Improved low-temperature rate constants for rotational excitation of CO by H$_\mathsf{2}$

Wernli, Michael; Valiron, P.; Fauré, Alexandre; Wiesenfeld, Laurent; Jankowski, Piotr; Szalewicz, Krzysztof

doi:10.1051/0004-6361:20053919

Cited by 102 publications

(106 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These include extrapolation to energy levels up to J = 40 and collisional temperatures up to 2000 K, based on the original datasets calculated by Flower (2001) and Wernli et al (2006) for temperatures in the range from 5 to 400 K and energy levels up to J = 29 and J = 20 for collisions with para-H2 and ortho-H2, respectively. We assumed a specific column density N CO Δv −1 ranging from 10 14 to 10 19 cm −2 (km s −1 ) −1 .…”

Section: Lvg Analysismentioning

confidence: 99%

Extremely high velocity gas from the massive young stellar objects in IRAS 17233-3606

Leurini¹,

Codella

Zapata

et al. 2009

A&A

View full text Add to dashboard Cite

Context. Molecular outflows from high-mass young stellar objects provide an excellent way to study the star formation process, and investigate if they are scaled-up versions of their low-mass counterparts. Aims. We selected the nearby massive star forming region IRAS 17233−3606 in order to study the kinematics and physics along the molecular outflow(s) originating from this source. Methods. We observed IRAS 17233−3606 in CO, a typical tracer of gas associated with molecular outflow, with the Submillimeter Array in the (2−1) transition, and with the APEX telescope in the higher excitation (6-5) line. Additional infrared H 2 observations were performed with the UKIRT telescope. The CO data were analysed using a LVG approach. Results. Our data resolve the previously detected molecular outflow into at least three different components, one of them with a high collimation factor (∼4), and characterised by emission at extremely high velocities (|v − v LSR | > 120 km s −1 ). The estimate of the kinematical outflow parameters are typical of massive YSOs, and in agreement with the measured bolometric luminosity of the source. The kinematic ages of the flows are in the range 10 2 −10 3 yr, and therefore point to young objects that still have not reached the main sequence.

show abstract

Section: Lvg Analysismentioning

confidence: 99%

Extremely high velocity gas from the massive young stellar objects in IRAS 17233-3606

Leurini¹,

Codella

Zapata

et al. 2009

A&A

View full text Add to dashboard Cite

show abstract

“…Many experimental and theoretical studies of the collision-inducing rotational energy transfer have been performed in the last four decades. Particularly, the collisional rate coefficients with the most abundant interstellar species, H, H 2 , and He, have been shown to be of great astrophysical importance (Wernli et al 2006;Kłos et al 2007;Guillon et al 2008;Buffa et al 2009;Lique et al 2009Lique et al , 2010Dubernet et al 2009;Najar et al 2009;Sarrasin et al 2010). …”

Section: Introductionmentioning

confidence: 99%

“…Astronomers usually estimated the rate coefficients for the collisions with para-H 2 ( j = 0) from those obtained by collision with He (Schöier et al 2005). The studies reported by Wernli et al (2006), Lique et al (2008), and Dumouchel et al (2010) indicated that the use of the scaled factor of 1.4 to deduce the rate coefficients of the collision with para-H 2 ( j = 0) from those corresponding to the collision with He provides the correct magnitude order. This was showen to be unlikely for charged species.…”

Section: Introductionmentioning

confidence: 99%

Induced rotational excitation of the fluoromethylidynium¹²CF⁺and¹³CF⁺through collision with helium

