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A comprehensive investigation of the variable overcontact system EH Cancri

Nelson, Robert H.; Alton, Kevin B.; StÈ©pień, Kazimierz

Precise multi-color CCD-derived photometric data were obtained from EH Cnc at two sites during 2010, 2014 and 2018 wherein each epoch used a different instrument. This has provided a unique opportunity to investigate parameter uncertainty following Roche modeling of light curves optimized by differential corrections using the Wilson–Devinney code.…

Vilnius photometry and Gaia astrometry of Melotte 105

Bilir, Selçuk; Yontan, Talar; Canbay, Remziye +1 more

Archival Vilnius CCD photometric observations are presented for the heavily reddened star cluster Melotte 105, resulting in colour-magnitude diagrams and spectral class estimates. There is considerable lack of agreement between studies for reddening, age and distance for this cluster explaining why the archival data are being made available by thi…

Quasar catalogue for the astrometric calibration of the forthcoming ILMT survey

Mathew, Blesson; Stalin, C. S.; Surdej, Jean +3 more

Quasars are ideal targets to use for astrometric calibration of large scale astronomical surveys as they have negligible proper motion and parallax. The forthcoming 4-m International Liquid Mirror Telescope (ILMT) will survey the sky that covers a width of about 27'

A search for variable stars in the four open star clusters

Bisht, D.; Rangwal, Geeta; Yadav, R. K. S. +3 more

We present a CCD photometric survey for the search of variable stars in four open clusters namely Berkeley 69, King 5, King 7 and Berkeley 20. The time series observations were carried out for 1 and/or 2 nights for each of the clusters in the year 1998, which have led to identify nineteen variable stars in these clusters. Out of these 19 variable …

[Rb/Zr] ratio in Ba stars as a diagnostic of the companion AGB stellar mass

Shejeelammal, J.; Goswami, Aruna

Understanding nucleosynthesis in and evolution of asymptotic giant branch (AGB) stars is of primary importance as these stars are the main producers of some of the key elements in the Universe. They are the predominant sites for slow-neutron-capture nucleosynthesis (s-process). The exact physical conditions and nucleosynthetic processes occurring …