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Weidong Li (1968–2011)

Published onDec 01, 2012
Weidong Li (1968–2011)

Dr. Weidong Li, an Associate Research Astronomer at the University of California, Berkeley, died tragically in Benicia, CA, on December 12, 2011. He was 42 years old, and a world-renowned expert on supernovae.

Weidong was born in 1968 in the mountainous Western River Village, Dongxin district, Dawu county, Hubei province, China – the son of Chuangang and Cuifang Li, who were farmers. His true date of birth is unknown, but he determined it to be around December 29 and that is the date he celebrated, although official documents list it as December 10. As a child he was interested in all kinds of scientific findings, and he decided to devote his life to science when he grew up. A great step toward accomplishing this goal came in 1986, when he became a student in the Department of Astronomy at the Beijing Normal University. He was the first person from Dongxin to attend college, and after his later success he became a real hero there.

He studied very hard as an undergraduate and was the top student in his graduating class of 1990. Thereafter, he remained at Beijing Normal University, conducting supernova (SN) research under the direction of Professor Zongwei Li; he obtained his Masters degree in 1992 and his doctorate in 1995. As a postdoctoral scholar at the Beijing Astronomical Observatory (BAO), under the direction of Professor Jingyao Hu, his main task was to establish the first systematic SN search in China using a 0.6-meter reflecting telescope at Xinglong Station. He participated in modifying the hardware and wrote much of the software, making the search nearly fully automated, and it became operational in early 1996. The BAO SN search, led by Weidong, discovered SN 1996W on April 10 – the first SN discovered by Chinese astronomers since the Crab SN of 1054 AD! Later that year, his group discovered five additional supernovae, and all but one was found before maximum brightness.

In 1996, my research team at UC Berkeley completed the Katzman Automatic Imaging Telescope (KAIT), a 0.76-meter robotic reflector at Lick Observatory on Mt. Hamilton, CA, whose purpose was to discover and monitor supernovae. Dr. Richard Treffers (my chief engineer) made most of the hardware work correctly, and Michael Richmond (my graduate student) had written much of the software several years earlier. We found SN 1997bs in April 1997, but progress on our Lick Observatory Supernova Search (LOSS) was very slow because there wasn’t anyone dedicated full time to the project.

At my invitation, Weidong joined my group as a postdoctoral researcher in September 1997. After spending a few months improving the software, in March 1998 he found SN 1998W and SN 1998Y, and then LOSS really got going: it became, for about a decade, by far the world's most successful nearby SN search, responsible for about 40% of those found each year. In total, it discovered almost 900 supernovae, many of which were quite young and thus scientifically most valuable. It also conducted filtered follow-up observations of hundreds of supernovae. Moreover, Weidong programmed KAIT to automatically respond to gamma-ray burst (GRB) alerts from Swift and other satellites, interrupting what it doing in order to obtain a set of follow-up observations of the optical afterglow. All of this was due to his incredible dedication, knowledge, ability, and enthusiasm. I have rarely met anyone as driven and passionate about their work; whenever there were problems with KAIT, for example, he would drive up to Lick Observatory and try to fix them, sometimes spending several days on the mountain with little sleep. If a really time-critical and exciting event came up, he would stay up late at home, making sure KAIT obtained excellent data. He was much admired for all that he did.

Weidong became my right-hand man, leading LOSS and also collaborating with me on a very large number of publications. (He published a total of about 180 refereed papers before his death, most of them coauthored with me.) I trusted him completely with everything KAIT did, and gave him nearly full authority in running LOSS. He also played a large role (and in many cases the leading role) in mentoring many dozens of undergraduate students who checked the KAIT supernova candidates each day, as well as some graduate students and postdoctoral researchers in my group. Weidong and I were very proud that he played such a major part in developing the careers of so many young new scholars.

In addition to running the wildly successful LOSS, as well as the KAIT SN and GRB follow-up programs, Weidong’s primary scientific contributions were as follows. (1) He helped determine the rate at which different types of supernovae occur in various kinds of galaxies, being the main advisor to Jesse Leaman whose doctoral thesis was this project. In particular, Weidong found that the rate per unit stellar mass of both core-collapse and (more surprisingly) thermonuclear supernovae is higher in low-mass galaxies than in massive galaxies. (2) He examined the location of specific supernovae in high-resolution pre-explosion images (such as those obtained with the Hubble Space Telescope) to possibly identify the progenitor star and measure its properties. (3) He determined the relative fractions of different subtypes of SN Ia, and he identified and carefully studied several new varieties of very peculiar supernovae such as SN 2000cx and SN 2002cx, providing new insights into stellar explosions. (4) In his last main work, published in Nature and widely publicized the week of his death, he led the team that set important constraints on the progenitor of the bright, nearby Type Ia SN 2011fe.

Weidong was a highly skilled astronomer, but also a very warm, generous, cheerful person who wanted to enrich the lives of others and make them happy. He had amazing spirit and was tremendously excited about his research. An excellent table tennis player, he enjoyed playing with friends and academic colleagues. He was also a devoted husband to his wife Ling Yang, and a loving father to his 12-year-old daughter Stella Li. He is survived by a younger brother, Yongxin Li of Dongxin, and a younger sister, Fenglian Li of Beijing. He will be greatly missed by all who knew him.

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