The HI Chronicles of LITTLE THINGS BCDs: Evidence for External Perturbations in the Morphology and Kinematics of Haro 29 and Haro 36

TL;DR

This study investigates the disturbed morphology and kinematics of two blue compact dwarf galaxies, Haro 29 and Haro 36, providing evidence for past and ongoing external interactions affecting their structures.

Contribution

It presents high-resolution HI data revealing signs of past interactions and possible mergers in these BCDs, highlighting external perturbations' role in their evolution.

Findings

Haro 29 shows a kinematic axis offset from its optical axis.

Haro 36 has two kinematically distinct components and a possible tidal tail.

Both galaxies exhibit signs of external interactions or mergers.

Abstract

We analyze high angular and velocity resolution HI-line data of two LITTLE THINGS (1) blue compact dwarfs (BCDs): Haro 29 and Haro 36. Both of these BCDs are disturbed morphologically and kinematically. Haro 29's HI data reveal a kinematic major axis that is offset from the optical major axis, and a disturbed outer HI component, indicating that Haro 29 may have had a past interaction. Position-velocity diagrams of Haro 36 indicate that it has two kinematically separate components at its center and a likely tidal tail in front of the galaxy. We find that Haro 36 most likely had an interaction in the past, is currently interacting with an unknown companion, or is a merger remnant. (1) "Local Irregulars That Trace Luminosity Extremes The HI Nearby Galaxy Survey" http://www2.lowell.edu/users/dah/littlethings/index.html