HI 21 cm - line observations with the GMRT towards interstellar clouds previously seen in optical absorption
نویسنده
چکیده
We have made HI 21cm-line absorption measurements using the GMRT towards 15 directions in the Galaxy which are known to have high random velocity clouds as seen in the optical absorption lines of CaII and NaI. For the first time, in 6 out of these 15 directions we detect HI absorption features corresponding to the high random velocity optical absorption lines. The mean optical depth of these detections is ∼ 0.08.
منابع مشابه
Kinematics of Di ff use Interstellar Clouds : Recent GMRT Results
A high latitude HI 21 cm-line absorption survey toward extragalactic sources was recently completed using the Giant Meterwave Radio Telescope (GMRT). A total of 104 sources with | b |> 15 o and with a 21 cm flux density greater than 1 Jy were observed for ∼ 120 hours. With an optical depth detection limit of ∼ 0.01 this is the most sensitive high-latitude survey as yet. Most of the detected HI ...
متن کاملGMRT detection of HI 21 cm associated absorption towards the z = 1 . 2 red quasar 3 C 190
We report the GMRT detection of associated HI 21 cm-line absorption in the z=1.1946 red quasar 3C 190. Most of the absorption is blue-shifted with respect to the systemic redshift. The absorption, at ∼ 647.7 MHz, is broad and complex, spanning a velocity width of ∼ 600 kms. Since the core is self-absorbed at this frequency, the absorption is most likely towards the hotspots. Comparison of the r...
متن کاملThe interstellar clouds of Adams and Blaauw revisited : an HI absorption study - I
This investigation is aimed at clarifying the nature of the interstellar gas seen in absorption against bright O and B stars. Towards this end we have obtained for the first time HI absorption spectra towards radio sources very close to the lines of sight towards 25 bright stars previously studied. In this paper we describe the selection criteria, the details regarding our observations, and fin...
متن کاملDetection of a multi - phase ISM at z = 0 . 2212
We present sensitive Giant Metrewave Radio Telescope (GMRT) and high-resolution Arecibo HI 21-cm observations of the damped Lyman-α absorber (DLA) at z = 0.2212 towards OI 363 (B2 0738+313). The GMRT and Arecibo spectra are in excellent agreement and yield a spin temperature Ts = 890 ± 160 K, consistent with earlier lower sensitivity observations of the system. This value of Ts is far higher th...
متن کاملGMRT and VLA observations of H and OH from the Seyfert galaxy Mrk 1
We present Giant Meterwave Radio Telescope (GMRT) observations of the H 21 cm line and Very Large Array (VLA) observations of the OH 18 cm line from the Seyfert 2 galaxy Mrk 1. H emission is detected from both Mrk 1 and its companion NGC 451. The H emission morphology and the velocity field of Mrk 1 are disturbed. We speculate that the nuclear activities of Mrk 1 are triggered by tidal in...
متن کامل