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Astronomy: High school students identify an ultra-rare star

This newly-discovered variable is one of only seven of its kind known in our galaxy.

Science journalist Alison Klesman with the online science news magazine Astronomy covered the discovery of a variable star by SMU professor Robert Kehoe and the astronomy team in the SMU Department of Physics.

A high school student in an SMU summer astronomy program made the initial discovery upon culling through archived star observation data recorded by the small but powerful ROTSE-I telescope formerly at Los Alamos National Laboratory in New Mexico.

Other authors on the study were SMU research astronomer Farley Ferrante, a member of the team, Plano Senior High School student Derek Horning, who first discovered the object in the ROTSE-I data, and Eric Guzman, a physics graduate from the University of Texas at Dallas who is entering SMU’s graduate program and who identified the star as pulsating.

The newest delta Scuti (SKOO-tee) star in our night sky is so rare it’s only one of seven identified by astronomers in the Milky Way. Discovered at SMU, the star — like our sun — is in the throes of stellar evolution, to conclude as a dying ember in millions of years. Until then, the exceptional star pulsates brightly, expanding and contracting from heating and cooling of hydrogen burning at its core.

The Astronomy article, “High school students identify an ultra-rare star,” published Feb. 15, 2017.

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By Alison Klesman
Astronomy

The stars shining in the night sky might seem steady and reliable, but in truth, they are constantly changing and evolving. Out of the 100 billion or so stars that inhabit the Milky Way, a little more than 400,900 are classified as variable, meaning they change in brightness over time.

Of those hundreds of thousands of variables catalogued in our galaxy, however, only seven belong to a class called Triple Mode high amplitude delta Scuti, or HADS(B), stars — and that seventh was just recently discovered by a high school student during a summer astronomy program at Southern Methodist University in Dallas.

The star, roughly the size of our Sun or possibly larger, is about 7,000 light-years away in the constellation Pegasus. It currently has only a catalog name: ROTSE1 J232056.45+345150.9. The name comes in part from the telescope used to discover it, the ROTSE-I telescope at Los Alamos National Laboratory in New Mexico.

While examining data from the telescope taken in September of 2000, Plano Senior High School student Derek Hornung noticed the star’s strange light curve, which shows the star’s brightness over time. A non-variable star’s light curve is simply a straight line, unchanging as the hours, days, and months go by. But a variable star exhibits periodic changes in brightness over the course of hours or days, creating a recognizable repeating pattern. Variable stars are classified by the patterns their light curves make, and named after the first star of each type discovered. Delta Scuti variables are thus named after the star delta Scuti.

But there’s more to this story, still. The star is not only a delta Scuti variable, of which there are thousands known, but it is also a rare type within the delta Scuti class, a HADS(B) star. HADS(B) stars show asymmetric light curves that change brightness quickly over time. These stars are pulsating in two modes, which means the star is expanding in two directions at once. There are only 114 HADS(B) stars currently known. Rarer still are Triple Mode HADS(B) stars, of which there were only six previously identified in the Milky way. Triple Mode HADS(B) stars pulsate in not two, but three directions at once. For ROTSE1 J232056.45+345150.9, this process repeats itself every 2.5 hours.

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New delta Scuti: Rare pulsating star 7,000 light years away is 1 of only 7 in Milky Way

A star — as big as or bigger than our sun — in the Pegasus constellation is expanding and contracting in three different directions simultaneously on a scale of once every 2.5 hours, the result of heating and cooling of hydrogen fuel burning 28 million degrees Fahrenheit at its core

The newest delta Scuti (SKOO-tee) star in our night sky is so rare it’s only one of seven identified by astronomers in the Milky Way. Discovered at Southern Methodist University in Dallas, the star — like our sun — is in the throes of stellar evolution, to conclude as a dying ember in millions of years. Until then, the exceptional star pulsates brightly, expanding and contracting from heating and cooling of hydrogen burning at its core.

Astronomers are reporting a rare star as big — or bigger — than the Earth’s sun that is expanding and contracting in a unique pattern in three different directions.

The star is one that pulsates and so is characterized by varying brightness over time. It’s situated 7,000 light years away from the Earth in the constellation Pegasus, said astronomer Farley Ferrante, a member of the team that made the discovery at Southern Methodist University, Dallas.

