Multiline CO Research Articles

CO survey of ARCHEOPS cold cores

Density and velocity distribution of 13 molecular clouds have been derived from multi-isotopic multi-line CO observations. These observations are investigations of the initial conditions for star formation in cold molecular cloud cores. The targets were selected from the ARCHEOPS point sources (Désert et al. 1987). The ARCHEOPS balloon born submm-mm telescope located cold interstellar clouds with ~ 12 arcmin angular resolution (Désert et al. 1987, Benoit et al. 2002). A sub-sample of 13 clouds have been mapped in 12CO(3-2), 13CO(2-1) and C18O(2-1). The observations have been carried out with the KOSMA-3m telescope (Kramer et al. 2000) in February, 2009. The measuring's pointing accuracy was around 10 arcsec. The calibration error was about 10-15%. The derived distribution of the gas column density indicated structured isolated molecular clouds with embedded cloud cores in 9 cases. Velocity gradient was found in 4 cases. The data set will be further used as input for Herschel target selection, observation and radiative transfer modelling.

Carbon monoxide laser emitting nanosecond pulses with 10 MHz repetition rate

Actively mode-locked electron-beam-sustained-discharge CO laser producing a train of ∼5–15 ns (FWHM) spikes following with repetition rate 10 MHz for both single-line and multiline mode of operation in the mid-IR range of ∼5 μm was experimentally studied. Total laser pulse duration was ∼0.5 ms for both mode-locked and free-running laser. Specific output energy in multiline CO laser mode of operation was up to 20 Jl −1 Amagat −1 and the laser efficiency up to 3.5%. The active mode-locking was achieved for single-line CO laser mode of operation in spectral range 5.2–5.3 μm. This sort of radiation can be used for pumping an optical parametric amplifier for optical stochastic cooling in relativistic heavy ion collider, for laser ablation, and for studying vibrational and rotational relaxation of CO and NO molecules.

APEX CO(3–2) observations of NGC 6822

We observed the 12CO() emission of the emission-line regions Hubble I, Hubble V, Hubble X, Holmberg 18, and the stellar emission-line object S28 in NGC 6822 with the ESO Atacama Pathfinder Experiment (APEX) 12 m telescope as part of its science verification. The very low system temperature of K enabled us to achieve detections in 4 single pointings and in a high spatial resolution map of Hubble V. We compare the spectra with Hi observations, obtained with the Australia Telescope Compact Array, of the same regions. In combination with previous multi-line CO observations, we perform a preliminary investigation of the physical conditions in Hubble V using a simple LTE model. We estimate the mass of the Hubble V region and the H conversion factor. Also, we show that Hubble V is located very near the line-width versus size relation traced by the Milky Way and LMC molecular clouds.

Mechanisms for the Origin of Turbulence in Non–Star‐forming Clouds: The Translucent Cloud MBM 40

We present a multiline, high spatial and velocity resolution CO, H I, and IRAS 100 μm study of the high-latitude, low-mass, non-star-forming, translucent molecular cloud MBM 40. The cloud mass is distributed into two ridges, or filaments, that form a hairpin structure. Velocity channel maps indicate a highly ordered flow in the molecular gas, with the northeastern part of the filament moving away from and the southwestern filament moving toward the observer relative to the mean cloud radial velocity. Significant changes in emissivity occur over 0.03 pc, indicating large transverse density gradients along the ridges. However, the velocity field appears to be continuous, showing no evidence for shock compression. The neutral hydrogen at the same velocity envelops the molecular gas but shows a decrease along the hairpin, indicating that the atomic hydrogen has converted to H2; the strongest 100 μm emission coincides with the CO, not the H I, emission peak. These results indicate that MBM 40 is condensing out of a larger scale flow and is structured by thermal instability and shear flow turbulence. This externally driven turbulence does not produce large compression and may explain why gravitational collapse and star formation do not occur in MBM 40.

Multiline CO 2 lasers and their uses

Etude des lasers fonctionnant sur plusieurs longueurs d'onde simultanement, et de leurs applications

An independently adjustable multiline AM mode-locked TEA CO2laser

A new method is described for constructing an AM mode-locked, multiline TEA CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> laser oscillator generating nanosecond pulses. The multiline behavior is achieved by spatial separation of the rotational transitions at the amplifying medium. The setup generates 1.15 ns pulses with an energy of 3.7 mJ per pulse and containing simultaneously six rotational transitions in the 10.6 μm <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</tex> -branch.

Development of a stable mode‐locked multiline CO2 oscillator

Development of a stable mode‐locked multiline CO₂ oscillator