Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Faculty Publications Article Faculty Publications -Articles Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Creator An entity primarily responsible for making the resource Bhattacherjee, Sree; Misra, Ranjeev; Sarkar, Biplob; Jithesh, V.; Roy, Jayashree; Bhulla, Yashpal Title A name given to the resource Spectral Evolution of GX 17+2 Using AstroSat and NICER Observations Date A point or period of time associated with an event in the lifecycle of the resource 01-01-2025 Source A related resource from which the described resource is derived Astrophysical Journal;Volume;989;Issue;1;Article No.;23; Identifier An unambiguous reference to the resource within a given context <a href="https://doi.org/10.3847/1538-4357/ade9ad" target="_blank" rel="noreferrer noopener">https://doi.org/10.3847/1538-4357/ade9ad</a> <br /><br /><a href="https://www.scopus.com/pages/publications/105012271188?origin=resultslist" target="_blank" rel="noreferrer noopener">https://www.scopus.com/pages/publications/105012271188?origin=resultslist</a> Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Bhattacherjee S., Department of Applied Sciences, Tezpur University, Assam, Napaam, 784028, India; Misra R., Inter-University Center for Astronomy and Astrophysics, Ganeshkhind, Pune, 411007, India; Sarkar B., Department of Applied Sciences, Tezpur University, Assam, Napaam, 784028, India; Jithesh V., Department of Physics and Electronics, Christ University, Hosur Main Road, Bengaluru, 560029, India; Roy J., Inter-University Center for Astronomy and Astrophysics, Ganeshkhind, Pune, 411007, India; Bhulla Y., Pacific Academy of Higher Education and Research University, Udaipur, 313003, India Description An account of the resource We study the spectral evolution of the Z-track source GX 17+2 using AstroSat and NICER observations taken between 2016 and 2020. The AstroSat observations cover the period when the source is in the normal branch (NB) and the flaring branch (FB), while for the NICER ones the variability can be associated with the FB branch. The source spectra at different regions of the branches are well described by accretion disk emission, blackbody surface emission, and a thermal Comptonization component. In the NB, the total bolometric unabsorbed flux remains constant and the variation is due to changes in the Comptonization, disk fluxes. In particular, the inferred luminosity (LT) and accretion rate ( M ? ) remain constant, while there is significant variation in the inner disk radii and fraction of disk photons entering the corona, indicating changes in the geometry of the system. On the other hand, in the FB, there is significant variation in luminosity from ?4.0 to ?7.0 1038 erg s?1. Despite this significant variation in luminosity and in the inner disk radii, the accretion efficiency, defined as ? = L T / M ? c 2 , remains nearly constant at ?0.20 throughout the evolution of the source, as expected for a neutron star system. 2025. The Author(s). Published by the American Astronomical Society. Publisher An entity responsible for making the resource available Institute of Physics Relation A related resource ISSN: 0004637X; Language A language of the resource English Type The nature or genre of the resource Article Rights Information about rights held in and over the resource All Open Access; Gold Open Access; Green Open Access Format The file format, physical medium, or dimensions of the resource online