The central region of the enigmatic Malin 1

TL;DR

This study reveals that Malin 1's central region resembles a typical SB0/a galaxy with recent star formation, while its outer disk exhibits low surface brightness features, highlighting complex structural and star-forming characteristics.

Contribution

The paper provides high-resolution UV and optical observations showing recent star formation in Malin 1's central and disk regions, and suggests interaction with Malin 1B influences star formation activity.

Findings

Central region resembles a normal SB0/a galaxy

Recent star formation activity detected across the disk

Interaction with Malin 1B likely triggers star formation

Abstract

Malin 1, being a class of giant low surface galaxies, continues to surprise us even today. The HST/F814W observation has shown that the central region of Malin 1 is more like a normal SB0/a galaxy, while the rest of the disk has the characteristic of a low surface brightness system. The AstroSat/UVIT observations suggest scattered recent star formation activity all over the disk, especially along the spiral arms. The central 9" ($\sim 14$ kpc) region, similar to the size of the Milky Way's stellar disk, has a number of far-UV clumps - indicating recent star-formation activity. The high resolution UVIT/F154W image reveals far-UV emission within the bar region ($\sim 4$ kpc) - suggesting the presence of hot, young stars in the bar. These young stars from the bar region are perhaps responsible for producing the strong emission lines such as H$\alpha$, [OII] seen in the SDSS spectra. Malin 1B, a dwarf early-type galaxy, is interacting with the central region and probably responsible for inducing the recent star-formation activity in this galaxy.