Stars Gallery

Orion nebula

Orion nebula. Coloured composite infrared and visible light image of the Orion nebula M42. This emission nebula, a cloud of gas and dust in which starbirth takes place, is found in the constellation Orion, some 1500 light years from Earth. Glowing clouds of ionised hydrogen and sulphur gases are green, and cool clouds of polycyclic aromatic hydrocarbons are orange and red. The gases are ionised by radiation from the four young Trapezium stars at the core (centre left). The small orange dots are embryonic stars, growing as they accumulate dust and gas. M42's neighbour, the M43 nebula, can also be seen (pale blue, top left). Infrared data from the Spitzer Space Telescope, visible light data from the Hubble Space Telescope

© NASA/JPL-CALTECH/STSCI/SCIENCE PHOTO LIBRARY

Diagram showing the spectral class and luminosity of stars

Diagram showing the spectral class and luminosity of stars. The diagram was named The Hertzsprung-Russell Diagram, or the H-R diagram for short. At the beginning of the 20th century two astronomers found that if stars were plotted on a diagram with their luminosity (brightness) on one axis, and their spectral class on the other, that stars formed three distinct groups. The largest group, the Main Sequence Stars, is where 90% of the stars are found. These stars are fusing hydrogen into helium in their cores. This group propagates diagonally from the upper left corner, down to the right corner. The group below the main sequence is the White Dwarfs, which is a group of small, earth-sized stellar remnants. The third group, which is found above the main sequence is that of the giants.
Stars appear on a specific place on the main sequence depending on their mass and age. The mass determines when it will leave the main sequence.The H-R diagram is a significant tool for astronomers, when it comes to understanding stellar evolution

© Fahad Sulehria/Stocktrek Images

Cygnus and Lyra constellations

Cygnus and Lyra constellations. Cygnus, the swan, is at centre left, with Lyra, the lyre, at centre right. The brightest star is Cygnus is Deneb (Alpha Cygni, upper left). This is one of the most powerful stars known, and is one of the brightest stars in the night sky despite its great distance of over 3000 light years. The brightest star in Lyra is Vega (Alpha Lyrae). This is the fifth brightest star in the night sky but is far closer than Deneb, at just 26 light years. Cygnus follows the path of the Milky Way from top left to bottom right. The Milky Way in this region is studded with nebulae (red), star clusters and dark dust clouds

© ECKHARD SLAWIK/SCIENCE PHOTO LIBRARY