Called a variable star, this particular star is one of only seven known stars of its kind in our Milky Way galaxy.

“It was challenging to identify it,” Ferrante said. “This is the first time we’d encountered this rare type.”

The Milky Way has more than 100 billion stars. But just over 400,900 are catalogued as variable stars. Of those, a mere seven — including the one identified at SMU — are the rare intrinsic variable star called a Triple Mode ‘high amplitude delta Scuti’ (pronounced SKOO-tee) or Triple Mode HADS(B), for short.

“The discovery of this object helps to flesh out the characteristics of this unique type of variable star. These and further measurements can be used to probe the way the pulsations happen,” said SMU’s Robert Kehoe, a professor in the Department of Physics who leads the SMU astronomy team. “Pulsating stars have also been important to improving our understanding of the expansion of the universe and its origins, which is another exciting piece of this puzzle.”

The star doesn’t yet have a common name, only an official designation based on the telescope that recorded it and its celestial coordinates. The star can be observed through a telescope, but identifying it was much more complicated.

A high school student in an SMU summer astronomy program made the initial discovery upon culling through archived star observation data recorded by the small but powerful ROTSE-I telescope formerly at Los Alamos National Laboratory in New Mexico.

Upon verification, the star was logged into the International Variable Star Index as ROTSE1 J232056.45+345150.9 by the American Association of Variable Star Observers at this link.

How in the universe was it discovered?
SMU’s astrophysicists discovered the variable star by analyzing light curve shape, a key identifier of star type. Light curves were created from archived data procured by ROTSE-I during multiple nights in September 2000. The telescope generates images of optical light from electrical signals based on the intensity of the source. Data representing light intensity versus time is plotted on a scale to create the light curves.

Plano Senior High School student Derek Hornung first discovered the object in the ROTSE-I data and prepared the initial light curves. From the light curves, the astronomers knew they had something special.

It became even more challenging to determine the specific kind of variable star. Then Eric Guzman, a physics graduate from the University of Texas at Dallas, who is entering SMU’s graduate program, solved the puzzle, identifying the star as pulsating.

“Light curve patterns are well established, and these standard shapes correspond to different types of stars,” Ferrante said. “In a particular field of the night sky under observation there may have been hundreds or even thousands of stars. So the software we use generates a light curve for each one, for one night. Then — and here’s the human part — we use our brain’s capacity for pattern recognition to find something that looks interesting and that has a variation. This allows the initial variable star candidate to be identified. From there, you look at data from several other nights. We combine all of those into one plot, as well as add data sets from other telescopes, and that’s the evidence for discerning what kind of variable star it is.”

That was accomplished conclusively during the referee process with the Variable Star Index moderator.

The work to discover and analyze this rare variable star was carried out in conjunction with analyses by eight other high school students and two other undergraduates working on other variable candidates. The high school students were supported by SMU’s chapter of the Department of Energy/National Science Foundation QuarkNet program.

Heating and cooling, expanding and contracting
Of the stars that vary in brightness intrinsically, a large number exhibit amazingly regular oscillations in their brightness which is a sign of some pulsation phenomenon in the star, Ferrante said.

Pulsation results from expanding and contracting as the star ages and exhausts the hydrogen fuel at its core. As the hydrogen fuel burns hotter, the star expands, then cools, then gravity shrinks it back, and contraction heats it back up.

“I’m speaking very generally, because there’s a lot of nuance, but there’s this continual struggle between thermal expansion and gravitational contraction,” Ferrante said. “The star oscillates like a spring, but it always overshoots its equilibrium, doing that for many millions of years until it evolves into the next phase, where it burns helium in its core. And if it’s about the size and mass of the sun — then helium fusion and carbon is the end stage. And when helium is used up, we’re left with a dying ember called a white dwarf.”

Within the pulsating category is a class of stars called delta Scuti, of which there are thousands. They are named for a prototype star whose characteristic features — including short periods of pulsating on the scale of a few hours — are typical of the entire class.

Within delta Scuti is a subtype of which hundreds have been identified, called high amplitude delta Scuti, or HADS. Their brightness varies to a particularly large degree, registering more than 10 percent difference between their minimum and maximum brightness, indicating larger pulsations.

