Journey to the centre of our galaxy
This infrared image from the NASA/ESA Hubble Space Telescope shows the centre of the Milky Way, 27 000 light-years away from Earth. Using the infrared capabilities of Hubble, astronomers were able to peer through the dust which normally obscures the view of this interesting region. At the centre of this nuclear star cluster — and also in the centre of this image — the Milky Way’s supermassive black hole is located. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) Acknowledgment: NASA, ESA, T. Do and A. Ghez (UCLA), and V. Bajaj (STScI)
The centre of the Milky Way, 27 000 light-years away in the constellation of Sagittarius, is a crowded place. This region is so tightly packed that it is equivalent to having one million stars crammed into the volume of space between us and Alpha Centauri, located 4.3 light-years away.
At the very hub of our galaxy, this dense nuclear star cluster surrounds the Milky Way’s central supermassive black hole, known as Sagittarius A*, which alone is about four million times the mass of the Sun.
Sagittarius A* is not the only mystery lurking in this part of the galaxy. The crowded centre contains numerous objects that are hidden at visible wavelengths by thick clouds of dust in the galaxy’s disc.
In order to truly understand the central part of our galaxy astronomers used the infrared vision of Hubble to peer through this obscuring dust. To reveal the image in all its glory the scientists then assigned visible colours to the different wavelengths of infrared light, which is invisible to human eyes.
The blue stars in the image are foreground stars, which are closer to Earth than the nuclear star cluster, whilst the red stars are either behind much more intervening dust, or are embedded in dust themselves. Some extremely dense clouds of gas and dust are seen in silhouette, appearing dark against the bright background stars.
These clouds are so thick that even Hubble’s infrared capability cannot penetrate them. In addition to the stars hidden by the dust astronomers estimate that there are about 10 million stars in the cluster which are too faint to see, even for Hubble.
Using Hubble’s vantage point above the atmosphere and its high resolution, astronomers were able not only to reveal the stars in this cluster but also to measure their movements over a period of four years. Using this information, they inferred important properties of the nuclear star cluster, such as its mass and structure.
The motion of the stars may also offer astronomers a glimpse into how the nuclear star cluster was formed — whether it was built up over time from globular star clusters that happened to fall into the centre of the galaxy, or from gas spiralling in from the Milky Way’s disc to form stars at the core.
The data for this picture was gathered in September 2011 and is a mosaic stitched together from nine separate images taken with the Wide Field Camera 3 (WFC3).
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
Image credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Acknowledgment: NASA, ESA, T. Do and A. Ghez (UCLA), and V. Bajaj (STScI)
Mathias Jäger
ESA/Hubble, Public Information Officer
Garching, Germany
Tel: +49 176 62397500
Email: mjaeger@partner.eso.org
Media Contact
All latest news from the category: Physics and Astronomy
This area deals with the fundamental laws and building blocks of nature and how they interact, the properties and the behavior of matter, and research into space and time and their structures.
innovations-report provides in-depth reports and articles on subjects such as astrophysics, laser technologies, nuclear, quantum, particle and solid-state physics, nanotechnologies, planetary research and findings (Mars, Venus) and developments related to the Hubble Telescope.
Newest articles
Innovative vortex beam technology
…unleashes ultra-secure, high-capacity data transmission. Scientists have developed a breakthrough optical technology that could dramatically enhance the capacity and security of data transmission (Fig. 1). By utilizing a new type…
Tiny dancers: Scientists synchronise bacterial motion
Researchers at TU Delft have discovered that E. coli bacteria can synchronise their movements, creating order in seemingly random biological systems. By trapping individual bacteria in micro-engineered circular cavities and…
Primary investigation on ram-rotor detonation engine
Detonation is a supersonic combustion wave, characterized by a shock wave driven by the energy release from closely coupled chemical reactions. It is a typical form of pressure gain combustion,…