CO mapping of the yellow
hypergiants IRC+10420 and AFGL2343
H
, the second interstellar anion
CHCH
): Missing Links in Interstellar Gas-Phase Chemistry
CO mapping of the yellow
hypergiants IRC+10420 and AFGL2343
, G. Quintana-Lacaci
, V. Bujarrabal ,
R. Neri and J. Alcolea
Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine,
38406 Saint Martin d'Hères, France,
Observatorio Astronómico Nacional (IGN), Apdo. 112,
E-28803 Alcalá de Henares, Spain,
Observatorio Astronómico Nacional (IGN), c/ Alfonso
XII n
13, E-28014 Madrid, Spain CO 
=2
1 and 10 emission in these
YHGs with the IRAM Plateau de Bure interferometer and the 30m
telescope. We developed LVG models in order to analyze their
circumstellar characteristics.
The maps show that the overall shape of both CSEs is approximately
spherical, although they also reveal several aspherical features. The
CSE around IRC+10420 shows a rounded extended halo surrounding a bright
inner region, with both components presenting aspherical
characteristics. It presents a brightness minimum at the center. The
envelope around AFGL2343 is a detached shell, showing spherical symmetry
and clumpiness at a level of 
% of the maximum
brightness. The envelopes expand isotropically at 
kms
,
about two or three times faster than typical CSEs around AGB
stars. High temperatures (
K) are derived for the innermost
regions in IRC+10420, while denser and cooler (
K) gas is found in
AFGL2343.
The mass-loss processes in these YHGs have been found to be
similar. The deduced mass-loss rates (
M
yr)
are much higher than those obtained in AGB stars, and they present
5significant variations on time scales of 
yr.
Appeared in: A&A 465, 457
, Jean-Paul Kneib,
Stéphane Guilloteau
and Michael Bremer
European Southern Observatory, Casilla 19001, Santiago 19, Chile,
AIM, CEA/DSM-CNRS-Université Paris 7, SAp, Bât.709, CE Saclay,
l'Orme des Merisiers, 91191 Gif-sur-Yvette Cédex, France,
Laboratoire d'Astrophysique de Marseille, OAMP Traverse du Siphon,
BP 8, 13376 Marseille Cedex 12, France,
UMR5804 CNRS, OASU, Université Bordeaux 1, BP 89, 33270 Floirac, France,
Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine,
38406 Saint Martin d'Hères, France 
velocity gradient is tentatively detected from the CO lines
across the central 
. The continuum SED in the range 0.45 mm
- 204 mm exhibits the signatures of two components: synchrotron
emission from a core/jet system, and thermal emission related to warm
dust. The CO line intensities are compatible with warm, dense
molecular gas, suggesting a location in the close environment of the
quasar. These observational constraints lead us to consider a
source/quasar model made of a point-like core, a radio jet, and a
molecular and dusty ring-like structure (
460 pc in radius)
located in a plane perpendicular to the jet axis and seen almost
edge-on. For this configuration, we derive a total magnification of 16
for the quasar radiation at rest frequency above 350 GHz and a
magnification of 25 below 350 GHz. The dust mass (assuming a likely
temperature 
K) is M
, the mass
of molecular material is M
H
and a
lower limit to the dynamical mass is M
.
Such values are comparable to those found in the small
sample of CO detected sources at high redshifts.
Accepted for publication in A&A
, Swinbank A.M., Neri R., Cox P., Smail Ian, Ellis R.S., Geach J.E., Siana B.,
Teplitz H., Dye S., Kneib J.-P.
, Edge A.C., Richard, J.
