Free Astronomy Magazine March-April 2015

SPACE CHRONICLES T his visible-light wide-field image of the region around the dark nebula LDN 483 was created from photographs forming part of the Digitized Sky Survey 2. LDN 483 appears at the centre. [ESO and Digitized Sky Survey 2] This earliest period of star growth lasts a mere thousands of years, an astonishingly short amount of time in astronomical terms, given that stars typically live for millions or bil- lions of years. In the following sta- ges, over the course of several mil- lion years, the protostar will grow warmer and denser. Its emission will increase in energy along the way, graduating from mainly cold, far-in- frared light to near-infrared and fi- nally to visible light. The once-dim protostar will have then become a fully luminous star. As more and more stars emerge from the inky depths of LDN 483, the dark nebula will disperse further and lose its opacity. The missing back- ground stars that are currently hidden will then come into view — but only after the pas- sage of millions of years, and they will be outshone by the bright young-born stars in the cloud. T his video takes you on a journey to the dark neb- ula LDN 483 as seen with the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at the La Silla Ob- servatory. The object is a re- gion of space clogged with gas and dust. These mate- rials are dense enough to effectively eclipse the light of background stars. [ESO/ N. Risinger (skysurvey.org) Digitized Sky Survey 2] true: dark nebulae offer the most fertile environments for eventual star formation. Astronomers studying star forma- tion in LDN 483 have discovered some of the youngest observable kinds of baby stars buried in LDN 483’s shrouded interior. These ges- tating stars can be thought of as still being in the womb, having not yet been born as complete, albeit im- mature, stars. In this first stage of stellar develop- ment, the star-to-be is just a ball of gas and dust contracting under the force of gravity within the surround- ing molecular cloud. The protostar is still quite cool — about –250 de- grees Celsius — and shines only in long-wavelength submillimetre light. (The Atacama Large Millime- ter/submillimeter Array (ALMA), operated in part by ESO, observes in submillimetre and millimetre light and is ideal for the study of such very young stars in molecular clouds.) Yet temperature and pres- sure are beginning to increase in the fledgling star’s core. n