galaxy formation tagged posts

A deep photographic image of M83 taken using the UK Schmidt Telescope by Malin & Hadley (1997, figure reproduced with permission) where the white scale bar corresponds to 30 arcmin. The northern stream appears not to be associated with dw1335-29, circled in red. Credit: Carrillo et al., 2016.

M83, Southern Pinwheel Galaxy has a newly found dwarf satellite 85,000 light years from its host. This satellite galaxy was designated dw1335-29 and could be an irregular or a transition dwarf. Messier 83 is one of the closest and brightest barred spiral galaxies. It is located about 15 million light years away in the constellation Hydra. Finding new satellites of galaxies beyond the Local Group such as Messier 83 could provide essential insights on galaxy formation in a cosmological context.

In 2015,...

The position of Virgo I in the constellation of Virgo (left). The right panel shows a density map of Virgo I’s member stars in a 0.1 deg x 0.1 deg area, based on the stars located inside the green zone in the color-magnitude diagram of Virgo I shown in Figure 4. The color range from blue -> white -> yellow -> red indicates increasing density. (Credit: Tohoku University/National Astronomical Observation of Japan)

An international team has found an extremely faint dwarf satellite galaxy of the Milky Way. The team’s discovery is part of the ongoing Subaru Strategic Survey using Hyper Suprime-Cam. The satellite, named Virgo I, lies in the direction of the constellation Virgo. At the absolute magnitude of -0.8 in the optical waveband, it may well be the faintest satellite galaxy yet found...

Age structure of the Milky Way’s halo

Using colors to identify the approximate ages of >130,000 stars in the Milky Way’s halo, Notre Dame astronomers have produced the clearest picture yet of how the galaxy formed more than 13.5 billion years ago. The chronographic (age) map supports a hierarchical model of galaxy formation. That model, developed by theoreticians over the past few decades, suggests that the Milky Way formed by merging and accretion of small mini-halos containing stars and gas, and that the oldest of the Milky Way’s stars are at the center of the galaxy and younger stars and galaxies merged with the Milky Way, drawn in by gravity over billions of years...