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    • Fulltext

       

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      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/042/0089

    • Keywords

       

      Open star clusters (1160); blue straggler stars (168); extreme horizontal branch stars (513); B subdwarf stars (129); ultraviolet astronomy (1736); spectral energy distribution (2129); binary stars (154).

    • Abstract

       

      King 2, one of the oldest clusters in the Milky Way, with an age of $\sim$6 Gyr and distance of $\sim$5700 pc, has been observed with UVIT payload on the AstroSat. With membership information derived from Gaia EDR3, the cluster is found to have 39 blue straggler stars (BSSs). We created multi-wavelength spectra-energy distributions (SED) of all the BSSs. Out of 10 UV detected BSSs, 6 bright ones were fitted with double component SEDs and were found to have hotter companions with properties similar to extreme horizontal branch (EHB)/subdwarf B (sdB) stars, with a range in luminosity and temperature, suggesting a diversity among the hot companions. We suggest that at least 15% of BSSs in this cluster are formed via mass-transfer pathway. When we compared their properties to EHBs and hotter companions to BSS in open and globular clusters, we suggest that EHB/sdBs like companions can form in binaries of open clusters as young as 6 Gyr.

    • Author Affiliations

       

      VIKRANT V. JADHAV1 2 SINDHU PANDEY3 ANNAPURNI SUBRAMANIAM1 RAM SAGAR1 3

      1. Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bangalore 560 034, India.
      2. Joint Astronomy Programme and Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
      3. Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263 002, India

    • Dates

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

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