# GASP. XV. A MUSE View of Extreme Ram-Pressure Stripping along the Line of Sight: Physical properties of the Jellyfish Galaxy JO201

## TL;DR

This study investigates the physical properties of the jellyfish galaxy JO201 undergoing extreme ram-pressure stripping in Abell 85, revealing details about its star formation, metallicity, and gas dynamics through MUSE observations.

## Contribution

It provides detailed spatial analysis of gas metallicity, stellar ages, and emission-line ratios in JO201, offering new insights into ram-pressure stripping effects along the line of sight.

## Key findings

- Star-forming knots with metallicity gradients are present.
- Tails formed less than 1 billion years ago.
- Ram-pressure stripping influences star formation and AGN activity.

## Abstract

We present a study of the physical properties of JO201, a unique disk galaxy with extended tails undergoing extreme ram-pressure stripping as it moves through the massive cluster Abell 85 at supersonic speeds mostly along the line of sight. JO201 was observed with MUSE as part of the GASP programme. In a previous paper (GASP II) we studied the stellar and gas kinematics. In this paper we present emission-line ratios, gas-phase metallicities and ages of the stellar populations across the galaxy disk and tails. We find that while the emission at the core of the galaxy is dominated by an active galactic nucleus (AGN), the disk is composed of star-forming knots surrounded by excited diffuse gas. The collection of star-forming knots presents a metallicity gradient steadily decreasing from the centre of the galaxy outwards, and the ages of the stars across the galaxy show that the tails formed <10^9 yr ago. This result is consistent with an estimate of the stripping timescale (1 Gyr), obtained from a toy orbital model. Overall, our results independently and consistently support a scenario in which a recent or ongoing event of intense ram-pressure stripping acting from the outer disk inwards, causes removal and compression of gas, thus altering the AGN and star-formation activity within and around the galaxy.