The Cold Gaseous Halo of NGC 891
By T. Oosterloo, Filippo Fraternali, R. Sancisi. 2007
240 citations recorded by the source corpus.
We present H I observations of the edge-on galaxy NGC 891. These are among the deepest ever performed on an external galaxy. They reveal a huge gaseous halo, much more extended than seen previously and containing almost 30% of the H I. This H I halo shows structures on various scales. On one side, there is a filament extending (in projection) up to 22 kpc vertically from the disk. Small (M ≳ 106 M⊙) halo clouds, some with forbidden (apparently counterrotating) velocities, are also detected. The overall kinematics of the halo gas is characterized by differential rotation lagging with respect to that of the disk. The lag, more pronounced at small radii, increases with height from the plane. There is evidence that a significant fraction of the halo is due to a galactic fountain. Accretion from intergalactic space may also play a role in building up the halo and providing the low angular momentum material needed to account for the observed rotation lag. The long H I filament and the counterrotating clouds may be direct evidence of such accretion.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/71b86f45cb0aae0860bea0f7e43e4f44fb741665
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In Astronomy and Astrophysics
Citations in the corpus
- Global properties of the H I distribution in the outer Milky Way - Planar and extra-planar gas (2008, background): “Maloney’s interpretation was questioned recently by Oosterloo et al. (2007) who found that a deeper mapping of NGC891 led predominantly to the detection of unknown low level emission in the vertical direction, while the radial limits remained.”
- The H i Distribution of the Milky Way (2009, background): “The blue box in Figure 9 represents an estimate of the lagging halo rotation in NGC 891 according to Oosterloo et al. (2007).”
- Chemical evolution with radial mixing (2008, methodology): “Although of the order of a quarter of the neutral hydrogen of NGC 891 is extraplanar (Oosterloo et al. 2007), some of this gas will be formerly cold interstellar gas that has been shock accelerated by stellar ejecta.”
- The Tully-Fisher relations of early-type spiral and S0 galaxies (2010, background): “…observations of planetary nebulae in the edge-on spiral NGC 891 (Merrifield et al. 2010) and of extraplanar gas (e.g. NGC 891, Heald et al. 2007, Oosterloo et al. 2007; NGC 4302 and NGC 5775, Heald et al. 2007; the Milky Way, Levine et al. 2008), which find a typical falloff in rotation dv/d|z|…”
- HI holes and high-velocity clouds in the spiral galaxy NGC 6946 (2008, background): “An extended, lagging H I halo has been discovered in the edge-on galaxy NGC 891 (Swaters et al. 1997; Oosterloo et al. 2007).”
- Gaseous Galaxy Halos (2012, background): “…the spiral galaxies observed to deep enough levels show a disk-halo component that lags the rotation of the disk (often referred to as an ‘HI beard’; Sancisi et al., 2001) with a typical gradient of magnitude 15-30 km s−1 kpc−1 (Fraternali et al., 2002; Oosterloo et al., 2007; Heald et al., 2011).”
- Simulations of magnetic fields in isolated disc galaxies (2012, background): “Qualitatively, these outflows are similar to galactic fountain models in which outflows are driven by supernova-powered bubbles (see, e.g., Shapiro & Field 1976; Oosterloo et al. 2007; Marinacci et al. 2011).”