Institute for Computational Cosmology, Durham University, South Road, Durham, DH1 3LE, UK,
IRAM, 300 rue de la Piscine, Domaine Universitaire,
38406 Saint Martin d'Hères, France,
Caltech, MC 105-24, 1200 East California Blvd, Pasadena, California, CA91125, USA,
Spitzer Science Center, Caltech, MC 314-6, 1200 East California Blvd, Pasadena, California, CA91125, USA,
School of Physics and Astronomy, Cardiff University, 5, The Parade, Cardiff, Wales, CF24AA, UK,
Laboratoire d'Astrophysique de Marseille, Traverse du Siphon - B.P.8 13376, Marseille Cedec 12, France 
using the Plateau de Bure
Interferometer. This is only the second detection of molecular gas
emission from an LBG and yields an intrinsic molecular gas mass of
M. The lens reconstruction of the UV
morphology of the LBG indicates that it comprises two components
separated by 
kpc. The CO emission is unresolved,
, and appears to be centered on the intrinsically
fainter (and also less highly magnified) of the two UV components. The
width of the CO line indicates a dynamical mass of
Mwithin the central 2 kpc. Employing
mid-infrared observations from Spitzer we derive a stellar mass
of
Mand a star-formation rate of
M/yr, indicating that the molecular gas will be consumed
in 
Myr. The gas fractions, star-formation efficiencies and
line widths suggests that LBG J213512 is a high-redshift, gas-rich
analog of a local luminous infrared galaxy. This galaxy has a similar
gas-to-dynamical mass fraction as observed in the
submillimeter-selected population, although the gas surface density
and star-formation efficiency is a factor of 
less,
suggesting less vigorous activity. We discuss the uncertainties in our
conclusions arising from adopting a CO-to-H conversion factor
appropriate for either the Milky Way or local luminous infrared
galaxies. These observations demonstrate that current facilities, when
aided by fortuitous gravitational magnification, can study 'ordinary'
galaxies at high-redshift and so act as pathfinders for ALMA.
Accepted for publication in ApJ
, Fabian Walter, Pierre Cox, Christopher L. Carilli,
Axel Weiß, Frank Bertoldi, and Roberto Neri
MPIA, Königstuhl 17, Heidelberg,
D-69117, Germany,
IRAM, 300 Rue de la Piscine, Domaine Universitaire, 38406 Saint Martin d'Hères, France,
NRAO, PO Box O, Socorro, NM 87801, USA,
MPIfR, Auf dem Hügel 69, Bonn, D-53121, Germany,
Argelander-Institut für Astronomie, Universität Bonn, Auf
dem Hügel 71, Bonn, D-53121, Germany 
emission towards the Cloverleaf quasar (z = 2.56) based
on observations with the IRAM Plateau de Bure Interferometer. This is the first clear detection of
emission from this radical at high redshift. CN emission is a tracer of dense molecular hydrogen
gas
within star-forming molecular clouds, in particular in regions where the
clouds are affected by UV radiation. The HCN/CN intensity ratio can be used as a diagnostic for
the relative importance of photodissociation regions (PDRs) in a source, and as a sensitive probe
of optical depth, the radiation field, and photochemical processes. We derive a lensing-corrected
CN
line luminosity of L'CN(3-2)
. The ratio between CN
luminosity and far-infrared luminosity falls within the scatter of the same relationship found for low-z
(ultra-) luminous infrared galaxies. Combining our new results with CO
and HCN
measurements from the literature and assuming thermal excitation for all transitions, we find a CO/CN
luminosity ratio of 
and a HCN/CN luminosity ratio of 
. However, we find that
the CN
line is likely only subthermally excited, implying that those ratios may only provide
upper limits for the intrinsic 1!0 line luminosity ratios. We conclude that, in combination with other
molecular gas tracers like CO, HCN, and HCO
, CN is an important probe of the physical conditions
and chemical composition of dense molecular environments at high redshift.
Accepted for publication in ApJ
H, the second interstellar anion
, M. Guélin, M. Agundez, K. Kawaguchi,
M. McCarthy and P. Thaddeus
Dpt. Molecular and Infrared Astrophysics. Instituto de Estructura
de la Materia, CSIC, Serrano 121, E28006, Spain,
IRAM, Domaine Universitaire, 300 rue de la Piscine,
38406 St Martin d'Hères, France,
Department of Chemistry, Faculty of Science,
Okayama University, Tsushimanaka, Okayama 700-8530, Japan
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA,
USA 
H may
be abundant. In particular, Millar et al. (2000) predicted an abundance
of C
H as large as 1/4 of that of its neutral counterpart
CH in the outer envelope of the C-star IRC +10216, a source
known to be particularly rich in C-chain molecules. For a long
time, however, negative ions escaped detection because of lack of
accurate transition frequencies.
 |
 |
 |
Recently, McCarthy et al. (2006) have succeeded in studying the microwave
spectrum of C
H in the laboratory and identified this
species as the carrier of a series of lines observed in 1996 by
Kawaguchi and co-workers in the C-rich circumstellar envelope IRC
+10216. Pursuing their laboratory work, McCarthy and colleagues have
measured the rotational spectra of
two more polyacetylenic anions, CH and CH
(Gupta et al. 2007). In this Letter, we report the astronomical
detection of the latter species in IRC+10216.
