| 29th of May 2015 |
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| Giant gas reservoir around an old lenticular galaxy |
| by Mustafa K. Yıldız (Kapteyn Astronomical Institute) |
| NGC 4203 is a lenticular galaxy surrounded by
an unusually large HI disc (radius ~ 30 kpc). In a paper now accepted for publication a team lead by CASS student
Mustafa Yıldız studied the impact of this large gas reservoir on the
host
galaxy. They find that the gas system (shown in blue in the
above image) consists of two separate components: an inner star-forming
ring and an outer HI disc. The inner ring contains metal-rich gas and
a large amount of dust (red in the image). In contrast,
the outer disc is likely to be poor of metals and dust. While the
star-formation efficiency in the inner HI ring is comparable to that of the
inner region of spiral galaxies, it is much lower in the outer disc - even in
regions with high gas density (see the bright HI arm on the right side of the
image). However, the star formation efficiency in the outer HI disc is still
consistent with that of the outer regions of spiral galaxies. The deep
optical image also reveals a dwarf galaxy which is interacting with NGC
4203 (left). Data for this study were collected with the WSRT and CFHT
telescopes. Reference: Yıldız, Serra, Oosterloo, Peletier, Morganti, Duc, Cuillandre, Karabal 2015, MNRAS, in press (http://arxiv.org/abs/1505.02981) |