UCF Physics

Category Archives: 2006

UCF, UCLA Astronomers First to Measure Night and Day on Extrasolar Planet

Date: Tuesday Oct. 31st, 2006

University of Central Florida Astronomy professor Joseph Harrington and University of California at Los Angeles professor Brad M. Hansen and their team have made the first direct observation of distinct day and night temperatures on a planet orbiting another star.

Their published work appears in this week’s Science Express, the online version of Science Magazine. The announcement was made today in Pasadena, Calif., at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society. UCF will host the meeting in Orlando next year. The DPS includes 1,282 planetary scientists and astronomers, including 232 non-U.S. members.

The team used NASA’s Spitzer Space Telescope to measure the infrared light emitted by the planet upsilon Andromedae b at five points around its orbit. The planet orbits a star located 263 trillion miles from Earth in the constellation Andromeda.

At each point during the observations, different portions of the planet’s day and night hemispheres were in view, creating a rise-and-fall pattern in the light level that was synchronized with the planet’s known orbit.

This information helps planetary scientists choose among several competing hypotheses regarding weather on so-called “hot Jupiter” planets, which orbit very close to their stars. Temperatures on these planets are about 3,000 degrees Fahrenheit, Harrington and Hansen calculated. Hot Jupiters have small enough orbits that the energy they absorb and reradiate from their host stars dominates their own internal energy losses.

“How they absorb and reradiate this energy is fundamental to understanding the behavior of their atmospheres,” Harrington and Hansen said in their published article. “Studying planetary atmospheres under such exotic conditions puts terrestrial and solar-system meteorology into a universal context, which aids in our understanding of weather on all planets,” Harrington added.

A number of models predict that strong winds transport energy from the day side to the night side. “But, our points are almost exactly synced up with the known orbit, which indicates almost immediate reradiation of energy, very little energy transport,” Harrington said. “That’s new, and very exciting. The temperature difference between day and night is also very strong, which is more evidence for immediate reradiation.”

Why don’t the models work for upsilon Andromedae b? “That’s going to be a hot topic now,” Harrington said.

Since the first planet orbiting another sun-like star was discovered in 1995, more than 200 such planets have been found, but scientists still cannot see the planets as separate images from their stars.

“In the past, we could only directly measure planets that happened to pass in front of and behind their stars from our point of view,” Harrington said. “That only works for certain planets, and only at two points in the orbit. Our new method doesn’t have those limitations, which opens up opportunities to observe more planets, and to get data all around their orbits. We need that to learn how their atmospheres work.”

So when will someone discover an Earth-like planet around a sun-like star with a temperature that could support life as we know it? “It may not be that long of a wait,” Harrington said. “NASA’s Kepler mission should find several such planets, but technology is moving so fast, it could be that someone else does it first.” The unmanned Kepler mission is scheduled for launch in October 2008.

Harrington recently joined the growing Planetary and Space Science Group in the Department of Physics at UCF. The group’s faculty members have worked on several NASA missions, including Stardust, Deep Impact, and the Mars rovers Spirit and Opportunity.

Hansen is a member of the Institute of Geophysics and Planetary Physics in UCLA’s Department of Physics and Astronomy.

The team includes Statia H. Luszcz, now a doctoral student in the Department of Astronomy at the University of California, Berkley; Sara Seager of the Department of Terrestrial Magnetism at the Carnegie Institution of Washington, D.C.; Drake Deming of the Planetary Systems Laboratory and the Goddard Center for Astrobiology at NASA’s Goddard Space Flight Center in Greenbelt, Md.; Kristen Menou of the Department of Astronomy at Columbia University in New York; James Y.-K. Cho from the School of Mathematical Studies at Queen Mary, University of London; and L. Jeremy Richardson of the Exoplanets and Stellar Astrophysics Laboratory at NASA Goddard.

The work was funded by the Spitzer Space Telescope. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.

The Phase-Dependent Infrared Brightness of the Extrasolar Planet Upsilon Andromedae

Date: Friday Oct. 27th, 2006

New Physics faculty member, Joseph Harrington, had one of his articles featured on the cover of Science magazine.

