SUB-PARSEC STRUCTURE OF INTERSTELLAR H<sub>2</sub>CO CLOUDS

Dieter-Conklin, Nan

doi:10.1088/0004-6256/140/2/628

Cited by 1 publication

(1 citation statement)

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“…Now, more than 40 years of observations have shown that the 6 cm H 2 CO line can trace large (> 5pc) molecular clouds (e.g., Araya et al 2007). Such large structures are not homogeneous, for example, Dieter-Conklin (2010) concluded that molecular clouds traced by H 2 CO absorption show different velocity dispersion when observed at effective resolutions greater or smaller than ∼ 0.5 pc, which gives direct evidence for sub-parsec structure traced by H 2 CO.…”

Section: Introductionmentioning

confidence: 99%

Study of Interstellar Molecular Clouds Using Formaldehyde Absorption Toward Extragalactic Radio Sources

Araya

Dieter-Conklin

Goss

et al. 2014

ApJ

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We present new Very Large Array 6 cm H 2 CO observations toward four extragalactic radio continuum sources (B0212+735, 3C 111, NRAO 150, BL Lac) to explore the structure of foreground Galactic clouds as revealed by absorption variability. This project adds a new epoch in the monitoring observations of the sources reported by Marscher and collaborators in the mid 1990's. Our new observations confirm the monotonic increase in H 2 CO absorption strength toward NRAO 150. We do not detect significant variability of our 2009 spectra with respect to the 1994 spectra of 3C111, B0212+735 and BL Lac; however we find significant variability of the 3C111 2009 spectrum with respect to archive observations conducted in 1991 and 1992. Our analysis supports that changes in absorption lines could be caused by chemical and/or geometrical gradients in the foreground clouds, and not necessarily by small scale (∼ 10 AU) high density molecular clumps within the clouds.

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Section: Introductionmentioning

confidence: 99%