We have observed five lines corresponding to
the = 9-8, 11-10, 12-11, 14-13 and 15-14 rotational transitions
of CH (Fig. 2). The CH lines have a cusped shape, denoting
that this ion is formed in the outer part of the envelope, like
its neutral counterpart CH (Fig. 3).
The abundance of CH in IRC+10216 is 1/6 of the abundance of
CH and 1/4200 of that of CH.
The detection of CH, after that of CH, confirms the
theoretical prediction that C-chain anions are abundant in
interstellar clouds (Fig. 4) and yields a first measurement of the electron radiative
attachment rates.
The abundance decrement between the two ions,
[CH]/[CH] = 1/6, is more than two orders of magnitude
smaller than that between their neutral counterparts,
[CH]/[CH] = 45. The two negative ions appear more abundant
than their positive ion analogs which, so far, have not been
identified.
The detection of CH and CH sustains the farsighted
prediction of Herbst and co-workers that carbon-chain
anions may be abundant in the interstellar medium. Other negative
ions from the same family, such as CN, CN, CCH and
CH, are likely to be detectable, although, probably, at
lower intensity levels. Some of these species have already been
studied in the laboratory and their millimeter rotational
frequencies are accurately known, awaiting only for deeper
astronomical searches. The observed [CH]/[CH]
abundance ratio differs significantly from that estimated from
statistical calculations of radiative electron attachment. This
shows that surprising results are likely in this matter.
Accepted for publication in A&A
, A. Eckart, T.P. Krichbaum,
J.-U. Pott
, S. Leon
, R. Neri
,
S. García-Burillo
, F.Combes
, F. Boone,
A.J. Baker
, L.J. Tacconi
, E. Schinnerer
,
and L.K. Hunt
Universität zu Köln, I.Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany,
Harvard-Smithsonian Center for Astrophysics, SMA project, 645 North A`ohoku Place, Hilo, HI 96720,
MPIfR, Auf dem Hügel 69, 53121 Bonn, Germany,
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany,
Instituto de Astrofísica de Andalucía (CSIC), C/ Camino Bajo de Huétor,24, Apartado 3004, 18080 Granada, Spain,
IRAM, Avenida Divina Pastora, 7, Núcleo Central, 18012 Granada, Spain,
Institut de Radio-Astronomie Millimétrique (IRAM), 300, rue de la Piscine, 38406 St.Martin-d'Hères, France,
Observatorio Astronómico Nacional (OAN)-Observatorio de Madrid, Alfonso XII, 3, 28014 Madrid, Spain,
Observatoire de Paris, LERMA, 61 Av. de l'Observatoire, 75014 Paris, France,
Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road,
Piscataway, NJ 08854-8019, United States,
Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany,
MPIA, Königstuhl 17, 69117 Heidelberg, Germany,
INAF-Istituto di Radioastronomia/Sezione Firenze, Largo E. Fermi, 5, 50125 Firenze, Italy % of the sources, consistent with the decrease of flux with
increasing angular resolution. The extended components resemble jet
emission in a majority of cases, consistent with the optically thin
synchrotron emission implied by their steep spectra. We consider the
compact 6cm EVN/VLBI radio emission of our sources in the context of
the ``fundamental plane'' that previous LLAGN studies identified
within the three-dimensional parameter space of radio luminosity,
X-ray luminosity, and black hole mass. We demonstrate, using NGC7217
and NGC1068 as particular examples, that high-resolution, multi-epoch
radio observations offer useful information about the origin of
offsets from the fundamental plane.
Appeared in A&A 464, 553
, Salomé P., Neri R., García-Burillo S.,
Graciá-Carpio J., Cernicharo J., Cox P.; Planesas P.,
Solomon P.M., Tacconi L.J., vanden Bout P.
