View source for Aidus (star)

{{Icons|B-class|Aidus}}
{{Infobox
| bodystyle        = border-collapse:collapse
| title            = Aidus
| image            = [[File:Aidus star.svg||frameless]]
| caption          = Aidus as seen in {{w|visible light}}, revealing its sunspots and condensate metal clouds.
| image2           = 
| caption2         = 
| headerstyle      = background:#ffb56b
| labelstyle       = padding:2px
| datastyle        = padding:2px
| label1           = Names
| data1            = Aidus, Eidus, Aydó, Ayd, Sun
| label2           = Adjectives
| data2            = Aidusal
<!-- section break, rows 1-19-->| header3          = Observation data
| label4           = Mean distance<br/>from [[Orbalia]]
| data4            = 1 OO ≈ 4.375 billion {{W|km}}<br>≈ 14.596 seconds at {{w|speed of light}}
| label5           = {{w|Apparent magnitude|Visual brightness}} (''v'')
| data5            = −26.74
| label6           = {{W|Absolute magnitude}}
| data6            = 18.1
| label7           = {{w|Stellar classification|Spectral classification}}
| data7            = M8v
| label8           = {{w|Metallicity}}
| data8            = ''Z'' = 0.04
| label9           = 
| data9            = 
| header10         = {{w|Orbit}}al characteristics
| label11          = Mean distance<br/>from {{W|Milky Way}} core
| data11           = ≈ 26,700 {{w|light-year}}s
| label12          = {{W|Galactic year|Galactic period}}
| data12           = 56.449 billion uecs
| label13          = {{w|Velocity}}
| data13           = ≈ 54 km/s (orbit around the center of the Milky Way)
<!-- section break, rows 20–39 -->| header20         = Physical characteristics
| label21          = Equatorial {{w|radius}}
| data21           = ≈ 82,927 km
| label22          = Equatorial {{w|circumference}}
| data22           = ≈ 521,046 km
| label23          = {{W|Flattening}}
| data23           = 9×10<sup>−6</sup>
| label24          = {{w|Surface area}}
| data24           = 8.64 × 10<sup>10</sup> km<sup>2</sup>
| label25          = {{W|Volume}}
| data25           = 2.39 x 10<sup>15</sup> km<sup>3</sup>
| label26          = {{w|Mass}}
| data26           = 1.786 x 10<sup>29</sup> kg
| label27          = Average {{w|density}}
| data27           = 74.728 g/cm<sup>3</sup>
| label28          = 
| data28           = 
| label29          = Equatorial {{w|surface gravity}}
| data29           = 5.2396 {{w|Centimetre–gram–second system of units|cgs}}
| label30          = 
| data30           = 
| label31          = 
| data31           = 
| label32          = Temperature
| data32           = 2566 {{w|Kelvin}}
| label33          = Luminosity
| data33           = 1.39875 x 10<sup>23</sup> {{w|Lumen}}s
| label34          = {{w|Color index}}
| data34           = 2.15
| label35          = 
| data35           = 
| label36          = Age
| data36           = ≈ 551.606 billion uecs
<!-- section break, rows 40–49 -->| header40         = {{W|Rotation}} characteristics
| label41          = 
| data41           = 
| label42          = 
| data42           = 
| label43          = 
| data43           = 
| label44          = Sidereal rotation period <br/>(at equator)
| data44           = 79.08 hr
| label45          = 
| data45           = 
| label46          = 
| data46           = 
| label47          = Rotation velocity<br/>(at equator)
| data47           = 6 km/s
}}
:''For the planetary system orbiting Aidus, see [[Aidus system]]''
'''Aidus''' ([[Volsh language|Volsh]]: ''Aidus''; [[Langin language|Langin]]: ''Aydó''; [[Podchin language|Podchin]]: ''Ayd'') is the {{w|star}} at the center of the [[Aidus system]]. It is a nearly perfect {{w|ball}} of hot {{w|plasma}} heated to {{w|incandescence}} by the {{w|nuclear fusion}} of {{w|hydrogen}} to {{w|helium}} at its core. It emits this fusion {{w|energy}} mainly as {{w|visible light}}, {{w|ultraviolet light}}, and {{w|infrared}} radiation. Aidus is considered the most important source of energy for {{w|life}} on three of its seven planets.

