J. N. Chengalur
Articles written in Journal of Astrophysics and Astronomy
Volume 23 Issue 1-2 March 2002 pp 165-171
Tracking the shadows through GMRT
D. Narasimha N. Kanekar J. N. Chengalur
The structures of faint high redshift galaxies cannot be observed directly. But if a luminous quasar is located farther along their line of sight, high resolution absorption lines offer a valuable and reliable probe to their structure. GMRT is suited to monitor the absorption spectra, if the redshifted neutral hydrogen or OH doublet fall in one of the windows of the telescope. We present the OH doublet absorption spectra for the system B0218+357, taken at GMRT this year at resolution of approx. 9.5 km/sec with an rms noise of the order of 1 mJy. Based on our study of the OH doublet and 21cm neutral hydrogen line we infer that, in the lensing spiral galaxy of B0218 + 357, neutral hydrogen and OH coexist in tenous clouds and there is possibly a hole in the central part of the galaxy. In contrast, the gas is seen in high density clouds in the lens in an otherwise similar system PKS1830-211.
Volume 32 Issue 4 December 2011 pp 451-455
The Central Point Source in G76.9+1.0
V. R. Marthi J. N. Chengalur Y. Gupta G. C. Dewangan D. Bhattacharya
We describe the serendipitous discovery of a very steep-spectrum radio point source in low-frequency Giant Metrewave Radio Telescope (GMRT) images of the supernova remnant (SNR) G76.9+1.0. The steep spectrum, as well as the location of the point source near the centre of this SNR confirm that this indeed is the pulsar J2022+3842. Archival
Volume 38 Issue 1 March 2017 Article ID 0016 Review Article
Space Weather and Solar Wind Studies with OWFA
P. K. Manoharan C. R. Subrahmanya J. N. Chengalur
In this paper, we review the results of interplanetary scintillation (IPS) observations made with the legacy system of the Ooty Radio Telescope (ORT) and compare them with the possibilities opened by the upgraded ORT, the Ooty Wide Field Array (OWFA). The stability and the sensitivity of the legacy system of ORT allowed the regular monitoring of IPS on a grid of large number of radio sources and the results of these studies have been useful to understand the physical processes in the heliosphere and space weather events, such as coronal mass ejections, interaction regions and their propagation effects. In the case of OWFA, its wide bandwidth of 38 MHz, the large field-of-view of $\sim$27$^\circ$ and increased sensitivity provide a unique capability for the heliospheric science at 326.5 MHz. IPS observations with the OWFA would allow one to monitor more than 5000 sources per day. This, in turn, will lead to much improved studies of space weather events and solar wind plasma, overcoming the limitations faced with the legacy system. We also highlight some of the specific aspects of the OWFA, potentially relevant for the studies of coronal plasma and its turbulence characteristics.
Volume 44, 2023
Continuous Article Publishing mode
Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.
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