Lambda Scorpii

Lambda Scorpii (λ Sco, λ Scorpii) is a blue star and the second brightest star system in the constellation Scorpius, and one of the brightest stars in the nighttime sky. It has the Bayer designation λ despite being the second brightest in its constellation. It has the traditional name Shaula, which comes from the Arabic الشولاء al-šawlā´ meaning the raised [tail], as it is found in the tail of the scorpion (Scorpius). It is known as Wei Xiu Ba 尾宿八 (the Eighth Star of the Tail) in Chinese.

Properties

Lambda Scorpii is located some 570 light years away from Earth. Spectroscopic and interferometric observations have shown that A is actually a triple system consisting of two B-type stars and a pre–main sequence star. The primary star is a beta Cephei variable star with rapid brightness changes of about a hundredth of a magnitude. The pre–main sequence star has an orbital period of 6 days and the B companion has a period of 1053 days. The three stars lie in the same orbital plane, strongly suggesting that they were formed at the same time. The masses of the primary, pre–main sequence star and the B companion are 14.5, 2.0 and 10.6 solar masses, respectively. The age of the system is estimated to be in the range 10–13 million years.

Macula of retina

The macula or macula lutea (from Latin macula, "spot" + lutea, "yellow") is an oval-shaped pigmented area near the center of the retina of the human eye. It has a diameter of around 5.5 mm (0.22 in). The macula is subdivided into the umbo, foveola, foveal avascular zone (FAZ), fovea, parafovea, and perifovea areas. After death or enucleation (removal of the eye) the macula appears yellow, a color that is not visible in the living eye except when viewed with light from which red has been filtered. The anatomical macula at 5.5 mm (0.22 in) is much larger than the clinical macula which, at 1.5 mm (0.059 in), corresponds to the anatomical fovea. The clinical macula is seen when viewed from the pupil, as in ophthalmoscopy or retinal photography. The anatomical macula is defined histologically in terms of having two or more layers of ganglion cells.

Near its center is the fovea, a small pit that contains the largest concentration of cone cells in the eye and is responsible for central, high-resolution vision. The umbo is the center of the foveola which is located at the centre of fovea.

Macula (disambiguation)

Macula is a spot on the retina of the human eye, but the term may also refer to:

Macula (archaeology)

Macula is a term used by archaeologists to describe small two-dimensional features of ancient human origin visible on an aerial photograph, such as points, spots or patches, which may represent features such as burial places, pits, Grubenhäuser (homesteads with sunken floors), constructions based on posthole or features above ground level. Maculae are differentiated from other features visible in aerial photographs such as enclosures, linear features and linear systems, which include path, roads, boundaries or limits. Identification and interpretation of maculae in air photographs is difficult and depends upon the experience of the observer, who has to take factors such as shape, size, relative position or proximity to other maculae, ground condition and knowledge of cultural practices of ancient humans in the region under observation, into account.

The term is used in a different context in art on objects where it refers to the mesh of a net (in singular), or its depiction, the plural being maculae.