By Patricia Daukantas

For the past year, “citizen scientists” have been observing the behavior of an unusual double star to gain insight into its mysterious eclipses. Recently, a team of professional astronomers used optical interferometry to catch the first glimpse of the dimmer star that eclipses its brighter companion every 27.1 years.

As we’ve blogged in the past, the star system Epsilon Aurigae has been the subject of an intensive observing campaign this year. Several of the professional astronomers behind the “citizen sky” project have now seen that the eclipsing object is a large, slightly tilted disk surrounding a single, hot star. The team reported its results in the April 8 issue of Nature.

It turns out that the central star of the pair is a F-type star, slightly hotter than our Sun and with up to three times its mass, and its eclipsing companion is an extremely hot B-type star, shrouded in dust warmed to about 550 K. But how do Robert Stencel (University of Denver, Colo., U.S.A.) and his colleagues know that?

As it turns out, they imaged the Epsilon Aurigae system with the CHARA array of six telescopes on Mount Wilson in California. (CHARA stands for the Center for High Angular Resolution Astronomy, located at Georgia State University in Atlanta.)

With apertures of only 1 m, the six CHARA scopes are tiny by professional standards. However, they are positioned over the mountainside to provide the resolving capability of a much larger single telescope – up to 331 m wide (that’s the array’s longest baseline). Radio astronomers may have been the first to use interferometry to boost the amount of detail we can see in the heavens, but optical (visible and infrared) astronomical interferometry has come of age in recent years – see this post about another interferometer on Mount Wilson, used by OSA Honorary Member Charles Townes and colleagues to study the size of the red giant star Betelgeuse.

For more information on CHARA and optical interferometry, see this PDF presentation or the CHARA website. For additional coverage of Epsilon Aurigae, see the U.S. National Science Foundation announcement or this article from Sky & Telescope magazine.

And don’t forget … the Citizen Sky website is still collecting observations of Epsilon Aurigae, and anyone can make them regardless of equipment (or the lack thereof). This makes a great class project.

By Patricia Daukantas

Once again, the folks who run the GLOBE at Night project are inviting people from all over the world to measure the brightness of the night sky – no special equipment required.

As we described last year, this project takes place during March because that’s when the prominent constellation Orion is high in the sky fairly early in the evening. (In the Northern Hemisphere autumn, one must be a night owl or a before-dawn riser to catch a glimpse of “the Hunter.”)

You don’t even have to be savvy about the apparent-magnitude system that professionals use. You don’t even need a telescope. Just carry out these five steps on a clear night between now and Tuesday, March 16:

• Find your latitude and longitude with a Global Positioning System device or online tools.
• Find Orion in the clear evening sky (simple pattern recognition).
• Match your view of the constellation to one of the magnitude charts developed by GLOBE at Night – how many stars do you see?
• Record your observation on the Web site.
• Compare what you saw to others’ views.

Your effort will help GLOBE at Night track the pervasiveness and spread of light pollution. As the organizers of this project said in a press release, “With half of the world’s population now living in cities, many urban dwellers have never experienced -- and maybe never will -- the wonderment of pristinely dark skies.” The more awareness of the problem of light pollution, the greater the chance to stop its spread.

By Patricia Daukantas

Alfred C. Webber of Chadds Ford, Pa. (U.S.A.), became an OSA Fellow in 1972. And tomorrow (October 10), he’s celebrating his 102^nd birthday.

A native of Lisbon Falls, Maine, Webber graduated from Bates College in 1928 with a degree in physics. He earned a master’s degree from Boston University and worked as a high school science teacher before joining DuPont in Wilmington, Del., in 1942. During the next 30 years he published several articles in JOSA on measuring the color and transparency of plastic materials. He served on a number of committees for the American Society for Testing and Materials (now ASTM International), including a term as chair of ASTM”s board of directors in the early 1960s. He also headed the technical committee on plastics for the International Organization for Standards (ISO).

And he is an OSA Fellow Emeritus. In fact, when I phoned him today to wish him a happy birthday, he quickly volunteered that he still has his OSA Fellow certificate on his wall. It was signed by his good friend Mary Warga, who served as OSA’s executive secretary from 1959 to 1972.

Webber retired the same year as he was designated an OSA Fellow, but he has never stopped pursuing the activities that he loves. “The great fun of retirement is that there are so many things you can play at and do,” he said.

Although one of his 74-year-old twin sons drives the car now, Webber still attends regular meetings of his lapidary, camera and astronomy hobby clubs. With bird feeders and an observatory in his backyard, he surveys feathered creatures by day and the stars by night.

His longtime friend and neighbor, the late artist Andrew Wyeth, used Webber’s telescope to observe the Moon for some of his paintings, and the Webber and Wyeth children played together while they were growing up. The Mount Cuba Astronomical Observatory in Delaware named Webber a fellow of the observatory for his many years of assistance with star parties and antique telescope refurbishing.

One of Webber’s more unusual hobbies is the study of micromounts – tiny mineral crystals viewed under a stereo microscope. He collected more than 2,600 of these small specimens, each fitting into a 2- by 2- by 2-cm box, and he has gone to conferences in Canada to trade crystals and photographs of crystals with fellow enthusiasts. He recently donated the collection to Bates so that students can study the gemstones.

Last year, he traveled to Lewiston, Maine, to celebrate his 80^th class reunion at Bates. He was the only representative of the classes of the 1920s at the reunion weekend – in fact, the next oldest alumnus was from the class of 1938. Webber enjoyed leading the 2008 Bates reunion parade, and tomorrow he will celebrate his birthday with a reunion of his children, grandchildren and great-grandchildren from as far away as California.

We would like to wish Alfred Webber a happy birthday. Also, if you know of any other OSA Members or Fellows who are marking their 100^th or higher birthdays, we would love to hear about them.