Press Release; Calling all Amateurs

Sometimes the little things in life count the most, especially when it comes to backyard stargazers making major contributions to the field of professional astronomy.

Dr. Janet A. Mattei, director of the American Association of Variable Star Observers (AAVSO), discusses some of the unique partnerships formed in the area of variable stars (stars that change in brightness) between professional and amateur astronomers at the American Astronomical Society meeting today in Rochester, N.Y.

In an era of 10-meter mountaintop telescopes and massive earth-orbiting observatories, amateur astronomers with modest telescopes continue to provide professional astronomers with critical data on star explosions and flares too numerous and random to track. These data are used often to point a satellite to those objects during these rare behaviors.

"Amateurs make crucial contributions when it comes to pointing a satellite like the Hubble Space Telescope (HST) to one of these bright exploding objects. Observations from amateurs help HST staff to determine if the object is too bright to be observed safely with a specific instrument aboard the satellite." said Mattei. "Often amateurs' observations drive the way the professionals plan observations with big telescopes or orbiting observatories."

"The AAVSO supports professional astronomers in scheduling observations with satellites and in providing follow-up optical data on cosmic events, as well as notification of bursting star systems," Mattei said.

In terms of follow-up, the members of AAVSO now actively monitor the sky for optical counterparts to gamma-ray bursts, the most powerful events known in the Universe. The bursts occur randomly from all directions and typically last only for a few hours. It is difficult to obtain good optical data of the bursts without the dedicated all-sky, and immediate, monitoring. AAVSO will be providing pagers to its observers so they can be immediately informed of these bursts and immediately make the crucial observations with their backyard telescopes.

In terms of notification, the AAVSO regularly informs professional astronomers when a known variable star or even an unknown star system suddenly becomes active. The outburst of SS Cygni, a close binary system in the constellation of Cygnus (the Swan) was discovered in its very earliest stages by observers in Kansas and California and confirmed by a Hawaiian observer, all amateurs and members of the AAVSO.

This early notification resulted in dedicated observations within 12 hours with two satellites -- the Extreme Ultraviolet Explorer (EUVE) and the Rossi X-ray Timing Explorer (RXTE) -- even before the outburst had reached the high-energy wavebands. Mattei discusses the results of this first-ever simultaneous optical, UV, and X-ray observation of a bursting white dwarf in greater detail at the Rochester meeting.

At another time, again both EUVE and RXTE pointed at U Geminorum, another compact binary in the constellation of Gemini (the Twins), during its outburst thanks to notification from one experienced amateur astronomer, Gene Hanson from Arizona. Hanson will join Mattei and share his experience during the Rochester meeting.

These close binary star systems contain a red dwarf star and a white dwarf. A red dwarf is a star a little cooler than the Sun. A white dwarf was once as large as the sun but subsequently ran out of fuel, blew its outer shell into space, and collapsed to form a white-hot ember. The dense white dwarf, with its strong gravitational potential, pulls a stream of gas off of its companion star. This transferred gas collects in a disk, called an accretion disk, around the white dwarf.

The dramatic brightening by many orders of magnitude in this system is the result of an instability in the disk which forces the disk material to drain down onto the surface of the white dwarf, causing a titanic energy release equivalent to that of billions of atomic bombs exploding every second. These stellar outbursts, which often occur without warning and rarely last more than one or two weeks, serve as floodlights that brighten a dim star system for scientists to study.

In gratitude for the successful observations of these close binary systems and to give new opportunities to amateur astronomers, the EUVE director granted the AAVSO nearly three days' worth of observation time on EUVE to observe an object of their choice. Ground-based variable star observers have also successfully collaborated on the alphabet soup of NASA and European Space Agency missions, such as HEAO-1 and -2, IUE, Voyager, ASTRO-1 and -2, ROSAT, HIPPARCOS, ISO, ORFEUS, CGRO, HST, and FUSE.

The AAVSO was founded in 1911 at Harvard College Observatory to coordinate variable star observations made largely by amateur astronomers and became an independent, non-profit organization in 1954. Today, AAVSO has members in over 40 countries and maintains the world's largest computer-readable variable star data archive, with over 10 million observations, and growing by almost half a million yearly. The AAVSO headquarters are in Cambridge, Massachusetts.

For more information, refer to the AAVSO website at http://www.aavso.org/. Mattei's talk, with colleague G. A. Hanson, will be held during session 12, "Amateur-Professional Collaboration in Astronomy," from 10:00-11:30 a.m. in the Highland A/K meeting room.