Detection of anhydrous hydrochloric acid, HCl, in IRC+10216 with the Herschel SPIRE and PACS spectrometers

Astronomy and Astrophysics (Impact Factor: 4.38). 05/2010; 518(4). DOI: 10.1051/0004-6361/201014553
Source: arXiv


We report on the detection of anhydrous hydrochloric acid (hydrogen chlorine,
HCl) in the carbon-rich star IRC+10216 using the spectroscopic facilities
onboard the Herschel satellite. Lines from J=1-0 up to J=7-6 have been
detected. From the observed intensities, we conclude that HCl is produced in
the innermost layers of the circumstellar envelope with an abundance relative
to H2 of 5x10^-8 and extends until the molecules reach its photodissociation
zone. Upper limits to the column densities of AlH, MgH, CaH, CuH, KH, NaH, FeH,
and other diatomic hydrides have also been obtained.

Download full-text


Available from: M. A. T. Groenewegen
    • "For this reason, they proposed HF as an excellent molecular hydrogen tracer that provides a sensitive probe of clouds retaining a small H 2 column density. Another study of the carbonrich star IRC+10216 with the Herschel SPIRE and PACS spectrometers by Cernicharo et al. [13] has quantified the abundance of HCl using the rotational lines from J ¼1←0 up to J ¼7←6 of HCl. They found that HCl is produced in the innermost layers of the circumstellar envelope and it has an abundance of eight orders of magnitude larger than molecular hydrogen, H 2 . "
    [Show abstract] [Hide abstract]
    ABSTRACT: Accurate spectroscopic parameters for the hydrogen halides, namely HF, HCl, HBr, and HI, together with their deuterated isotopologues, are crucial for the quantitative study of terrestrial and planetary atmospheres, astrophysical objects, and chemical lasers. A thorough evaluation of all the hydrogen halide line parameters in previous HITRAN editions has been carried out. A new set of line lists was generated for the HITRAN2012 edition using methods described here. In total, 131,798 entries were generated for numerous pure-rotational and ro-vibrational transitions (fundamental, overtone, and hot bands) for hydrogen halides and their deuterated species in a standard HITRAN 160-character format. Data for the deuterated isotopologues have been entered into HITRAN for the first time. The calculations employ the recently developed semi-empirical dipole moment functions [Li G, et al. J Quant Spectrosc Radiat Transfer 2013;121:78–90] and very accurate analytical potential energy functions and associated functions characterizing Born–Oppenheimer breakdown effects. Line-shape parameters have also been updated using the most recent available experimental and theoretical studies. Comparison with the previous HITRAN compilation has shown significant improvements.
    No preview · Article · Nov 2013 · Journal of Quantitative Spectroscopy and Radiative Transfer
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The interstellar medium is enriched primarily by matter ejected from evolved low and intermediate mass stars. The outflows from these stars create a circumstellar envelope in which a rich gas-phase and dust-nucleation chemistry takes place. We observed the nearest carbon-rich evolved star, IRC+10216, using the PACS (55-210 {\mu}m) and SPIRE (194-672 {\mu}m) spectrometers on board Herschel. We find several tens of lines from SiS and SiO, including lines from the v=1 vibrational level. For SiS these transitions range up to J=124-123, corresponding to energies around 6700K, while the highest detectable transition is J=90-89 for SiO, which corresponds to an energy around 8400K. Both species trace the dust formation zone of IRC+10216, and the broad energy ranges involved in their detected transitions permit us to derive the physical properties of the gas and the particular zone in which each species has been formed. This allows us to check the accuracy of chemical thermodynamical equilibrium models and the suggested depletion of SiS and SiO due to accretion onto dust grains. Comment: 5 pages, 3 figures, 7 pages in online appendix, Astronomy & Astrophysics in press
    Full-text · Article · May 2010 · Astronomy and Astrophysics
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report on the detection with the HIFI instrument on board the Herschel satellite of the two hydrogen chloride isotopologues, H35Cl and H37Cl, towards the massive star-forming region W3 A. The J = 1-0 line of both species was observed with receiver 1b of the HIFI instrument at ~625.9 and ~624.9 GHz. The different hyperfine components were resolved. The observations were modeled with a non-local, non-LTE radiative transfer model that includes hyperfine line overlap and radiative pumping by dust. Both effects are found to play an important role in the emerging intensity from the different hyperfine components. The inferred H35Cl column density (a few times ~1014 cm-2), and fractional abundance relative to H nuclei (~7.5 × 10-10), supports an upper limit to the gas phase chlorine depletion of ≈200. Our best-fit model estimate of the H35Cl/H37Cl abundance ratio is ≈ 2.1 ± 0.5, slightly lower, but still compatible with the solar isotopic abundance ratio (≈3.1). Since both species were observed simultaneously, this is the first accurate estimation of the [35Cl] /[37Cl] isotopic ratio in molecular clouds. Our models indicate that even for large line opacities and possible hyperfine intensity anomalies, the H35Cl and H37Cl J = 1-0 integrated line-intensity ratio provides a good estimate of the 35Cl/37Cl isotopic abundance ratio. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important particiation from NASA.
    Full-text · Article · Jul 2010 · Astronomy and Astrophysics
Show more