Discovery of a Large Scale Structure of Wandering
Public Release Date: 12-Mar-2010 (Seoul National University)
Contact: Myung Gyoon LEE
(Email) firstname.lastname@example.org (Phone) 82-2-880-6684
Department of Physics and Astronomy, Seoul National University, Seoul, Korea
Source: Science Express
(http://www.sciencemag.org/sciencexpress Mar 11, 2010)
Wandering Globular Clusters Fill in between Galaxies in Virgo
Astronomers (Myung Gyoon LEE, Hong Soo PARK in Seoul National University, Korea and Ho Seong HWANG in CEA, France) have discovered a large population of globular clusters wandering between galaxies in the Virgo cluster of galaxies.
Globular clusters, millionaires with stars, are the oldest objects in the universe and are an excellent tracer of dark matter. Globular clusters are usually found in galaxies that are billionaires with stars.
Decades ago it was predicted that there may be a large group of globular clusters wandering between galaxies in a cluster of galaxies. A cluster of galaxies is a huge system containing thousands of galaxies.
They detected a large scale structure made of globular clusters wandering between galaxies in the nearby Virgo cluster of galaxies. They are as far as 54 million light years away so that they look like single stars in the images. The spatial distribution of these wanderers is as large as millions of light years, much larger than normal galaxies. These wandering globular clusters might have been stripped off from small dwarf galaxies. These wanderers may be the first objects formed after the Big Bang in the universe. These astronomers made a map of globular clusters using data in the Sloan Digital Sky Survey to find these wanders. This job is like finding needles in haystacks or making a map of the bottom of the deep ocean.
(Figure 1). Wandering Globular Clusters in Virgo
(Lee M.G., Park, H.S., and Hwang, H.S. 2010)
(Left) A number density map of globular clusters in the Virgo cluster of galaxies being at the distance of 54 million light years (redder color represents higher number density). The Virgo cluster of galaxies includes more than 2000 galaxies, of which some bright ones are labelled with numbers. Among them Messier 49 and Messier 87 are the brightest and most massive galaxies, respectively. The center of the Virgo cluster is located between Messier 87 and Messier 86.
Globular clusters are the oldest objects in the universe and are an excellent tracer of dark matter. While globular clusters in red and yellow regions are controlled by the gravity of bright galaxies, those in green and cyan regions are mostly floating around between galaxies like wanderers, forming a large scale structure (they are called intracluster globular clusters). This large scale structure of the wandering globular clusters in Virgo is revealed for the first time in this map. This map was made using the Sloan Digital Sky Survey data. (source: Lee, M.G., Park, H.S., and Hwang, H.S. 2010, Science Express, Mar 11, 2010).
(Upper right) An optical image of Messier 49, a giant elliptical galaxy in Virgo, being an expanded map of the small square in the left panel. Tiny yellow dots in this image are mostly globular clusters in this galaxy. A giant elliptical galaxy like M49 includes several thousands of globular clusters. This image was made with data taken at the Kitt Peak National Observatory 4m telescope. (source: Lee, M.G. 2003, Journal of Korean Astronomical Society, 36, 187).
(Lower right) An optical image of Messier 80, a rich globular cluster (GC) in our Galaxy. This globular cluster is seen in the constellation Scorpion, being at the distance of about 30,000 light years. A bright globular cluster includes millions of stars, but appears as a tiny dot at the distance of Virgo. This image was made with data taken using the Hubble Space Telescope. (source: the Hubble Heritage Team/AURA/STScI/NASA/ESA).