Stellar rotationStellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulge due to centrifugal force. As stars are not solid bodies, they can also undergo differential rotation. Thus the equator of the star can rotate at a different angular velocity than the higher latitudes.
A-type main-sequence starAn A-type main-sequence star (A) or A dwarf star is a main-sequence (hydrogen burning) star of spectral type A and luminosity class (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1.4 and 2.1 solar masses () and have surface temperatures between 7,600 and 10,000 K. Bright and nearby examples are Altair (A7), Sirius A (A1), and Vega (A0). A-type stars do not have convective zones and thus are not expected to harbor magnetic dynamos.
Flag of BrazilThe national flag of Brazil (bandeira do Brasil), is a blue disc depicting a starry sky (which includes the Southern Cross) spanned by a curved band inscribed with the national motto "Ordem e Progresso" ("Order and Progress"), within a yellow rhombus, on a green field. It was officially adopted on 19 November 1889 — four days after the Proclamation of the Republic, to replace the flag of the Empire of Brazil. The concept was the work of Raimundo Teixeira Mendes, with the collaboration of pt, pt and Décio Villares.
Stellar massStellar mass is a phrase that is used by astronomers to describe the mass of a star. It is usually enumerated in terms of the Sun's mass as a proportion of a solar mass (). Hence, the bright star Sirius has around . A star's mass will vary over its lifetime as mass is lost with the stellar wind or ejected via pulsational behavior, or if additional mass is accreted, such as from a companion star. Stars are sometimes grouped by mass based upon their evolutionary behavior as they approach the end of their nuclear fusion lifetimes.
AlgolAlgol ˈælgɒl, designated Beta Persei (β Persei, abbreviated Beta Per, β Per), known colloquially as the Demon Star, is a bright multiple star in the constellation of Perseus and one of the first non-nova variable stars to be discovered. Algol is a three-star system, consisting of Beta Persei Aa1, Aa2, and Ab – in which the hot luminous primary β Persei Aa1 and the larger, but cooler and fainter, β Persei Aa2 regularly pass in front of each other, causing eclipses. Thus Algol's magnitude is usually near-constant at 2.
Behenian fixed starThe Behenian fixed stars are a selection of fifteen stars considered especially useful for magical applications in the medieval astrology of Europe and the Arab world. Their name derives from Arabic bahman, "root," as each was considered a source of astrological power for one or more planets. Each is also connected with a gemstone and plant that would be used in rituals meant to draw the star's influence (e.g., into a talisman). When a planet was within six degrees of an associated star, this influence was thought to be particularly strong.
Hellenistic astrologyHellenistic astrology is a tradition of horoscopic astrology that was developed and practiced in the late Hellenistic period in and around the Mediterranean Basin region, especially in Egypt. The texts and technical terminology of this tradition of astrology were largely written in Greek (or sometimes Latin). The tradition originated sometime around the late 2nd or early 1st century BCE, and then was practiced until the 6th or 7th century CE.
DuatThe Duat (dwꜣt, Egyptological pronunciation "do-aht", ⲧⲏ, also appearing as Tuat, Tuaut or Akert, Amenthes, Amenti, or Neter-khertet) is the underworld in ancient Egyptian mythology. It has been represented in hieroglyphs as a star-in-circle: 𓇽. The god Osiris was believed to be the lord of the underworld. He was the first mummy as depicted in the Osiris myth and he personified rebirth and life after death. The underworld was also the residence of various other gods along with Osiris.
SopdetSopdet is the ancient Egyptian name of the star Sirius and its personification as an Egyptian goddess. Known to the Greeks as Sothis, she was conflated with Isis as a goddess and Anubis as a god. The exact pronunciation of ancient Egyptian is uncertain, as vowels were not recorded until a very late period. In modern transcription, her name usually appears as Sopdet (, Triangle), after the known Greek and Latin form Sothis (Sō̂this). During the early period of Egyptian civilization, the heliacal rising of the bright star preceded the usual annual flooding of the Nile.
