TrES-2A

The designation GSC 03549-02811 comes from the Guide Star Catalog.

The star is often called TrES-2,^[9] in reference to its planet discovered by the Trans-Atlantic Exoplanet Survey (TrES). The discovery paper^[3] and the SIMBAD database^[5] use this designation for the planet itself, but other sources call the star TrES-2 (or TrES-2A)^[10] and the planet TrES-2b,^[11] following the standard exoplanet naming convention. In keeping with the planet being component b, the companion star is designated TrES-2C, although it is also designated Kepler-1B.^[5]

The planet was also observed by the Kepler space telescope, and so the star is also known as Kepler-1.^[5] Since the planet transits the star, the star is classified as a planetary transit variable and has received the variable star designation V581 Draconis.^[12]

In 2008 a study was undertaken of fourteen stars with exoplanets that were originally discovered using the transit method through relatively small telescopes. These systems were re-examined with the 2.2M reflector telescope at the Calar Alto Observatory in Spain. This star system, along with two others, was determined to be a previously unknown binary star system. The previously unknown secondary star is a dim magnitude 15 K-type star separated by about 232 AU from the primary, appearing offset from the primary by about one arc second in the images. This discovery resulted in a significant recalculation of parameters for both the planet and the primary star.^[4]

In 2006, the exoplanet TrES-2b was discovered by the Trans-Atlantic Exoplanet Survey using the transit method. It was also within the field of view of the Kepler Mission planet-hunter spacecraft.^[3] This system continues to be studied by other projects and the parameters are continuously improved.^[14] The planet orbits the primary star.^[4]

TrES-2b is a hot Jupiter, with a mass and size similar to those of Jupiter but an orbital period of only two days. Its orbit is prograde relative to its star's rotation.^[11] In 2011, TrES-2b was found to have a very low albedo, reflecting less than 1 percent of the light from its star, making it the darkest known exoplanet at the time. However, it also emits a significant amount of light because its surface temperature is so hot that it glows red.^[15] Due to its close orbit, it is assumed to be tidally locked to its parent star.^[16]

In March 2009, NASA launched the Kepler spacecraft. This spacecraft was a dedicated mission to discover extrasolar planets by the transit method from solar orbit. In April 2009 the project released the first light images from the spacecraft, and TrES-2b was one of two objects highlighted in these images. Although TrES-2b was not the only known exoplanet in the field of view of this spacecraft, it was the only one identified in the first-light images. This object was important for calibration and check-out.^[18]

• List of extrasolar planets