Bar in spiral galaxy NGC 2903 (WFPC2)

This colourful image, obtained by the Wide Field and Planetary Camera 2 (WFPC2) onboard the NASA/ESA Hubble Space Telescope, shows a close-up of the barred spiral galaxy NGC 2903. The galaxy bears a close resemblance to our Milky Way, which is also believed to be a barred spiral galaxy. Huge dust lanes appearing dark in the image and lots of young stars gathered in hot blue clusters, are sprinkled all over the spiral arms. Barred spirals are excellent laboratories with which to study the processes that trigger star formation. An international group of astronomers has used Hubble to study how the galaxys bar (seen as the reddish glow running diagonally through the image) feeds material to form new stars near the centre. The newly born stars show up partly in a so-called circumnuclear ring around the bright yellowish core of the galaxy and partly as bright star clusters (white knots in the circumnuclear ring). The image was combined from three separate exposures in visible light lasting 820 seconds. The red part of the image was exposed through a 820 nm filter, the green through a 520 nm filter and the blue through a 331 nm filter. Acknowledgements: The data that went into this Hubble image were originally obtained by: John Trauger (Jet Propulsion Laboratory), John Hoessel (University of Wisconsin  Madison), Richard Griffiths (Carnegie Mellon University), Dave Crisp (Jet Propulsion Laboratory), John Clarke (University of Michigan), Christopher Burrows (Space Telescope Science Institute), J. Westphal (California Institute of Technology), Jeff Hester (Arizona State University), Jeremy Mould (National Optical Astronomy Observatories, AURA) and Jon Holtzman (New Mexico State University).