Uncovering the kiloparsec-scale stellar ring of NGC 5128

Kainulainen, J.; Beletsky, Y.; Ascenso, Joana; Kainulainen, Juha; Amorim, A.; Lima, Jorge; Ferreira‐Marques, R.; Moitinho, A.; Pinhão, J.; Rebordão, J.; Santos, F.D.

doi:10.1051/0004-6361/200912624

Cited by 17 publications

(28 citation statements)

References 22 publications

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“…There is a lack of H i between 0.1-1 kpc, confirming results from observations of CO, ionised gas and dust. The parameters of the model (in particular the inclination) are different from what derived in previous models (Quillen et al 2006;Nicholson et al 1992) but nicely consistent with those from the study of the central stellar ring of Kainulainen et al (2009). Outside 6 kpc radius, asymmetries and arm structures are observed as well as radial motions.…”

Section: Discussionsupporting

confidence: 76%

“…The main noticeable difference is in the inclination that appears to stay closer to edge-on for r > 90 in our model. Remarkable is the similarity of our parameters with the independent results from the study of the stellar light emerging from the kiloparsec-scale, ring-like structure detected using the VLT (Kainulainen et al 2009). …”

Section: The H I Modelsupporting

confidence: 79%

“…Whether the newly discovered H i clouds are a cooling Nicholson et al (1992). In addition, also the values from the stellar modelling of Kainulainen et al (2009) are plotted (dotted line).…”

Section: Modelling Implications: the Large-scale H I Distributionmentioning

confidence: 99%

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Centaurus A: morphology and kinematics of the atomic hydrogen

Struve

Oosterloo

Morganti

et al. 2010

A&A

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We present new ATCA 21-cm line observations of the neutral hydrogen in the nearby radio galaxy Centaurus A. We image in detail (with a resolution down to 7 , ∼100 pc) the distribution of H i along the dust lane. Our data have better velocity resolution and better sensitivity than previous observations. The H i extends for a total of ∼15 kpc. The data, combined with a titled-ring model of the disk, allow to conclude that the kinematics of the H i is that of a regularly rotating, highly warped structure down to the nuclear scale.The parameters (in particular the inclination) of our model are somewhat different from some of the previously proposed models but consistent with what was recently derived from stellar light in a central ring. The model nicely describes also the morphology of the dust lane as observed with Spitzer. There are no indications that large-scale anomalies in the kinematics exist that could be related to supplying material for the AGN. Large-scale radial motions do exist, but these are only present at larger radii (r > 6 kpc). This unsettled gas is mainly part of a tail/arm like structure. The relatively regular kinematics of the gas in this structure suggests that it is in the process of settling down into the main disk. The presence of this structure further supports the merger/interaction origin of the H i in Cen A. From the structure and kinematics we estimate a timescale of 1.6−3.2 × 10 8 yr since the merging event. No bar structure is needed to describe the kinematics of the H i. The comparison of the timescale derived from the large-scale H i structure and those of the radio structure together with the relative regularity of the H i down to the sub-kpc regions does not suggest a oneto-one correspondence between the merger and the phase of radio activity. Interestingly, the radial motions of the outer regions are such that the projected velocities are redshifted compared to the regular orbits. This means that the blueshifted absorption discovered earlier and discussed in our previous paper cannot be caused by out-moving gas at large radius projected onto the centre. Therefore, the interpretation of the blueshifted absorption, together with at least a fraction of the redshifted nuclear absorption, as evidence for a regular inner disk, still holds. Finally, we also report the discovery of two unresolved clouds detected at 5.2 and 11 kpc away (in projection) from the H i disk. They are likely an other example of a left-over of the merger that brought the H i gas.

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Section: Discussionsupporting

confidence: 76%

Section: The H I Modelsupporting

confidence: 79%

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Centaurus A: morphology and kinematics of the atomic hydrogen

Struve

Oosterloo

Morganti

et al. 2010

A&A

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“…The "anomalous" features in NGC 5128, such as the central dust lane with its star forming regions and the ring of young massive stars (Graham 1979;Moellenhoff 1981;Quillen et al 1993;Kainulainen et al 2009) are significantly younger than the 2−4 Gyr younger halo component. Therefore it is possible that NGC 5128 has suffered several merger episodes.…”

Section: Discussionmentioning

confidence: 99%

How old are the stars in the halo of NGC 5128 (Centaurus A)?

