• B. S. Shylaja

Articles written in Journal of Astrophysics and Astronomy

• Spectrophotometric studies of CQ Cephei

Spectrophotometric and spectroscopic observations of CQ Cep — the shortest-period binary with WN component — are presented. Excepting the NV λ4603, the fluxes of all other emission lines show enhancement at minima. They can be explained by the Roche surfaces that take into account the strong wind of the WN7 component. Various radial velocity curves for emission and absorption give different orbital solutions with a general positive shift of λ axes. Although N IV λ4058 represents the true motion of the WN7 component, its flux variations are influenced by geometric effects. There is no signature of the companion. The extent of the atmosphere of CQ Cephei appears larger than in V444Cyg, another eclipsing binary with a Wolf-Rayet component.

• A spectrophotometric study of the Wolf-Rayet star HD 50896

New spectrophotometric observations of the Wolf-Rayet system HD 50896 are presented and interpreted in terms of its binary nature. The lines of N V, N IV and C IV show moderate variations, which can be explained using a binary model with a compact companion. He n λ4686 appears to arise from a larger region compared to other lines. The distortion caused by the wind can partly explain its flux variations. The emission fluxes of He I lines are generally constant indicating their non-participation in the orbit. The results are compared with other Wolf-Rayet binaries (V444 Cyg and CQ Cep) and the evolutionary status is discussed.

• The He II line λ4686 in WN binaries

The behaviour of the λ4686 line of He II in various WN binaries is studied for variations in total flux as well as radial velocities. It appears that the true motion of the WN component is not depicted by this line especially for short-period binaries. A qualitative explanation is sought in terms of a large, extended line-emitting region and multiple-component line profile.

• Study of the Wolf-Rayet members of the cluster NGC 6231

Two Wolf-Rayet members of the cluster NGC 6231 are studied spectrophotometrically. HD 151932, a suspected variable, shows variations in the emission line flux as well as continuum magnitude measurements. An attempt is made to understand this variation as due to the asymmetric atmospheric structure. The other, HD 152270, a (WC7 + O) binary, shows variation of emission line flux for C III and C IV lines only. This variation is studied as a possible phenomenon of atmospheric eclipses.

• $\bar{A}$pa and Ap$\bar{a}$mvatsa – enigmatic stars catalogued in $S\bar{u}ryasiddh\bar{a}nta$

Indian $siddh\bar{a}ntic$ texts are well known for their indigenous approach to solutions of problems in astronomy which also speaks of their expertise in mathematics. The text $S\bar{u}ryasiddh\bar{a}nta$ is considered as an authority and we come across a number of texts as commentaries on this text. They range from 8th Century CE to 19th century CE. The study of the stars that have been listed in the text appears relatively easy for the 27 stars of the zodiac. However, there are other stars for which optical identifications are not easy. Here we present possible identifications for two stars called $\bar{A}pa$ and $Ap\bar{a}mvatsa$, in the constellation of Virgo. We use the NASA Skyview Survey and other catalogues to see if these two correspond to variablestars.

• # Journal of Astrophysics and Astronomy

Current Issue
Volume 40 | Issue 6
December 2019

• # Continuous Article Publication

Posted on January 27, 2016

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.

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019