, R. Bachiller , B. Reipurth 
Observatorio Astronomico Nacional (IGN),
Apartado 1143, E-28800 Alcalá de Henares (Madrid), Spain CASA, University of Colorado, Campus Box 389,
Boulder, CO 80309, USA 
/ 
ratio of 1.8
10 
.
The SiO lines exhibit a variety of profiles, ranging from
narrow lines (1-3 km s 
width) at ambient velocities to broad profiles
(10-20 km s ), with
complex profiles consisting of a blend of low and high velocity
components as intermediate stages. In the regions where SiO was mapped, the
low velocity SiO emission comes from regions definitely
offset from the position where the high velocity emission is
present, indicating that the low and high velocity SiO emissions
trace two distinct regimes.
The SiO abundances are different in those two regimes:
we estimate that typical SiO abundances are
10 
-10 
in the high velocity components,
but they decrease by two orders of magnitude
(10 
-10 ) when SiO is detected at low velocities.
The hydrogen volume densities estimated from the multiline SiO
observations are in the range 10 
to fews 10 
cm 
, in both the
low and the high velocity regimes, indicating that all the SiO
emission arises in shock-compressed regions. We argue that the
different observed SiO profiles could be caused by an evolutionary
effect: the SiO molecules produced at high velocities could be slowed
down because of their interaction with the surrounding gas before they
stick onto the dust grains. However, the possibility that the low
velocity SiO emission is due to slow shocks cannot be ruled out,
but this would require the presence of a small amount of silicon
compounds on the dust grain mantles.Astronomy & Astrophysics, in press
e-mail: codella@oan.es
Preprints:
http://www.oan.es/preprints/lista.html
, N. Neininger , R. Lucas and J.
Cernicharo 
IRAM, 300 rue de la piscine, F-38406 St Martin d'Hères,
France Radioastron. Institut der Universität Bonn, Germany Instituto de Estructura de la Materia, Madrid, Spain 
). Age, however, is not observationally constrained
in most astronomical sources. An exception is IRC+10216, an expanding
circumstellar envelope, where the distance to the central
star is also a measure of age. An analysis of the spatial distribution
of carbon chains in that source shows that the agreement
between predicted and observed abundances is fortuitous.
Figure 13: Observed (filled symbols) and predicted (open symbols)
column densities of the carbon-chain radicals in IRC+10216
(after Guélin et al. 1997&98). The predicted column densities are taken
from Millar & Herbst (1994) and correspond to the peak abundances of the
different species.
The current chemical models predict that C 
H forms from C 
H and
C H from C 
H.
C H itself results from the photodissociation of acetylene.
A lower limit to the formation times of C H and C H can be derived by
using the largest possible reaction rates, gas density and acetylene abundance. It takes 
yr to form C H from C H and C H from C H,
which means, considering the envelope expansion velocity (14 kms )
and its distance (simeq 200 pc), that the abundances of these species
should peak respectively
and 
further out than 
H. In contrast,
Figure 14 shows that the 3 species coexist spatially
within 
and should form quasi-simultaneously (i.e.
within 120 yr).
The very good agreement of Figure 13 is thus fortuitous and a new formation mechanism must be sought. This mechanism could be the desorption from dust grains of weakly attached carbon-chains, under the influence of interstellar UV and/or shocks.
Figure 14: Brightness temperature distribution of the 
3-mm lines of C H,
C H and C H, observed in IRC+10216 with the IRAM interferometer.
The intensities (multiplied by 1,1.3, and 7, respectively) have been
integrated over a narrow band centred on the star velocity and represent
roughly the species' abundance distribution in a meridian plane. Except for
the larger noise in C H, the 3 maps look very similar; their brightest
spots lie all along a circle of radius 16''. Note that
the emission from the central star has been removed.
Proc. 3rd Cologne-Zermatt Symposium The Physics and Chemistry of the Interstellar Medium, ed V. Ossenkopf.
\
and S. Guilloteau Institut de Radioastronomie Millimétrique (IRAM),
300 rue de la Piscine, 38406 Saint Martin d'Hères, France Max-Planck-Institut für Radioastronomie,
Auf dem Hügel 69, 53121 Bonn, Germany 
Figure: CO 
emission (thin contours) integrated in two
different velocity intervals and superimposed on the
H v=1-0 S(1) emission (greyscale; from McCaughrean et al. 1994)
and the 230 GHz continuum emission (thick contours; contours are
10, 30, 50 and 70 mJy/beam).
The angular resolutions are 
for the H ,
at PA 
for the CO, and
at PA 
for the continuum
observations.
Upper panel: CO emission integrated between LSR
velocities 2.2 and 18.2kms (the systemic velocity is 9.2kms );
contours are 1.6 Jykms /beam.
Lower panel: CO emission integrated for velocities
lower than 2.2kms and larger than 18.2kms ; first contour is
1 Jykms /beam and contour step is 1.5 Jykms /beam.
We present high angular resolution (down to 
)
interferometric maps of the CO 
and 
emission in the
molecular outflow associated with the extremely young HH211
jet, which is located in the IC348 molecular complex. At
velocities close to the systemic velocity, the CO emission
traces the outflow cavities, while an extremely collimated,
continuous jet-like structure is observed at high CO velocities.
