# Detection of White Dwarf Companions to Blue Straggler Stars from UVIT Observations of M67

## TL;DR

This study uses ultraviolet observations to identify white dwarf companions to blue straggler stars in M67, providing evidence for binary formation channels of blue stragglers.

## Contribution

First confirmed detection of white dwarf companions to blue straggler stars in M67 using UVIT data, supporting binary formation theories.

## Key findings

- Detected WD companions to 5 BSSs in M67.
- WDs have masses 0.2-0.35 M_sun and temperatures 11,000-24,000 K.
- Binary spectral fits required for 5 BSSs.

## Abstract

We investigate the old open cluster M67 using ultraviolet photometric data of Ultra-Violet Imaging Telescope in multi-filter far-UV bands. M67, well known for the presence of several blue straggler stars (BSS), has been put to detailed tests to understand their formation pathways. Currently, there are three accepted formation channels: mass transfer due to Roche-lobe overflow in binary systems, stellar mergers either due to dynamical collisions or through coalescence of close binaries. So far, there had not been any confirmed detection of a white dwarf (WD) companion to any of the BSSs in this cluster. Here, we present the detection of WD companions to 5 bright BSSs in M67. The multiwavelength spectral energy distributions covering 0.12 -11.5 $\mu$m range, were found to require binary spectral fits for 5 BSSs, consisting of a cool (BSS) and a hot companion. The parameters (Luminosity, Temperature, Radius and Mass) of the hot companions suggest them to be WDs with mass in the range 0.2 - 0.35 M$_{\odot}$ with T$_{eff}$ $\sim$ 11000 - 24000 K.