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Constraints on the Hubble constant from observations of the brightest red-giant stars in a Virgo-cluster galaxy
Harris, William E.; Durrell, Patrick R.; Pierce, Michael J. +1 more
The nearest large groups of elliptical galaxies, in the Virgo and Fornax clusters, play a central role in determinations of the Hubble constant, H0, and hence the cosmological rate of expansion. Because the relative distances between these two clusters and more remote clusters are well known, absolute distance determinations to Virgo an…
Star formation triggered by galaxy collisions
Lutz, Dieter; Genzel, Reinhard; Tacconi, Linda
It is becoming increasingly clear that collisions between galaxies play an important role in galaxy evolution. The ultraluminous infrared galaxies are predominantly powered by enormous star-formation events that are triggered in the last phases of such collisions. These bursts occur just before the galaxies merge to form single elliptical galaxies.
Unexpected stellar velocity distribution in the warped Galactic disk
Lattanzi, M. G.; Drimmel, R.; Smart, R. L. +1 more
It is now over 40 years since radio observations of neutral hydrogen revealed the gaseous disk of our Galaxy to be warped. Subsequently, the warp has been detected in the distribution of Galactic dust, molecular clouds, and luminous stars,. Roughly half of all spiral galaxies have similarly warped disks, which suggests that warps are a common and …
The formation and evolution of galaxies.
Ellis, Richard
Galaxies represent the visible fabric of the Universe and there has been considerable progress recently in both observational and theoretical studies. The underlying goal is to understand the present-day diversity of galaxy forms, masses and luminosities. Popular models predict the bulk of the population assembled recently, in apparent agreement w…
The optical counterparts of γ-ray bursts
Harrison, Thomas E.; McNamara, Bernard J.
The origin of γ-ray bursts-which are among the most energetic events in the Universe-has puzzled astronomers for 25 years. Since 1991, new events have been discovered at a rate of about one per day, but because their positions were poorly determined, the objects responsible for these outbursts could not be identified. Now, following the launch of …