Aidus' mass is 35,300 times that of [[Orbalia]]'s and accounts for about 98% of the Aidus system's total mass. Roughly three fourths of the mass of Aidus is {{W|hydrogen}}, with the remainder being mostly {{w|helium}}. As a late {{w|red dwarf}}, Aidus has a comparatively high percentage of {{w|metallicity}}, at around 4% of the star's mass (metals referring generally to anything heavier than hydrogen and helium). {{w|Oxygen}}, {{w|carbon}}, {{w|iron}}, {{w|neon}}, {{w|nitrogen}}, {{w|silicon}}, {{W|magnesium}}, and {{w|sulphur}} are all substantially present in Aidus' {{w|photosphere}}. Due to the star's comparatively low effective temperature of 2566 {{w|Kelvin|K}}, condensates and dust form in the star's photosphere, along with a general proclivity for {{w|sunspot}}s.

The hydrogen fusion at the core of the star is the source of its light and heat. Due to its comparatively low density and temperature, Aidus' rate of hydrogen-to-helium fusion is expected to continue for hundreds of trillions of uecs. This means that Aidus will likely be one of the last stars with fusion occurring in the entire {{w|Universe}}, should the process continue unhindered. At an age of about 551.606 billion uecs, it is a comparatively old star in the {{w|Milky Way}} galaxy, having been formed around the same time as the {{w|thin disk}} in which it lies.

Aidus has long been of biological and cultural significant to Human life in the planetary system. In [[Drevnian mythology]], it is believed to have been considered a {{w|deity}}. The orbit of {{w|tidally locked}} Orbalia around Aidus is used as the basis for the [[Orbalian calendar]], which continues in widepsread usage in the contemporary period. 

==Name and etymology==
According to the [[Zemaian migration theory]], the [[Anglatin language|Anglatin]] word ''Aidus'' is believed to derive from the name of a God in [[Zemaian mythology]]. Deducing from the external application of the name ''Aidus'' to a star outside of the theorized home system of humanity, the god Aidus is regarded then to have been a central figure in Zemaian mythology which shared importance with at least one other god. Whereas the {{w|polytheistic}} [[Starveryanism]] native to [[Velesa]] often dichotomizes between its own gods, some scholars believe that Aidus was likely held in such a dichotomy to the sun god of Zemais as well. This argument holds that the persons undergoing the migration to Aidus from Zamais would have been undergoing a voyage similar to dying; from the perspective of their relatives on Zemais, it may well have resembled as much. Hence, in this manner, Aidus is believed to have been a god of the {{w|underworld}} or {{W|death}}. Alternatively, some scholars suggest that the name ''Aidus'' was simply another name for the same sun god of Zemais, who from etymological studies of Anglatin would have been regularly known as either ''Sun'' or ''Sol''.

Those who do no believe in the Zemaian migration theory otherwise posit that the word ''Aidus'' merely descends from the Anglatin word ''aether'' or the supposedly adjectival form ''aetherous'', meaning ''heaven'' or ''sky'' and ''heavenly'' or ''of the sky'' respectively. These scholars suggest that over the course of the Forgotten and First Ages, as the contemporary languages of the Aidus system shifted into their present form, the "th" of ''aether'' was slowly morphed into a ''d'', while the suffixal ''-us'' was added from the Anglatin singular suffixal ending. This theory, however, does not account for the vocabulary presence of the words ''Sun'' or ''Sol'' in the etymologies of the Anglatin-descendent languages of the contemporary day, which are considered by supporters of the ''aether'' theory to be merely insignificant synonyms.