IRAM, Domaine Universitaire, 300 rue de la Piscine, St Martin d'Hères, 38400, France
Observatorio Astronómico Nacional, Calle Alfonso XII 3, 28014 Madrid, Spain,
IEM-DAMIR, CSIC, Serrano 121, 28006, Spain,
Dept. of Physics and Astronomy, State Univ. of N.Y., Stony Brook, NY 11974, USA,
Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany,
NRAO, 520 Edgemont road, Charlottesville, VA 22903, USA 
line of HNC and the tentative detection of
the 
line of CN in the quasar APM 08279+5255 at z=3.9. These
are the 4th and 5th molecular species detected at such a high
redshift. The derived HNC and CN line intensities are 0.6 and 0.4
times that of HCN . If HNC and HCN are co-spatial and if their
lines are collisionally excited, the [HNC]/[HCN] abundance
ratio must be equal to 0.6 within a factor of 2, similar to its value
in the cold Galactic clouds and much larger than in the hot molecular
gas associated with Galactic HII regions. It is possible, however,
that fluorescent infrared radiation plays an important role in the
excitation of HNC and HCN.
Appeared in: A&A 462, L45
, Krips M., Markoff S., Neri R., Eckart A.
I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany,
Harvard-Smithsonian Center for Astrophysics, SMA project, 645 North A'ohoku Place, Hilo, HI 96720, USA,
Sterrenkundig Instituut "Anton Pannekoek", Universiteit van Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands,
IRAM, 300 rue de la Piscine, Domaine Universitaire, 38406 Saint Martin d'Hères Appeared in: A&A 463, 551
, D. Downes, R. Neri, F. Walter, C. Henkel,
D.J. Wilner, J. Wagg
, and T. Wiklind
MPIfR, Auf dem Hügel 69, 53121 Bonn, Germany,
IRAM, Domaine Universitaire, 38406 St-Martin-d'Hères, France,
MPIA, Königstuhl 17, 69117 Heidelberg, Germany,
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, 02138,
Instituto Nacional de Astrofisica, Óptica y Electrónica (INAOE), Aptdo. Postal 51 y 216, Puebla, Mexico,
ESA-Space Telescope Division, STScI, 3700 San Martin Drive, Baltimore, MD 21218, USA 
, 
, 
, 
, and 
lines in the Broad Absorption Line quasar APM08279+5255 at z=3.9 using
the IRAM 30m telescope. We also present IRAM PdBI high spatial
resolution observations of the CO and lines, and of the 1.4mm
dust radiation as well as an improved spectrum of the HCN
line. Unlike CO in other QSO host galaxies, the CO line SED of
APM08279+5255 rises up to the CO
transition. The line fluxes in
the CO ladder and the dust continuum fluxes are best fit by a two
component model, a ``cold'' component at 
K with a high density of
cm
, and a ``warm'', 
K component with a density of
cm. We show that IR pumping via the 14 micron bending mode
of HCN is the most likely channel for the HCN excitation. From our
models we find, that the CO(1-0) emission is dominated by the dense gas component which implies that the CO conversion factor is
higher than usually assumed for high-z galaxies with
M/(K
km/s pc
). Using brightness temperature arguments, the results from
our high-resolution mapping, and lens models from the literature, we
argue that the molecular lines and the dust continuum emission arise
from a very compact (
pc), highly gravitationally magnified
(
) region surrounding the central AGN. Part of the difference
relative to other high-
QSOs may therefore be due to the
configuration of the gravitational lens, which gives us a
high-magnification zoom right into the central 200-pc radius of
APM08279+5255 where IR pumping plays a significant role for the
excitation of the molecular lines.
Accepted for publication in A&A
, Martín-Pintado J., Fuente A., Neri R.
Observatorio Astronómico Nacional (OAN), Observatorio de Madrid, C/Alfonso XII, 3, 28014 Madrid, Spain,
Instituto de Estructura de la Materia, DAMIR-CSIC, C/Serrano 121, 28006 Madrid, Spain,
IRAM, 300 rue de la Piscine, Domaine Universitaire, 38406 St. Martin d'Hères, Cedex, France 
) images of the emission of silicon monoxide (SiO) in
the nuclei of the nearby galaxies NGC 253, IC 342 and M 82. From
observations in the Galaxy and theoretical models, SiO is known to be
a privileged tracer of molecular shock chemistry. The large SiO
abundances,
, found
along several hundreds of pc imply that large-scale shock chemistry
must be at play in the inner disks of the three surveyed
galaxies. Noticeable differences in the morphology of the SiO emission
call to different driving mechanisms, however. In NGC 253 and IC 342,
the most plausible scenario is that of shocks arising in cloud cloud
collisions, dynamically triggered along the bar potential. In the case
of M 82, shocks arise in the disk halo interface, probably boosted by
local episodes of mass ejection from the disk. These dissimilarities
are explained in terms of the evolutionary stage of the starburst
episodes. This work illustrates how high-resolution imaging of
specific chemical tracers provide useful inputs to the understanding
of galaxy evolution.
