The intriguing giant bow shocks near HH 131

• Published in: arXiv.org 2005-08
• Main Authors: wang, Min, Noumaru, Junichi, Wang, Hongchi, Yang, Ji, Chen, Jiansheng
• Format: Article
• Language: English
• Subjects: Astronomical observatories; Diagnostic systems; Emission analysis; Herbig-Haro objects; Molecular clouds; Object recognition; Observatories; Radial velocity; Reflecting telescopes; Spectra; Velocity
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.0508203

Using the High Dispersion Spectrograph at the Subaru Telescope, echelle spectra of two giant arcs, i.e. nebulosities Cw and L associated with HH 131 in Orion are presented. Typical emission lines of Herbig-Haro objects have been detected towards Cw. With the 2.16 m telescope of National Astronomical Observatories, spectra of Nebu. C, L and K are obtained, which also show strong [SII]6717/6731, H\(\alpha\) and [NII]6583 emission lines. Position-velocity distributions of Cw and L are analyzed. The fastest radial velocity of Cw is V_r ~ -18.0 km/s. When the flow at L goes to the south, it slows down. The fastest radial velocity of L has been observed of -45.0 km/s and the slowest value is about -18.3 km/s. The similarity of the velocities and their positional connection indicate that Cw and L are physically associated. The entire flow tends to become less excited and less ionized when going further to the south (i.e., from Nebu. K, L to C). The electron densities of all the observed nebulosities are low (n_e ~ 10^2 cm^-3). Double kinematic signatures have been found in Cw from its [NII]6583 profiles while the observed H\(\alpha\) profiles of Cw are almost symmetric. Bow shock models appear to agree with the observed position-velocity diagrams of the [NII spectra better than H\(\alpha\) spectra. With the suggestion that these arcs are HH shocks possibly ejected out of the Orion A molecular cloud by an uncertain source, their spectra show low to intermediate excitation from their diagnostic line ratios.