2006 Feature of the Month Archive

'Encyclopedia of Stars' aimed at anyone who enjoys astronomy

"The Cambridge Encyclopedia of Stars" is ermeritus professor James B. Kaler's 14th book.

An astronomy expert looking for in-depth research about stars can consult the same new reference book that an undergraduate freshman with a limited knowledge of astronomy might use.

"The Cambridge Encyclopedia of Stars," by James B. Kaler, a professor emeritus of astronomy at the University of Illinois at Urbana-Champaign, covers topics from ancient to modern times. According to Kaler, this 324-page, hardcover book - his 14th - is for anyone who enjoys astronomy. Undergraduates, graduates and professionals all can benefit from using it, he said.

The new book contains detailed discussions on topics such as stars, constellations, magnitudes, locations, motion, double stars, star clusters and stellar evolution. The book also contains more than 230 images, including color photographs, graphs, tables and sidebars. The photographs were gathered from observatories and private photographers around the world. "It struck me that putting everything together would make a great resource," Kaler said.

Each of the 14 chapters covers a different topic and stands alone. The book contains forward and backward referencing to connect information from different chapters. Kaler considers each chapter as important and interesting as the next. "The one I was doing at the moment was always my favorite," Kaler said.

The book, completed this year, is now in bookstores and also may be found in libraries.

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Credits: UIUC News Bureau, Laura Prusik (Text), Mark McCaughrean, Astrophysical Institute Potsdam/ESO (Image)

Supernova byproducts show the Sun was born in a star cluster

A possible baby picture of the solar system? At the center of this cluster is a 20 solar mass star, surrounded by about 100 low-mass siblings. When the central star explodes in a few million years, it will shower its siblings with radioactive material.

The death of a massive nearby star billions of years ago offers evidence the Sun was born in a star cluster, say astronomy professors Leslie Looney and Brian Fields, and undergraduate student John Tobin.

Massive stars end their lives in spectacular explosions called supernovas. In these explosions, bits of radioactive material are blown out into interstellar space and mix with gas and dust in still-forming solar systems. Some of this material fell to Earth in meteorites. By examining meteorites for the byproducts of the radioactive material, the researchers have calculated how far away and how long ago the supernova was.

"The supernova was stunningly close; much closer to the Sun than any star is today," Fields said. The massive star that exploded was formed in a group or cluster of stars with perhaps hundreds, or even thousands, of low-mass stars like the Sun. Because the stars were not gravitationally bound to one another, the Sun's siblings wandered away millennia ago.

"We know that the majority of stars in our galaxy were born in star clusters," Looney said. "Now we also know that the newborn solar system not only arose in such a cluster, but also survived the impact of an exploding star."

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Credits: UIUC News Bureau, James E. Kloeppel (Text), Wang et al. 2007 (Image)

Unlocking the Secrets of Galaxy Clustering

Using a dataset of 11 million galaxies observered by the Sloan Digital Sky Survey, Illinois astronomers Ashley Ross, Adam Myers, and Professor Robert Brunner have been studying clustering of galaxies in the Universe. This is the largest sample ever used to study higher-order correlations in the clustering of galaxies. The results of their study have been accepted for publication in the Astrophysical Journal.

The sample figure at right (click on the image for an enlarged view) shows the ratio of the 3rd- (blue) and 4th- (red) order clustering statistics of early- (typically elliptical) and late- (typically spiral) type galaxies, as a function of the angular scale. These statistics are akin to the skewness and kurtosis, respectively, of a statistical distribution. The figure shows that the relationship between the clustering of galaxies and the clustering of dark matter (known as bias) is significantly non-linear, scale dependent, and greatly influenced by galaxy type. The data displayed in this plot allowed for the best-to-date quantification of higher-order clustering as a function of galaxy type.

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Image Credits: A.J. Ross, R.J. Brunner, A.D. Myers

MISSION UPDATE: Mars Exploration Rover Mission

The Astronomy Department is pleased to announce the eighth Icko Iben Jr. Distinguished Lecturer will be Dr. Steven W. Squyres, Goldwin Smith Professor of Astronomy at Cornell University in Ithaca, New York. This presentation is also part of the National Center for Supercomputing Applications 20th Anniversary Distinguished Lecture Series. The event is free and open to the public.

Prof. Squyres will give a talk entitled "The Mars Exploration Rover Mission" on Tuesday, March 28th at 7PM in Foellinger Auditorium. The talk will provide an up-to-date summary of the mission of the twin robotic explorers named Spirit and Opportunity, from their initial conception through their launch, landing, and operations on the surface of Mars. Their objective is to search for evidence of past water on Mars, and to determine if Mars ever had conditions that would have been suitable for life. Expected to last for 90 days, the two rovers have now been exploring the Martian surface for since January 2004.

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Studying Star Birth & Death

From their birth to their death, massive stars have a tremendous impact on their galactic surroundings. While alive, these stars energize and enrich the interstellar medium with their strong ultraviolet radiation and their fast stellar winds. As they die, shock waves from their death throes inject vast quantities of mechanical energy into the interstellar medium and can lead to the formation of future stars.

New composite images of optical, radio, infrared, ultraviolet and X-ray wavelengths are giving astronomers at the University of Illinois at Urbana-Champaign a clearer picture of the birth, life and death of massive stars, and their effect on the gas and dust of the interstellar medium surrounding them. "Comparing images at different wavelengths lets us create a more complete picture, rather than seeing only a few features in isolation," said You-Hua Chu, chair of the astronomy department at Illinois. "Using multi-spectral data sets, we can examine the physical structure of the interstellar medium and study the conditions that lead to star formation." In the above image of the star-forming complex N51, the false-color image reveals the relative position of the expanding shell N51D and the recently formed proto-stars, allowing astronomers to determine whether the star formation is triggered by pressure from hot gas or by compression by a passing shock wave.

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Caption Credit: James E. Kloeppel, UIUC News Bureau
Image Credit: NASA/SSC/MCELS/ESA/U.Illinois (Y.-H. Chu and R.A. Gruendl)