Research Interests

My research focuses broadly on the formation of stars, planets, and the origin of life. This involves using molecules to probe the conditions deep inside molecular clouds, the sites of stellar birth, and determining how chemical composition changes during the process of star and planet formation.

Star Formation:

Comparison of N2H+ J = 10 integrated emission (contours) and the visual extinction image. 2002ApJ...570L.101B, Bergin, Alves, Huard, Lada Click to Enlarge

Stars are born inside giant clouds composed of gas and tiny solid particles that astronomers call dust grains. These clouds contain enough mass to create of millions of stars like the Sun and are predominantly molecular in composition. Over the past 25 years the emission line radiation arising from gaseous molecules has held the promise of being effective probes of the physical and dynamical state of the birth sites of star and planetary systems.

My research has found that during the earliest stages of star formation, the chemical composition is significantly altered. In general terms, stellar birth involves the collapse of portions of the cloud under the weight of gravity. During the gravitation collapse gaseous molecules freeze onto the surfaces of the dust grains in the form of ice. This reduces our ability to study star formation because frozen molecules are not as effective probes as are gaseous molecules. Using detailed models of the chemistry my collaborators and I have isolated a few key molecular species that do not freeze onto grains as readily. Using these species as probes allows us to begin the process of deciphering the true initial conditions of star formation and more fully realize the long-standing promise of using molecular line observations to study star formation.

Planet Formation

Schematic of a few of the major processes that effect the chemistry in protoplanetary disks. Click to Enlarge

Planets are born inside disks of gas and dust around solar type stars. The gas inside this disk is expected to show significant gradients in the chemical composition both radially (distance from the star) and vertically (from the disk surface to mid-plane where planets will be born). While limited by current telescope capabilities, we are just beginning to understand the conditions inside these so-called "proto-planetary" disk systems around distant stars.

Here my research has focused on the determination of the ongoing physical processes that govern the chemistry inside the disk. This involves using NASA's Hubble Space Telescope to determine the strength of the molecule destroying ultraviolet radiation field and using theory to explore the effects of energetic X-ray radiation on the chemistry. The ultimate goal of this research is the development of more reliable and predictive models of the evolving chemistry in protoplanetary disks.

Astrobiology and the Origin of Life

Emission from water molecules in the NGC1333 molecular cloud. Bergin, Kaufman, Melnick, Snell, & Howe Click to Enlarge

The emerging field of astrobiology seeks to explore possible links between chemistry in space and the origins of life. While the exact nature of this connection is uncertain, the presence of water in the interstellar medium, in comets within our own solar system, and on the Earth (Mars?) provides the clearest relation.

For the past decade I have been associated with NASA's Submillimeter Wave Astronomy Satellite (SWAS) which was in operation from 1998 through 2003. During this time SWAS found the surprising result that water vapor in the interstellar medium was not as abundant as had been previously theorized. Water is likely present, but mainly in the form of water ice. Ice-covered grains could collide, stick together and form increasingly larger objects, eventually becoming the building blocks of planets in a new solar system. The trapped water could then be released when these planets form and may collect into oceans and lakes. With the strong evidence that water is plentiful in interstellar space it is likely that it could perhaps have been delivered to other proto-Earths. These suggestions are fascinating but much more work needs to be done.

The search for water and other important organic species in interstellar space will continue through other NASA and ESA missions such as the Spitzer Space Telescope and the Herschel Space Observatory. I will be using both of these observatories to continue the search for the presence of the molecules of life in space.