HIGH POINT, N.C., Aug. 3, 2015 – Dr. Brad Barlow, assistant professor of astrophysics at High Point University, recently shared six years worth of data on a “pulsating” star he discovered at the Seventh Meeting on Hot Subdwarfs and Related Objects at the University of Oxford. He also chaired a section of the conference focused on hot subdwarfs in globular clusters, stellar winds, kinematics and Type 1a supernova.
In his presentation, “Now You See It, Now You Don’t: The Disappearing Pulsations of the Hot Subdwarf Star CS 1246,” Barlow shared data collected by him and his students showing that the star’s pulsations have weakened considerably in a short amount of time. He says this type of discovery is particularly exciting, because most astronomical processes occur over millions or billions of years.
“Observations like this are usually difficult to make, because most stars don’t change this considerably in our lifetimes,” Barlow says. “In less than a decade, CS 1246 has gone from a strong pulsator to barely one at all, implying that stars can change their structure in a shorter amount of time. The timescale we have measured will allow theorists to better understand why these stars pulsate, and how dense their atmospheres are.”
When Barlow first discovered the hot subdwarf in 2009, it showed some of the strongest pulsations in its class.
“Like a heart beating, this star grows and shrinks in size every six minutes, and as it does, it varies in brightness,” Barlow says.
However, when Stephen Vultaggio, a 2015 HPU graduate, observed the star in 2013 with robotic telescopes in Chile, he found that the pulsations were much weaker. Alan Vasquez, a rising sophomore, made further observations this summer as part of HPU’s Summer Undergraduate Research Program in the Sciences. He devoted his research project to CS 1246, using the robotic SKYNET telescopes to better characterize the decrease in the strength of the pulsations.
Throughout the project, Vasquez captured 200 to 400 images of the star each night and analyzed them with his own software to produce a “light curve.” His results confirmed the weakening of the pulsations and provided helpful insight into other characteristics measured by Python codes he created.
“Our conclusion is that the star must be undergoing some sort of structural changes on the inside,” Barlow explains. He says their research could provide new insight into how stars evolve over time.
Barlow and Vasquez plan to publish their most recent findings this fall.