Press Release

UC Santa Cruz Astronomer Wins Herzberg Memorial Prize

By SpaceRef Editor
February 27, 2002
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SANTA CRUZ, CA–The National Research Council of Canada (NRC) has
awarded the 2001 Herzberg Memorial Prize and Fellowship to Puragra
GuhaThakurta, associate professor of astronomy and astrophysics at
the University of California, Santa Cruz.

The honor recognizes GuhaThakurta’s outstanding work in observational
astrophysics. The award consists of a prize and a one-year
fellowship. GuhaThakurta will spend his fellowship year at NRC’s
Herzberg Institute of Astrophysics in Victoria, British Columbia.

“I’m really happy and totally surprised,” said GuhaThakurta, who was
honored at NRC’s annual awards dinner and ceremony on February 20 in
Ottawa.

GuhaThakurta earned international renown in the field of astrophysics
for his influential work on a wide range of subjects, including
interstellar dust, dark matter, planets, supernovae, and globular
star clusters. His current focus is understanding how galaxies
formed. GuhaThakurta charts the history of our galaxy, the Milky Way,
by observing its closest relative, the nearby Andromeda galaxy.

“There are no mirrors in astronomy to tell us what the Milky Way
looks like from the outside,” said GuhaThakurta. The next best thing
to looking in a mirror, he said, is looking at a close relative.
Andromeda is a bigger version of the spiral-shaped Milky Way and, at
a distance of two million light-years, is also its cosmic neighbor.

GuhaThakurta tracks individual stars in the Andromeda galaxy using
the Keck Telescope in Hawaii and the Hubble Space Telescope. An
instrument called a spectrograph separates the light from each star
into its basic colors, like a prism. These colors tell the story of
the star: its temperature, how fast it’s moving, and its chemical
makeup.

“It’s pretty remarkable that light from a star two million
light-years away can tell us so much about the evolutionary state of
the star,” GuhaThakurta said.

Stars are mainly hydrogen and helium, the simplest elements in the
universe. But they make small amounts of heavier elements, such as
calcium, during their lifetimes via the nuclear fusion reactions that
cause stars to shine. When massive stars finally die in a grand
explosion called a supernova, they inject these elements into their
surroundings.

“The next generation of stars is born with these pollutants,”
GuhaThakurta said. The process then perpetuates: When some of these
baby stars grow up and explode, they transmit the traces of their
ancestors, along with newly made chemicals, to the next generation.
Like traits in a pedigree, the amounts of metals in a star tell us
about its ancestry.

What’s surprising is that when GuhaThakurta examined 100 stars in a
small area of Andromeda, their chemical tags were so diverse that he
concluded the stars must have formed in different places and at
different times.

“Andromeda’s halo of stars appears to be the result of the smooshing
together of many small galaxies, and the same process probably formed
the Milky Way’s halo,” GuhaThakurta said.

During his fellowship at the Herzberg Institute of Astrophysics,
GuhaThakurta will use the Canada-France-Hawaii telescope to continue
his detailed survey of Andromeda. This telescope will provide
complementary data to the Keck and Hubble telescopes. GuhaThakurta
will begin his fellowship in summer 2002.

GuhaThakurta previously received a Hubble Fellowship, widely
considered to be the most prestigious postdoctoral fellowship in
international astronomy, and was an Alfred P. Sloan Research Fellow
through 2001.

The National Research Council of Canada (NRC) established the
international Herzberg Memorial Prize and Fellowship Award in 1999 to
commemorate the late Gerhard Herzberg, NRC scientist and Nobel
laureate known worldwide as the “father of modern molecular
spectroscopy.” This prestigious honor is given annually to an active
researcher who has distinguished himself or herself through many
years of outstanding achievements in a field that is relevant to
NRC’s programs.

SpaceRef staff editor.