The adjectival form of the star ''Aidus'' is ''Aidusal''. This is not to be confused with ''Aidusian'', which is commonly used to describe characteristic relation to the Aidus system as a whole, as is implied in the Anglatin suffix ''-ia'', meaning ''territory'' or ''country'', present in that adjectival form.

==Characteristics==
Aidus is an {{w|M-type star|M-type}} {{w|main sequence}} star that constitutes approximately 98% of the mass of the Aidus system. It has an {{w|absolute magnitude}} of 18.1, putting it on the lower end of luminosity when compared with other {{w|red dwarf}}s. Aidus is a {{w|Population I}} star, meaning that it is rich in elements heavier than hydrogen and helium. Aidus and its two closest stellar neighbors, Vecin and Efesa, are believed to have originated from a common {{w|nebula}}, which would have been one of the first in the Milky Way galaxy at the time of its formation. The formation of Aidus and its neighboring stars are believed to have been triggered by the shockwaves from one or more nearby {{w|supernova}}e, due to the high abundance of heavy elements like {{w|gold}} and {{w|uranium}} in the system.

Aidus is the brightest object in the sky of Orbalia, with an apparent magnitude of -26.74, although only one side of the planet ever experiences direct light from the star. One Orbalian Orbit (approximately 4.338 million km) is defined as the mean distance of Aidus' center to Orbalia's center; the exact distance varies as Orbalia moves from {{w|perihelion}} to {{W|aphelion}} during one uec around the star. At this average distance, light travels from Aidus' horizon to Orbalia's horizon in 14.596 seconds. The energy of this light supports almost all terrestrial life on the planet, driving its climate and weather cycles, as well as some life and the climate cycles on the respectively inward and outward planets of [[Pechlus]] and [[Velesa]].

Aidus does not have a definite boundary, but its density exponentially decreases with increasing height above the {{w|photosphere}}. For the purposes of measurement, Aidus' radius is considered to be the distance from its center to the edge of the photosphere. By this measure, Aidus is a near-perfect sphere, with an {{w|oblateness}} estimated at 9 millionths, meaning that its polar diameter differs from its equatorial diameter by only about 10 kilometers. The tidal effect of the planets is comparatively week, and does not alter the shape of Aidus. The star makes a complete rotation on its axis every 79.08 hours, a little more than twice per Orbalian uec. Viewed from a hypothetical vantage point above its north pole, Aidus rotates counterclockwise around its axis of spin.

==Composition and structure==
Aidus is composed primarily of the chemical elements {{w|hydrogen}} and {{w|helium}}. At the present stage of Aidus' life, its photosphere is composed of about 78.5% hydrogen and 17.3% helium. All heavier elements, known as metals, account for a little over 4.2% of the photosphere, with oxygen, carbon, neon, and iron being the most abundant. The chemical composition was inherited from the {{w|nebula}} and {{w|supernova}}e of the {{w|interstellar medium}} that preceded Aidus' existence in the first hundreds of billions of uecs of the Milky Way galaxy. While the rate of hydrogen-to-helium fusion in the core of Aidus is comparatively among the slowest, when the hydrogen of the core is eventually depleted, the core itself will contract under its own gravity. As the core retracts, the outer layers of the star will expand greatly, causing Aidus to become a {{W|red giant}} which would encompass most if not all of its planetary system.

The structure of Aidus contains the following layers:
*''Core'': the innermost 20% to 25% of the star's radius, where temperature and pressure are sufficient for nuclear fusion to occur. The fusion process released energy, and the core gradually becomes enriched in helium.
*''Radiative zone'': convection cannot occur until much nearer to the surface of the star, and so lysing between 20% to 70% of the radius, this zone is where energy transfer is facilitated through the radiation of photons rather than convection.
*''Tachocline'': the boundary between the radiative and convective zones.
*''Convective zone'': between 70% of the radius and the visible surface, the star is cool and diffuse enough for convection to occur, and this becomes the primary means of outward heat transfer.
*''Photosphere'': the deepest part of the star that can be observed directly within the spectrum of visible light.
*''Atmosphere'': the gaseous halo surrounding Aidus, comprising the {{w|chromosphere}}, the {{w|solar transition region|transition region}}, the {{w|solar corona|corona}}, and the aidosphere.

