Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ghosts of galaxies

16.04.2008
An international team of astronomers has identified huge star streams in the outskirts of two nearby spiral galaxies. For the first time, they have obtained a panoramic overview of an example of galactic cannibalism similar to that involving the Sagittarius dwarf galaxy in the vicinity of the Milky Way.

The detection of these immense stellar fossils confirms the predictions of the cold dark matter model of cosmology, which proposes that present-day grand design spiral galaxies were formed from the merging of less massive stellar systems.

The first of these debris structures surrounds the galaxy NGC 5907, located 40 million light-years from Earth and formed from the destruction of one of its dwarf satellite galaxies at least four thousand million years ago. According to the research team, the dwarf galaxy has lost the greater part of its mass in the form of stars, star clusters and dark matter, all of which has become strewn out along its orbit, giving rise to a complicated assembly of criss-crossing galactic fossils whose radius exceeds 150 000 light-years.

“Our results provide a fresh insight itno this spectacular phenomenon surrounding spiral galaxies and show that haloes contain fossil dwarf galaxies, thus providing us with a unique opportunity to study the final stages in the assembly of galaxies like ours,” maintains David Martínez, a researcher at the Instituto de Astrofísica de Canarias (IAC) leading the team that carried out the observations.

The astronomers’ search has not been able to find the main bodies of the devoured galaxies, which leads them to conclude that they have by now been completely destroyed. “These star streams are very difficult to detect and have a very low density of stars,” comments Martínez. “It is this that gives them their ghostly aspect. Hence, being related with the death of a dwarf galaxy, they may be considered as the ghosts of now vanished galaxies.”

The team has discovered another huge, tenuous stream in the shape of a loop in the galaxy NGC 4013, almost 50 million light-years away in the constellation Ursa Major. Its ghostly trail stretches more than 80 000 light-years from the nucleus and is made up of old, metal-poor stars. Although its three-dimensional geometry is unknown, it possesses a structure very similar to that of the Monoceros tidal stream, a ring of stars surrounding the Milky Way that was formed through the destruction of a dwarf galaxy three thousand million years ago.

Jorge Peñarrubia, a theoretical astrophysicist at the University of Victoria (Canada) and member of the team, specializes in modelling these star streams. According to Peñarrubia, “fitting theoretical models to these star streams enables us to reconstruct their history and describe one of the most mysterious and controversial components of galaxies: dark matter.”

Astrophotographers join the chase

For the job of seeking out and detecting the streams, the team has enlisted the help of the renowned astrophotographer R. Jay Gabany, whose contribution towards obtaining the images “has been decisive,” says Martínez, “a fact that underlines yet again the great contribution made by amateurs.”

For years, R. Jay Gabany has obtained spectacular colour images of the deep sky with small robotic telescopes in New Mexico and Australia. His images have been published in the best popular astronomy magazines in the world. His work on this project demonstrates the potential contribution of amateur astronomers to XXI century astronomy. With the new technologies, they are capable of participating in highly competitive scientific projects at an international level.

Nadjejda Vicente Cabañas | alfa
Further information:
http://www.iac.es/divulgacion.php?op1=16&id=519&lang=en

More articles from Physics and Astronomy:

nachricht Hubble sees Neptune's mysterious shrinking storm
16.02.2018 | NASA/Goddard Space Flight Center

nachricht Supermassive black hole model predicts characteristic light signals at cusp of collision
15.02.2018 | Rochester Institute of Technology

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: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

Im Focus: Autonomous 3D scanner supports individual manufacturing processes

Let’s say the armrest is broken in your vintage car. As things stand, you would need a lot of luck and persistence to find the right spare part. But in the world of Industrie 4.0 and production with batch sizes of one, you can simply scan the armrest and print it out. This is made possible by the first ever 3D scanner capable of working autonomously and in real time. The autonomous scanning system will be on display at the Hannover Messe Preview on February 6 and at the Hannover Messe proper from April 23 to 27, 2018 (Hall 6, Booth A30).

Part of the charm of vintage cars is that they stopped making them long ago, so it is special when you do see one out on the roads. If something breaks or...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Fingerprints of quantum entanglement

16.02.2018 | Information Technology

'Living bandages': NUST MISIS scientists develop biocompatible anti-burn nanofibers

16.02.2018 | Health and Medicine

Hubble sees Neptune's mysterious shrinking storm

16.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>