Stellar kinematics in blue compact galaxies

TL;DR

This study investigates the kinematics of stars and ionized gas in blue compact galaxies, using spectroscopy to compare their velocity fields and assess the stellar populations traced by the Ca II triplet.

Contribution

The paper presents new spatially-resolved spectroscopic data on a local Lyman break galaxy analogue, analyzing stellar and gas kinematics and their implications for stellar population tracing.

Findings

Stars and ionized gas have similar velocity fields in Haro 11.

Emission line velocities can differ locally from stellar velocities by tens of km/s.

The Ca II triplet traces specific stellar populations, with potential for studying distant galaxies.

Abstract

In a programme of observations of local luminous blue compact galaxies (BCGs), we are investigating kinematics by using tracers of both stars and ionized gas. Here we summarise our program and present new data on the local Lyman break galaxy analogue Haro 11. From spatially-resolved spectroscopy around the near-infrared Ca II triplet, we find that its stars and ionized gas have similar velocity fields. Our programme so far indicates however that emission line velocities can differ locally by a few tens of km/s from the Ca II values. Comparing our data to simple stellar population models, we assess which stellar population the Ca II triplet traces and its potential beyond the local universe.