UBC Astronomy prof., Harvey Richer, and his former PhD student, Jason Kalirai have uncovered the most distant star clusters ever seen, shedding light on the evolution of galaxies like ours.
While using NASA’s Hubble Space Telescope to examine NGC 6397, a globular star cluster in the Milky Way and one of the nearest to Earth, the team serendipitously found another star cluster system in a distant galaxy hidden behind it.
“We were surveying white dwarf stars to determine the age of NGC 6397 when I noticed an unusual high concentration of stars in one area,” says Richer.
“Upon closer inspection, we discovered it’s in fact another cluster system surrounding a distant galaxy, but it’s so far away that the collective light emitted by hundreds of thousands of stars in a cluster appear as a faint star-like point.”
Richer and Kalirai then used the Gemini South Telescope in Chile to determine the distance of the galaxy, pegging it at more than one billion light-years away, 10 times farther away than the most distant previously-observed clusters. (A light-year is approximately nine trillion kilometres.)
“This means that the light we see coming from these stars today was emitted more than a billion years ago,” says Richer. “When you look so far away, you’re really looking back in time, seeing clusters as they were a billion years ago.”
“Comparing this cluster system — which is at an early stage of evolution — with that around our own galaxy paints a clearer picture of how galaxies form and evolve,” says Kalirai, now a post-doctoral fellow at the University of California, Santa Cruz.
Kalirai received his BSc., MSc. at UBC and did his PhD with Richer before receiving a Hubble Fellowship in 2005.
NB: Kalirai will present the findings at the American Astronomical Society Meeting in Seattle on Jan. 10 at 10 a.m. For more information visit www.aas.org/meetings.
Prof. Richer is available for embargoed interviews before Jan. 10. Please contact Brian Lin at 604.822.2234 or firstname.lastname@example.org. Images of Prof. Richer and the discovery are also available.
Biography: Harvey B. Richer
Prof. Harvey Richer was born in Montreal, Quebec. He studied at McGill University and obtained his doctorate in physics and astronomy from the University of Rochester.
Richer has been at the University of British Columbia since the early 1970s. He has received various awards and distinctions including: Canada-U.S. Fulbright Scholar (2005), Canada Council for the Arts Killam Fellowship (2001-03), and the Gemini Scientist for Canada (2000-03).
His research is largely focused on stellar astronomy and on what systems of stars can tell us about dark matter, the age of the Universe, the dynamical evolution of stellar systems, and the formation of galaxies. To investigate these diverse subjects, he observes a wide range of objects, including nearby stars, open and globular star clusters, and the components of our neighbouring galaxies.
To accomplish his research goals, he uses a variety of telescopes, particularly the Twin Gemini Telescopes in Chile, the Canada-France-Hawaii Telescope and the Hubble Space Telescope.
Astronomy at UBC
UBC was ranked the top Canadian university in the field of space science, with 26.54 average citations per paper, in the 2000-04 Science Watch. UBC ranks second, behind the University of Toronto, in total citations in the same time period.
Other world-renowned UBC astronomers include Jaymie Matthews, lead investigator of the Microvariability & Oscillations of STars (MOST), Canada’s suitcase-sized space telescope; Mark Halpern, part of the Balloon-borne Large Aperture Submillimetre Telescope (BLAST) project, which recently concluded a one-week deep-space observation over Antarctica; Brett Gladman, Canada Research Chair in Planetary Astronomy and Ingrid Stairs, an expert on rotating neutron stars, or pulsars.
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