Abstract:
The star Upsilon Andromedae is orbited by three known planets, the innermost of which has an orbital period of 4.617 days and a mass at least 0.69 that of Jupiter. This planet is close enough to its host star that the radiation it absorbs overwhelms its internal heat losses. Here, we present the 24-micrometer light curve of this system, obtained with the Spitzer Space Telescope. It shows a variation in phase with the orbital motion of the innermost planet, demonstrating that such planets possess distinct hot substellar (day) and cold antistellar (night) faces.

Read the entire article.
View the Cover of Science Magazine.

UCF Professor Drives Scientific Stake into the Heart of Ghost, Vampire Myths

Date: Friday Oct. 20th, 2006

As the weather cools and Halloween approaches, chilling creaks in the stairs, bloodcurdling screams from the attic and other paranormal activity become more believable – but not to UCF physics professor Costas Efthimiou.

The laws of physics and math debunk popular myths about ghosts and vampires, according to a paper published by Efthimiou and Sohang Gandhi, a UCF graduate now studying at Cornell University.

Using Isaac Newton’s Laws of Motion, Efthimiou demonstrates that ghosts would not be able to walk and pass through walls. Basic math disproves the legend of humans turning into vampires after they are bitten, Efthimiou explains, because the entire human population in 1600 would have been wiped out in less than three years.

“These popular myths make for a lot of Halloween fun and great movies with special effects, but they just don’t hold up to the strict tests of science,” Efthimiou said.

In movies such as “Ghost,” starring Patrick Swayze and Demi Moore, ghosts often walk like humans, pass through walls and pick up objects. But that portrayal cannot be accurate, Efthimiou says. For ghosts to have the ability to walk like humans, they would need to put a force upon the floor, which would exert an equal and opposite force in return. But ghosts’ ability to pass through walls and have humans walk right through them demonstrates that they cannot apply any force.

Movies such as “Blade,” featuring Wesley Snipes, suggest that vampires feed on human blood and that once a human has been bitten, he or she turns into a vampire and begins feeding on other humans. To disprove the existence of vampires, Efthimiou relied on a basic math principle known as geometric progression.

Efthimiou supposed that the first vampire arrived Jan. 1, 1600, when the human population was 536,870,911. Assuming that the vampire fed once a month and the victim turned into a vampire, there would be two vampires and 536,870,910 humans on Feb. 1. There would be four vampires on March 1 and eight on April 1. If this trend continued, all of the original humans would become vampires within two and a half years and the vampires’ food source would disappear.

Efthimiou did not take into consideration mortality rates, which would have increased the speed at which the human population would have been vanquished. And even factoring in a birth rate would not change the outcome.

“In the long run, humans cannot survive under these conditions, even if our population were doubling each month,” Efthimiou said. “And doubling is clearly way beyond the human capacity of reproduction.”

Efthimiou also provides a practical explanation for “voodoo zombiefication,” which suggests that zombies “come about by a voodoo hex being placed by a sorcerer on one of his enemies.” He reviewed the case of a Haitian adolescent who was pronounced dead by a local doctor after a week of dramatic convulsions.

After the boy was buried, he returned in an incoherent state, and Haitians pronounced that a sorcerer had raised him from the dead in the state of a zombie.

Science, however, has a less-supernatural explanation. A highly-toxic substance called tetrodotoxin is found in a breed of puffer fish native to Haitian waters. Contact with this substance generally results in a rapid death. However, in some cases, the right dose of the toxin will result in a state that mimics death and slows vital signs to a level that is unable to be measured. Eventually, the victim snaps out of the death-like coma and returns to his or her regular condition.

Scientific analysis has shown that oxygen deprivation is consistent with the boy’s brain damage and his incoherent state.

“It would seem that zombiefication is nothing more than a skillful act of poisoning,” Efthimiou said.

The full paper can be viewed at www.arxiv.org/abs/physics/0608059.

Nobel Prize-Winning Chemist to Speak at UCF About Future of Nanoscience

Date: Wednesday Feb. 22nd, 2006

ORLANDO — Sir Harry Kroto, a Florida State University professor who won a Nobel Prize in chemistry 10 years ago, will discuss the future of nanoscience and nanotechnology Friday, Feb. 24, at the University of Central Florida.

Kroto will speak at 10 a.m. in the Cape Florida Ballroom, Room 316, of the University of Central Florida Student Union. His presentation, “Architecture in NanoSpace,” is free and open to the public.

