Brown dwarfs hunt in outer space

Press, 28 June 1989, Page 17

Brown dwarfs hunt in outer space

NfZ. astronomer to foster her with nonptellg/r compaiiiQns Qf_ stars

KAYLENE MURDOCH is looking for brown dwarfs. A 24-year-old with a ready smile and a laid-back manner, she is good natured about the reaction she gets to her imaginatively named area of star-gazing. “Is that anthropology or astrophysics?” joked a friend, seeing a volume on “The Astrophysics of Brown Dwarfs” on her bookshelves.

The subject of her research is, in fact, non-stellar companions to nearby stars, particularly planets and “brown dwarfs” — objects more massive than planets, but not large enough to be stars. The work is part of a four-year PhD project, which has won her a number of grants and awards, most recently Zonta International’s Amelia Earhart Fellowship. She is only the second New Zealander to be so honoured.

The fellowship is one of 40 awarded world wide this year to women “of outstanding character and scholastic achievement, who are entering or continuing fulltime graduate study with career objectives in aerospace-related fields.” It is named after an aviation pioneer and early advocate of women’s rights who disappeared in 1938, during an attempt to be the first to circle the Earth at the Equator by air. Worth SUS6OOO, the fellowship will enable Murdoch to spend the next seven months studying in the United States, at the Harvard Smithsonian Center for Astrophysics. The centre and the University of Canterbury’s Mount John Observatory at Lake Tekapo already enjoy close collaboration, she says. The centre has no observatory in the Southern Hemisphere, and much of Mount John’s instrumentation is modelled on instruments at Harvard.

Since Harvard have been working in the field for seven or eight years, and the New Zealand programme has only just started, the aim of her visit is to observe their progress and learn how to develop the programme further in New Zealand. After she finishes at Harvard, she will go on to spend a few weeks at the Dominion Astrophysical Observatory in Victoria, British Columbia, which is using slightly different techniques on the same problem. For the Canterbury part of the study, she spends five days every second month observing at Mount John. “I always take my knitting,” she says, with a grin. “Sitting up all night, waiting for the skies to clear, you’re too tired to do any work: it’s the ideal solution to keeping awake. I’ll get half a jersey done on a good run.” During observations, light from a star is collected by the obser-

MAVIS AIREY talks with a young Christchurch astronomer who has become only the second New Zealander to be awarded an Amelia Earhart Fellowship. With it, she plans to spend seven months at the Harvard-Smithsonian Centre for Astrophysics in Cambridge, Massachusetts, where her tutor, David Latham, is working on a collaborative search for hitherto unknown planets and unseen companions of stars. Next year, Latham is to be the visiting Erskine Fellow at Canterbury University.

vatory’s one-metre telescope and passes down an optical fibre to a spectrograph located in a room next to the dome. The spectograph disperses the starlight into its component colours, and the resulting spectrum is recorded digitally on a computer, for later analysis. “A spectrum is a ‘fingerprint’ of a star,” she explains. "From it, astronomers can find out many things about the star, such as its composition, mass, age, and so on. One can also deduce how fast the star is moving towards or away from us. It is this ‘radial velocity’ that can be used to detect planets around a star. “The gravitational pull of a planet orbiting a star causes the star to wobble in position slightly. Astronomers may detect this wobble by picking up very small changes in the star’s radial velocity.” In her research programme, spectra of about 30 stars similar to the Sun are obtained at monthly intervals. The radial velocities of the stars are calculated using a computer. The

radial velocities are then analysed to look for changes which might suggest the presence of non-stellar companions.

When she gets her PhD, Kaylene Murdoch will be only the fifth doctor of astronomy New Zealand has produced. Beatrice Tinsley, who was perhaps New Zealand’s most famous astronomer, did her masters degree at Canterbury, but had to go to the United States to work, and Murdoch feels the chances are very high that she will have to follow suit. “New Zealand is too small to support a large number of academic astronomers — something like one or two jobs pop up per decade,” 3he says. Not that she has ever been one to worry about job prospects. “I didn’t even consider that — I thought if I’m good enough, I’ll get something.” She was quite struck by the difference in attitude of younger students she met at the Physics Winter School held by the university in the May holidays for secondary school pupils. It was

the first time the Physics Department had held such an event, and 120 students attended. She found them very keen, but when she asked them if they were going on to study physics, the reaction was, What are the job prospects?

The course introduced them to aspects of physics they would not get at school, and would otherwise only have known about from reading popular journals, she says.

Despite these students’ enthusiasm, physics is not a popular subject at school. “When I tell people I study physics they always say, ‘lt was my worst subject at school’ — and that’s true of men as well as women.”

“My interest in physics is probably unusual,” she admits. When she was at Christchurch Girls' High School, from 1978 to 1982, out of 100 girls in her seventh form year only eight took physics, and she was the only one who went on to study it at university. Why the lack of interest? “At school we were not encouraged to go for an academic career, more the service professions, like medicine,” she comments. Another reason, she thinks, may be the amount of mathematics involved.

“You need to learn maths way ahead of physics in order to be able to use its applications. Also, the really very interesting aspects of physics like particle physics and quantum physics need to be taught with a lot of maths which students don’t have in the school syllabus,” she says. Nevertheless, she enjoyed physics at school. “I enjoyed it a lot, so I took as many physics papers as possible — including astronomy, which is- a very interesting area to do research in — and I got a taste of research doing my BSc,” she says. “Through luck or good management, I managed to make it

through physics at school and still retain an interest in it.” After the BSc, she went overseas for two years, but the thought of doing further research, possibly a PhD in the United States, was always in the back of her mind. She saw an advertisement for the Amelia

Earhart Fellowship while she was in England, and wrote back to Canterbury University asking for advice about where she might go to study in the United States. The reply was unexpected: “Why don’t you come back here — we’ve got this great research project going!”

Thanks to a scholarship from the University Grants Committee in New Zealand, and a D.S.I.R. women’s study award, she was able to start work at Canterbury last October on about $lO,OOO a year — almost twice what she would earn as a teaching assistant, she says.

As well as the Zonta fellowship, she has also been awarded a travel grant from the Royal Astronomical Society, and hopes she may get other grants as well. "Looking for grants is actually a big part of my research,” she admits. “It takes up a relatively big part of my PhD time.” Paradoxically, being a woman has helped. “Women are underrepresented in science at this level,” she says. “In some respects, I’ve been in the right place at the right time.”

Of the 15 PhD students at the Physics Department, only one other is a woman — who is doing solid state physics — although another woman is due to start soon, doing astronomy, she says. Interesting though she finds the research, she admits it’s lonely work. A keen choral singer, a recent convert to skiing, and a member of the Physics Department’s flourishing squash club, she jokes that she looks forward to going down to Mount John to get away from it all; then she adds, seriously, “I think I’m a bit too gregarious to be a really good astronomer.”

She leaves for Harvard in early July.