Star formation history of the post-collisional Cartwheel galaxy using Astrosat/UVIT FUV images

Abstract

We present the results obtained by analysing new Astrosat/UVIT far ultraviolet (FUV) image of the collisional-ring galaxy Cartwheel. The FUV emission is principally associated with the star-forming outer ring, with no UV detection from the nucleus and inner ring. A few sources are detected in the region between the inner and the outer rings, all of which lie along the spokes. The FUV fluxes from the detected sources are combined with aperture-matched multi-band photometric data from archival images to explore the post-collision star formation history of the Cartwheel. The data were corrected for extinction using Av derived from the Balmer decrement ratios and commonly used extinction curves. We find that the ring regions contain stellar populations of wide range of ages, with the bulk of the FUV emission coming from non-ionizing stars, formed over the last 20 to 150 Myr, that are ~25 times more massive than the ionizing populations. On the other hand, regions belonging to the spokes have negligible current star formation, with the age of the dominant older population systematically increasing as its distance from the outer ring increases. The presence of populations of a wide range of ages in the ring suggests that the stars formed in the wave in the past were dragged along it to the current position of the ring. We derive an average steady star formation rate, SFR=5 Msun/yr, over the past 150 Myr, with an increase to ~18 Msun/yr in the recent 10 Myr.

arXiv comment16 pages, to appear in MNRAS

References in corpus (17)

• On the variation of the Initial Mass Function
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• A Quantitative Comparison of SMC, LMC, and Milky Way UV to NIR Extinction Curves
• Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
• The Absolute Magnitude of the Sun in Several Filters
• Evolutionary Stellar Population Synthesis at High Spectral Resolution: Optical Wavelengths
• In-orbit Calibrations of the Ultra-Violet Imaging Telescope
• Additional Calibration of the Ultra-Violet Imaging Telescope on board AstroSat
• Emission-line diagnostics of nearby HII regions including interacting binary populations
• Ultra Violet Imaging Telescope (UVIT) on ASTROSAT
• Morphology and enhanced star formation in a Cartwheel-like ring galaxy
• Embedded Clusters in Giant Extragalactic HII Regions III. Extinction and Star Formation
• The detection of non-thermal radio continuum spokes and the study of star formation in the Cartwheel
• Optical Color Gradients in Star-Forming Ring Galaxies
• An Automated Pipeline for Ultra-Violet Imaging Telescope (UVIT)
• Discovery of a near-infrared bar and a pseudobulge in the collisional ring galaxy Cartwheel
• Performance of the UVIT Level-2 Pipeline

Cited by in corpus (2)

• Connecting the dots: Tracing the evolutionary pathway of Polar Ring Galaxies in the cases of NGC 3718, NGC 2685, and NGC 4262
• Massive star clusters and clumps in the collisional ring galaxy Arp 147