Judith Provencal, astronomer, UD professorDec 30, 2020 11:24AM ● By Tricia Hoadley
Not only does Judith “Judi” Provencal teach about the stars, she’s also unlocking their secrets.
And Provencal knows her stars. A University of Delaware associate professor in the Department of Physics & Astronomy and director of the Delaware Asteroseismic Research Center, Provencal is also resident astronomer at Mt. Cuba Observatory in Greenville. Newark Life asked her about telescopes, white dwarf stars and the skies.
Question: As an astronomer, what is your latest project?
Answer: We have a big project going on at Mt. Cuba Observatory right now that's going to benefit the observatory and the university, too. We’re building a new telescope at Mt. Cuba and it's going to have about a 50-inch diameter mirror. It's going to be one of the largest telescopes on the East Coast. New Castle County finally approved our building permit.
We’re going to start digging in the next couple weeks and they're building the telescope now at a company in Colorado. We're putting up a whole new building at the observatory. The students at the university are going to be able to use this telescope to do research projects, and so will graduate students and my Observational Astronomy classes. It's going to be a really exciting.
Q: What will the new telescope enable the observer to see?
A: The telescope that we have now at Mt. Cuba that we use with my class and with the students -- the mirror is only about two feet, a 24-inch mirror. How faint a star you can detect depends on the size of the mirror, so the bigger the mirror, the fainter you can go.
We're going to be able to see much fainter stars. You’ll be able to look at galaxies, to look planets around other stars. We can do just about anything with this new telescope.
Q: Sounds like quite a venture. When will it be finished?
A: We’re hoping to have the building up before winter comes; the telescope itself will be ready about next fall.
They’ve got to use a big crane to lift the telescope, then put in through a slit in the dome’s roof. That’s going to be scary to watch. [Laughs]
Q: What about the existing telescope?
A: The existing telescope is going to remain. It’ll still be good for some research and some public nights. It was built in the 1960s, so it’s definitely not modern and computerized. But the students have a lot of fun, because to move that telescope around to find things you actually have to pull on it and push. There are no buttons to make it move. The students think it’s great fun to do.
Q: What is asteroseismology and how do you use it to study white dwarf stars?
A: A white dwarf is a dead star. So a star like the Sun, in about four billion years, is going to end up with just a core left after all the nuclear fusion is finished. We wanted to figure out a way to look inside of a dwarf star, because the photons [light particles] that you see when you go outside at night are coming from the surface, not the inside. Asteroseismology uses pulsations of the star to probe the inside of the star.
Q: But you said white dwarfs are dead stars. They still pulsate?
A: Yes. They do have temperatures where they pulsate and those are the stars that I study. Like when the Earth has an earthquake and they can use how the earthquake propagates through the earth to figure out what the interior of the planet is like, we do the same thing with the pulsating stars. It’s like they’re having earthquakes and if we can figure out how this pulsation propagates, we can learn what’s going on inside of the star. It’s kind of like being a stellar archaeologist. You’re digging around in the remnants of the white dwarf. And that’s pretty cool.
Q: And that’s all done with telescopes? How?
A: Yes, with telescopes. But observing a pulsating star can be kind of [tedious]. Once you're set up, you just kind of sit there all night and make sure nothing crashes, taking picture after picture. Then at the end of the night, you end up with -- it depends on the star -- 3,000 or 4,000 pictures. You go back later next day, after you've gotten some sleep, and you take all these images and you extract the brightness of the star from every single one of those pictures. You turn that into what's called a light curve on the x-axis and then the brightness of the star on the y-axis and so you see the brightness go up and down and up and down as the star pulsates.
With the white dwarfs, their pulsation period is about 10 minutes or so. So, they go up and down once every 10 minutes. You can get a lot of pulsation cycles in a reasonable amount of time.
Q: Is this done with the Whole Earth Telescope?
A: Yes, the idea of the Whole Earth Telescope comes from wanting to observe a star 24 hours a day, but I could only observe eight or nine hours until the sun came up. Then you have gaps in your data and it makes analysis really hard. You want to get rid of the gaps, so that’s where the Whole Earth Telescope came from. A bunch of friends from around the planet are interested in the same kinds of stars that we study. So, every once in a while, we organize. I’ll be observing a pulsating star here in Delaware. And then I have some friends in Texas who start observing when the sun rises here, then friends in Hawaii. We’ve got friends in China and Thailand and lots of telescopes in Europe.
The idea is to keep everything going continuously 24 hours a day, which makes it easier to figure out how the star’s pulsating.
Q: What would you like the average person to know about the skies?
A: That there are so many more things in the sky than they’re seeing. There’s so much light pollution now. It’s sad that you go outside in New York and you see maybe five stars, if you’re lucky.
I wish there was one night a year when we could all just turn off all the lights and let everybody go outside. With no telescope, no nothing. Just take a blanket and lie down on the ground and stay outside for about half an hour or so [until] your eyes are fully dark adapted and you can see what's really there. The Milky Way is really there and it's this glowing mass of stars that go across the whole sky. [Watching the stars] was like video games to people back before lights. That's what they did. There were no TVs or computers. They went out at night and watched the sky. We’ve lost that. I just wish people would go outside and look up.
There’s not any place really dark around here. Maybe Fair Hill [Natural Resources Management Area in Elkton, Md.] or someplace like that. Even if you had a pair of binoculars, you could go out and look at the moon and see its craters. It would help you understand how special this planet is and how it’s just a small part of something that’s so much bigger.
We used to think the Earth was the center of everything and it’s not. And then the Sun was the center, but, no, it’s not and then that the Milky Way was the center. Nope. There is no center.
Natalie Smith may be contacted at [email protected].