Rejkuba¹,

Harris

Greggio

et al. 2011

A&A

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Context. NGC 5128 (Centaurus A) is, at the distance of just 3.8 Mpc, the nearest easily observable giant elliptical galaxy. Therefore it is the best target to investigate the early star formation history of an elliptical galaxy. Aims. Our aims are to establish when the oldest stars formed in NGC 5128, and whether this galaxy formed stars over a long period. Methods. We compare simulated colour−magnitude diagrams with the deep ACS/HST photometry. The simulations assume in input either the observed metallicity distribution function, based on the colour distribution of the upper red giant branch stars, or the closed box chemical enrichment. Simulations are constructed for single age bursts using BASTI evolutionary isochrones; more complex star formation histories are constructed as well by combining several individual simulations. Comparisons with data are made by fitting the whole colour−magnitude diagram as well as the the luminosity functions in V and I band. In addition we inspect carefully the red clump and asymptotic giant branch bump luminosities and number counts, since these features are the primary constraints on the ages of the observed stars. Results. We find that that the observed colour−magnitude diagram can be reproduced satisfactorily only by simulations that have the bulk of the stars with ages in excess of ∼10 Gyr, and that the alpha-enhanced models fit the data much better than the solar scaled ones. Data are not consistent with extended star formation over more than 3−4 Gyr. Two burst models, with 70−80% of the stars formed 12 ± 1 Gyr ago and with 20−30% younger contribution with 2−4 Gyr old stars provide the best agreement with the data. The old component spans the whole metallicity range of the models (Z = 0.0001−0.04), while for the young component the best fitting models indicate higher minimum metallicity (∼1/10−1/4 Z ). Conclusions. The bulk of the halo stars in NGC 5128 must have formed at redshift z > ∼ 2 and the chemical enrichment was very fast, reaching solar or even twice-solar metallicity already for the ∼11−12 Gyr old population. The minor young component, adding ∼20−30% of the stars to the halo, and contributing less than 10% of the mass, may have resulted from a later star formation event ∼2−4 Gyr ago.

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“…Many of these have concentrated on its active nucleus, which is observed over the whole electromagnetic spectrum from γ rays to low frequency radio (see Israel 1998, for an earlier review), and the galaxy is often referred to by its radio source name as Centaurus A. NGC 5128 shows signs of major nuclear activity, including the AGN and supermassive black hole (Neumayer 2010, and references therein). There is also evidence of past interaction events, in the form of a dust lane with a ring of young clusters and H ii regions (Kainulainen et al 2009;Graham 1979), a young (∼0.3 Gyr) tidal stream (Peng et al 2002) and Based on observations collected at the ESO La Silla-Paranal Observatory within observing programmes 060.A-9140 (FLAMES Science Verification) and 073.B-0434.…”

Section: Introductionmentioning

confidence: 99%

An imaging and spectroscopic study of the planetary nebulae in NGC 5128 (Centaurus A)

Walsh¹,

Rejkuba²,

Walton³

2015

A&A

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Context. Planetary nebulae (PNe) are excellent tracers of the common low mass stars through their strong and narrow emission lines. The velocities of large numbers of PNe are excellent tracers of galaxy kinematics. NGC 5128, the nearest large early-type galaxy, offers the possibility to gather a large sample. Aims. Imaging and spectroscopic observations of PNe in NGC 5128 were obtained to find and measure their velocities. Combined with literature data, a large sample of high quality kinematic probes is assembled for dynamical studies. Conclusions. The total of 1267 confirmed PNe in NGC 5128 with radial velocity measurements (1135 with small velocity errors) is the largest collection of individual kinematic probes in an early-type galaxy. This PN dataset, as well as the catalogue of PN candidates, are valuable resources for detailed investigation of NGC 5128.

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Uncovering the kiloparsec-scale stellar ring of NGC 5128

Cited by 17 publications

References 22 publications

Centaurus A: morphology and kinematics of the atomic hydrogen

Centaurus A: morphology and kinematics of the atomic hydrogen

How old are the stars in the halo of NGC 5128 (Centaurus A)?

An imaging and spectroscopic study of the planetary nebulae in NGC 5128 (Centaurus A)

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