AB Boötis, also known as Nova Boötis 1877 and occasionally Nova Comae Berenices 1877, is an object that may have undergone a

nova A nova ( novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", Latin for "new") that slowly fades over weeks or months. All observed novae involve white ...

outburst in 1877. It was discovered by Friedrich Schwab at

Technische Universität Ilmenau The Technische Universität Ilmenau (''Ilmenau University of Technology'', TU Ilmenau) is a German public research university located in Ilmenau, Thuringia, central Germany. Founded in 1894, it has five academic departments (faculties) with ...

in 1877. He reported observing the star as a 5th

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

object, visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

, on 14 nights during the period from 30 May 1877 through 14 July 1877. During that time interval, his estimate of the star's brightness only changed by 0.42 magnitudes. The star was lost (Schwab noticed its absence on January 9, 1878), and despite several searches in subsequent years, no other 19th century observations of the nova were reported. Downes ''et al.'' estimate that Schwab's reported coordinates for the star may have had a precision no better than 1/2 degree. In 1971, A. Sh. Khatisov suggested that the star Schwab saw was BD +21°2606 (whose visual magnitude is 10.64 in the

Tycho-2 Catalogue The Tycho-2 Catalogue is an astronomical catalogue of more than 2.5 million of the brightest stars. Catalogue The astrometric reference catalogue contain positions, proper motions, and two-color photometric data for 2,539,913 of the brightest ...

, roughly 100 times fainter than the object Schwab reported), but that identification may be incorrect. In 1988 Downes and Szkody imaged the area around AB Boötis' reported position, to try to identify the nova in its quiescent state based on its color, but their search was unsuccessful. In 2000, Liu ''et al.'' published a spectrum of AB Boötis, which they describe as a cataclysmic variable (a class which includes novae), but they did not publish the coordinates of the star they examined, so exactly which star they observed is unclear. In 2020, Hoffmann and Vogt suggested that AB Boötis might be a re-appearance of a

guest star The term guest appearance generally denotes the appearance of a guest in an artistic or pop-culture setting. The guests themselves (referred to as guest artists, featured artists, guest stars, or guest fighters, depending on context), are disting ...

that Chinese astronomers saw near

Arcturus , - bgcolor="#FFFAFA" , Note (category: variability): , , H and K emission vary. Arcturus is a red giant star in the Northern celestial hemisphere, northern constellation of Boötes, and the brightest star in the constellation. It ha ...

in 203 BCE.

References

{{Stars of Boötes Novae Boötes 1877 in science Boötis, AB 18770530