From Science Node: Women in Stem -“A Hoosier’s view of the heavens” Caty Pilachowski

Science Node bloc
Science Node

24 Aug, 2017
Tristan Fitzpatrick

Caty Pilachowski

Courtesy Emily Sterneman; Indiana University.

“An eclipse violates our sense of what’s right.”

So says Caty Pilachowski. Pilachowski, past president of the American Astronomical Society and now the Kirkwood Chair in Astronomy at Indiana University, has just returned from Hopkinsville, Kentucky where she observed the eclipse on the path of totality and watched the phenomena associated with a solar eclipse.

“There are all kinds of effects that we can see during an eclipse,” says Pilachowski. “For example, we’re able to see the corona, which we can never see during the daytime without special equipment.”

The surface of the sun, Pilachowski explains, has a temperature of roughly 5,780 kelvins (10,000º Fahrenheit). The thin gas that makes up the corona far above the sun, however, has a much hotter temperature— over a million degrees K.

“That process of transporting energy into the highest atmosphere of the sun is not well understood,” she observes. “It’s the region just above the bright lower atmosphere of the sun that we’re best able to see during the eclipse, and that’s where the energy transport occurs.”

Smile for the camera

But the star in our own neighborhood isn’t the only one Pilachowski is keeping her eye on.

When they’re not watching eclipses, Pilachowski and her colleagues at the IU Department of Astronomy use the One Degree Imager (ODI) on the WIYN 3.5M Observatory at Kitt Peak outside Tucson, Arizona.

One Degree Imager (ODI) on the WIYN 3.5M Observatory

NOAO WIYN 3.5 meter telescope at Kitt Peak, AZ, USA

The ODI was designed to image one square degree of sky at a time (the full moon takes up about half a square degree). Each image produced with the ODI is potentially 1 – 2 gigabytes in size.

Kitt Peak outside of Tucson, Arizona hosts the 3.5 meter WIYN telescope, the primary research telescope for IU astronomers. Courtesy IU Astronomy; UITS Advanced Visualization Laboratory.

IU astronomers collect thousands of these images, creating huge datasets that need to be examined quickly for scholarly insight.

“Datasets from the ODI are much larger than can be handled with methods astronomers previously used, such as a CD-ROM or a portable hard drive” says Arvind Gopu, manager of the Scalable Compute Archive team.

This is where IU’s computationally rich resources are critically important.

The ODI Portal, Pipeline, and Archive (ODI-PPA) leverages the Karst, Big Red II, and Carbonate supercomputers at IU to quickly process these large amounts of data for analysis.

Karst supercomputer

Big Red II supercomputer

These HPC tools allow researchers to perform statistical analysis and source extraction from the original image data. With these resources, they can determine if they’ve located stars, galaxies, or other items of interest from the large slice of the universe they’ve been viewing.

“The advantage of using ODI-PPA is that you don’t have to have a lot of supercomputing experience,” says Gopu. “The idea is for astronomers to do the astronomy, and for us at UITS Research Technologies to do the computer science for them.”

This makes the workflow on the ODI much faster than for other optical instruments. When collecting images of the universe, some instruments run into the crowded field problem, where stars are so close to each other they blend together when imaged. Teasing them apart requires a lot of computational heft.

Another advantage ODI-PPA offers is its user-friendly web portal that makes it easy for researchers to view out-of-this-world images on their own machines, without requiring multiple trips to Kitt Peak.

“Without the portal, IU astronomers would be dead in the water,” Pilachowski admits. “Lots and lots of data, with no way to get the science done.”

Out of the fire and into the frying pan

Pilachowski is also a principal investigtor on the Blanco DECam Bulge Survey (BDBS). A three-year US National Science Foundation-funded project, BDBS uses the Dark Energy Camera (DECam) attached to the Blanco Telescope in Chile to map the bulge at the heart of the Milky Way.

Dark Energy Survey

Dark Energy Camera [DECam], built at FNAL

NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

Like the yolk of a fried egg rising above egg whites in a frying pan, billions of stars orbit together to form a bulge that rises out of the galactic center.

With the help of the DECam, Pilachowski can analyze populations of stars in the Milky Way’s bulge to study their properties.

Astronomers use three different variables to catalog stars: How much hydrogen a star has, how much helium it has, and how much ‘metals’ it has (or, all the elements that aren’t hydrogen or helium).

When the data from the survey is processed, Pilchowski can explore a large amount of information about stares in the Bulge, giving her clues about how the Milky Way’s central star system formed.

“Most large astronomical catalogues are in the range of 500 million stars,” says Michael Young, astronomer and senior developer analyst at UITS Research Technologies. “When we’re done with this project, we should have a catalog of about a billion stars for researchers to use.”

Journey of two eclipses

As a child of the atomic age, Pilachowski grew up devouring books about the evolution of stars. She read as many books as she could about how they were formed, what stages they went through, and how they died.

“That interest in stars has been a lifelong love for me,” Pilachowski says. “It’s neat to me that what I found exciting as a kid is what I get to spend my whole career studying.”

She observed the last total solar eclipse in the continental US on February 26, 1979, an event she says further inspired her research in astronomy.

“For me that eclipse was a combination of, ‘Wow, this is so amazing,’” Pilachowski recalls.

“On the other hand, the observer in me saw cool things that were present, like planets that were visible right near the sun in the day time.”

Regardless of whether scientists get closer to answering why the sun’s outer atmosphere is much hotter than its surface, Pilachowski says the eclipse has an eerie, unnerving effect on viewers.

“We have this deep, ingrained understanding that the sun rises every morning and sets every evening,” says Pilachowski. “Things are as they’re supposed to be. An eclipse is something so rare and counter to our intuition that it just affects us deeply.”

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