The New Center for Star and Planet Formation

by Bo Reipurth

The Trifid Nebula, " a stellar nursery," allows astronomers to study newborn stars as they emerge from their dusty cocoons. This image was obtained by the CFHT at Mauna Kea. Image by J.-C. Cuillandre and Coelum, (c) 2000 Canada-France-Hawaii Telescope. For more CFHT images: www.cfht.hawaii.edu/HawaiianStarlight/

One night, when Huck Finn was in a reflective mood, he looked at the stars in the sky and wondered ". . . did they just happen or was they made?" When Mark Twain wrote his masterpiece, The Adventures of Huckleberry Finn, this was a profound question with no answer. Today, more than a hundred years later, the question of the origin of stars remains a profound one, and the search for an answer is still challenging astronomers all over the world.

Stars are the building blocks of the visible Universe. During the first half of the twentieth century, advances in spectroscopy, quantum mechanics, and nuclear physics led to an understanding of the main-sequence lives of stars. Concerted efforts in the latter half of the century explained most of the bewildering array of phenomena associated with the final stages of stellar evolution. In sharp contrast, progress in our efforts to understand how and why interstellar clouds turn into stars has, until very recently, been limited. Understanding how stars are born is the single most important remaining problem in stellar evolution.

When our own Sun was born, its retinue of planets formed as well. With the recent discovery of numerous planets orbiting around other stars, it has become clear that planets must be a common by-product of the birth of stars. This in turn leads to fundamental questions about whether other planets have conditions conducive to life, and thus whether life itself is widespread throughout our Milky Way.

Astronomers at the IfA have been interested for many years in the complex problems of star birth, and have contributed significantly to our current understanding of this field. To encourage and further strengthen research in this area, IfA astronomers and their nearby colleagues inaugurated the Center for Star and Planet Formation (CSPF) earlier this year.

The CSPF has multiple goals. First, it strives to facilitate communication among researchers who specialize in different disciplines, each of which provides insight into important but limited aspects of the main problem. Like the proverbial blind men who are touching different parts of an elephant, we are trying to help each other to see the full outline of a much larger structure.

Some of us specifically study the properties of newborn stars and of the dark clouds out of which they form. Others are experts on the small bodies of the planetary system, such as asteroids and comets, which form a fossil disk of leftover material from the formation period of our own planetary system. Yet others work on extrasolar planets and brown dwarfs, exploring the borderline between giant planets and the smallest stellarlike objects. Finally, we are fortunate to have nearby colleagues at the Hawaii Institute of Geophysics and Planetology who are world-renowned experts on meteorites. Their collection of meteorites permits us to learn from direct hands-on study about the building blocks of our planetary system. This multifaceted effort encourages the cross-fertilization of ideas, out of which new directions of research can spring.

Weekly CSPF seminars by IfA staff and visitors help us to keep abreast of the latest research and of developments in the field. A visitor program is on the drawing board, and plans are also underway for starting a summer school that will bring together, from all over the world, graduate students working on a doctorate in star or planet formation. In addition, the CSPF is in the process of organizing a major international meeting, "Protostars and Planets," to be held in November 2005.

Because newborn stars are shrouded in dust and gas, they are all but invisible at optical wavelengths. But at infrared wavelengths, we begin to be able to peer into the heart of the dark clouds. Infrared observations are, however, hampered by Earth's atmosphere, so studies of stellar nurseries are best done from Mauna Kea, which at 13,800 feet above sea level, is beyond most of the atmosphere. Sub-millimeter observations, which are even more affected by the atmosphere, have turned out to be crucial to our understanding of how planetary systems form, and the Submillimeter Array, which will soon begin operation on Mauna Kea, will give us unprecedented views of the circumstellar disks out of which planets will condense.

Because IfA operates the Mauna Kea Observatories, it follows that the IfA is perhaps better suited than almost any other institute to host a center like the CSPF.

For more information: www.ifa.hawaii.edu/CSPF

The Whirlpool Galaxy is a vast system of stars similar in many respects to our own Milky Way Galaxy. It is rich in regions of star formation, which can be seen as reddish clusters of stars and nebulae strung out along the well-defined spiral arms. The Whirlpool Galaxy is particularly interesting because it is colliding with another smaller galaxy on the right side of the image. Such collisions trigger additional violent star formation events. Image by J.-C. Cuillandre and Coelum, (c) 2000 Canada-France-Hawaii Telescope. For more CFHT images: www.cfht.hawaii.edu/HawaiianStarlight/

The Lives of Stars

Main-sequence stars, including the Sun, convert hydrogen to helium in their cores. Stars spend most of their lives on the main sequence, but the length of time they spend there depends on their mass. Very massive stars stay on the main sequence for only about a million years before they die in a supernova explosion. Smaller stars such as the Sun spend billions of years on the main sequence and become red giants and then white dwarfs. For more information about stars: imagine.gsfc.nasa.gov/index.html