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Vol. LXII, No. 22
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Wednesday, May 28, 2008
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Vol. LXII, No. 22
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Wednesday, May 28, 2008
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Alicia Soderberg was at Michigan State University in January giving a colloquium about the Swift satellite when she received an alert from the satellite itself. As a Hubble Postdoctoral Fellow and a Carnegie-Princeton Fellow at Princeton University, she had been studying Supernova 2007uy (supernovae are assigned names by year and letters) and had directed the Swift’s technologies to that site, when she spotted a new, “extremely luminous” object within the field of vision of the satellite. Realizing that something extraordinary was going on, she immediately alerted other astronomers around the world. They all turned their eyes, telescopes, and computers toward the light, and after about a day and a half collectively determined that the “nature of the source had to be [another] supernova.”
Describing astronomy as a dynamic discipline, Ms. Soderberg noted that “you have to be ready for the unexpected.” She added, “I’ve been working in the field of supernovae and other things that go ‘bump’ in the night long enough to know that you have to know how to react immediately, and that what you find could end up changing the next few months of your life completely.”
The discovery of Supernova 2008d has changed not only the subsequent months, but has and will continue to augment our understanding of supernovae themselves. This is the first instance of a star’s death being recorded becoming a supernova in real time. For years, astronomers have speculated that just prior to combustion, the progenitor stars of supernovae emit a high frequency blast, probably produced by a pressure wave created within the star as it interacts with the star’s surface. Ms. Soderberg’s discovery confirmed the theory and determined that the initial blast the star emitted was an X-ray pulse that lasted for five minutes, and heralded the death of the star.
In the past, visual discoveries of supernovae happen weeks after they explode, and prior to this moment, no one knew for certain what stars looked like as they were exploding. Ms. Soderberg remarked during a teleconference last week that “the physics of the explosion is encoded in x-ray light” and this finding will lead to the increased identification of stars on the verge of explosion, and will revolutionize the study of supernovae.
Ms. Soderberg and her colleagues are already working on “a new tool” through which the exploding astral bodies may be found. Timeliness is paramount, and Ms. Soderberg’s main focus is “understanding how to put this new tool into place as quickly as possible.”
Ms. Soderberg concluded the teleconference by noting that “the future of supernova studies is quite bright.” Robert Kirshner, Professor of Astronomy at Harvard College and Clowes Professor of Science at Harvard University, speculates that supernovae will soon be found with greater frequency. Ms. Soderberg estimates that using X-ray satellites, it is even possible that a new supernova will be discovered every few days.
Detecting the initial X-ray blast is crucial since the visual light from the star’s collapse arrives about a month after the event. According to Ms. Soderberg, gleaning information beforehand would not only alert the astronomical community as to where to focus, but also assist astronomers in locating neutrinos and gravitational waves happening at the same time as the original explosion. This data could lead to finding out what causes supernovae to explode.
Though Ms. Soderberg considers herself fortunate to have pointed the Swift satellite’s telescopes at the right place at the right time, she has been credited by her colleagues for the dedication and energy that made her discovery possible. Interest in stellar explosions was piqued early in Ms. Soderberg’s academic career. When she entered Bates College, she had plans to study chemistry, but was intrigued most by physics and mathematics. She “dabbled in supernovae right away” as a first-year student, branched out to other celestial phenomena, but subsequently returned to these exploding stars.
They ignite the imagination as well. According to Mr. Kirshner, supernova explosions “perform a real alchemy, turning iron to gold, gold to lead, lead to uranium.” What Ms. Soderberg found unexpectedly is perhaps the philosopher’s stone of astronomy, certainly of supernova studies. She commented, “nature has many surprises and this supernova was certainly one of them.”