Ajili

Hammami

2013

A&A

View full text Add to dashboard Cite

Aims. The present paper focuses on the calculation of the collision rate coefficients for rotational excitation of the 12 CF + and its isotopologue 13 CF + by He for temperature ranging from 10 to 300 K. Methods. A two-dimentional (2D) potential energy surface (PES) of the CF + (X 1 Σ + )-He( 1 S) system is calculated at the ab initio coupled cluster with single, double, and perturbative triple excitation level of theory with the aug-cc-pV5Z basis set. The basis set superposition errors were taken into account in our computation. Dynamical calculations of state-to-state rotational integral cross sections of the CF + by collision with He were performed using the close-coupling method. Results. The PES presents a global minimum of ∼212 cm −1 below the CF + -He dissociation limit. Collisional cross sections among the first 11 rotational levels of CF + were calculated for total energies up to 1500 cm −1 . Downward rate coefficients between the rotational levels were calculated for temperature ranging from 10 to 300 K. A propensity toward an even parity of ∆J is observed.

show abstract

“…It should be mentioned that calculations of collisional excitation by ortho-H 2 have been carried out solely on 4 diatomic molecules CO (Flower & Launay 1985;Mengel et al 2001;Flower 2001;Wernli et al 2006), H 2 (Flower & Roueff 1999b), HD (Flower 1999;Flower & Roueff 1999a), SiS (Kłos & Lique 2008, and on water (Phillips et al 1996;Grosjean et al 2003;Faure et al 2007), and that all quantum calculations except those of restricted the H 2 basis set to j 2 = 1.…”

Section: Introductionmentioning

confidence: 99%

Rotational excitation of 20 levels of para-H₂O by ortho-H₂(j₂= 1, 3, 5, 7) at high temperature

Daniel

Dubernet

Pacaud³

et al. 2010

A&A

View full text Add to dashboard Cite

Aims. The objective is to obtain the best possible set of rotational (de)-excitation state-to-state and effective rate coefficients for temperatures up to 1500 K. State-to-state rate coefficients are presented among the 20 lowest levels of para-H 2 O with H 2 ( j 2 = 1) and Δ j 2 = 0, +2, and among the 10 lowest levels of para-H 2 O with H 2 ( j 2 = 3) and Δ j 2 = 0, −2. Methods. Calculations are performed with the close coupling (CC) method over the whole energy range, using the same 5D potential energy surface (PES) as the one employed in our latest publications on water. We compare our CC results both with thermalized quasi-classical trajectory (QCT) calculations using the same PES and with previous quantum calculations obtained between T = 20 K and T = 140 K with a different PES. Results. Comparisons with thermalized QCT calculations show factors from 1 to 3. Until recently the only other available set of rate coefficients were scaled collisional rate coefficients obtained with He as a collision partner, and differences between CC and scaled results are shown to be greater than with QCT calculations. The use of the CC accurate sets of rate coefficients might lead to re-estimation of water abundance in the astrophysical whenever models include the scaled H 2 O-He rate coefficients.

show abstract

Improved low-temperature rate constants for rotational excitation of CO by H$_\mathsf{2}$

Cited by 102 publications

References 29 publications

Extremely high velocity gas from the massive young stellar objects in IRAS 17233-3606

Extremely high velocity gas from the massive young stellar objects in IRAS 17233-3606

Induced rotational excitation of the fluoromethylidynium¹²CF⁺and¹³CF⁺through collision with helium

Rotational excitation of 20 levels of para-H₂O by ortho-H₂(j₂= 1, 3, 5, 7) at high temperature

Contact Info

Product

Resources

About

Improved low-temperature rate constants for rotational excitation of CO by H$_\mathsf{2}$

Cited by 102 publications

References 29 publications

Extremely high velocity gas from the massive young stellar objects in IRAS 17233-3606

Extremely high velocity gas from the massive young stellar objects in IRAS 17233-3606

Induced rotational excitation of the fluoromethylidynium12CF+and13CF+through collision with helium

Rotational excitation of 20 levels of para-H2O by ortho-H2(j2= 1, 3, 5, 7) at high temperature

Contact Info

Product

Resources

About

Induced rotational excitation of the fluoromethylidynium¹²CF⁺and¹³CF⁺through collision with helium

Rotational excitation of 20 levels of para-H₂O by ortho-H₂(j₂= 1, 3, 5, 7) at high temperature