# Spectral Energy Distribution of Blue Stragglers in the core of 47 Tucanae

## TL;DR

This study constructs detailed spectral energy distributions of Blue Straggler Stars in 47 Tucanae's core, deriving their physical parameters and revealing a mass sequence correlated with luminosity, including potential supermassive BSSs.

## Contribution

It provides the first comprehensive SED-based analysis of BSSs in 47 Tucanae, estimating their physical properties and identifying candidates with masses exceeding typical limits.

## Key findings

- BSSs define a mass sequence increasing with luminosity.
- SED-derived masses agree with those from evolutionary tracks.
- Identification of supermassive BSS candidates exceeding twice the turn-off mass.

## Abstract

We have constructed the Spectral Energy Distributions (SEDs) of a sample of Blue Straggler Stars (BSSs) in the core of the globular cluster 47 Tucanae, taking advantage of the large set of high resolution images, ranging from the ultraviolet to the near infrared, obtained with the ACS/HRC camera of the Hubble Space Telescope. Our final BSS sample consists of 22 objects, spanning the whole color and magnitude extension of the BSS sequence in 47 Tucanae. We fitted the BSS broadband SEDs with models to derive temperature, surface gravity, radius, luminosity and mass. We show that BSSs indeed define a mass sequence, where the mass increases for increasing luminosity. Interestingly, the BSS masses estimates from the SED fitting turn out to be comparable to those derived from the projection of the stellar position in the color-magnitude diagram onto standard star evolutionary tracks. We compare our results with previous, direct mass estimates of a few BSSs in 47 Tucanae. We also find a couple of supermassive BSS candidates, i.e., BSSs with a mass larger than twice the turn-off mass, the formation of which must have involved more than two progenitors.