Interstellar H<sub>2</sub>toward HD 37903

Gnaciński, P.

doi:10.1051/0004-6361/201014260

Cited by 17 publications

(28 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Gerin et al (2015) have used the 158 µm [C ii] absorption spectra observed by HIFI towards a few se- lected Galactic objects to derive the thermal pressure in the diffuse ISM. In the solar neighborhood (∼1 kpc) measurements of the thermal gas pressure have been made with C i UV absorption spectra towards a sample of about 89 selected target stars (Jenkins et al 1983;Jenkins & Tripp 2001, 2011 and CO UV absorption towards 76 stars (Goldsmith 2013).…”

mentioning

confidence: 99%

Thermal Pressure in Diffuse H₂ Gas Measured by Herschel Emission and FUSE UV H₂ Absorption

Velusamy

Langer

Goldsmith

et al. 2017

ApJ

View full text Add to dashboard Cite

UV absorption studies with the FUSE satellite have made important observations of H 2 molecular gas in Galactic interstellar translucent and diffuse clouds. Observations of the 158 µm [C ii] fine structure line with Herschel trace the same H 2 molecular gas in emission. We present [C ii] observations along 27 lines of sight (LOSs) towards target stars of which 25 have FUSE H 2 UV absorption. Two stars have only HST STIS C iiλ2325 absorption data. We detect [C ii] 158 µm emission features in all but one target LOS. For three target LOSs which are close to the Galactic plane, |b| < 1• , we also present position-velocity maps of [C ii] emission observed by Herschel HIFI in on-the-fly spectral line mapping. We use the velocity resolved [C ii] spectra observed by the HIFI instrument towards the target LOSs observed by FUSE to identify [C ii] velocity components associated with the H 2 clouds. We analyze the observed velocity integrated [C ii] spectral line intensities in terms of the densities and thermal pressures in the H 2 gas using the H 2 column densities and temperatures measured by the UV absorption data. We present the H 2 gas densities and thermal pressures for 26 target LOSs and from the [C ii] intensities derive a mean thermal pressure in the range of ∼ 6100 to 7700 K cm −3 in diffuse H 2 clouds. We discuss the thermal pressures and densities towards 14 targets, comparing them to results obtained using the UV absorption data for two other tracers C i and CO. Our results demonstrate the richness of the far-IR [C ii] spectral data which is a valuable complement to the UV H 2 absorption data for studying diffuse H 2 molecular clouds. While the UV absorption is restricted to the directions of the target star, far-IR [C ii] line emission offers an opportunity to employ velocity resolved spectral line mapping capability to study in detail the clouds' spatial and velocity structures.

show abstract

mentioning

confidence: 99%

Thermal Pressure in Diffuse H₂ Gas Measured by Herschel Emission and FUSE UV H₂ Absorption

Velusamy

Langer

Goldsmith

et al. 2017

ApJ

View full text Add to dashboard Cite

show abstract

“…The excellent agreement with the Boltzmann distribution confirms the correctness of the H 2 column densities. For the sightline towards HD 37903, the rotational temperatures fall with increased vibrational number ν (Gnaciński 2011). This behavior is not observed towards HD 147888.…”

Section: Ortho To Para H 2 and Temperaturesmentioning

confidence: 97%

“…The H 2 in the cloud towards HD 147888 does not satisfy this equation because 1.13 √ 0.15 = 0.39. Also the cloud toward HD 37903 (see Gnaciński 2011 for O/P H 2 values) does not satisfy the (O/P)* = √ (O/P) J=1 equation. One of the reasons for the discrepancy is that the bulk of H 2 * and H 2 (J = 0,1) are located in different parts of the cloud, so the column densities ratio of H 2 * and H 2 (J = 0,1) are not equal to the local density ratio.…”

Section: Ortho To Para H 2 and Temperaturesmentioning

confidence: 99%

See 1 more Smart Citation

Interstellar H2 toward HD 147888

Gnaciński

2012

A&A

Self Cite

View full text Add to dashboard Cite

The ultraviolet and far-ultraviolet spectra of HD 147888 allows the H 2 vibrational level ν = 0 to be accessed along with higher vibrational levels of the ground H 2 electronic level. The large number of H 2 absorption lines in the HST spectra allows column densities to be determined even from a noisy spectra. We have determined column densities of the H 2 molecule on vibrational levels ν = 0-5 and rotational levels J = 0-6 using the profile fitting method. No variations in the column densities of H 2 on vibrationally excited levels were observed from 2000 through 2009. The ortho to para H 2 ratio (O/P)* for the excited vibrational states ν = 1-4 equals to 1.13. For the lowest vibrational state ν = 0 and rotational level J = 1 the ortho to para H 2 ratio is only 0.15. The temperature of ortho-para thermodynamical equilibrium is T OP = 42 ± 3 K. The measurements of H 2 column densities on excited vibrational levels (from the HST spectra) leads to constraints on the radiation field in photon-dominated region (PDR) models of the interstellar cloud towards HD 147888. The Meudon PDR model locates the cloud 0.62 pc from the star. The modeled hydrogen cloud density (89-336 cm −3 ) agrees with independent density estimations based on the C 2 molecule and the chemical model. The observed (O/P) J = 1 and (O/P)* H 2 ratios cannot be explained by a simple model.

show abstract

“…(1) are appropriate for diatomic systems, but can be generalized for polyatomic ones. All the above processes drive the particle densities in fusion plasmas close to the walls and in the divertor region [5][6][7][8], in various media of astrophysical interest [9][10][11][12], in the hypersonic entry plasmas [13], and in many other environments of fundamental or technological relevance.…”

Section: Introductionmentioning

confidence: 99%

Advances in the MQDT approach of electron/molecular cation reactive collisions: High precision extensive calculations for applications

Motapon

Niyonzima

Chakrabarti

et al. 2015

EPJ Web of Conferences

View full text Add to dashboard Cite

Abstract. Recent advances in the stepwise multichannel quantum defect theory approach of electron/molecular cation reactive collisions have been applied to perform computations of cross sections and rate coefficients for dissociative recombination and electron-impact rovibrational transitions of H + 2 , BeH + and their deuterated isotopomers. At very low energy, rovibronic interactions play a significant role in the dynamics, whereas at high energy, the dissociative excitation strongly competes with all other reactive processes.a Corresponding author: Ioan.Schneider@univ-lehavre.fr This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

show abstract

Interstellar H₂toward HD 37903

Cited by 17 publications

References 13 publications

Thermal Pressure in Diffuse H₂ Gas Measured by Herschel Emission and FUSE UV H₂ Absorption

Thermal Pressure in Diffuse H₂ Gas Measured by Herschel Emission and FUSE UV H₂ Absorption

Interstellar H2 toward HD 147888

Advances in the MQDT approach of electron/molecular cation reactive collisions: High precision extensive calculations for applications

Contact Info

Product

Resources

About

Interstellar H2toward HD 37903

Cited by 17 publications

References 13 publications

Thermal Pressure in Diffuse H2 Gas Measured by Herschel Emission and FUSE UV H2 Absorption

Thermal Pressure in Diffuse H2 Gas Measured by Herschel Emission and FUSE UV H2 Absorption

Interstellar H2 toward HD 147888

Advances in the MQDT approach of electron/molecular cation reactive collisions: High precision extensive calculations for applications

Contact Info

Product

Resources

About

Interstellar H₂toward HD 37903

Thermal Pressure in Diffuse H₂ Gas Measured by Herschel Emission and FUSE UV H₂ Absorption

Thermal Pressure in Diffuse H₂ Gas Measured by Herschel Emission and FUSE UV H₂ Absorption