The continuum emission reveals a 
dust condensation
surrounding the central exciting (Class 0) protostar, clearly
resolved and elongated perpendicular to the jet axis. The strong
(bow-)shocks observed in vibrationally excited H emission are
located at the terminal ends of the jet and the low-velocity CO
cavities are precisely situated in their wake. Hence, the overall
structure of HH211 perfectly fits into the picture of a
jet-driven flow and strongly supports shock-entrainment models as
the formation mechanisms of young, embedded molecular outflows.
The shape of the cavities traced by the low-velocity CO emission
can actually be (surprisingly well) reproduced by a simple,
semi-analytical toy-model of a jet-driven flow, in which prompt
entrainment occurs at the head of a travelling bow-shock. The
estimated jet mass and mass loss rate yield a timescale of order
one thousand years, in agreement with the kinematical age.
Finally, we discuss the physical properties of the different
parts of the outflow, and especially the actual nature of the
high-velocity CO jet.
Astronomy & Astrophysics, in press
e-mail: gueth@mpifr-bonn.mpg.de
Preprints:http://iram.fr/PP/papers.html
and D. Morris , Institut de Radioastronomie Millimétrique, Grenoble, France 
Figure 16: Zeeman observations of the H 
transition in MWC349
obtained with an autocorrelator backend and smoothed to a resolution of
0.7 kms .
All data obtained during 23-28 June 1996 have been averaged,
representing 245 min of polarization-switched spectra.
The three subframes show:
(a) the total power spectrum (Stokes I),
(b) the V-spectrum (RHC-LHC), corrected for instrumental
polarization,
(c) same as (b), but observed with the filter bank at a
spectral resolution 1.3 kms .
Vertical dotted lines mark the maxima of the total power maser spikes.
Using Zeeman observations of the H recombination line maser
transition
at 1.3 mm we have detected a magnetic field which is associated with the
corona of the circumstellar disk of MWC349A.
At a radial distance of 40 a.u.,where the H
maser is located, the line-of-sight component of the field is
approximately parallel to the plane of this edge-on disk,
and its average strength is 22 mG. The corresponding magnetic energy
density is 
% of the thermal energy density of the plasma where the
maser emission originates, very likely making the detected field dynamically
important. Spectral fine structure of the detected Zeeman pattern suggests
that the field may have a strong radial component, although other
models for the field configurations are possible.
The strength of the field at such a large distance from the star makes it
unlikely that the field is of stellar origin. We suggest that it is
generated by a local disk dynamo.%
, R. Neri , T. Wiklind , Wilner and
Shaver 
IRAM, 300 rue de la piscine, F-38406 St Martin d'Hères, France Onsala Space Observatory, S-43992 Onsala, Sweden Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA European Southern Observatory, D-85648 Garching bei München, Germany , and, along with
the broad absorption lines, are probably emitted in the quasar's wind
or jet, moving toward us. The CO line ratios suggest the molecular
gas is at a temperature of about 200 K, at a density of
about 4000 cm . We also detected the dust emission at 94 and
214 GHz (emitted wavelengths 650 and 290 
m). The spectral
index of the mm/submm continuum is +3.2, indicating the dust
emission is optically thin in this part of the spectrum. The
extremely high CO and dust luminosities suggest magnification by
gravitational lensing. Using the optical extent and our limit on
the size of the CO region, we estimate a magnification of 7 to 30
for the CO lines and the far-IR continuum, and 14 to 60 for the
optical/UV. In this interpretation, the molecular gas and dust is in
a nuclear disk of radius 90 to 270 pc around the quasar. The quasar
is 25 to 100 times stronger than, but otherwise resembles, the nucleus of
Mrk 231.
Astron. & Astrophys., in press
CO observations of the box-shaped
bulge spiral NGC4013 , F. Combes
and R. Neri , Observatorio Astronomico Nacional (IGN),
Apartado 1143, E-28800 Alcalá de Henares (Madrid), Spain Observatoire de Paris, 61 av. de l'Observatoire, 75014 Paris, France IRAM, 300 rue de la piscine, 38406 St Martin d'Hères, France CO. Our maps
show the existence of a fast-rotating (130 km/s) molecular gas disk
of radius r=110 pc. Several arguments support the existence of a bar
potential in NGC 4013. The figure-of-eight pattern of the major axis
p-v plot, the ring-like distribution of gas, and the existence of gas
emission at non-circular velocities are best accounted by a bar. We
have also detected gas at high z distances from the plane
(z=200-300 pc). The latter component is related to a system of 4 Halpha
filaments of diffuse ionized gas that come out from the nucleus. The
galactic fountain model seems the best to account for the Halpha and
CO filaments. Although the peanut distortion can be spontaneously
formed by a stellar bar in the disk, gas at high z might have been
ejected after a nuclear starburst. The Halpha filaments start in the
plane of the disk at r=200 pc, and reach several Kpc height at r=600 pc,
coinciding with the maximum peanut distortion. Although a link
between the bar and the box-shaped bulge in NGC4013 is suggested we
find noticeable differences between the results of previous numerical
simulations and the present observations. The discrepancy concerns the
parameters of the bar generating the peanut. We see in NGC 4013 the
existence of a strong ILR region. The inclusion of a dissipative
component, which remains to be thoroughly studied, may change the
evolution of the stellar peanut: although in simulations the peanut
appears initially near a marginal ILR, the inflow of gas driven by the
bar, can make two ILRs appear.