Common delta Scuti pulsate along the radius in a uniform contraction like blowing up a balloon. A smaller sub-category are the HADS, which show asymmetrical-like pulsating curves.

Within HADS, there’s the relatively rare subtype called HADS(B) , of which there are only 114 identified.

Star evolution — just a matter of time
A HADS(B) is distinguished by its two modes of oscillation — different parts of the star expanding at different rates in different directions but the ratio of those two periods is always the same.

For the SMU star, two modes of oscillation weren’t immediately obvious in its light curve.

“But we knew there was something going on because the light curve didn’t quite match known light curves of other delta Scuti’s and HADS’ objects we had studied. The light curves — when laid on top of each other — presented an asymmetry,” Ferrante said. “Ultimately the HADS(B) we discovered is even more unique than that though — it’s a Triple Mode HADS(B) and there were previously only six identified in the Milky Way. So it has three modes of oscillation, all three with a distinct period, overlapping, and happening simultaneously.”

So rare, in fact, there’s no name yet for this new category nor a separate registry designation for it. Guzman, the student researcher who analyzed and categorized the object, recalled how the mystery unfolded.

“When I began the analysis of the object, we had an initial idea of what type it could be,” Guzman said. “My task was to take the data and try to confirm the type by finding a second period that matched a known constant period ratio. After successfully finding the second mode, I noticed a third signal. After checking the results, I discovered the third signal coincided with what is predicted of a third pulsation mode.”

The SMU Triple Mode HADS(B) oscillates on a scale of 2.5 hours, so it will expand and contract 10 times in one Earth day. It and the other known six HADS(B)’s are in the same general region of the Milky Way galaxy, within a few thousand light years of one another.

“I’m sure there are more out there,” Ferrante said, “but they’re still rare, a small fraction.”

Red giant the final phase of star’s evolution
SMU’s Triple Mode HADS(B) is unstable and further along in its stellar evolution than our sun, which is about middle-aged and whose pulsating variations occur over a much longer period of time. SMU’s Triple Mode HADS(B) core temperature, heated from the burning of hydrogen fuel, is about 15 million Kelvin or 28 million degrees Fahrenheit.

Someday, millions of years from now, SMU’s Triple Mode HADS(B) will deplete the hydrogen fuel at its core, and expand into a red giant.

“Our sun might eventually experience this as well,” Ferrante said. “But Earth will be inhospitable long before then. We won’t be here to see it.”

Funding was through the Texas Space Grant Consortium, an affiliate of NASA; SMU Dedman College. Department of Energy/National Science Foundation QuarkNet program.

ROTSE-I began operating in late 1997, surveying the sky all night, every clear night of the year for three years. It was decommissioned in 2001 and replaced by ROTSE-III. SMU owns the ROTSE-IIIb telescope at McDonald Observatory, Fort Davis, Texas.

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KERA: Telescope-Wielding Twosome: High School Students Discover New Stars

Their five stars will be known by 16-digit serial numbers. Dominik would have rather immortalized his four dogs.

Lake Highlands High School students Dominik Fritz (left) and Jason Barton collected data until they had what they needed to define their star-to-be as a variable — a star that changes brightness. (Credit: KERA)
Lake Highlands High School students Dominik Fritz (right) and Jason Barton collected data until they had what they needed to define their star-to-be as a variable — a star that changes brightness. (Credit: KERA)

Reporter Courtney Collins with the news team at public radio station KERA covered the discovery of five stars made by two Dallas high school students as members of an SMU summer physics research program. Called Quarknet, the program enabled the students to analyze data gleaned from a high-powered telescope in the New Mexico desert.

All five stars are eclipsing contact binary stars, pairs of stars that orbit around each other so closely that their outer atmospheres touch. As the stars eclipse, they dim and then brighten as one emerges from behind the other. These stars are categorized as variable stars, stars that change brightness, which make up half the stars in the universe.

Lake Highlands High School seniors Dominik Fritz and Jason Barton are the first high school researchers at SMU to discover new stars.

Fritz and Barton are among nine high school students and two high school physics teachers who conducted physics research at SMU through the QuarkNet program.

Collins’ segment published and aired Sept. 4, “Telescope-Wielding Twosome: High School Students Discover New Stars.”

Listen to the segment and read the full story.

EXCERPT:

By Courtney Collins
KERA News
To most teenagers, star-gazing is the stuff of first dates.

