Johan H. Knapen

Secular evolution of galaxies

Preface 1. Secular evolution in disk galaxies John Kormendy 2. Galaxy morphology Ronald J. Buta 3. Dynamics of secular evolution James Binney 4. Bars and secular evolution in disk galaxies: theoretical input E. Athanassoula 5. Stellar populations Reynier F. Peletier 6. Star formation rate indicators Daniela Calzetti 7. The evolving interstellar medium Jacqueline van Gorkom 8. Evolution of star formation and gas Nick Z. Scoville 9. Cosmological evolution of galaxies Isaac Shlosman.

Outskirts of Galaxies

The first € price and the £ and

Kinematical evidence for secular evolution in Spitzer Survey of Stellar Structure in Galaxies (S 4 G) spirals

price are net prices, subject to local VAT. Prices indicated with * include VAT for books; the €(D) includes 7% for Germany, the €(A) includes 10% for Austria. Prices indicated with ** include VAT for electronic products; 19% for Germany, 20% for Austria. All prices exclusive of carriage charges. Prices and other details are subject to change without notice. All errors and omissions excepted. J.H. Knapen, J.C. Lee, A. Gil de Paz (Eds.) Outskirts of Galaxies

Morphology, Kinematics and Star Formation in Spiral Galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S4G)

We present a study of the kinematics of a sample of isolated spiral galaxies in the Spitzer Survey of Stellar Structure in Galaxies (SG). We use Hα Fabry-Perot data from the GHαFaS instrument at the William Herschel Telescope (WHT) in La Palma, complemented with images at 3.6 microns, in the R band and in the Hα filter. The resulting data cubes and velocity field maps allow a complete study of the kinematics of a galaxy, including in-depth investigations of the rotation curve, velocity moment maps, velocity residual maps, gradient maps and position-velocity (PV) diagrams. We find clear evidence of the secular evolution processes going on in these galaxies, such as asymmetries in the velocity field in the bar zone, and non-circular motions, probably in response to the potential of the structural components of the galaxies, or to past or present interactions.

A SINFONI view of circum-nuclear star-forming rings in spiral galaxies

We present a study of the morphology, kinematics and star formation of a sample of 27 isolated spiral galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S 4 G), on the basis of Hα Fabry-Perot (FP) data from the GHαFaS instrument at the William Herschel Telescope (WHT) in La Palma, complemented with images at 3.6 micron from the Spitzer Space Telescope, and with images in the R -band and in Hα taken with the ACAM instrument mounted on the WHT. With the FP data we can investigate the gas kinematics in terms of velocity maps and position-velocity diagrams, keys to constrain the secular evolution processes. We can also analyse the morphology and compute the star formation rate (SFR) with the ancillary data.

Physical conditions of ionized gas and stellar populations in circumnuclear starbursts

We present near-infrared (Hand K-band) SINFONI integral-field observations of the circumnuclear star formation rings in five nearby spiral galaxies. We made use of the relative intensities of different emission lines (i.e. [FeII], HeI, Brγ) to age date the stellar clusters present along the rings. This qualitative, yet robust, method allows us to discriminate between two distinct scenarios that describe how star formation progresses along the rings. Our findings favour a model where star formation is triggered predominantly at the intersection between the bar major axis and the inner Lindblad resonance and then passively evolves as the clusters rotate around the ring (’Pearls on a string’ scenario), although models of stochastically distributed star formation (’Popcorn’ model) cannot be completely ruled out.

Interactions, Starbursts, and Star Formation

We present an emission-line diagnostic analysis of integral-field spectroscopic observations that cover the circumnuclear ring-like regions in a small number of spiral galaxies. We concentrate on the specific case of the Sa galaxy NGC 7742, which hosts a spectacular circumnuclear starburst ring and nuclear regions characterised by low-ionisation emission. The gas in the ring rotates in the opposite sense to the stars in the galaxy, suggesting a recent merging or acquisition event. The combination of integral-field measurements for the Hα+N[ ii ] emission lines from DensePak and the Hβ and [O iii ] emission from SAURON allows the construction of diagnostic diagrams that highlight the transition from star formation in the ring to excitation by high-velocity shocks or by an AGN near the centre. DensePak measurements for the [S ii ] line ratio reveal very low gas densities in the ring, N e −3 , characteristic of massive H ii regions. Comparison with MAPPINGS III models for starbursts with low gas densities shows that the ring is of roughly solar metallicity. We suggest that NGC 7742 cannibalised a smaller galaxy rich in metal-poor gas, and that star formation episodes in the ring have since increased the metallicity to its present value.