text-only page produced automatically by LIFT Text Transcoder Skip all navigation and go to page contentSkip top navigation and go to directorate navigationSkip top navigation and go to page navigation
National Science Foundation Home National Science Foundation - Mathematical & Physical Sciences (MPS)
Astronomical Sciences (AST)
design element
AST Home
About AST
Funding Opportunities
Awards
News
Events
Discoveries
Publications
Career Opportunities
AST Presentations
Astronomy & Astrophysics Advisory Committee (AAAC)
AST Portfolio Review
View AST Staff
MPS Organizations
Astronomical Sciences (AST)
Chemistry (CHE)
Materials Research (DMR)
Mathematical Sciences (DMS)
Physics (PHY)
Office of Multidisciplinary Activities (OMA)
Proposals and Awards
Proposal and Award Policies and Procedures Guide
  Introduction
Proposal Preparation and Submission
bullet Grant Proposal Guide
  bullet Grants.gov Application Guide
Award and Administration
bullet Award and Administration Guide
Award Conditions
Other Types of Proposals
Merit Review
NSF Outreach
Policy Office
Other Site Features
Special Reports
Research Overviews
Multimedia Gallery
Classroom Resources
NSF-Wide Investments

Email this pagePrint this page

Discovery
Search Is on for Hot Young Stars

Long duration gamma-ray bursts allow astronomers to collect more information than ever imagined

Composite image of supernova remnant W49B showing a barrel-shaped nebula.

Composite image of supernova remnant W49B showing a barrel-shaped nebula.
Credit and Larger Version

September 21, 2007

On average, at least three gamma-ray bursts occur somewhere in the heavens each day. Shri Kulkarni has trained his eyes up to these new wonders with his latest research in this emerging field.

Kulkarni's studies focus on long duration gamma-ray bursts. These bursts occur when a young massive star burns through its hydrogen core.

(Gamma rays are the most energetic form of radiation on the electromagnetic spectrum, which includes x-rays, visible light and radio waves.)

"The gamma-ray burst goes off and we use the Keck I telescope to measure its spectrum, which tells how far away it is," said Kulkarni, the John D. and Catherine T. McArthur Professor of Astronomy and Planetary Science at the California Institute of Technology. "Most gamma-ray bursts are very far away, and we believe that they occurred with much greater frequency when the universe was young."

When the pressure generated by this reaction diminishes, the pull of gravity forces the star's matter to collapse in on itself. For some extremely massive stars, the force of the collapse is strong enough to create a black hole and the energy is sufficient to power a massive explosion, resulting in an eruption of energy and light.

Occurring on the very edges of our universe, these stunning explosions create a powerful light source which allows astronomers to gaze deeper into space. Long-duration gamma-ray bursts last for just a few seconds, but the light is sometimes so strong that the 'afterglow' exists for months at a time, illuminating details in space that would have been nearly impossible to see before. This "long-duration class" of illumination is what helps Kulkarni undertake detailed observations with the Keck telescope.

"Gamma-ray bursts are nature's light post, and you can use their luminescence to study everything between the gamma-ray burst and you," added Kulkarni. "If you happen to be there the hour after a gamma-ray burst happens, you can collect more information than you can possibly imagine."

Seventy-five percent of all gamma-ray bursts are in the long-duration class, the soulful death cries of a once massive star. The other 25 percent exist in the short-duration class.

The differences between the two classes raise questions that are driving the research horizons in this field. Kulkarni is hoping to focus next on what differentiates the power between the two types of gamma-ray bursts while also investigating the unknown forces that initiate these galactic marvels.

"How do you decide what to do next?" ponders Kulkarni. "I think most scientists do not take a critical view. It is very easy to keep doing what you're doing, especially when the science questions are interesting. Yet, I believe it is important to assess your work and see if it is worth continuing. You can become a guru of the field, and maybe this is comfortable . . . my life has been pleasantly full because of discoveries I have made. But, by throwing myself into a new area, there is an opportunity to see things differently."

-- Tiare Devenot, W. M. Keck Observatory tdevenot@hpa.edu

This Behind the Scenes article was provided to LiveScience in partnership with the National Science Foundation.

Investigators
Shrinivas Kulkarni

Related Institutions/Organizations
W. M. Keck Observatory
California Institute of Technology

Locations
Hawaii
California

Related Awards
#9987438 Supernovae and their Cosmological Applications
#9115174 Spectroscopic and Photometric Studies of Supernovae
#9417213 Discovery, Photometry, and Spectroscopy of Supernovae
#0607485 Supernovae In Nearby Galaxies: Discovery, Rates, and Detailed Studies
#0307894 The Lick Observatory Supernova Search, and Detailed Studies of Nearby Supernovae
#8957063 Presidential Young Investigator Award-Active Galactic Nuclei and Supernovae

Total Grants
$1,786,710

Related Websites
LiveScience.com: Behind the Scenes: Search is on for Hot Young Stars: http://www.livescience.com/space/070921_bts_gamma_rays.html

Series of Hubble Space Telescope images, labeled A Supernova in GRB 011121
This series of Hubble Space Telescope images shows the likely home of the gamma-ray burster.
Credit and Larger Version



Email this pagePrint this page
Back to Top of page