By Jeffrey Berg and Gilli Rodriguez
The Bucket List Astronomy Class says farewell to the skies Down Under, but not before splitting our allegiance between SHSU and Australia. Dr. George Hobbs is on the far right. // Photo by Samuel I. Beard, Jr.
Just that morning, he had been in Parkes after installing and testing a new ultra-wide-band receiver on the Dish, but by 11 a.m., he was in Marsfield, ready to tell the BLAsT Class all about pulsars.
“He” is Dr. George Hobbs, a pulsar researcher and radio astronomer who gave us a lecture on pulsars and how they help us learn more about the universe. He started by explaining how radio astronomers “listen” in on the sky, and he played for us a signal that sounded like a loud grandfather clock ticking. This was the first known pulsar, discovered almost exactly 50 years ago. In 1967, the first pulsar was discovered when radio telescopes picked up a mysterious ticking noise (okay…it was a bit of scruff in the data) which astronomers then dubbed LGM1, or Little Green Men 1.
Pulsars themselves do not transmit sound. They transmit radio waves – a form of light - that we then are able to pick up and transform into sound. The tapping or ticking sounds that we hear is one rotation of the pulsar; so the faster the tick, the faster the rotation of the pulsar. So in that sense a pulsar IS like a clock ticking. The fastest known pulsar is rotating at around 700 times per second, and it sounded like a buzzing insect. Something the size of a city was whipping around as fast as a blender motor!
No, it's not a map of all the Starbucks in the country, but a map of all the radio transmitters, which cause real problems for radio astronomers. // Provided by Dr. George Hobbs
Some pulsar stars maintain a steady “tick,” and some even turn off entirely sometimes, but astronomers are still puzzled about why that happens. Dr. Hobbs also explained that was an instance when astronomers found a pulsar’s tick to be around 60 microseconds off, and this change in timing was due to the pulsar going behind the Sun. The Sun’s strong gravitation forced distorted the time causing the delay. We’d heard about the effect that mass has on time in both Dr. Lasky’s lecture and Dr. McDermid’s lecture, as well. When a clock is close to a high source of gravitation force, it slows the clock down compared to a clock that is away from such a strong force of gravitation.
But what IS a pulsar? In 1932, James Chadwick discovered neutrons, an incredibly dense neutral particle in an atom’s nucleus. As it turns out, when massive star goes supernova, it has a chance to become a black hole (collapsing into a singularity) or a neutron star (collapsing into something made almost completely of neutrons). Neutron stars are only 20 or so kilometers in diameter, but they have the mass of the Sun.
Dr. Hobbs was very excited to tell us about the future of pulsars and radio astronomy in general. For example, the Chinese have completed a 500-meter diameter radio telescope called FAST (Five-hundred metre Aperture Spherical Telescope). FAST is being worked on as we speak, to get it fully operational, and it is the largest radio telescope in the world. Dr. Hobbs said it was fitting that the same culture that recorded a supernova explosion in 1054 has, nearly 1000 years later, created a telescope that will help us listen in on its ticking heart.
The first data from the new ultra-wide-band receiver installed at Parkes just days before Dr. Hobbs' visit. And we were the first group to see it! // Photo by Benjamin Blume
Pulsars might play a crucial part in how we will navigate the universe by being natural GPS “satellites,” probe extreme magnetic fields, test theories of gravity, improve terrestrial time standards, measure planet masses… the list goes on and on. We are grateful to Dr. Hobbs for such an energetic lecture about objects that help us discover more and more about what’s in our universe.
ABOUT THE AUTHORS:
My name is Jeffrey Berg, I am a sophomore and I am a Computer Science major. I took this class because I felt like this was a great opportunity to knock out all my science credits, and I always wanted to travel across the world to the isolated Australia. Even though my major has nothing to do with the stars and constellations that we are learning about here, I have always been fascinated with space.
My name is Gilli Rodriguez and I’m a sophomore at Sam Houston State. I’m studying to be an elementary teacher and I took this crazy class because I love learning and traveling. And there ain't a better way to do both!