Frank Shu (1943–2023)

The Chinese language American astrophysicist Frank Hsia-San Shu made seminal contributions to the understanding of galaxies and star formation, leaving a legacy of scientific work characterised by originality and deep perception. He wrote two extensively consulted textbooks, and, later in life, launched into a second profession investigating power applied sciences to assist fight the local weather disaster. For his lifelong contributions to theoretical astrophysics, in 2009 he was awarded the Shaw Prize in astronomy — typically described because the ‘Nobel of the East’ — and the Catherine Wolfe Bruce Gold Medal from the Astronomical Society of the Pacific. He died at his dwelling in California on 22 April, aged 79.

Shu was born in 1943 within the southern Chinese language metropolis of Kunming, a refuge for intellectuals through the Second World Struggle, owing partially to the evacuation of many universities to the town. He emigrated to the US on the age of six when his father, the mathematician and engineer Shien-Siu Shu, joined the arithmetic college at Purdue College in West Lafayette, Indiana. Rising up within the Midwest, he fervently pursued pursuits in maths and physics. He was admitted to the Massachusetts Institute of Know-how in Cambridge, as one among its youngest undergraduate college students in physics, and graduated in 1963.

JWST spots planetary constructing blocks in a shocking galaxy

At MIT, Shu started working along with his mentor Chia-Chiao Lin on the dynamics of disk galaxies. This collaboration continued at Harvard College, additionally in Cambridge, the place Shu acquired his PhD in 1968. Utilizing wave-mechanic strategies, Shu and Lin postulated that the spiral arms noticed in disk galaxies had been a wave phenomenon consisting of spiral patterns propagating via the fluid medium of stars and fuel. How these patterns grew to become amplified to their large dimension stays a matter of debate, however ‘density-wave concept’ has allowed predictions of spiral-galaxy properties to be derived from first ideas. It has additionally been used to check the gravitational stability and construction of many astrophysical objects, together with galactic disks, binary stars, planet-forming disks orbiting younger stars and the rings of Saturn.

Shu’s work was motivated by basic theoretical points. He paid particular consideration to stars not simply as factors of mass, however as factors of sunshine. He was at all times fascinated with how they fashioned, taking a look at huge OB stars, which gentle up the spiral construction of disk galaxies seen at optical and ultraviolet wavelengths. At Stony Brook College in New York Metropolis, the place Shu moved after his PhD, he led a staff that confirmed how shocks induced by density waves might compress a diffuse stellar medium right into a higher-density part of star-forming large molecular clouds. In collaboration with radio astronomers on the College of Groningen within the Netherlands, Shu supplied additional proof for the density-wave concept.

After becoming a member of the college at College of California, Berkeley, in 1973, Shu shifted his consideration to the formation of particular person stars, the topic of his most influential contribution. Though molecular clouds had been recognized because the delivery websites of latest stars, and the final image of star formation via the collapse of fabric below its personal gravity had been thought of, few particular particulars had been recognized. Shu and his collaborators needed to handle how nature overcomes the limitations to gravitational collapse, resembling angular momentum and ambient magnetic fields.

Black-hole picture reveals particulars of turmoil across the abyss

The paradigm that emerged was the now-standard ‘four-phase’ image: the formation of cores of upper density in a molecular cloud; their subsequent dynamic collapse; an sudden (however observable) part through which robust winds of fuel move out of the still-forming protostar; and the emergence of stars accompanied by planet-forming disks. This framework carefully linked concept and observations, and was bolstered additional by impartial developments, resembling the concept once-radioactive relics present in probably the most primitive meteorites would possibly initially have been the merchandise of historical photo voltaic flares.

Though a few of Shu’s theoretical hypotheses stay controversial, he by no means hesitated to sort out unsettled basic ideas and to discover revolutionary explanations of probably the most hanging observations. He was additionally a prolific and lucid author. Along with many extremely cited papers, Shu authored the universally adopted introductory textbook The Bodily Universe (1982) and the two-volume graduate textbook The Physics of Astrophysics (1991–92).

Shu served because the president of the American Astronomical Society from 1994 to 1996. He engaged with a burgeoning astronomical-research group in Taiwan, main efforts in direction of the launch of the Institute of Astronomy and Astrophysics, a part of the analysis institute Academia Sinica primarily based in Taipei. In 2002, he grew to become president of Nationwide Tsing Hua College in Hsinchu, Taiwan, following within the footsteps of his father, who had held that place from 1970 to 1975.

Shu returned to the US in 2006 to the College of California, San Diego, the place he grew to become professor emeritus in 2009. For the previous dozen years, his concern in regards to the local weather disaster led him to check using molten-salt reactors to generate power from nuclear waste and to transform waste biomass into inert merchandise that may be sequestered, eradicating carbon from the ambiance. He was additionally writing an undergraduate textbook referred to as The Story of Science, which was to recount how science has underpinned human progress, and the teachings that holds for addressing local weather change. That e book stays unfinished, however Shu’s personal place within the story of science is assured.

Competing Pursuits

The authors declare no competing pursuits.