As Illinois celebrates its 200th anniversary, one prominent star in particular can be deemed its Bicentennial Star. Scheat is a corner star in the Great Square of Pegasus, the flying horse. The starlight that left Scheat 200 years ago when Illinois became a state--light that is traveling at 186,000 miles per second--is just now reaching our eyes. Scheat is approximately 200 light years away*.
Illinois statehood occurred on December 3, 1818. The stars of 2018 appear the same as in 1818. On the 200th anniversary of Illinois' first night as a state, at 7:00 p.m. the star Scheat is high toward the south, with the Great Square of Pegasus east of the setting Summer Triangle.
Illinois astronomer Jim Kaler describes the star Scheat:
SCHEAT (Beta Pegasi). Scheat (she-at), at the northwest corner of the famed Great Square of Pegasus, rises first to announce the coming appearance of the constellation of the "Winged Horse," which in mythology Perseus rode to rescue Andromeda. From Arabic meaning "the shin," the name has nothing to do with the horse, having been misplaced from another constellation, though it is sometimes translated as "the foreleg." At the fainter end of second magnitude (2.42) and the Beta star of Pegasus, variable Scheat averages the second brightest star in the Great Square. Unusual for a modestly bright star, Scheat has a fairly low surface temperature of about 3700 degrees Kelvin, 65% that of the Sun, and is categorized as a class M (M2.5) red giant or even "bright giant," its color quite noticeable, especially through binoculars or the telescope. From its distance of 200 light years, we calculate the star to be 340 times more luminous to the eye than the Sun. However, Scheat radiates most of its light in the invisible infrared, and when that is taken into account, the true luminosity climbs to 1500 times the solar energy output. To produce this much radiation at that temperature requires the star to be 95 times the solar radius. Consistent with its giant status, the star, if placed at the Sun, would extend 70% of the way to the orbit of Venus. Scheat is big enough and close enough that its angular diameter of 0.015 seconds of arc (6-millionths of a degree) is easily measured, from which we derive the same physical size. Like many red giants of its class, Scheat is actually an irregular variable star that slowly changes from middle second magnitude to bright third, a range of half a magnitude that is easily visible to the naked eye. There is no particular period of variation, and the star's changes are unpredictable. Scheat is surrounded by a thin envelope of gas, produced by its strong wind, in which water vapor has been found.
Used with permission of Jim Kaler.
Also at 200 Light Years
While the star Scheat is bright enough to be seen with the naked eye from Illinois, other faint celestial objects are also 200 light years distant. Astronomers using the Kepler spacecraft have recently employed the transit method to find small planets around stars named Kepler 37 and Kepler 138. A team from the European Southern Observatory (ESO) found a Jupiter-sized planet around the star dubbed HIP 11915. Another ESO discovery was a planetary nebula ejected from a star 200 light years away, in which the red giant star puffed off its outer layer of gas late in the star's lifespan. Other stars near 200 light years include Alpha Tucanae, slightly fainter than Scheat, and Beta Phoenicis, both of which are best seen in the southern hemisphere.
If Illinois residents had sent out a news broadcast at the speed of light on December 3, 1818, that message announcing statehood would just be reaching those stars and newly discovered planets. What message would you have sent? What message would you send today?
Stars merit an integral role in the Illinois bicentennial celebration in 2018. The Illinois state flag includes stars as the ideal symbol of statehood. In addition to recognizing the prominence of stars in Illinois iconography, choose to value the real stars that inspired the stellar depictions.
Value the Stars
Consider that half of Illinois history has occurred between sunset and sunrise. Get outside at night, discover the starry firmament, and find Scheat, the Illinois Bicentennial Star.
The other half of Illinois--nighttime--awaits!
Download the black and white star chart to find Scheat relative to nearby constellations. Chart depicts the night sky in December around 7:00 p.m.
Pegasus, the Flying Horse
Lore suggests Pegasus the flying horse was borne of the blood of Medusa when Perseus cut off Medusa's head. In modern times, astronomers have studied Stephan's Quintet, 51 Pegasi, and Einstein's Cross--among other highlights--within the constellation boundaries.
* The distance to Scheat is approximately 200 light years. However, Jim Kaler notes, "the second Hipparcos parallax gives 196 light years, give or take 2."