An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

The technique used in a radio receiver in which the frequency of an incoming signal is changed by adding it to a signal generated within the receiver to produce fluctuations or beats of a frequency equal to the difference between the two signals. See also → mixer.

→ superheterodyne receiver; → technique.

An ion which is responsible for the existence of a strong → P Cygni profile observed in many early O stars. Since the → effective temperature of the star is too low to produce such an ion appreciably, the ion is termed a superion. For example, the ion O⁵⁺ which is at the origin of a strong O VI λλ1031, 1038 P Cygni profile observed in many O stars. Similarly, the lines due to N V λλ1238, 1242 belong to the superion category, while in later spectral types C IV λλ1548, 1552 also falls into this category. Initial modeling of the → ultraviolet line superions assumed the → stellar winds were smooth and homogeneous. However it is now generally accepted that the winds are (→ clumped wind), and this can have a profound influence on the formation of the superion profiles. We know that the strength of lines due to the superions is strongly influenced by the → interclump medium. Indeed, the interclump medium may be more important for producing the lines than are the clumps -- this is simply a consequence of the higher ionization in the interclump medium which occurs because of its lower density (see D. John Hillier, 2020, https://www.mdpi.com/2075-4434/8/3/60/htm, and references therein).

→ super-; → ion.

Upper or situated higher up in rank, degree, etc.

M.E., from O.Fr., from L. superiorem (nominative superior) "higher," comparative of superus "situated above, upper," from super "above, over," → super-.

Zabar, from Mid.Pers. azabar "above," related to abar (Mod.Pers. bar- "on, upon, up"); O.Pers. upariy "above; over, upon, according to;" Av. upairi "above, over," upairi.zəma- "located above the earth;" cf. Gk. hyper- "over, above;" L. super-, as above; O.H.G. ubir "over" + -in comparative suffix.

The conjunction of a planet with the Sun which occurs when the planet is beyond the Sun. → inferior conjunction.

→ superior; → conjunction.

The meridian transit of a star between the celestial pole and the south point of the horizon. Same as → upper culmination. → inferior culmination.

→ superior; → culmination.

A planet whose orbit lies outside that of the Earth. The superior planets are Mars, Jupiter, Saturn, Uranus, and Neptune. → planet.

→ superior; → planet.

Apparent proper motion exceeding the velocity of light seen toward certain astronomical objects, such as the jets of radio galaxies and quasars. However, these jets are not actually moving at speeds in excess of the speed of light: the apparent superluminal motion is a projection effect caused by objects moving near the speed of light and at a small angle to the line of sight.

→ super-; luminal, from → lumen; → motion.

Jonbeš, → motion; abar→ super-; nur, → light.

The quality of an object whose luminosity exceeds a certain value.

→ super-; → luminous.

A → supernova with an → absolute magnitude of about -22 in optical. Examples of these newly discovered SNe include SN 2006gy, SN 2005ap, and SNe 2003ma. The nature of these objects is poorly known. Some of them are powered by the circumstellar interaction, or by the shock breakout from the dense circumstellar medium, as suggested by the presence of narrow emission lines in superluminous → Type II-N supernovae. It is also argued that superluminous SNe could be powered by a large amount of ⁵⁶Ni which is synthesized as a result of energetic → core-collapse supernovae. Other scenarios include the interaction between shells ejected by the pulsational → pair-instability. See, e.g. Tanaka et al. 2012, MNRAS 422, 2675, arXiv:1202.3610, and references therein.

→ superluminous; → supernova.

Having a mass highly exceeding a certain limit. → supermassive black hole, → supermassive neutron star, → supermassive star.

→ super-; → massive.

A → black hole of tremendous mass, equivalent to those of millions or even billions of stars, which is believed to exist and occupy the centers of many galaxies. The supermassive black hole residing in the center of our → Milky Way Galaxy is the object → Sgr A* with a mass of 4 x 10⁶→ solar masses within a radius of 100 → astronomical units.

→ supermassive; → black hole.

A → neutron star of mass above the typical value that is temporarily prevented from → collapseing into a → black hole because of its rapid → rotation.

→ supermassive; → neutron; → star.

A star with an initial mass over about 120 solar masses. The existence of such stars is the present Universe is not confirmed. Such stars were proposed as an explanation for very bright O type stars in the Large Magellanic Cloud, but these are now known to be clusters of ordinary O stars. → very massive star; → massive star.

→ supermassive; → star.

Same as → perigee full Moon.

→ super-; → moon.

A generalization of the concept of multiplet to the case when there are several quantum numbers that describe the quantum-mechanical states.

→ super-; multiplet.

1) Of, pertaining to, or being above or beyond what is natural; unexplainable by natural; abnormal.
2) Of, pertaining to, characteristic of, or attributed to God or a deity (Dictionary.com).

→ super-; → natural.

Belief in the doctrine of supernatural or divine agency as manifested in the world, in human events, religious revelation, etc. (Dictionary.com).

→ super-; → naturalism.

A violent stellar explosion which blows off all or most of the star's material at high velocity leaving a compact stellar remnant such as a → neutron star or → black hole. At → maximum light, the supernova can have → luminosity about 10⁸ or 10⁹ times the → solar luminosity. The phenomenon results from the later evolution of stars when an instability sets in the core following the → nucleosynthesis of → iron. In → massive stars, the supernova occurs when the star has used up all its available → nuclear fuel and it reaches a lower energy state through → gravitational collapse to form a more compact object. In → white dwarfs forming → binary systems, → accretion of mass onto the surface of a neutron star can be sufficient to take the star over the upper mass limit for stability as a white dwarf. Consequently, the white dwarf collapses in a → supernova explosion to form a neutron star. There are several → supernova types.

→ super-; → nova.

A star which according to observational data could become a supernova.

→ supernova; → candidate.

The material ejected by a → supernova explosion.

→ supernova; → ejecta.