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Understanding the Structure of Galaxies:
Angular Momentum & Cores
| Astrophysics Research at Oxford |
Quality of the SAURON stellar kinematics in the ATLAS3D survey. Each column from left to right shows the Voronoi binned kinematic moments extracted via pPXF from the SAURON data: mean velocity, V, velocity dispersion, σ, and higher Gauss–Hermite moments, h3 and h4. From top to bottom the data for seven newly observed fast rotators in the ATLAS3D sample are sorted according to the luminosity-weighted dispersion σe within 1Re.
Same as in Fig. 5 for the fast-rotators ETGs in the ATLAS3D sample, sorted by increasing λR. The first panel contains mostly round objects. Many of them are barred (Paper II), nearly face-on, S0 galaxies and often contain stellar rings (e.g. NGC 4608), while others appears face-on from the geometry of their dust. This suggests that the round shape and low λR of these objects is not intrinsic, but due to their low inclination (i = 90◦ being edge on). On the contrary the last panel is dominated by nearly edge-on discs, which explains their high λR.
Hubble Space Telescopes (HST) images of galaxies that couldn't be classified as CORES or CORE-LESS.
Figure B1 from; The ATLAS3D Project XXIII. Angular momentum and nuclear surface brightness profiles (Krajnovic & Karick et al. 2013).
Read more here: https://arxiv.org/abs/1305.4973
Embedded disks and strong dust features (dark areas) prevent accurate modelling, however their existence means that these galaxies are unlikely to have cores. All images were taken with the Wide Field Planetary Camera (WPC2/PC1), except for NGC 4435 and NGC 4526, which were taken with the newer Advanced Camera for Surveys (ACS/WFC).
λ_R versus the ellipticity ε for 260 ATLAS3D galaxies.
Open small symbols are galaxies with no available HST observations, and filled small symbols are galaxies for which the classification was not possible (uncertain).
Source: Fig 4a. from Krajnovic, D., Karick, A.M., Davies, R.L, Thorsten, N., Sarzi, M, Emsellem, E., Cappellari, M., et al. 2013, MNRAS, 433, 2812 (23)
This long-exposure Hubble Space Telescope image shows the majestic face-on spiral galaxy, NGC 4911 located deep within the Coma Cluster of galaxies, which lies 320 million light- years away in the northern constellation Coma Berenices. This galaxy contains rich lanes of dust and gas near its centre. These are silhouetted against glowing newborn star clusters and iridescent pink clouds of hydrogen, the existence of which indicates ongoing star formation. Hubble has also captured the outer spiral arms of NGC 4911, along with thousands of other galaxies of varying sizes. The high resolution of Hubble's cameras, paired with considerably long exposures, made it possible to observe these faint details.
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