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تسجيل مستخدم جديدUltra-Violet Imaging Telescope view of ram-pressure stripping in action: Star formation in the stripped gas of the GASP jellyfish galaxy JO201 in Abell 85
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Jellyfish are cluster galaxies that experience strong ram-pressure effects that strip their gas. Their H$alpha$ images reveal ionized gas tails up to 100 kpc, which could be hosting ongoing star formation. Here we report the ultraviolet (UV) imaging observation of the jellyfish galaxy JO201 obtained at a spatial resolution $sim$ 1.3 kpc. The intense burst of star formation happening in the tentacles is the focus of the present study. JO201 is the UV-brightest cluster galaxy in Abell 85 ($z sim$ 0.056) with knots and streams of star formation in the ultraviolet. We identify star forming knots both in the stripped gas and in the galaxy disk and compare the UV features with the ones traced by H$alpha$ emission. Overall, the two emissions remarkably correlate, both in the main body and along the tentacles. Similarly, also the star formation rates of individual knots derived from the extinction-corrected FUV emission agree with those derived from the H$alpha$ emission and range from $sim$ 0.01 -to- 2.07 $M_{odot} , yr^{-1}$. The integrated star formation rate from FUV flux is $sim$ 15 $M_{odot} , yr^{-1}$. The unprecedented deep UV imaging study of the jellyfish galaxy JO201 shows clear signs of extraplanar star-formation activity due to a recent/ongoing gas stripping event.
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X-ray studies of jellyfish galaxies play a crucial role in understanding the interactions between the interstellar medium (ISM) and the intracluster medium (ICM). In this paper, we focused on the jellyfish galaxy JO201. By combining archival Chandra
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This paper presents a spatially-resolved kinematic study of the jellyfish galaxy JO201, one of the most spectacular cases of ram-pressure stripping (RPS) in the GASP (GAs Stripping Phenomena in Galaxies with MUSE) survey. By studying the environment
of JO201, we find that it is moving through the dense intra-cluster medium of Abell 85 at supersonic speeds along our line of sight, and that it is likely accompanied by a small group of galaxies. Given the density of the intra-cluster medium and the galaxys mass, projected position and velocity within the cluster, we estimate that JO201 must so far have lost ~50% of its gas during infall via RPS. The MUSE data indeed reveal a smooth stellar disk, accompanied by large projected tails of ionised (Halpha) gas, composed of kinematically cold (velocity dispersion <40km/s) star-forming knots and very warm (>100km/s) diffuse emission which extend out to at least ~50 kpc from the galaxy centre. The ionised Halpha-emitting gas in the disk rotates with the stars out to ~6 kpc but in the disk outskirts becomes increasingly redshifted with respect to the (undisturbed) stellar disk. The observed disturbances are consistent with the presence of gas trailing behind the stellar component, resulting from intense face-on RPS happening along the line of sight. Our kinematic analysis is consistent with the estimated fraction of lost gas, and reveals that stripping of the disk happens outside-in, causing shock heating and gas compression in the stripped tails.
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