Appeared in: NewAR, 51, 75
, José Cernicharo, Bo Reipurth,
Juan Ramon Pardo, Roberto Neri
Laboratoire d'Astrophysique de l'Observatoire de Grenoble, Grenoble, France,
Instituto de Estructura de la Materia, Departamento Física Molecular, Madrid, Spain,
Institute for Astronomy, University of Hawaii, Hilo, HI,
IRAM, Domaine Universitaire, St. Martin d'Hères, France 
line with the Caltech Submillimeter
Observatory. The emission reveals a small condensation of cold
(T
K) and dense gas [
cm]. The outflow has been
mapped with the IRAM Plateau de Bure interferometer (PdBI). The cold
gas is distributed in a hollow cylinder surrounding the optical
jet. The formation of this cavity and its kinematics are well
accounted for in the frame of outflow gas entrainment by jet bow
shocks. Evidence of gas acceleration is found along the cavity walls,
correlated with the presence of optical bow shocks. The separation of
the inner walls reaches
, which matches the transverse size of
the wings in the bow shock. CSO observations of the
line show
evidence of a high-velocity and hot gas component (
K) with
a low filling factor. This emission probably arises from shocked gas
in the jet. Observations of the 
[C I] line are consistent with
C-type nondissociative shocks. Mapping of the high-velocity molecular
bullets B1-B3, located beyond the optical jet, reveals small
structures of
flattened perpendicular to the flow
direction. They are made of cold (
K), moderate density gas
[
cm], expanding into the low-density surrounding
medium. Their properties are consistent with their being shocked gas
knots resulting from past time-variable ejections in the jet.
Appeared in: ApJ 658, 498
, Leonardo Testi, Antonella Natta, Roberto Neri,
David Wilner, and Chunhua Qi
Osservatorio Astrofisico di Arcetri, INAF, Largo E.Fermi 5, I-50125 Firenze, Italy,
Dipartimento di Fisica, Universitá di Milano, Via Celoria 16, 20133 Milano, Italy,
Institut de Radio Astronomie Millimétrique (IRAM), 300 Rue de la Piscine,
Domaine Universitaire de Grenoble, St. Martin d'Hères F-38406, France,
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 42, Cambridge, MA 02138, USA CO,
CO and C
O emission lines. Gas and dust properties have
been obtained comparing the observations with self-consistent disk
models for the dust and CO emission. The circumstellar disk is
resolved both in the continuum and in CO.We find strong evidence that
the circumstellar material is in Keplerian rotation around a central
star of 2.6 M. The disk inclination with respect to the line of
sight is
with a position angle of
. The slope of the dust opacity measured between 0.87 and
7 mm (
) confirms the presence of mm/cm-size grains in the
disk midplane. The dust continuum emission is asymmetric and confined
inside a radius of 200 AU while the CO emission extends up to 540
AU. The comparison between dust and CO temperature indicates that CO
is present only in the disk interior. Finally, we obtain an increasing
depletion of CO isotopomers from CO to CO and
CO. We argue that these results support the idea that the disk
of HD 163296 is strongly evolved. In particular, we suggest that there
is a strong depletion of dust relative to gas outside 200 AU; this may
be due to the inward migration of large bodies that form in the outer
disk or to clearing of a large gap in the dust distribution by a low
mass companion.
Accepted for publication in A&A
, T. Henning, S. Guilloteau, D. Semenov, V. Piétu,
K. Schreyer, A. Bacmann, R. Launhardt, J. Pety, and F. Gueth
L3AB, Observatoire de Bordeaux, 2 rue de l'Observatoire, BP 89, 33270 Floirac, France,
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany,
IRAM, 300 rue de la Piscine, 38406 Saint-Martin-d'Hères, France,
Astrophysikalisches Institut und Universitäts-Sternwarte, Schillergässchen 2-3, 07745 Jena, Germany H in three disks surrounding DM Tau, LkCa 15, and MWC 480.
We used the IRAM PdBI array to observe the NH 
line and applied a 
-minimization technique to estimate
corresponding column densities. These values are compared, together with HCO column densities, to results of a steady-state disk
model with a vertical temperature gradient coupled to gas-grain chemistry.
