http://prints.iiap.res.in The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Search the Channel search http://prints.iiap.res.in/simple-search http://hdl.handle.net/2248/5079 Title: Advances in spectral classification<br/><br/>Authors: Giridhar, S<br/><br/>Abstract: In this article we give an overview of the developments in the field of spectralclassification, its continued importance in the fields of stellar and galactic evolution. The extension of MK system to cool stars as well as refined classificationof the hot stars using the new data obtained from modern ground based facilities and space missions has been described. A brief summary of automated methods of spectral classifications developed for the quick and objective classification of the ongoing and future surveys is presented. A new spectral class encoding system developed for exploitation of databases is described. Recent large scale spectral classification catalogues are listed. Wed, 17 Mar 2010 22:58:59 GMT http://hdl.handle.net/2248/5078 Title: Chemical composition of A–F type post-AGB candidates<br/><br/>Authors: Giridhar, S; Molina, R; Arellano Ferro, A; Selvakumar, G<br/><br/>Abstract: An abundance analysis has been conducted for a sample of nine post-AGB candidate stars; eight of them have not been explored before.We find four very promising objectslike HD 105262, HD 53300 and CpD−62o5428 among them. We find strong evidenceof dust-gas separation through selective depletion of refractive elements in HD 105262. The same effect is also observed in HD 53300, CpD−62o5428 and HD 114855 althoughabundance peculiarities are relatively smaller for the last two stars. We find strong enrichment of nitrogen for HD 725, HD 842, HD 1457, HD 9233 and HD 61227 but nofurther evidence to support their post-AGB nature. We have compared the observed [N/C] ratios of these stars with the predictions of evolutionary models which include the rotation induced mixing. Fri, 26 Feb 2010 22:58:59 GMT http://hdl.handle.net/2248/5077 Title: Study of the continuous solar spectrum in the visible rouge<br/><br/>Authors: Ramanathan, A. S<br/><br/>Abstract: Limb darkening observations made under excellent observing conditions are given for twenty-two wavelengths in the continuous spectrum of the sun in the region λ 3600-λ 6800; these observations were made at a time when the disc was completely free from spots and also other forms of solar activity were at a minimum. It is verified that for the visible region between λ 4000 and λ 6000 the variation of continuous absorption coefficient with wavelength agrees with the theoretical values given by CHANDRASEKHAR and BREEN for the H-ion. However beyond 6000 Å divergence between theory and observation begins to appear, Variation of optical depth with temperature for λ 5000 is deduced from observations.<br/><br/>Description: Open Access Tue, 29 Dec 1953 22:58:59 GMT http://hdl.handle.net/2248/5076 Title: Geomagnetic field variations at Kodaikanal<br/><br/>Authors: Sivaramakrishnan, M. V<br/><br/>Description: Restricted Access Wed, 27 Feb 1952 22:58:59 GMT