1. Home
    2. Journals
    3. Journal of Astrophysics and Astronomy
    4. Volume 42
    5. All articles

    • Fulltext

       

        Click here to view fulltext PDF


      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/042/0047

    • Keywords

       

      Galaxy: open clusters: individual: NGC 188; stars: horizontal-branch; stars: blue stragglers; stars: Hertzsprung–Russell and colour-magnitude diagrams.

    • Abstract

       

      We present the UV photometry of the old open cluster NGC188 obtained using images acquired with Ultraviolet Imaging Telescope (UVIT) on board the AstroSat satellite, in two far-UV (FUV) and one near-UV (NUV) filters. UVIT data is utilised in combination with optical photometric data to construct the optical and UV colour-magnitude diagrams (CMDs). In the FUV images, we detect only hot and bright blue straggler stars (BSSs), one hot subdwarf, and one white dwarf (WD) candidate. In the NUV images, we detect members up to a faintness limit of $\sim$22 mag including 21 BSSs, 2 yellow straggler stars (YSSs), and one WD candidate. This study presents the first NUV-optical CMDs, and are overlaid with updated BaSTIIAC isochrones and WD cooling sequence, which are found to fit well to the observed CMDs. We use spectral energy distribution (SED) fitting to estimate the effective temperatures, radii, and luminosities of the UV-bright stars. We find the cluster to have an HB population with three stars ($T_{\rm eff}=4750–21000$ K). We also detect two yellow straggler stars, with one of them with UV excess connected to its binarity and X-ray emission.

    • Author Affiliations

       

      SHARMILA RANI1 2 ANNAPURNI SUBRAMANIAM1 SINDHU PANDEY3 SNEHALATA SAHU1 CHAYAN MONDAL1 GAJENDRA PANDEY1

      1. Indian Institute of Astrophysics, Koramangala II Block, Bengaluru 560 034, India.
      2. Pondicherry University, R.V. Nagar, Kalapet 605 014, India.
      3. Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital 263 001, India.

    • Dates

       
      Published
      15 June 2021
      Manuscript received
      7 November 2020
      Accepted
      30 November 2020
      Final version published online
      15 June 2021

  • Journal of Astrophysics and Astronomy | News

    • 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

      Click here for Editorial Note on CAP Mode

© 2021-2022 Indian Academy of Sciences, Bengaluru.

Contact | Site index