Kroto will discuss the challenges of the 21st century in creating large molecules with accurately defined atomic structures and how that could lead to advances such as constructing stronger buildings and developing small supercomputers and more delicate surgical techniques

Kroto, who now teaches in FSU’s Department of Chemistry and Biochemistry, won a Nobel Prize in chemistry in 1996 while he was a professor at the University of Sussex in the United Kingdom. He won the prize with two Rice University professors for their discovery of fullerenes, new forms of carbon in which the atoms are arranged in closed shells.

Kroto’s research at that time focused on microwave spectroscopy, a process that is useful for analyzing gases in space. His other research specialties include astrophysics; analyses of carbon and metal clusters; and fullerene chemistry, nanoscience and nanotechnology. Kroto also gives frequent lectures to students and others interested in chemistry.

Kroto taught at the University of Sussex for 37 years before taking a position at FSU in 2004. Named a Royal Society Research Professor at Sussex in 1991, he won the Royal Society’s Michael Faraday Award 10 years later for his efforts to advance public communication in science and technology in the United Kingdom. Kroto was awarded knighthood status in 1996.

Kroto also set up the Vega Science Trust to improve the awareness and understanding of science research by making programming about outstanding scientists available for free on television and on the Internet. Lectures, interviews and children’s workshops are among the programs available at http://www.vega.org.uk.

Sponsors of Kroto’s presentation at UCF include the Office of Research and Commercialization and the student Materials Research Society. For more information, call 407-882-1119.

Physics, Honors Student Sohang Gandhi Named to USA Today All-Academic Team

ORLANDO — Sohang Gandhi, a University of Central Florida senior and honors student, was one of 60 students nationwide selected to USA Today’s All-USA College Academic Team this week.

Gandhi, a physics major from Casselberry, was one of 20 students named to the College Academic Third Team. USA Today honored him for his research related to Heisenberg’s Uncertainty Relation, which is critical to the understanding of quantum mechanics.

Gandhi is the second UCF student selected to a USA Today College Academic Team in the past two years. Andrea Wesser, a graduate student in engineering who helped to design a wheelchair for young victims of land mines, was named to the second team in 2005. Like Gandhi, Wesser attended UCF’s Burnett Honors College.

“This second USA Today winner in two years confirms the fact that the Burnett Honors College and UCF are attracting stronger, better students and, once we get them here, we’re able to give them better research opportunities and mentors who help them shine when they apply for competitive awards,” said Alvin Wang, the college’s dean.

USA Today reported Tuesday that more than 600 students were nominated for the 17th annual all-academic teams.

Gandhi never thought of pursuing a career in physics until a lesson on Newton’s Laws of Motion inspired him during his senior year of high school. Since then, he has impressed UCF faculty and administrators with his academic success and high-quality research.

Gandhi spends about 30 hours a week on research through UCF’s selective Research And Mentoring Program and Student Mentor Academic Research Teams. He works mainly with his mentor and physics professor Costas Efthimiou.

Wang said Gandhi’s award is “an affirmation of all of the hard work that he has put into his research. We’re talking about a student who, even as a sophomore and junior, was doing high-level theoretical physics research.”

Gandhi runs the UCF Society of Physics Students’ group research project, which provides students with an introduction to the research process. Through his involvement with the society’s Youth Outreach Program, he created a “Reel Physics” initiative that aims to attract the interest of middle and high school students in physics through the showing of popular films.

Gandhi received the Barry M. Goldwater Scholarship, a premier award for undergraduates in mathematics, science and engineering. He was one of 320 students nationwide who won the scholarship in 2005. The award covers up to $7,500 of the cost of his tuition, fees and books for the 2005-06 school year.

He was one of two U.S. students who received the Society of Physics Students’ Outstanding Student Award for Undergraduate Research in May. As part of this honor, Gandhi presented his research in July at a conference in Portugal.

Gandhi is secretary of the Sigma Pi Sigma physics honor society. He also is president of the Society of Physics Students and president of the Campus Freethought Alliance, which promotes the acceptance and application of science, reason and critical thinking in all areas of human behavior.

After completing his studies at UCF, Gandhi hopes to pursue graduate research, possibly at Cornell University, Harvard University or the University of California at Berkeley. He wants to stay in academia because “the university environment nurtures ideas and is all the richer for it.”

To read the USA Today coverage of the all-academic teams, go tohttp://www.usatoday.com/news/education/2006-02-14-allstars-third-team_x.htm.