A Hole in the Stars?


LDN 483Some of the stars appear to be missing, but the black gap in this starfield is not really a hole. It’s a region clogged with gas and dust. This dark cloud is called Lynds Dark Nebula 483 0r LDN 483. Clouds such as this are the birthplaces of future stars.

LDN 483 is about 700 light-years away in the constellation of Serpens (The Serpent). The cloud contains enough dusty material to completely block the visible light from background stars. Such a dense molecular cloud qualifies as a dark nebulae because of this obscuring property. One might think that the starless nature of a cloud like LDN 483 would suggest that it’s not a place where stars can take root and grow. The opposite is true: dark nebulae offer the most fertile environments for eventual star formation.

Studies of star formation in LDN 483 have discovered some of the youngest observable kinds of baby stars hidden in LDN 483. These gestating stars can be thought of as still being in the womb, having not yet been born as immature stars. In this first stage of stellar development, the star-to-be is just a clump of gas and dust contracting under the force of gravity within the surrounding molecular cloud. The protostar is still quite cool. At about -250°C they are colder than liquid oxygen on the Earth’s surface, and they “shine” only in long-wavelength submillimetrer light. Still, temperature and pressure are beginning to increase in the fledgling star’s core.

This earliest period of star growth lasts for a few thousands of years, an very short amount of time in astronomical terms.Stars typically live for millions or billions of years. Over the course of several million years, the protostar will grow warmer and denser. Its emission will increase, graduating from mainly cold, far-infrared light to near-infrared and finally to visible light. The once-dim protostar will have then become a fully luminous star.

As more and more stars emerge from LDN 483, the dark nebula will disperse and lose its opacity. Finally, the missing background stars that are currently hidden will then come into view, but they will be outshone by the bright young-born stars in the cloud.

Image Credit: ESO

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