Results. We report two NH detections for LkCa 15 and DM Tau at the 
level and an upper limit for MWC 480. The column density
derived from the data for LkCa 15 is much lower than previously reported. The [NH/HCO] ratio is on the order of 
.
So far, HCO remains the most abundant observed molecular ion in disks.
All the observed values generally agree with the modelled column densities of disks at an evolutionary stage of a few
million years (within the uncertainty limits), but the radial distribution of the molecules is not reproduced well. The low inferred
concentration of NH in three disks around low-mass and intermediate-mass young stars implies that this ion is not a sensitive tracer
of the overall disk ionization fraction.
Appeared in: A&A 464, 615
, J. Pety, M. Gerin,
D. Teyssier, E. Roueff, P. Hily-Blant
LERMA-LRA, UMR 8112, CNRS, Observatoire de Paris and
Ecole Normale Supérieure, 24 Rue Lhomond, 75231 Paris, France,
IRAM, 300 rue de la Piscine, 38406 Grenoble cedex, France,
European Space Astronomy Centre, Urb. Villafranca del
Castillo, P.O. Box 50727, Madrid 28080, Spain,
LUTH UMR 8102, CNRS and Observatoire de Paris, Place J.
Janssen 92195 Meudon cedex, France
Sulfur is an abundant element which remains undepleted in diffuse
interstellar gas (
) but it is traditionally assumed to
deplete on dust grains at higher densities and larger AV.
Photodissociation regions (PDRs) are an interesting intermediate
medium between translucent and dark clouds where the chemistry and
energetics are domi- nated by the illuminating FUV radiation
field. Thus they can provide new insights about the sulfur depletion
problem. However, physical and chemical gradients in PDRs take place
at small angular scales (
to
). Aperture synthesis
observations are therefore required to resolve such
gradients. Besides, a complete understanding of molecular excitation
is needed to correctly determine molecular abundances but also the
preavailing physical conditions. Hence, multi-J observations at
increasing frequencies are also required. Such high an- gular
resolution and broad frequency coverage observa- tions will be
provided by ALMA in the near future. In this work we present
IRAM-PdBI observations of the CS 
line toward the Horsehead PDR
comple- mented with IRAM-30m observations of several rota- tional
lines of different sulfur bearing molecules (CS, HCS, SO, HS,
etc.). Photochemical and nonlocal, non-LTE radiative transfer models
adapted to the Horsehead geometry have been developed. The gas phase
sulfur abundance has been inferred in the PDR.
To appear in: Astrophysics and Space Science, ``Science with ALMA: a new era for Astrophysics'' conf. proc., November 13-17 2006, ed. R. Bachiller
, J. R. Goicoechea, P. Hily-Blant, M. Gerin, and D. Teyssier
IRAM, 300 rue de la Piscine, 38406 Grenoble Cedex, France,
LERMA, UMR 8112, CNRS, Observatoire de Paris and École Normale Supérieure, 24 rue Lhomond,
75231 Paris Cedex 05, France,
European Space Astronomy Centre, Urb. Villafranca del Castillo, PO Box 50727, Madrid 28080, Spain ]/[HCO] abundance ratio over the
elemental ratio in
the cold and dense gas typically found in pre-stellar cores.
We report the first detection and mapping of very bright DCO 
and lines (3 and 4K respectively) towards
the Horsehead photodissociation region (PDR) observed with the IRAM-30m telescope. The DCO emission peaks close to the
illuminated warm edge of the nebula (
or
pc away).
Detailed nonlocal, non-LTE excitation and radiative transfer analyses have been used to determine the prevailing physical
conditions and to estimate the DCO and HCO abundances from their line intensities.
A large [DCO]/[HCO+] abundance ratio (
) is inferred at the DCO emission peak, a condensation shielded from the
illuminating far-UV radiation field where the gas must be cold (
K) and dense (
cm). DCO is not detected in the
warmer photodissociation front, implying a lower [DCO]/[HCO] ratio (
).
According to our gas phase chemical predictions, such a high deuterium fractionation of HCO can only be explained
if the gas temperature is below 20K, in good agreement with DCO excitation calculations.
