C. MUTHUMARIAPPAN
Articles written in Journal of Astrophysics and Astronomy
Volume 31 Issue 1 March 2010 pp 17-29
Three-Component Dust Models for Interstellar Extinction
Interstellar extinction curves obtained from the ‘extinction without standard’ method were used to constrain the dust characteristics in the mean ISM (𝑅V = 3.1), along the lines of sight through a high latitude diffuse molecular cloud towards HD 210121 (𝑅V = 2.1) and in a dense interstellar environment towards the cluster NGC 1977 (𝑅V = 6.42). We have used three-component dust models comprising silicate, graphite and very small carbonaceous grains (polycyclic aromatic hydrocarbons) following the grain size distributions introduced by Li & Draine in 2001. It is shown that oxygen, carbon and silicon abundances derived from our models are closer with the available elemental abundances for the dust grains in the ISM if F & G type stars atmospheric abundances are taken for the ISM than the solar. The importance of very small grains in modelling the variation of interstellar extinction curves has been investigated. Grain size distributions and elemental abundances locked up in dust are studied and compared at different interstellar environments using these three extinction curves. We present the albedo and the scattering asymmetry parameter evaluated from optical to extreme-UV wavelengths for the proposed dust models.
Volume 43 All articles Published: 31 May 2022 Article ID 0032 OBSERVATIONAL FACILITIES
A 10-m class national large optical-IR telescope
G. C. ANUPAMA G. MAHESWAR S. SRIRAM T. SIVARANI P. S. PARIHAR S. NAGABHUSHAN DORJE ANGCHUK S. BARWAY B. C. BHATT R. BANYAL ALIKHAN BASHEER PRASANNA DESHMUKH DEVIKA DIVAKAR TSEWANG DORJAI ARUNA GOSWAMI K. V. GOVINDA SONAM JORPHAIL U. S. KAMATH MADAN MOHAN KEMKAR TASHI TSERING MAHAY S. MUNEER C. MUTHUMARIAPPAN SHANTIKUMAR SINGH NINGOMBAM G. PANDEY B. E. REDDY D. K. SAHU D. S. SANDEEP RAMYA SETHURAM C. S. STALIN S. SUBRAMANIAN STANZIN TSEWANG A. SUBRAMANIAM
An observatory class national large optical-IR telescope (NLOT), is proposed to be built and located in the country. The telescope consists of a 10–12 m segmented primary. In order to cater to a diversity of observational programs, the telescope is designed with high throughput in both the optical and IRregions (0.3–5 $\mu$m). It should perform reasonably well up to 30 $\mu$m. The telescope and instruments should have remote operations capability, allowing for the queue as well as classical scheduling and high reliability and robustness. This article provides a brief description of the science cases that drive the telescope requirements, activities related to optics design and some thoughts on the instruments.
Volume 44, 2023
All articles
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