Abnormal reversal of V/R ratio of Hα line in the shell star HD 142983

Abstract

In this communication we report the spectroscopic observations of Hα line profiles of HD 142983. The star showed very interesting behavior at Hα line. The Hα line was found to be strongly in emission displaying two emission peaks. The V emission component of the line was found to be much stronger than the R emission component.We have also collected other available data on Hα line from the literature to explore the variation of this line. Our data combined with others exhibited very interesting behavior. During the year 2001 the V component was smaller than the R component (i.e. V/R<1); during 2003 the V and R components became almost equal (i.e. V/R~1) and during 2004 the V component became larger than the R component (i.e. V/R>1). Our present investigation shows that during the period 2001-2007, this star underwent an abnormal reversal of V/R ratio. From the line profiles we have measured the important parameters like: equivalent width (W), Ip/Ic ratio and V/R ratio.