Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ultra-compact dwarf galaxies are bright star clusters

20.12.2011
Astronomy & Astrophysics is publishing the results of a detailed investigation of how many 'ultra-compact dwarf galaxies' (UCDs) can be found in nearby galaxy clusters.

UCDs were recognized as a populous and potentially distinct class of stellar systems about a decade ago. But they are still mysterious objects that are characterized by a compact morphology (30-300 light-years in size) and high masses (more than one million solar masses).

More generally, their properties (e.g., their size, shape, or luminosity) are similar to those of both star clusters and dwarf galaxies. Several hundred UCDs have been found to date. Two main formation channels for these puzzling objects have been proposed so far. UCDs might either be very massive star clusters or be 'normal' dwarf galaxies transformed by tidal effects.

S. Mieske, M. Hilker, and I. Misgeld (ESO) present a statistical study of the UCD population: they define new statistical tools that relate the number of UCDs to the total luminosity of their host environment. This allows them to use statistical arguments to test the hypothesis that UCDs are bright star clusters. They predict that if UCDs are bright star clusters, we would expect to find only one or two UCDs around the Milky Way, which corresponds to what is seen, as omega Centauri is the only Milky Way satellite that can be considered a UCD.

With their new tools at hand, the authors have investigated the results of spectroscopic UCD surveys in the environment of massive galaxy clusters such as Fornax, Hydra, and Centaurus, as well as in galaxy groups like our very own Local Group. Most data analysed were obtained at ESO's Very Large Telescope in Chile, using the instruments FLAMES, VIMOS, and FORS2. For the Fornax cluster, they also used a large database of compact stellar objects, which contained about 180 UCDs (see Fig. 1).

This statistical study clearly shows that the luminosity distribution of UCDs match very well that of the brightest globular star clusters. It supports the hypothesis that the vast majority of UCDs are actually very massive star clusters. From a statistical point of view, there is no need to invoke another scenario to explain the origin of UCDs.

[1] The team of astronomers includes S. Mieske (ESO/Chile), M. Hilker, and I. Misgeld (ESO/Germany)

The specific frequencies of ultra-compact dwarf galaxies, by S. Mieske, M. Hilker, and I. Misgeld

Published in Astronomy & Astrophysics, 2012, vol. 537, A3

Dr. Jennifer Martin | EurekAlert!
Further information:
http://www.aanda.org/index.php?option=com_content&task=view&id=788&Itemid=277&lang=en_GB.utf8%2C+en_GB.UT

Further reports about: Astrophysics Milky Way galaxy cluster massive star star cluster

More articles from Physics and Astronomy:

nachricht Rapid water formation in diffuse interstellar clouds
25.06.2018 | Max-Planck-Institut für Kernphysik

nachricht When fluid flows almost as fast as light -- with quantum rotation
22.06.2018 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany

25.06.2018 | Ecology, The Environment and Conservation

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>