==Motion and location==
Aidus is moved very slightly by the gravitational pull of its planets. If the {{w|barycenter}} of the Aidus system is thought of as stationary, then Aidus remains within 1.5 Aidusal radii of that barycenter. The movement of Aidus around the barycenter generally has a {{w|foil (architecture)|sextifoil}} shape, moving in a circular motion towards the alignment of two or more planets due to the high level of synchronicity in the planets' orbital ratios. After roughly 9.3 uecs, three times the {{w|synodic period}} of the planet [[Mora]], the pattern more or less repeats, but rotated by a slight angle.  The orbits of the planets are similarly displaced by the same gravitational forces, so the movement of Aidus has little effect on the relative positions of any one planet in the system.

Aidus orbits the center of the Milky Way. With an average orbital distance of roughly 26,700 {{W|light-year}}s from the {{w|Galactic Center}}, and an orbital speed of approximately 54 km/s, it takes Aidus roughly 56.449 billion uecs to complete a full {{w|galactic year|galactic uec}}. The star is thought to have completed only 10 full orbits during its lifetime, and it is presently on its 11th. At this speed, it takes Aidus a little under one sextent to travel one Orbalian distance through the {{W|interstellar medium}}. Curiously, Aidus, along with its Local Bubble neighbours Vecin and Efesa, are moving in the opposite direction of most other stars in the stellar neighborhood. Given the age of Aidus and its neighboring stars, the cause of this could be a vast number of factors, and no one reason can be singled out conclusively.

Aidus lies close to the middle of the {{w|Orion Arm}} of the {{w|Milky Way}}. Aidus, along with the stars Vecin and Efesa, lie in what is known as the Local Bubble, a space of rarefied hot gas believed to have been produced by a nearby supernova, possibly in the {{W|Pleiades|Septoiles}} moving group. Aidus and the stars of the Local Bubble move relatively slowly compared to other stars within a 5 parsec radius around Aidus. While most of these other stars have orbital speeds between 200 to 300 km/s, stars in the Local Bubble move only at speeds around roughly 50 km/s. Additionally, no other star outside of the Local Bubble and within a 5 parsec radius of Aidus moves in the same direction. Due to this discrepancy, there are some who theorize that the originative nebular star from which the stars of the Local Bubble are derived was actually deposited into the Milky Way during a {{w|galaxy merger}} which took place 660 billion uecs before present, but the similarities between the Local Bubble stars and other {{W|Population I}} stars in the galaxy make this theory inconclusive.

==Planetary system==
[[File:Aidus system diagram with names.svg|thumb|right|350px|Aidus and its seven planets, with sizes to scale and distances not to scale.]]
{{main|Aidus system}}
Aidus has seven known planets, all of which are {{w|terrestrial planet}}s of relatively similar size; in order from closest to furthest they are [[Svarus]], [[Achlisa]], [[Pechlus]], [[Orbalia]], [[Velesa]], [[Chaius]], and [[Mora]]. All seven of the planets are coplanar; their orbits are aligned on the same plane of revolution. Additionally, all seven planets have highly circular, nonirregular orbits with minimal {{w|orbital eccentricity|eccentricities}}. Considered relative to exoplanetary systems, the planets of Aidus share tight orbits around the star, making the system one of the most compact in the stellar neighborhood. None of the planets have any natural satellites, a feature often attributed to their close orbits. Beyond the seven planets lies the [[Circumtorus]], a ring of {{w|planetesimal}}s and other protoplanetary material which extends to the farthest reaches of the system, the largest being the {{w|dwarf planet}}s [[Lubof]], [[Aloina]], and [[Temnoa]]. 19 {{w|comet}}s cross the inner threshold of the Circumtorus, with two of these believed to be of extrasolar origin.

