Dr. Brian Thomas leads the research
team studying astrobiophysics (also called astrobiology) in
the Department of Physics and Astronomy at Washburn University. Our
group works on several different projects which study the
impact on the Earth by radiation from space. Details of some
projects can be found below.
Astrobiophysics studies the effect of astrophysical processes of life on Earth, as well as effects on possible life elsewhere. We distinguish it from astrobiology, which is concerned with finding extraterrestrial life. To do this work, a wide variety of research areas which include astrophysics, astronomy, biochemistry, evolutionary biology, paleontology, atmospheric science, and a host of others are combined.
The Washburn Astrobiophysics group's primary research tool is computational modeling. This modeling makes use of the Washburn High Performance Academic Computing Envrionment, HiPACE.
Our current focus is a NASA funded project entitled "Terrestrial Impact of
Nearby Supernovae." Dr. Thomas was
the principal investigator of this project and it was being
conducted in collaboration with Dr. Adrian Mellott at the
University of Kansas and Dr. Andrew Overholt at MidAmerica
Nazarene University. The purpose of this project is to
undertake the first realistic assessment of the effects of a
nearby supernova upon the Earth, using parameters derived from
an event with terrestrial evidence and combining effects of
atmospheric ionizations and radiation impact on organisms on
the ground and in the ocean.
Supernova (SN) explosions arise from the same star-forming processes that give rise to planetary systems. The ionizing radiation during and immediately after SN explosions poses an ongoing hazard to the biosphere. This extrasolar influence on the planetary conditions for life can be crucially important, but the true threat of nearby supernovae, and detailed nature of their impact on the biosphere, has not yet been studied in a systematic way. Past work on understanding nearby SN effects has been approximate.
Evidence exists in the form of iron-60 in sediment cores that a relatively nearby SN—close enough to modify surface UV levels, boost muon radiation levels, and possibly modify climate—happened within the last few million years. Additional evidence, sufficient to make estimates of the distance of an event 2-3 million years ago, was announced in 2013.
The key question is: What overall impact do we expect from event(s) implied by the recent ocean core isotopic signal? What is the ionizing photon dose and time history from a SN explosion, and how does this vary with SN type? What is the dose/history of SN cosmic rays and their interaction with the heliosphere? What terrestrial effects does the SN radiation cause?
A previous project was a NASA funded project entitled "Astrophysical Ionizing Photon Events and Primary Productivity of Earth's Oceans." Dr. Thomas was the principal investigator of this project and it was being conducted in collaboration with Dr. Adrian Mellott at the University of Kansas and Dr. Patrick Neale at the Smithsonian Environmental Research Center. The purpose of the project was two-fold:
Our work in the area began in 2003 with an exploration of the effect on the Earth radiation (X-Rays & Gamma-Rays) from a gamma-ray burst in our galaxy. From there it has expanded and diversified. Dr. Thomas and the Washburn Astrobiophysics group have been heavily involved the following projects in collaboration with the KU Astrobiophysics Working Group.
Please see the Working Group's website for more: http://kusmos.phsx.ku.edu/~melott/Astrobiology.htm
I. Astrophysical Ionizing Radiation Events--the Effect on Our Biosphere:
Large explosions in the Sun’s atmosphere called Solar Flares emit X-Rays & UV-Radiation. There are also occasional much more powerful flares. Stars with an 8 solar mass or greater create supernovae. A Supernova is created once every 50 years. Earth would have to be within a 10 Light Year Radius of the blast for the affect to be disastrous by. A star that has a mass 30 times or greater than our Sun creates a Hypernova, which is 10 times more powerful than a typical Supernova. The core collapses into a Black Hole. Two energetic jets of plasma are emitted from the star’s rotational poles along the dying star’s axis at nearly the speed of light producing an intense long-duration Gamma-Ray Bursts (GRBs). A GRB 6,500 light years away from Earth could cause potentially severely damaging events likely on a timescale of a few hundred million years. Our first efforts, and still the most prolific, lie in this area. In the sections below, we explore several different likely or possible kinds of radiation events and their effects on the Earth.
Through atmospheric modeling, we have estimated that a Gamma Ray Burst could have contributed to the Ordovician extinction 450 million years ago; 60% of all marine invertebrates were lost. An ice age is thought to have caused this extinction, however, a Gamma-Ray Burst could have caused a fast die-out early on and also could have triggered the significant drop in surface temperature on Earth. Scientists calculated that Gamma-Ray radiation from a relatively nearby star explosion, hitting the Earth for only ten seconds, could deplete up to half of the atmosphere's protective ozone layer. Recovery could take at least five years.
have conducted a study of the atmospheric chemistry effects of
comets, especially as related to the hypothesis that the Clovis
culture and North American megafauna may have been killed off by a
comet impact 12,900 years ago. See here for more
Study of Comets and Atmospheric Chemistry
American Astronomical Society workshop "Astrophysical ionizing
radiation sources and their impact on life." For more
information look here.
At the Astrobiology Science Conference, 2008. We organized
one of the 39 parallel sessions. Two of the talks pegged
as most exciting in a review by Astrobiology
Magazine were in our session: The
Some of our work was featured prominently in a
National Geographic Television program entitled
"Extinctions." The program will be rebroadcast periodically.
Research in our group constituted approximately the last
third of the program. Their summary: "Planet earth
teems with life, but imagine it disappearing in one go: a victim
of catastrophic events that leave the planet almost uninhabitable.
Naked Science travels back in time to examine three of the
largest mass extinctions that decimated life on the planet in the
past. What caused these wipe-outs and could they happen
again in the future, threatening our very survival? Worse
still, are we already in the middle of a mass extinction--not one
created by nature, but by man? This program unravels the
clues and likely suspects behind the dinosaur, Permian, and late
Ordovician wipe-outs. Even given human adaptability and know-how,
would we fare any better than the previous victims of these
disasters? Could we be wiped out? "We discover that we
are not as safe as we'd like to think."
A History Channel presentation features our research. This hour long science special on the destructive potential of gamma-ray bursts was on Megadisasters. It is repeated occasionally on the History Channel. The science content is solid, in spite of the hype surrounding the series as a whole.
Our group has been involved with the Astrobiophysics
Opportunities exist for students to be involved in
research. Contact Dr. Thomas for more information:
brian.thomas @ washburn.edu
We have a block
of supercomputer time at the National Center for
Supercomputer Appications for those computations too large for local
We maintain an active net of collaborators especially
including NASA Goddard
Flight Center, in their Astroparticle
Physics Laboratory and their Laboratory
for Atmospheres. We have an active
project with the Photobiology and Solar Radiation Lab at the Smithsonian
Environmental Research Center. The SWIFT
mission is providing new information about Gamma-ray
bursts, including much-needed data on their rate in the "recent"
Universe (since the Earth formed.)
Our recent research publications can usually be found in
Older published research is listed elsewhere.
Washburn University faculty involved in research:
-- Brian C. Thomas
Current and past Washburn student collaborators (links go to papers authored with those students on arXiv.org):
-- Glen Riley
-- Sean Dalton
-- Nick VanCamp
-- Jacob Peterson
-- Bianca Lewis
-- Anna Lischke
-- Nadia May
Research is Funded by NASA
Design by Bianca L. Lewis
Last Updated: July 22th, 2014