For two seniors at Lake Highlands High School in Dallas, star-gazing over the summer led to five unusual discoveries.

In some respects, Dominik Fritz and Jason Barton are typical high-schoolers. Jason’s haircut would make a pop star envious and Dominik’s snazzy specs are effortlessly cool.

When these two kids start to talk science, you realize quickly, they’re two in a million.

“I’m personally fascinated by nuclear reactions and that’s basically what happens in stars, it’s full of nuclear reactions, nuclear fusion, a little bit of fission,” Dominik says.

That set of interests made Dominik a perfect candidate for a summer physics program at SMU. Jason and two other Richardson school district students joined him.

While analyzing data from a high-powered telescope, Jason noticed a few stars that weren’t already in the database.

“I started looking over several nights and seeing if they were actual variable stars and if they did change in brightness over time, and then I combined them all and then I eventually submitted it,” Jason says.

In fact, both teens made submission to an international star index that were accepted. Between them, they’d discovered five eclipsing binary contact stars. Dominik translates:

“Two very, very large star systems that are so close that they actually share their atmospheres.”

Lake Highlands physics teacher Ken Taylor says not many kids make it to upper level physics. That’s why he was so keen to get these students out of the textbook and into real research.

“It was beautiful for me to see my students who were going and forging ahead and taking things that they had learned and going into new territory and seeing the looks on their faces when they began to go somewhere where, in a sense, no one had gone before.”

Listen to the segment and read the full story.

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DMN: Two high school students discover variable stars during SMU summer program

Two high school students collected data until they had what they needed to define their star-to-be as a variable — a star that changes brightness.

Lake Highlands High School students Dominik Fritz (left) and Jason Barton collected data until they had what they needed to define their star-to-be as a variable — a star that changes brightness. (Credit: DMN)
Lake Highlands High School students Dominik Fritz (left) and Jason Barton collected data until they had what they needed to define their star-to-be as a variable — a star that changes brightness. (Credit: DMN)

Reporter Alexis Espinosa with the Dallas Morning News covered the discovery of five stars made by two Dallas high school students as members of an SMU summer physics research program. Called Quarknet, the program enabled the students to analyze data gleaned from a high-powered telescope in the New Mexico desert.

All five stars are eclipsing contact binary stars, pairs of stars that orbit around each other so closely that their outer atmospheres touch. As the stars eclipse, they dim and then brighten as one emerges from behind the other. These stars are categorized as variable stars, stars that change brightness, which make up half the stars in the universe.

Lake Highlands High School seniors Dominik Fritz and Jason Barton are the first high school researchers at SMU to discover new stars.

Fritz and Barton are among nine high school students and two high school physics teachers who conducted physics research at SMU through the QuarkNet program.

Read the full story.

EXCERPT:

By Alexis Espinosa
Dallas Morning News

Dominik Fritz sat in a Southern Methodist University science lab sifting through data. He hoped to discover a star by searching through months of information collected from a telescope in the New Mexico desert 14 years ago.
And then he found it.

He found a star whose variation had not yet been defined. And he would be the one to define it.

He collected data until he had everything he needed to define it as a variable — a star that changes brightness. A day after he submitted the star to the American Association of Variable Star Observers, the organization requested a few minor corrections.

And then, his star was accepted.

“I was so, so happy. My name is out there. I felt like I really accomplished something,” Fritz said. “I can literally tell people … ‘I found a star.’”

Fritz and a classmate, Jason Barton, both discovered stars this summer as part of the SMU’s QuarkNet program.

QuarkNet is a physics teacher development program funded by the National Science Foundation and the U.S. Department of Energy in universities and laboratories across the country. SMU’s QuarkNet program, which began in 2000, also provides research opportunities to high school students like Fritz and Barton, who are seniors at Lake Highlands High School in Richardson ISD.

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Eclipsing binary stars discovered by high school students at SMU summer research program

Treasures of the night sky: Pairs of stars orbit around each other so closely their outer atmospheres touch, so they dim and brighten.

Artist's impression of an eclipsing binary star system. As the two stars orbit each other they pass in front of one another and their combined brightness, seen from a distance, decreases.
Artist’s impression of an eclipsing binary star system. The stars pass in front of one another and their combined brightness decreases. (Credit: European Southern Observatory)

Two Dallas high school students discovered five stars as members of an SMU summer physics research program that enabled them to analyze data gleaned from a high-powered telescope in the New Mexico desert.

