Making Massive Stars

Sep 15, 2009
A brightness contour-level diagram of a complex, massive star forming region as seen at radio wavelengths. At the center of the ensemble is the luminous core, which appears to be forming one (or perhaps more) massive stars; its total luminosity is equal to that of about 62,000 suns. Astronomers have found evidence that some key processes underway here are like those that occur when forming low mass stars. Credit: L. Rodriguez et al., and the Very Large Array

( -- Our understanding of star formation leans heavily on observations of stars like the sun, namely, those that are modest in mass and that are born and evolve at a relatively leisurely pace.

By way of contrast, more massive stars mature so quickly that both observations and theory are hard pressed to follow their progress in detail. In the current theoretical description of star formation, a central protostar accretes material from a circumstellar disk that in turn is surrounded by a much larger, more nearly spherical envelope of infalling dust and gas. One result, a consequence of the star's spin, is that the young star produces polar jets of ionized gas and molecular outflows during its early stages of evolution. These outflows are widely seen, and are important markers of stellar youth. The issue for astronomers is whether this basic paradigm also applies to the formation of all stars, including massive stars, or whether there might be other processes at work.

It is possible that are formed by processes that are radically different from those that produce low-mass stars. One suggested alternative, for example, is formation via the merging of lower mass protostars. If are formed by accretion processes like those in low mass counterparts, astronomers expect that disks and jets will also be present during their earliest stages of evolution. On the other hand, if they are formed through coalescence of lower-mass stars, then neither disks nor jets are expected since they would be disrupted during the mergers.

SAO astronomers Ramiro Franco-Hernandez and Jim Moran, together with two colleagues, used the Submillimeter Array and other to probe the activity in one region shining with the brightness of about 62,000 suns and known to be the site of massive young stars. They observed the detailed motions of the gas clouds in the region by looking at emission from masers. Masers are the radio wavelength analogues of lasers; because the maser emission is so bright and monochromatic, small motions of the maser gas can be detected and then modeled.

The maser emission in this region reveals evidence of multiple sources in the central, massive source along with outflow activity and a rotating structure. The scientists estimate that the mass of the central source is around 30 solar masses. The results suggest that the formation of this source, one of the most luminous protostars (or perhaps cluster of protostars) known, is taking place with the presence of ionized jets and disk-like structures in much the same way that lower mass stars form.

Provided by Smithsonian Astrophysical Observatory

Explore further: What are extrasolar planets?

Related Stories

How to Build A Big Star

Sep 06, 2005

The most massive stars in our galaxy weigh as much as 100 small stars like the Sun. How do such monsters form? Do they grow rapidly by swallowing smaller protostars within crowded star-forming regions?

Turbulence May Promote the Birth of Massive Stars

Feb 23, 2009

( -- On long, dark winter nights, the constellation of Orion the Hunter dominates the sky. Within the Hunter's sword, the Orion Nebula swaddles a cluster of newborn stars called the Trapezium. These stars are ...

Massive Star Formation: Inside, Outside and All Around

Sep 27, 2006

Scientists think they know how stars the size of our Sun are formed, but the theory breaks down for much larger stars. How do they accumulate masses up to 10 times or more than that of our own Sun? Now, new ...

How do massive stars form?

Nov 08, 2005

In an upcoming issue, the journal Astronomy & Astrophysics will publish the most complete picture of a “triggered” star-forming region. Induced (or “triggered”) star formation is one of the processes that are suppos ...

Making Jupiters

Aug 21, 2009

IC348 is a glowing nebula of young stars, hot gas, and cold dust seen in the direction of the constellation of Perseus. It is the nearest rich cluster of young stars to earth, being only about one thousand ...

Recommended for you

What are extrasolar planets?

22 hours ago

For countless generations, human beings have looked out at the night sky and wondered if they were alone in the universe. With the discovery of other planets in our solar system, the true extent of the Milky ...

A curious family of giant exoplanets

23 hours ago

There are 565 exoplanets currently known that are as massive as Jupiter or bigger, about one third of the total known, confirmed exoplanet population. About one quarter of the massive population orbits very ...

Astrobiology students explore alien environment on Earth

23 hours ago

Sonny Harman never thought he'd be able to travel far enough to do field work. That's because the Penn State doctoral student studies atmospheres on other planets. But to his surprise, Harman recently stepped ...

NASA image: Hubble revisits tangled NGC 6240

23 hours ago

Not all galaxies are neatly shaped, as this new NASA/ESA Hubble Space Telescope image of NGC 6240 clearly demonstrates. Hubble previously released an image of this galaxy back in 2008, but the knotted region, shown ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.