ASTROPHYSICS: Galaxy Evolution: A Dim Future

Astronomy & Astrophysics The H α galaxy survey

We discuss the selection and observations of a large sample of nearby galaxies, which we are using to quantify the star formation activity in the local Universe. The sample consists of 334 galaxies across all Hubble types from S0/a to Im and with recession velocities of between 0 and 3000 km s−1. The basic data for each galaxy are narrow band Hα+[N] and R-band imaging, from which we derive st...

ASTRONOMY AND ASTROPHYSICS Galaxy coordinates I . Accuracy

Using a generalization of the triple intercomparison method introduced by de Vaucouleurs and Head we calculated the accuracy of galaxy coordinates taken from the large catalogues. The result confirms the qualitative estimation we had in mind about the different catalogues, but for the first time it will be now possible to give a quantitative estimation of the accuracy of the position of individ...

The Astrophysics of Early Galaxy Formation

Hydrogen in the universe recombined about half a million years after the Big Bang, and cooled down to a temperature of a few kelvins until the first non-linearities developed, and evolved into stars, galaxies, and black holes that lit up the universe again. In currently popular cold dark matter flat cosmologies (ΛCDM), some time beyond a redshift of 10 the gas within halos with virial temperatu...

Astronomy and Astrophysics Is I Zw 18 a Young Galaxy?

Hubble Space Telescope (HST) colour magnitude diagrams in B, V and R along with long-slit Multiple Mirror Telescope (MMT) spectrophotometric data are used to investigate the evolutionary status of the nearby blue compact dwarf (BCD) galaxy I Zw 18. We find that the distance to I Zw 18 should be as high as 20 Mpc, twice the previously accepted distance, to be consistent with existing observation...

Galaxy Evolution