All five stars are eclipsing contact binary stars, pairs of stars that orbit around each other so closely that their outer atmospheres touch. As the stars eclipse, they dim and then brighten as one emerges from behind the other. These stars are categorized as variable stars, stars that change brightness, which make up half the stars in the universe.

Lake Highlands High School seniors Dominik Fritz and Jason Barton are the first high school researchers at SMU to discover new stars.

Their discoveries have been accepted into the American Association of Variable Star Observers International Variable Star Index (VSX).

New discoveries in Pegasus, Ursa Major are registered with Variable Star Index

The stars are located in the northern sky constellations of Pegasus and Ursa Major, but can’t be seen by the naked eye.

Lake Highlands High School student Dominik Fritz and teacher Ken Taylor at SMU. Fritz participated in Quarknet, a Dedman Physics program for area high school students. (Photo Credit here)
Lake Highlands High School student Dominik Fritz and teacher Ken Taylor at SMU. Fritz participated in Quarknet, an SMU Physics Department program for area high school students. (Photo Credit here)

Working in a campus science building basement laboratory, the students used analysis software, perseverance and patience to parse the data collected (but never analyzed for the purpose of studying binary stars) in 2000 by Robert Kehoe, SMU associate professor of physics.

Kehoe collected the data through ROTSE-I, a prototype robotic telescope at Los Alamos, New Mexico.

“Scientists are driven by the sense of discovery,” says Kehoe, who took the data originally to study gamma ray bursts. “These students can lay claim to information that didn’t exist before their research.”

SMU only university in North Texas offering the nation’s QuarkNet program
Fritz and Barton are among nine high school students and two high school physics teachers conducting physics research at SMU through the QuarkNet program.

QuarkNet is a physics teacher development program with 50 centers at U.S. universities and national laboratories. Funded by the National Science Foundation and the U.S. Department of Energy, the program gives teachers and students opportunities to learn about the most recent discoveries in physics.

Other sponsors include two of the world’s leading high-energy physics research centers — CERN in Switzerland and Fermilab in Illinois. SMU is one of four Texas universities to offer the QuarkNet program and the only QuarkNet university in North Texas.

“High school physics curriculum includes very little modern physics,” says Simon Dalley, a member of the SMU physics faculty and coordinator of its QuarkNet program. “This hurts recruitment to the field and prevents the general population from understanding physics’ contribution to the modern world.”

Ken Taylor, Lake Highlands High School physics teacher, is determined to introduce new physics research to his students. He has participated in QuarkNet at SMU since 2000, seizing opportunities to join physics researchers at high-energy particle colliders at CERN and Fermilab. This is the first summer he has selected students to join him in physics research at SMU.

“I like to support students beyond the classroom walls,” he says. “These students have gone through the whole process of scientific discovery and can use these projects as jumping off points for the next phases of their lives.”

With acceptance into the VSX catalog of variable stars, the students’ names are forever linked with their stars on the official registry.

But instead of creating new star names, star discoverers follow a protocol that includes the name of the telescope and the stellar coordinates.

Dominik Fritz discovered ROTSE1 J115128.40+493130.5, ROTSE1 J120809.03+503321.7 and ROTSE1 J232109.31+170125.6.

Jason Barton can include his stars, ROTSE1 J223452.37+175210.5 and ROTSE1 J223707.20+212657.9, on his resume.

Both students plan to pursue science careers, Fritz in nuclear engineering and Barton in medicine.

Other student QuarkNet researchers include KeShawn Ivory from Garland High School and Madison Monzingo and Lane Toungate from Lake Highlands High School. In addition, Hockaday School teacher Leon de Oliveira and his four students – Eliza Cope, Allison Aldrich, Sarah Zhou and Mary Zhong — also conducted QuarkNet research this summer.

“These students have made a real contribution to science,” says Farley Ferrante, the former high school physics teacher and current SMU astrophysics graduate student who supervised the students’ research. “A better understanding of variable stars helps us to understand the age and formation of the universe; the sun, which is a variable star; and even the possibility of extra-terrestrial life.”