Appeared in: A&A 464, L41
, N. Brouillet, J. Cernicharo, F. Combes
and A. Wooten
IRAM, 300 rue de la Piscine, 38406 St. Martin d'Hères, France,
Observatoire de Bordeaux, France,
DAMIR/CSIC, Madrid, Spain,
Observatoire de Paris, France,
NRAO, Charlottesville, USA 
AU. As can be seen on the maps of
Fig. 6, the bulk of the emission from ethyl cyanide
(CHCHCN), vinyl cyanide (CHCHCN), ethanol (CHCHOH)
and, to a lesser degree, methanol (CHOH) arise from such cores.
Ethyl- and vinyl cyanide emission is observed in two small sources
located few arcsec NE and W of IRC2 (triangle) and devoid of any
visible ethanol or methanol emission. The alcohol emission actually
peaks in another clump, S of IRC2, called the Orion ``Hot Core''.
 |
 |
The absence of vinyl- and ethyl cyanide in the ``Hot Core'' has yet to
be explained. It does not result from a lack of nitrogen as HCN,
NH and HCO are abundant in both the NE core and in the ``Hot
Core'' (as a matter of fact, the NH column density is a factor of 8
larger in the NE core). It is not a temperature effect, as both cores
have teperatures 
K, high enough for desorbing from grains most
molecular species. The chemical differences may come from the warm-up
time of the cores, a critical parameter according to models, which
depends on the mass of the protostar.
The emission from each molecule covers only a small fraction (1/10 to 1/30) of the 30-m telescope beam, so that the column densities of the species in the cores are more than one order of magnitude larger than the beam-averaged column densities observed with the 30-m telescope or the JCMT. The abundance ratios between e.g. ethyl- or vinyl cyanide, on the one hand, and ethanol or methyl formate, on the other hand, also differ by large factors from those derived with single dish telescopes. Obviously, the predictions of hot core chemistry models must be compared only with high resolution interferometric observations.
 |
The PdBI observations were part of a search for interstellar glycine,
also carried out with the IRAM 30-m telescope and the Green Bank
Telescope. We derive a 
upper limit of
cm
per
beam in the Orion Hot Core and Compact
Ridge - the lowest to date at this scale.
Accepted for publication in conf. proc: Science with ALMA: a new era for astrophysics, Springer 2007.
, Arnaud Belloche
, Frédérique Motte and Nicolas Peretto
CEA/DSM/DAPNIA, Service d'Astrophysique, C.E. Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette, France,
Laboratoire AIM, Unité Mixte de Recherche CEA - CNRS - Université Paris Diderot, C.E. Saclay, France,
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany,
Physics & Astronomy Department, University of Manchester, P.O. Box 88, Manchester M60 1QD, UK H(1-0) mapping, of the Ophiuchus protocluster condensations
using the IRAM 30m telescope. We measured subsonic or at most
transonic levels of internal turbulence within the condensations,
implying virial masses which generally agree within a factor of with the masses derived from the 1.2 mm dust continuum. This
supports the notion that most of the L1688 starless condensations are
gravitationally bound and prestellar in nature. We detected the
classical spectroscopic signature of infall motions in CS(2-1),
CS(3-2), HCO(
), and/or HCO(3-2) toward six
condensations, and obtained tentative infall signatures toward 10
other condensations. In addition, we measured a global
one-dimensional velocity dispersion of less than 
km s (or
twice the sound speed) between condensations. The small relative
velocity dispersion implies that, in general, the condensations do not
have time to interact with one another before evolving into pre-main
sequence objects.
Our observations support the view that the IMF is partly
determined by cloud fragmentation at the prestellar stage. Competitive
accretion is unlikely to be the dominant mechanism at the protostellar
stage in the Ophiuchus protocluster, but it may possibly govern the
growth of starless, self-gravitating condensations initially produced
by gravoturbulent fragmentation toward an IMF, Salpeter-like mass
spectrum.
Accepted for publication in A&A
CHCH): Missing Links in Interstellar Gas-Phase Chemistry
, J. Cernicharo, M. Agundez, E. Roueff,
M. Gerin, J. Martin-Pintado, R. Mauersberger, and C. Thum
DAMIR-IEM-CSIC, Spain, LUTH, Obs. de Paris, France, LERMA, Obs. de
Paris and Ecole Normale Superieure, France, IRAM, Spain, IRAM, France CHCH) with
the IRAM 30-m radio telescope toward the dark cloud TMC-1. Propylene is the
most saturated hydrocarbon ever detected in space through radio astronomical
techniques. In spite of its weak dipole moment, 6 doublets (A and E species)
plus another line from the A species have been observed with main beam
temperatures above 20 mK. The derived total column density of propylene is
cm, which corresponds to an abundance relative to H of
,
i.e., comparable to that of other well known and abundant hydrocarbons in this
cloud, such as c-CH. Although this isomer of CH could play an important
role in interstellar chemistry, it has been ignored by previous chemical models
of dark clouds as there seems to be no obvious formation pathway in gas phase.
