virialized structures in overdensities dates back to ~9 Gyr ago, i.e. in the redshift range z ~ 1. Read More

2013Apr
Affiliations: 1Osservatorio Astrofisico di Arcetri - INAF, Italy, 2Institut Ciencies de l'Espai - CSIC, Spain, 3Osservatorio Astrofisico di Arcetri - INAF, Italy, 4INAF - IAPS, Italy, 5Institut Ciencies de l'Espai - CSIC, Spain, 6Dpt Astronomia i Meteorologia - UB, Spain, 7Dpts of Astronomy and Physics - University of Florida, USA, 8Dpt Astronomia i Meteorologia - UB, Spain, 9Institue of Astronomy and Astrophysics, Academia Sinica, Taiwan, 10CfA, USA, 11CRyA - UNAM, Mexico

We aim at characterising dense cores in the clustered environments associated with massive star-forming regions. For this, we present an uniform analysis of VLA NH3(1,1) and (2,2) observations towards a sample of 15 massive star-forming regions, where we identify a total of 73 cores, classify them as protostellar, quiescent starless, or perturbed starless, and derive some physical properties. The average sizes and ammonia column densities are 0. Read More

OMC-2 FIR 4 is one of the closest known young intermediate-mass protoclusters, located at a distance of 420 pc in Orion. This region is one of the few where the complete 500-2000 GHz spectrum has been observed with the heterodyne spectrometer HIFI on board the Herschel satellite, and unbiased spectral surveys at 0.8, 1, 2 and 3 mm have been obtained with the JCMT and IRAM 30-m telescopes. Read More

2013Mar
Affiliations: 1Dept. of Astronomy, University of Florida, 2Dept. of Astronomy, University of Florida, 3Dept. of Astronomy, University of Florida, 4School of Physics and Astronomy, University of Leeds, 5INAF - Osservatorio Astrofisico di Arcetri

How do stars that are more massive than the Sun form, and thus how is the stellar initial mass function (IMF) established? Such intermediate- and high-mass stars may be born from relatively massive pre-stellar gas cores, which are more massive than the thermal Jeans mass. The Turbulent Core Accretion model invokes such cores as being in approximate virial equilibrium and in approximate pressure equilibrium with their surrounding clump medium. Their internal pressure is provided by a combination of turbulence and magnetic fields. Read More

In order to study the fragmentation of massive dense cores, which constitute the cluster cradles, we observed with the PdBI in the most extended configuration the continuum at 1.3 mm and the CO(2-1) emission of four massive cores. We detect dust condensations down to ~0. Read More

We present ATCA observations of the H2O maser line and radio continuum at 18.0GHz and 22.8GHz, toward a sample of 192 massive star forming regions containing several clumps already imaged at 1. Read More

Infrared Dark Clouds (IRDCs) host the initial conditions under which massive stars and stellar clusters form. We have obtained high sensitivity and high spectral resolution observations with the IRAM 30m antenna, which allowed us to perform detailed analysis of the kinematics within one IRDC, G035.39-00. Read More

2012Jul
Affiliations: 1Department of Astronomy, University of Wisconsin-Madison, 2Departments of Astronomy and Physics, University of Florida, 3Max-Planck-Institute for Astronomy, 4School of Physics and Astronomy, University of Leeds, 5Department of Astronomy, University of Florida, 6Harvard-Smithsonian Center for Astrophysics, 7INAF - Osservatorio Astrofisico di Arcetri

The initial conditions of massive star and star cluster formation are expected to be cold, dense and high column density regions of the interstellar medium, which can reveal themselves via near, mid and even far-infrared absorption as Infrared Dark Clouds (IRDCs). Elucidating the dynamical state of IRDCs thus constrains theoretical models of these complex processes. In particular, it is important to assess whether IRDCs have reached virial equilibrium, where the internal pressure balances that due to the self-gravitating weight of the cloud plus the pressure of the external environmental. Read More

2012May
Affiliations: 1INAF-Osservatorio Astrofisico di Arcetri, 2INAF-Osservatorio Astrofisico di Arcetri, 3INAF-Osservatorio Astrofisico di Arcetri, 4INAF-Osservatorio Astrofisico di Arcetri, 5Universitat de Barcelona

We have mapped in the 2.7 mm continuum and 12CO with the PdBI the IR-dark "tail" that crosses the IC 1396N globule from south to north, and is the most extincted part of this cloud. These observations have allowed us to distinguish all possible associations of molecular hydrogen emission features by revealing the presence of two well-collimated low-mass protostellar outflows at the northern part of the globule. Read More