Dr. Tana Dale Joseph: An Astronomical Journey
It was the daily newspaper in South Africa that sparked a love of astronomy in future Fulbright Scholar and Royal Society Newton Fellow, Tana Dale Joseph.
“The major newspaper in Cape Town, the Cape Times, used to print Hubble Legacy images on its front cover in the 90s. My father bought the paper everyday and I just fell in love with the beautiful pictures of space. Then, once I realised that these were also scientific images, I decided that I wanted to do astronomy.”
The Cape Times is online now; when recently checked, it neither prints Hubble images on its front page, nor has a science section. However, during the 1990s astronomy awareness was rising in South Africa, so it did make sense to splash Hubble’s pictures on the front page. While the Hubble is not a South African telescope, the country does have a long tradition in astronomy, starting during the colonial period.
“The observatory in Cape Town was established 200 years ago during colonial times to service the British empire’s navigational needs. And the astronomy grew from there,” says Tana.
This observatory, the Royal Observatory at the Cape of Good Hope, was eventually rebuilt as a site for an optical and infrared telescope, the South African Astronomical Observatory (SAAO). The SAAO became a hub for the international astronomical community from the 1970s through present day. Over the years, it has expanded to include a network of telescopes, eventually including the South African Large Telescope (“Africa’s Giant Eye On The Sky”) in 2005.
But when Tana was young, South Africa’s astronomy arsenal was more modest.
“When I decided to become an astronomer, I was 11 years old. Throughout my school career, my decision was seen as rather odd, but I had the unwavering support of my parents and that is why I never bothered with the naysayers. At that stage, there was one 26 meter dish radio telescope in the north east of the country and a few small optical telescopes.
“Then things started to change in the late 90s/early 2000s, when I was in high school. The Southern African Large Telescope (SALT) was built and completed by the time I had completed … my undergraduate degree in 2005. SALT was highly publicised. It really changed the conversation around my wanting to become an astronomer because now people knew that we had this amazing ten meter optical telescope, the largest mirror in the southern hemisphere.”
After the success of SALT, South Africa built up its astronomical research community. Astronomers from around the world performed ground-breaking research using South Africa’s network of telescopes. They used the telescopes to discover new comets, measure the retrograde motion of an exoplanet, studied variable stars and other transient events, looked at galaxies and quasars, and participated in astronomical surveys, from optical to radio and infrared wavelengths.
Around the same time, Dr. Naledi Pandor, the visionary Science Minister of South Africa, successfully landed a project to build the Square Kilometre Array (SKA) telescope. Her bid to build the radio telescope array in the elevated, low-humidity areas around South Africa succeeded after a highly competitive bidding process, including China and Argentina. The array is exactly what it sounds like: thousands of radio dishes spread across Africa and Australia, with a total collecting area equivalent to one square kilometer. It cemented South Africa’s place as a leader in modern day radio astronomy.
“The SKA brought radio astronomy to South Africa [on] a large scale. Our successful bid to host the SKA and subsequent building of the MeerKAT radio telescope is down to a careful and concerted effort from our government, spearheaded by Dr. Naledi Pandor.”
The primary purpose of SKA was radio astronomy, but the organization also gave back to the community— they funded scholarships for local students to study astronomy.
“I was funded by SKA South Africa for my Master’s degree. After being selected as joint hosts for the SKA, South Africa had much more funding to really grow the astronomy research community.”
Following her Masters, Dr. Joseph was awarded a Fulbright Scholarship to do a postdoc in astrophysics at Texas Tech University. “I’ve been really fortunate to have had Tana as a graduate student. In addition to her terrific research, Tana has done an amazing job publicizing science and in growing the world scientific community,” commented her advisor, Tom Maccarone.
Tana currently uses the SKA telescope to study X-ray binaries in other galaxies. There is a very good reason to study binaries in other galaxies as opposed to binaries in our own galaxy, the Milky Way. It turns out it is difficult to accurately measure the distance to binaries in the Milky Way: the error is around 50%. But the distance between our galaxy and other galaxies is easier to measure, so the distance to the binaries in those galaxies is known to within 10%. Knowing the distance to these binaries is important because it is part of the calculation for the power output of the binary.
X-ray binaries look like a pair of stars, but are composed of one star that is being slowly eaten by a nearby black hole or neutron star. When matter flows from the donor star, it emits energy as X-rays.
Tana was kind enough to upload a preprint of a recent paper she published on X-ray binary systems. The binary system studied in the paper consists of a black hole and a white dwarf inside of a globular cluster outside our galaxy. When she and her collaborators looked at the data, they were surprised to see it was ten times brighter than a previous measurement. Spectral measurements showed that the black hole was eating the white dwarf, sucking out the oxygen-rich material, which they suspect caused the increase in brightness. You can read more details here: Deep Chandra observations of the NGC 4472 globular cluster black hole XMMU 122939.7+075333: Short term variability from the first globular cluster black hole binary
“I am also looking forward to studying these systems with the MeerKAT and ASKAP radio telescopes and will have a major paper coming out soon on the latest ASKAP data.”
Tana is currently a Royal Society Newton International Fellow at The University of Manchester. In addition to her academic career in astronomy, she has recently made the leap into becoming a science communicator, launching her own consultancy, AstroComms. AstroComms provides a range of communication services, including giving free talks on astronomy for schools and consulting for paid media projects that need a science advisor. She feels very strongly that the public deserves to learn what is going on in modern research, since most science is publicly funded: “The science isn’t done until it is communicated.” Her word of advice: “There is a lot of good that comes from a science literate society.”
“Ultimately, I am a person whose time had come. I was in the right place at the right time to be able to take advantage of the astronomy resources that have become available during my studies and early career.”