==Human history==
Extraidusally, the light and heat produced by the star has long impacted human life on the planets which orbit it. It is believed that Aidusal energy was and remains the ultimate source of energy for all biological life across the planetary system. Since the [[Drevnian Empire]] of the Forgotten Age, humans have further utilized this light for a variety of economic, infrastructural, and technological purposes. {{w|Agriculture}} would not be possible without Aidus' light. [[Solsailing]], in its most primitive form, relied almost entirely upon Aidus' {{w|solar wind}} to power outer space locomotion. {{w|Photovoltaic cell}}s harness the energy of Aidus to generate electricity, which has had and continues to have innumerable applications across a wide swath of human activities.

Local to the star itself, it is believed that the first humans "arrived" in the Forgotten Age, possibly researchers and prospectors from a scientific or economic institution respectively of the Drevnian Empire. There is no evidence that any longstanding effort was made by the Drevnians to inhabit anywhere near the star, though this is potentially due to the impacts of the [[Belvisajine Inquisition]], as the metal condensate clouds of the star would have made it quite appealing in any period of human history for economic exploitation.

The next phase of permanent human habitation within the vicinity of Aidus began during the early-to-middle Second Age. Designed with heat-resistant metal "sunshields" providing protection from the high-intensity light and heat, these earliest space stations were specialized mineral processing plants owned by various [[Obmenism|obmenist]] ''[[Sofesoyia|sofesoyi]]'' of Orbalia and Velesa. After the [[Coalition War]], many of these sofesoyi transitioned to asteroid-based mining operations in the Circumtorus, due to the typical transit path from Aidus to anywhere else being intercepted by a number of other planetary spaces.

It would not be until the later Third Age, with the rise of the [[Transvelesan Empire]], that condensate processing operations resumed within Aidus orbit. With the construction of [[Imperiya Station]] being a primary driver of this renewed economic activity, the completion of the station in III.24891 would resultantly lead to a general stagnation and slow decline of condensate extraction. This trend has continued into the Fourth Age, and as of the 13th millennium of the present Age, less than 10,000 people permanently inhabit the stations in Aidusal orbit.

==Human impacts==
As the principle source of light and heat in its planetary system, Aidus' great importance extends to all surface-dwelling biological life alongside humanity. Aidus is believed to have served an important cultural role to early human civilization, evidenced through its veneration in [[Drevnian mythology]] and even in the major religions of [[Drevianicism]] and [[Starveryanism]] in the contemporary period. The ''septigram'', a seven-pointed star, is a major symbol of the entire Aidus system, being represented on the flag of the modern [[Aidusian Empire]] through its direct representation in those aforementioned religions. 

On Orbalia, the homeworld of humanity in the system and the only planet where terrestrial habitation is possible, Aidus has even more particular significance in its defining of the [[Orbalian calendar]] through the sextents and uecs, in which the position of Aidus in the sky provides a transition by which time is measured locally. The application of the Orbalian calendar to the entire system with the spread of humanity has since meant that Aidus' time-keeping role has been extended to the whole of humanity.

In the visual and literary arts, Aidus has come to broadly represent the concepts of {{w|life}}, {{W|kindness|warmth}}, and {{w|divine light}}, held in contrast with the representation of the {{W|outer space|void}} as a source of {{W|death}}, {{W|freezing}}, and {{W|emptiness}}.

==See also==
*[[Aidus system]]
*[[Zemais system]]
{{Aidus system}}
{{Aquarius (constellation)}}
{{WPAN|Sun}}

[[Category:Aidus]]
[[Category:Aidus system]]
[[Category:M-type main-sequence stars]]
[[Category:Astronomical objects known since antiquity]]
[[Category:Aquarius (constellation)]]
[[Category:Stars with proper names]]