NGC 90: a hidden jelly-fish galaxy?

We study a peculiar galaxy NGC 90, a pair member of interacting system Arp 65 (NGC 90/93), using the long-slit spectral observations carried out at the Russian 6m telescope BTA and the available SDSS photometric data. This galaxy demonstrates two tidal tails containing young stellar population, bein...

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Bibliographic Details
Published in:arXiv.org 2020-07
Main Authors: Zasov, Anatoly V, Saburova, Anna S, Egorov, Oleg V, Moiseev, Alexey V
Format: Article
Language:English
Subjects:
Abundance
Clouds
Emission
Galactic structure
Interacting galaxies
Peculiar galaxies
Photoionization
Ram pressure
Star & galaxy formation
Star formation
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Summary:We study a peculiar galaxy NGC 90, a pair member of interacting system Arp 65 (NGC 90/93), using the long-slit spectral observations carried out at the Russian 6m telescope BTA and the available SDSS photometric data. This galaxy demonstrates two tidal tails containing young stellar population, being an extension of its `Grand Design' spiral arms. We obtained the distribution of velocity and oxygen abundance of emission gas (O/H) for two slit orientations. In the central part of the galaxy a significant role belongs to non-photoionization mechanism of line emission probably caused by shocks due to LINER-like activity of the nucleus. The O/H has a shallow abundance gradient, typical for interacting galaxies. The most intriguing peculiarity of the galaxy is the presence of the discovered earlier huge HI `cloud' containing about half of total mass of galaxy gas, which is strongly displaced outwards and has a velocity exceeding at about 340 km/s the central velocity of the main galaxy. We found traces of current star formation in the `cloud', even though the cloud is apparently not gravitationally bound with the galaxy. A possible nature of the `cloud' is discussed. We argue that it presents a flow of gas sweeping by ram pressure and elongated along a line of sight.
ISSN:2331-8422
DOI:10.48550/arxiv.2007.09432