Hubble Tarantula Treasury Project V. The star cluster Hodge 301: the old face of 30 Doradus

TL;DR

This study uses Hubble Space Telescope data to determine that the star cluster Hodge 301 in the Tarantula Nebula is older than previously thought, with an age between 26.5 and 31.5 million years, and estimates its supernova history.

Contribution

First time determination of Hodge 301's age using the PMS turn-on feature with synthetic CMDs, revealing it is older than previously believed.

Findings

Hodge 301 is 26.5-31.5 Myr old.

Between 38 and 61 Type-II supernovae occurred.

Total stellar mass is approximately 8800 solar masses.

Abstract

Based on color-magnitude diagrams (CMDs) from the Hubble Space Telescope Hubble Tarantula Treasury Project (HTTP) survey, we present the star formation history (SFH) of Hodge~301, the oldest star cluster in the Tarantula Nebula. The HTTP photometry extends faint enough to reach, for the first time, the cluster pre-main sequence (PMS) turn-on, where the PMS joins the main sequence. Using the location of this feature, along with synthetic CMDs generated with the latest PARSEC models, we find that Hodge~301 is older than previously thought, with an age between 26.5 and 31.5 Myr. From this age, we also estimate that between 38 and 61 supernovae Type-II exploded in the region. The same age is derived from the main sequence turn-off, whereas the age derived from the post-main sequence stars is younger and between 20 and 25 Myr. Other relevant parameters are a total stellar mass of $\approx 8800\,\pm 800$M$_{\odot}$ and average reddening E(B$-$V) $\approx 0.22-0.24$ mag, with a differential reddening $\delta$E(B$-$V)$\approx 0.04$ mag.