Bengt Westerlund (January 17, 1921 - June 4, 2008) was a

Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...

astronomer who specialised in observational

astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

. He received his

PhD PHD or PhD may refer to: * Doctor of Philosophy (PhD), an academic qualification Entertainment * '' PhD: Phantasy Degree'', a Korean comic series * ''Piled Higher and Deeper'', a web comic * Ph.D. (band), a 1980s British group ** Ph.D. (Ph.D. albu ...

from

Uppsala University Uppsala University ( sv, Uppsala universitet) is a public research university in Uppsala, Sweden. Founded in 1477, it is the oldest university in Sweden and the Nordic countries still in operation. The university rose to significance durin ...

in 1954. In 1957 he was appointed astronomer at the Uppsala Southern Station at

Mount Stromlo Observatory Mount Stromlo Observatory located just outside Canberra, Australia, is part of the Research School of Astronomy and Astrophysics at the Australian National University (ANU). History The observatory was established in 1924 as The Commonw ...

in Australia, where he made extensive studies of the southern

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked ey ...

and the

Magellanic Clouds The Magellanic Clouds (''Magellanic system'' or ''Nubeculae Magellani'') are two irregular dwarf galaxies in the southern celestial hemisphere. Orbiting the Milky Way galaxy, these satellite galaxies are members of the Local Group. Because bo ...

. In 1967 he took a position as astronomer at

Steward Observatory Steward Observatory is the research arm of the Department of Astronomy at the University of Arizona (UArizona). Its offices are located on the UArizona campus in Tucson, Arizona (US). Established in 1916, the first telescope and building were f ...

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a U.S. state, state in the Southwestern United States. It is the list of U.S. states and territories by area, 6th largest and the list of U.S. states and territories by population, 14 ...

and in 1969 was appointed Director of ESO in

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...

, a position he held until 1975, when he returned to Sweden to become Professor of Astronomy at Uppsala Astronomical Observatory, retiring in 1987. His work on the structure of the Milky Way and the Magellanic Clouds was held in high regard. He contributed significantly in studies of

star cluster Star clusters are large groups of stars. Two main types of star clusters can be distinguished: globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound, while open clusters are more loosely clus ...

s, stellar populations,

carbon stars A carbon star (C-type star) is typically an asymptotic giant branch star, a luminous red giant, whose atmosphere contains more carbon than oxygen. The two elements combine in the upper layers of the star, forming carbon monoxide, which consumes mos ...

planetary nebula A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelate ...

e, Wolf-Rayet stars,

stellar classification In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...

and

supernova remnant A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar ma ...

s. He was regarded as an expert on the Magellanic Clouds and wrote a book on them (The Magellanic Clouds, Cambridge University Press, 1997 ). He discovered or rediscovered three open star clusters,

Westerlund 1 Westerlund 1 (abbreviated Wd1, sometimes called Ara Cluster) is a compact young super star cluster about 3.8 kpc (12,000 ly) away from Earth. It is thought to be the most massive young star cluster in the Milky Way, and was discovered by Beng ...

Westerlund 2 Westerlund 2 is an obscured compact young star cluster (perhaps even a super star cluster) in the Milky Way, with an estimated age of about one or two million years. It contains some of the hottest, brightest, and most massive stars known. The ...

and Westerlund 3.

Asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic o ...

2902 Westerlund 9 (nine) is the natural number following and preceding . Evolution of the Arabic digit In the beginning, various Indians wrote a digit 9 similar in shape to the modern closing question mark without the bottom dot. The Kshatrapa, Andhra a ...

was named after him when he retired from his professorship and the

Westerlund telescope The Westerlund telescope was inaugurated in 2004. and is named after Bengt Westerlund (1921–2008). The telescope belongs to Uppsala Astronomical Observatory and serves as a training telescope. It is used in courses for undergraduates, gradua ...

Uppsala Uppsala (, or all ending in , ; archaically spelled ''Upsala'') is the county seat of Uppsala County and the List of urban areas in Sweden by population, fourth-largest city in Sweden, after Stockholm, Gothenburg, and Malmö. It had 177,074 inha ...

was named in his honour in 2004.

References

{{DEFAULTSORT:Westerlund, Bengt 1921 births 2008 deaths 20th-century Swedish astronomers Uppsala University alumni Members of the Royal Swedish Academy of Sciences