We present the stellar atmospheric parameters (effective temperature, surface gravity, overall metallicity), radial velocities, individual abundances and distances determined for 425 561 stars, which constitute the fourth public data release of the RAdial Velocity Experiment (RAVE). The stellar atmospheric parameters are computed using a new pipeline, based on the algorithms of MATISSE and DEGAS. The spectral degeneracies and the 2MASS photometric information are now better taken into consideration, improving the parameter determination compared to the previous RAVE data releases. The individual abundances for six elements (magnesium, aluminium, silicon, titanium, iron and nickel) are also given, based on a special-purpose pipeline which is also improved compared to that available for the RAVE DR3 and Chemical DR1 data releases. Together with photometric information and proper motions, these data can be retrieved from the RAVE collaboration website and the Vizier database.

We use more than 110 500 galaxies from the 2dF Galaxy Redshift Survey (2dFGRS) to estimate the bJ‐band galaxy luminosity function at redshift z= 0, taking account of evolution, the distribution of magnitude measurement errors and small corrections for incompleteness in the galaxy catalogue. Throughout the interval −16.5 > M italicb J− 5 log10h > −22, the luminosity function is accurately described by a Schechter function with M★ italicb J− 5 log10h=−19.66 ± 0.07, α=−1.21 ± 0.03 and Φ★= (1.61 ± 0.08) × 10−2h3 Mpc−3, giving an integrated luminosity density of ρL= (1.82 ± 0.17) × 108h L⊙ Mpc−3 (assuming an Ω0= 0.3, Λ0= 0.7 cosmology). The quoted errors have contributions from the accuracy of the photometric zero‐point, from large‐scale structure in the galaxy distribution and, importantly, from the uncertainty in the appropriate evolutionary corrections. Our luminosity function is in excellent agreement with, but has much smaller statistical errors than, an estimate from the Sloan Digital Sky Survey (SDSS) data when the SDSS data are accurately translated to the bJ band and the luminosity functions are normalized in the same way. We use the luminosity function, along with maps describing the redshift completeness of the current 2dFGRS catalogue, and its weak dependence on apparent magnitude, to define a complete description of the 2dFGRS selection function. Details and tests of the calibration of the 2dFGRS photometric parent catalogue are also presented.

We use the energy-balance code MAGPHYS to determine stellar and dust masses, and dust corrected star-formation rates for over 200,000 GAMA galaxies, 170,000 G10-COSMOS galaxies and 200,000 3D-HST galaxies. Our values agree well with previously reported measurements and constitute a representative and homogeneous dataset spanning a broad range in stellar mass (10 8 -10 12 M ), dust mass (10 6 -10 9 M ), and star-formation rates (0.01-100M yr −1 ), and over a broad redshift range (0.0 < z < 5.0). We combine these data to measure the cosmic star-formation history (CSFH), the stellar-mass density (SMD), and the dust-mass density (DMD) over a 12 Gyr timeline. The data mostly agree with previous estimates, where they exist, and provide a quasi-homogeneous dataset using consistent mass and star-formation estimators with consistent underlying assumptions over the full time range. As a consequence our formal errors are significantly reduced when compared to the historic literature. Integrating our cosmic star-formation history we precisely reproduce the stellar-mass density with an ISM replenishment factor of 0.50 ± 0.07, consistent with our choice of Chabrier IMF plus some modest amount of stripped stellar mass. Exploring the cosmic dust density evolution, we find a gradual increase in dust density with lookback time. We build a simple phenomenological model from the CSFH to account for the dust mass evolution, and infer two key conclusions: (1) For every unit of stellar mass which is formed 0.0065-0.004 units of dust mass is also formed; (2) Over the history of the Universe approximately 90 to 95 per cent of all dust formed has been destroyed and/or ejected.

The Magellanic Stream and several high-velocity clouds have now been detected in optical line emission. The observed emission measures and kinematics are most plausibly explained by photoionization due to hot, young stars in the Galactic disk. The highly favorable orientation of the Stream allows an unambiguous determination of the fraction of ionizing photons which escape the Galactic disk. We have modeled the production and f esc transport of ionizing photons through an opaque interstellar medium. Normalization to the Stream detections requires , which is in reasonable agreement with the flux required to ionize the Reynolds layer. Neither f ≈ 6% esc shock heating nor emission within a hot Galactic corona can be important in producing the observed Ha emission. If such a large escape fraction is typical of galaxies, star-forming systems dominate the extragalactic ionizing L * background. Within the context of this model, both the three-dimensional orientation of the Stream and the distances to high-velocity clouds can be determined by sensitive Ha observations.

The recently identified Circinus Galaxy is the nearest (about 4 Mpc) Seyfert 2 galaxy known and we now demonstrate to be one of the best laboratories for studying the effects of nuclear activity on the surrounding environment. Here we present new imaging Fabry-Perot observations of Circinus which confirm the existence of an ionization cone in this object but also show for the first time a complex of ionized filaments extending radially from the nucleus out to distances of 1 kpc. Arcs suggestive of bow shocks are observed at the terminus of some of these filamentary structures. Most spectacular of all, one of the structures appears to be a scaled-up version of a Herbig-Haro jet. The velocity field of the filaments confirms that they represent material expelled from the nucleus (possibly in the form of `bullets') or entrained in a wide-angle wind roughly aligned with the polar axis of the galaxy. The motions observed across the ionization cone are highly supersonic, so high-velocity shocks are likely to contribute to the ionization of the line emitting gas. However, it is not clear at present whether shock ionization dominates over photoionization by the Seyfert 2 nucleus. Extrapolation of the filaments to smaller radii comes to within 1 arcsec (about 20 pc) of the infrared nucleus, therefore suggesting a AGN or nuclear starburst origin to these features. The complex of radial filaments detected in the Circinus galaxy is unique among active galaxies. The frequency of such events is unknown since only a handful of galaxies have been observed at the sensitivity level of our present observations. The event in the Circinus galaxy may represent a relatively common evolutionary phase in the lives of gas-rich active galaxies during which the dusty cocoon surrounding the nucleus is expelled by the action of jet or wind phenomena.Comment: 22 pages including 5 figures, Latex, requires aasms4.sty. To appear in ApJ Letters 479 (1997