Abstract
The structure of our Galaxy has been studied from ultraviolet (UV) star counts obtained with the Ultra-Violet Imaging Telescope (UVIT) on board the AstroSat satellite, in Far-UV (FUV) and Near-UV (NUV) bands. The F154W (BaF2) and N263M (NUVB4) filters were used in the FUV and NUV bands, respectively. The point sources are separated from the extra-galactic sources of UVIT observations using infrared (IR) color cut method. The observed UVIT star counts match well with the simulations obtained from the Besançon model of stellar population synthesis towards several Galactic directions. We also estimated the scale length and scale height of the thick disc and the scale height of the thin disc using the space density function and the exponential density law for the stars of intermediate galactic latitudes. The scale length of the thick disc ranges from 3.11 to 5.40 kpc whereas the scale height ranges from \(530\pm 32\) pc to \(630\pm 29\) pc. The scale height of the thin disc comes out to be in the range of \(230\pm 20\) pc to \(330\pm 11\) pc.
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Acknowledgements
We would like to thank the referee for giving useful suggestions to improve the manuscript. We would like to thank Dr. A. C. Robin for letting us use their model of stellar population synthesis and for giving her useful inputs on the Besançon model. RK would like to acknowledge CSIR Research Fellowship (JRF) Grant No. 09/983(0034)/2019-EMR-1 for the financial support. ACP would like to acknowledge the support by Indian Space Research Organization, Department of Space, Government of India (ISRO RESPOND project No. ISRO/RES/2/409/17-18). ACP also thanks Inter University centre for Astronomy and Astrophysics (IUCAA), Pune, India for providing facilities to carry out his work. DKO and SKG acknowledge the support of the Department of Atomic Energy, Government of India, under Project Identification No. RTI 4002. TB acknowledges the support from the National Key Research and Development Program of China (2017YFA0402702, 2019YFA0405100). This publication uses the data from the AstroSat mission of the Indian Space Research Organisation (ISRO), archived at the Indian Space Science Data Center (ISSDC). The UVIT data used here was processed by the Payload Operations Centre at IIA. The UVIT is built in collaboration between IIA, IUCAA, TIFR, ISRO and CSA.
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This article is part of the Special Issue on “AstroSat: Five Years in Orbit”.
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Kumar, R., Pradhan, A.C., Ojha, D.K. et al. Study of Galactic structure using UVIT/AstroSat star counts. J Astrophys Astron 42, 42 (2021). https://doi.org/10.1007/s12036-020-09684-1
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DOI: https://doi.org/10.1007/s12036-020-09684-1