The discovery of this species in a dark cloud indicates that a thorough
analysis of the completeness of gas phase chemistry has to be done.
Accepted for publication in ApJ Letters
, José Cernicharo and Michel Guélin
Departamento de Astrofisica Molecular e Infrarroja,
Instituto de Estructura de la Materia, CSIC, Serrano
121, E-28006 Madrid, Spain,
Institut de Radioastronomie Millimétrique, 300
rue de la Piscine, F-38406 St. Martin d'Hères, France Appeared in: ApJ Letters, 662, L91
, J. Braine, K.F. Schuster,
N. Brouillet, A. Sievers
Université Bordeaux 1, CNRS, Laboratoire d'Astrophysique, Observatoire de Bordeaux, OASU, UMR 5804, Floirac, F-33270,
IRAM, 300 Rue de la Piscine, F-38406 St Martin d'Hères, France 
line
with the HERA heterodyne array on the IRAM 30m telescope. A
region in the northern part of M33 was observed, reaching a detection
threshold of a few M. The correlation in this field between the CO
emission and tracers of SF (8
m, 24m, H
, FUV) is excellent and CO is
detected very far North, showing that molecular gas forms far out in
the disk even in a small spiral with a subsolar metallicity. One major
molecular cloud was discovered in an interarm region with no HI peak
and little if any signs of SF - without a complete survey this
cloud would never have been found. The radial dependence of the CO
emission has a scale length similar to the dust emission, less
extended than the H or FUV. If, however, the 
ratio varies
inversely with metallicity, then the scale length of the H becomes
similar to that of the H or FUV. Comparing the SF rate to the H mass
shows that M33, like the intermediate redshift galaxies it resembles,
has a significantly higher SF eciency than large local universe
spirals. The data presented here also provide an ideal test for
theories of molecular cloud formation and cover a new region in
parameter space, where
. We find that a simple
pressure-based prescription for estimating the molecular to atomic gas
fraction does not perform well for M33, at least in the outer
parts. On the other hand, we show that the molecular gas fraction is
influenced by (i) the total Hydrogen column density, dominated in M33
by the HI, and (ii) the galactocentric distance.
Accepted for publication in A&A
, R. Keller, D. Koelle, T. Scherer, K.F.Schuster
Physikalisches Institut-Experimentalphysik II, Universität Tübingen,
Auf der Morgenstelle 14, D-72076 Tübingen, Germany,
Institut de Radio Astronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 St. Martin d'Hères, France Accepted for publ. in: Applied Physics Letters 90, 1
, A. Barbier, D. Billon-Pierron,
S. Halleguen, M. Schicke and K. F. Schuster
Institut de Radio Astronomie Millimétrique (IRAM), 300 rue
de la Piscine, 38406 St. Martin d'Hères, France inductively coupled plasma
etching. Chemical-mechanical polishing, which is difficult to control
for low volume production is not required. We further show that a new
type of spin-on glass can be used as a reliable replacement for
sputtered SiO. We present yield and parameter scattering of these
devices.
Accepted for publ. in: IEEE Trans. Appl. Supercond.
, Alessandro Navarrini, Philippe Ferrari, Teresa
Zöpfl, Franz Wittmann, Witek Bedyk, Gabi Schrag, and Karl-Friedrich
Schuster
IRAM, 300, rue de la Piscine, Domaine Universitaire de Grenoble, 38406 St. Martin d'Hères Cedex, France,
Osservatorio Astronomico di Cagliari /INAF Loc. Poggio dei Pini, Strada 54 09012 Capoterra (CA) - Italy,
Institute for Microelectronics Electromagnetism and Photonics (IMEP) - INPG/Université Joseph Fourier, 23 rue de Martyrs, 38016 Grenoble, France,
Institute for Physics of Electrotechnology, Munich University of Technology, Arcisstraße 21, 80290 Munich, Germany Accepted for publ. in in: IEEE Trans. Appl. Supercond.
.
, as indicated. The
triangle shows the position of IRC2. Axis are J2000 coordinates.