What are S0 (0) Galaxies?

Among early-type galaxies with almost circular isophotes E0 and E1 galaxies are, at 99.3% significance, more luminous than face-on objects classified as S0 (0) and S(0) (1). This result supports the view that rotation and "diskiness" are more important in the outer regions of faint-early type galaxies than they are for more luminous galaxies of very early morphological type.Comment: 7 pages. 0 figures. Astrophysical Jounral Letters in pres

Ten Billion Years of Galaxy Evolution

Observations in the Hubble Deep Fields have been used to study the evolution of galaxy morphology over time. The majority of galaxies with z < 1 are seen to be disk like, whereas most objects with z > 2 appear to be either chaotic or centrally concentrated ``blobs''. Such blobs might be the ancestral objects of ellipticals or of galaxy bulges. About 1/3 of objects with z > 2 appear to be in the process of merging. The region with 1 < z < 2 marks an important transition in the global history of star formation from a merger dominated regime at z > 2, to one at z < 1 in which most star formation takes place in galactic disks. It is speculated that the break in the Madau plot at z sim 1.5 might be related to the transition from merger-dominated star formation at z > 2 to disk-dominated star formation at at z < 1.Comment: 19 pages. 1 figure. To be published in the August 2002 issue of PAS

Caltech Faint Galaxy Redshift Survey XV: Classification of Galaxies with 0.2 < z < 1.1 in the Hubble Deep Field (North) and its Flanking Fields

To circumvent the spatial effects of resolution on galaxy classification, the images of 233 objects of known redshift in the Hubble Deep Field (HDF) and its Flanking Fields (FF) that have redshifts in the range 0.20 < z < 1.10 were degraded to the resolution that they would have had if they were all located at a redshift z= 1.00. As in paper XIV of the present series, the effects of shifts in rest wavelength were mitigated by using R-band images for the classification of galaxies with 0.2 < z < 0.6 and I-band images for objects with redshifts 0.6 < z < 1.1. A special effort was made to search for bars in distant galaxies. The present data strongly confirm the previous conclusion that the Hubble tuning fork diagram only provides a satisfactory framework for the classification of galaxies with z ~< 0.3. More distant disk galaxies are often difficult to shoehorn into the Hubble classification scheme. The paucity of barred spirals and of grand-design spirals at large redshifts is confirmed. It is concluded that the morphology of disk galaxies observed at look-back times smaller than 3--4 Gyr differs systematically from that of more distant galaxies viewed at look-back times of 4--8 Gyr. The disks of late-type spirals at z >0.5 are seen to be more chaotic than those of their nearer counterparts. Furthermore the spiral structure in distant early-type spirals appears to be less well-developed than it is in nearby early-galaxies.Comment: Accepted for publication in the A

Killing spinor space-times and constant-eigenvalue Killing tensors

A class of Petrov type D Killing spinor space-times is presented, having the peculiar property that their conformal representants can only admit Killing tensors with constant eigenvalues.Comment: 11 pages, submitted to CQ

The three British Occupations of Potchefstroom during the Anglo-Boer War 1899-1902

No Abstac

Caltech Faint Galaxy Redshift Survey XIV: Galaxy Morphology in the HDF (North) and its Flanking Fields to z=1.2

Morphological classifications are reported for Hubble Space Telescope (HST) images of 241 galaxies in the Hubble Deep Field (HDF) and its Flanking Fields (FF) with measured redshifts in the interval 0.25 < z < 1.2, drawn from a magnitude-limited redshift survey to R = 24.0. The galaxies are divided into three groups with redshifts in the intervals [0.25,0.6], [0.6,0.8], [0.8,1.2]. R606 images from the first group and I814 images from the second and third groups are compared with B-band images of nearby galaxies. All classifications were therefore made at approximately the same rest wavelength. Selection biases are discussed. We corroborate and extend the results of earlier investigations by observing that: Most intermediate and late-type galaxies with $z\gtrsim0.5$ have morphologies that are dramatically different from those of local galaxies and cannot be shoehorned into the Hubble ``tuning fork'' classification scheme. Grand-design spirals appear to be rare or absent for $z\gtrsim0.3$. Many Sa and Sb spirals with $z\gtrsim0.6$ do not exhibit well-defined spiral arms. The arms of distant Sc galaxies appear more chaotic than those of their nearby counterparts. (abridged) On the basis of these and similar observations, it is inferred that the development of pronounced spiral structure was delayed until \~5 Gyr and that most bulges are probably not formed by disintegrating bars. Major morphological changes were still taking place only ~5 Gyr ago even though changes in the integrated light of most galaxies were then much slower than they were ~10 Gyr ago.Comment: Accepted by the Astronomical Journa

The Stellar Mass Spectrum in the Young Populous Cluster NGC 1866

The young populous cluster NGC 1866 in the Large Magellanic Cloud LMC), which is probably one of the most massive object formed in the LMC during the last ~ 3 Gyr, appears to have an unexpectedly high mass-to-light ratio. From its velocity dispersion Fischer et al. (1992) find its mass to be (1.35 " 0.25) x 105 Mu. The luminosity of this cluster is MV = -8.93 " 0.13, corresponding to LV = (3.2 " 0.4) x 105 LV (u). This yields M/LV = 0.42 " 0.09 in solar units. For a cluster of age 0.1 Gyr such a relatively high mass-to-light ratio requires a mass spectrum with an exponent x = 1.72 " 0.09; or x = 1.75 " 0.09 if mass loss by evolving stars is taken into account.Comment: To be published in the October 1999 issue of the Publications of the Astronomical Society of the Pacifi

The Interconnection between Processes of State and Class Formation: Problems of Conceptualisation

In recent years a great deal of attention has been given to the exploitative character of the political and economic relations between the rich industrial ('developed') countries and the poor agrarian ('underdeveloped' or 'developing') countries, as interconnected parts of the global capitalist 'system'. The global network of capitalist relations or system has been called 'imperialism' and the parts or components of this whole have been named centers and peripheries or metropoles and satellites