Star Finders

Pulsars are rotating neutron stars that appear to be blinking from where we see them on Earth, and astronomers have not found very many of them. Watch as High Point University students travel to an observatory in Chile to discover one of of these rare stars.

HIGH POINT — If you want to observe and study the universe up close, the best way to do this would be to venture out into space yourself. Just look at the amazing images and discoveries that the Hubble Space Telescope has produced. 

The trouble is, going to space is not as easy as say, going to the mall. You would need special equipment to avoid the powerful radiation from the sun and to provide oxygen to breathe. And that's just to name a couple of the hazardous conditions in outer space. Yes, it's best to keep your feet on good ‘ole terra firma. 

The difficulties of space travel may be why astronomers flock to the Cerro Tololo Inter-American Observatory instead. High atop the Andes Mountains in Chile, the air is clear and there is no light pollution. 

There are six telescopes of various sizes at the observatory. However, astronomers don’t look through these telescopes; sensitive cameras and computers do the looking. And the astronomers analyze what is found. 

“So what you do initially is, once you have the target star and coordinates, you enter it into the tracking system, the telescope moves, and then you tell it to track the star,” says Alan Vasquez, a sophomore physics major at High Point University. “That way the star always stays in the field of view, and then you tell [the system] how many images you want it to take over the next couple of hours.” 

Vasquez was part of a special team from High Point University, which traveled to the Chilean observatory in search of something really rare: a pulsating star. 

Pulsating stars are basically a type of neutron star. Becoming a neutron stars is one possible end for a star, and results from massive stars that have finished burning their nuclear fuel and then explode. The explosion blows off the outer layers of a star, and what's left collapses under gravity, so much so that the protons and electrons combine to form neutrons.  

Astrophysics professor Dr. Brad Barlow led the HPU team searching for a pulsating star. He explains how these stars act like musical instruments, because they vibrate. 

“There are a lot of reasons for the vibration which we don’t quite understand, because it deals with the atmospheric conditions of the star,” says Barlow. “But as the star gets large and small, its temperature and density change, and so its brightness changes, and if you monitor the star over time you can see the variations.” 

And if you’re an astronomer observing a neutron star, you can learn a lot about the star by studying how the energy travels through the star’s atmosphere and through the star itself. Energy moves slower through denser material and faster through lighter material. And neutron stars are really dense. A teaspoon of their material is estimated to weigh as much as Mount Everest. 

“You can almost think of pulsating stars as star quake objects,” adds Dr. Barlow. “Just as earthquakes propagate through the earth, these waves go through the atmosphere of the star producing brightness variations. And just as geologists can infer the interior of the earth by the way waves propagate through the earth, we can also see inside stars by monitoring their pulsations.” 

In short, study how the waves travel through the star and you’ll know what kind of material that star is made up of. 

Pulsating stars are a little larger than our sun, but they are much older; roughly 10 billion years old. They have also burned off most of their fuel and have started to collapse, turning into a neutron star. 

“Pulsating stars are interesting for many reasons, but the primary reason is that these stars are basically the future of our sun,” explains Dr. J.J. Hermes, a Hubble Postdoctoral Fellow at the University of North Carolina Chapel Hill. “So we can go into them and learn what their interior composition is made of, what those compositional gradients are made of, and how much of a certain element is in each layer." 

The team had a target list of stars to study. These stars had the right size and additional characteristics to make them pulsating star candidates. 

Eugene Filik, a junior physics major at HPU admits that simply looking at a photo of the star isn’t always exciting. 

“That’s the star,” says Filik, pointing to a few fuzzy squares on a computer screen. “It’s a few thousand light years away, so it’s not much of an image. That’s why you look at this graph and the light coming from the star.” 

A graph appears on the screen, with two large and distinct humps on both sides of the screen, with smaller waves in between. 

“These two spikes tell you that you have pulsations, but it’s not enough to see in one night,” explains Filik, pointing to the high spikes. “So we went back the next night and did exactly the same thing and we saw these two pulses again. So if you flip through all of our recordings of the star, here are two pulses and the next night there are two pulses; that tells you that you have a pulsating star because we were able to replicate the data.” 

The pattern confirmed the discovery of a pulsating star. Further analysis determined the target pulsating star was orbiting another, much smaller, neutron star, which creates a double neutron star system. Such systems are incredibly rare. To date, only 12 in the entire universe have been found. 

“It was really cool to see it all pay off; after all of the code we wrote and staying up all night and doing all these observations,” says Filik, smiling as he looks again at the computer screen. “What was even more amazing was to see the outcome and know that only me, the professor and another student were the only ones to know it. You don’t know how to react at first, you have to take it all in.” 

“My rule for students is that if they find something, they can’t tell anyone for 20 minutes,” says Barlow. “It might sound silly, but I really stick to it because for those 20 minutes, they might be the only people in the history of humanity to know this. And that is such a cool feeling I can’t even begin to describe it to you.”

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