93 research outputs found
HfS, Hyperfine Structure Fitting Tool
Hyperfine Structure Fitting (HfS) is a tool to fit the hyperfine structure of spectral lines with multiple velocity components. The HfS_nh3 procedures included in HfS simultaneously fit the hyperfine structure of the NH3 (J, K) = (1, 1) and (2, 2) transitions, and perform a standard analysis to derive , NH3 column density, , and . HfS uses a Monte Carlo approach for fitting the line parameters. Special attention is paid to the derivation of the parameter uncertainties. HfS includes procedures that make use of parallel computing for fitting spectra from a data cube
Unveiling the nature and interaction of the intermediate/high-mass YSOs in IRAS 20343+4129
In order to elucidate the nature of the brightest infrared sources associated
with IRAS 20343+4129, IRS1 and IRS3, we observed with the Submillimeter Array
(SMA) the 1.3 mm continuum and CO(2-1) emission of the region. Faint millimeter
dust continuum emission was detected toward IRS1, and we derived an associated
gas mass of ~0.8 Msun. The IRS1 spectral energy distribution agrees with IRS1
being an intermediate-mass Class I source of about 1000 Lsun, whose
circumstellar material is producing the observed large infrared excess. We have
discovered a high-velocity CO bipolar outflow in the east-west direction, which
is clearly associated with IRS1, and the outflow parameters are similar to
those of intermediate-mass young stellar objects. Associated with the blue
large scale CO outflow lobe, detected with single-dish observations, we only
found two elongated low-velocity structures on either side of IRS3. The
large-scale outflow lobe is almost completely resolved out by the SMA. Our
detected low-velocity CO structures are coincident with elongated H2 emission
features. The strongest millimeter continuum condensations in the region are
found on either side of IRS3, where the infrared emission is extremely weak,
and the CO and H2 elongated structures follow the border of the millimeter
continuum emission that is facing IRS3. All these results suggest that the dust
is associated with the walls of an expanding cavity driven by IRS3, estimated
to be a B2 star. Within and beyond the expanding cavity, the millimeter
continuum sources can be sites of future low-mass star formation.Comment: 12 pages, 7 figures, accepted for publication in A&
3-D Kinematics of the HH 110 jet
We present new results on the kinematics of the jet HH 110. New proper motion
measurements have been calculated from [SII] CCD images obtained with a time
baseline of nearly fifteen years. HH 110 proper motions show a strong asymmetry
with respect to the outflow axis, with a general trend of pointing towards the
west of the axis direction. Spatial velocities have been obtained by combining
the proper motions and radial velocities from Fabry-Perot data. Velocities
decrease by a factor ~3 over a distance of ~10 cm, much shorter than the
distances expected for the braking caused by the jet/environment interaction.
Our results show evidence of an anomalously strong interaction between the
outflow and the surrounding environment, and are compatible with the scenario
in which HH 110 emerges from a deflection in a jet/cloud collision.Comment: (1)Universitat de Barcelona; (2)UNAM; (3)UPC; (4)University of
Hawaii; (5)Southern Astrophysical Research Telescope. 9 pages; 7 Figures
Accepted by A&
A survey of IRAS young stellar object candidates: Searching for large-scale Herbig-Haro objects
Context. Jets and outflows are associated with young stellar objects across the stellar mass spectrum, from brown dwarf protostars to massive Ae/Be stars. Frequently the jet morphology is spatially discontinuous because of the temporal variability of the ejection from the driving source. Images covering a wide field of view around the jet-driving source are useful to map the large-scale jet emission and to explore the mass ejection history. Aims. The aim of our work was to search for large-scale optical Herbig-Haro (HH) objects lying in a wide field around a sample of IRAS sources, which are candidates to trace young stellar objects. Methods. Deep narrowband images through the Hα and [S II ] emission lines, and through an off-line continuum filter, covering a wide (∼15 0 ) field around the IRAS targets were acquired. The images in the three filters were analyzed to identify shock-excited line emission (i.e., HH) in contrast to scattered line emission. Results. New images of a sample of 15 IRAS sources, obtained in a homogeneous way are presented. HH emission was detected in six fields, and the astrometry of the knot features is given. The nature of the extended emission as scattered emission around nine of the IRAS targets is confirmed. For seven IRAS sources with unclear optical counterparts, a more plausible counterpart is proposed. A refined value of the source distance is reported for seven targets. An update of the main data available for each of the sampled fields, including images from public data archives, is also presented
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