Triggered Star Formation (IMAGE) University of Kent Caption This is a text-book example of triggered star formation. There is the outline of a molecular cloud, which is illuminated by ionizing radiation of massive stars situated off the bottom of the image. The radiation pressure has compressed the cloud and started the process of star formation. The forming stars can be identified by reflection nebulae surrounding them, or by their jets. Models of the process of triggered star formation predict an age gradient of the forming stars with younger objects further inside, away from the source of the ionizing radiation. The object shown here is a prime example that confirms this scenario with reflection nebulae ranging in colors from blue, near the tip of the molecular cloud, to green and yellow further inside. The color change towards red indicates the objects are further embedded in their parental cloud core and thus younger. The youngest object is completely invisible even at these infrared wavelengths, and can only by identified by the jet it is launching (top of image). Credit University of Kent Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.