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  • Astronomy  (1)
  • submillimeter  (1)
  • variability  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    A Search for Variability in the HCCN to H2CO Ratio in Comet Hale-Bopp (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 53-61 
    Details
    ISSN: 1573-0794
    Keywords: Comet ; HCN ; H2CO ; variability ; submillimeter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We observed submillimeter lines of H2CO and HCN in comet Hale-Bopp near perihelion. One of our goals was to search for short term variability. Our observations are suggestive, but not conclusive, of temporal and/or spatial changes in the coma's HCN/H2CO abundance ratio of ∼25%. If due to spatial variability, the ratio on the sunward side of the coma is enhanced over other regions. If due to temporal variability, we find the bulk ratio in the coma changed in less than 16 hours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006211025695
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    Paper (German National Licenses)
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  • 2
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    SOFIA Observations of S106: Dynamics of the Warm Gas (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Context The H II region/PDR/molecular cloud complex S106 is excited by a single O-star. The full extent of the warm and dense gas close to the star has not been mapped in spectrally resolved high-J CO or [C II] lines, so the kinematics of the warm. partially ionized gas, are unknown. Whether the prominent dark lane bisecting the hourglass-shaped nebula is due solely to the shadow cast by a small disk around the exciting star or also to extinction in high column foreground gas was an open question until now. Aims. To disentangle the morphology and kinematics of warm neutral and ionized gas close to the star, study their relation to the bulk of the molecular gas. and to investigate the nature of the dark lane. Methods. We use the heterodyne receiver GREAT on board SOFIA to observe velocity resolved spectral lines of [C II] and CO 11 yields 10 in comparison with so far unpublished submm continuum data at 350 micron (8HARC-Il) and complementary molecular line data. Results. The high angular and spectral resolution observations show a very complex morphology and kinematics of the inner S106 region, with many different components at different excitation conditions contributing to the observed emission. The [C II] lines are found to be bright and very broad. tracing high velocity gas close to the interface of molecular cloud and H II region. CO 11 yields 10 emission is more confined.. both spatially and in velocity, to the immediate surroundings of S 106 IR showing the presence of warm, high density (clumpy) gas. Our high angular resolution submm continuum observations rule out the scenario where the dark lane separating the two lobes is due solely to the shadow cast by a small disk close to the star. The lane is clearly seen also as warm, high column density gas at the boundary of the molecular cloud and H II region.
    Keywords: Astronomy
    Type: GSFC.JA.01135.2012 , GSFC.ABS.6371.2012
    Format: application/pdf
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