Difference between revisions of "Alpha Centauri (Star)"

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'''EDITING IN PROGRESS'''
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{{InfoboxStar
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|name=Alpha Centauri A
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{{InfoboxStar|name=Alpha Centauri A
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|image    = [[File: Imperial Sunburst-Sun-IISS-Traveller.gif]]
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|spectral=G2 V
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|spectral=G2 V
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|type=Main Sequence
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|type=Main Sequence
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|multiple=Trinary
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|multiple= Trinary
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|lum=1.519 L<sub>Sol</sub>
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|lum=1.519  
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|lrank=21<sup>st</sup>
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|lref= 0.01
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|lref= +0.01
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|lrworld=[[Terra]]
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|lrworld=[[Terra]]
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|lrank=21<sup>st</sup>
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|mag=+4.38
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|mag= +4.38
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|temp=5,790K
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|temp=5,790
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|mass=1.100 M<sub>Sol</sub>
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|mass=1.100  
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|companion=Alpha Centauri B & Alpha Centauri C
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|radius= 1.227
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|companion=Alpha Centauri B & Alpha Centauri C
 
}}
 
}}
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{{InfoboxStar
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{{InfoboxStar|name=Alpha Centauri B
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|name=Alpha Centauri B
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|spectral=K1 V
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|image    = [[File: Imperial Sunburst-Sun-IISS-Traveller.gif]]
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|type=Main Sequence
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|spectral=K1 V
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|multiple=
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|type=Main Sequence
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|lum= 0.50 L<sub>Sol</sub>
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|multiple= Near Companion
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|lrank=
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|lum= 0.50  
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|lref= +1.33
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|lref= 1.33
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|lrworld=[[Terra]]
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|lrworld=[[Terra]]  
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|mag= +5.71
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|lrank=
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|temp= K
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|mag= +5.71
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|mass= M<sub>Sol</sub>
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|temp= 5,260
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|companion=  
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|mass= 0.9
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|radius= 0.865
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|companion=  
 
}}
 
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{{InfoboxStar
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{{InfoboxStar|name=Alpha Centauri C (Proxima Centauri)
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|name=Alpha Centauri C (Proxima Centauri)
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|spectral=M5 Ve
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|image    = [[File: Imperial Sunburst-Sun-IISS-Traveller.gif]]
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|type=Main Sequence
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|spectral=M5.5 Ve
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|multiple=
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|type=Main Sequence
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|lum= L<sub>Sol</sub>
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|multiple= Far Companion
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|lrank=
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|lum= 0.00005
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|lref=
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|lref= 11.05
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|lrworld=[[Terra]]
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|lrworld=[[Terra]]
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|mag=
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|lrank=
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|temp= K
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|mag= +15.6
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|mass= M<sub>Sol</sub>
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|temp= 3,040
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|companion=
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|mass= 0.123 (<small>= 129 M<sub>J</sub>)</small> 
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|radius= 0.141
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|companion=
 
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'''Alpha Centauri''' (also called '''Rigil Kentaurus''' or '''Toliman''') is a multiple [[Star|star]] system consisting of a main binary pair ('''''Alpha Centauri A''''' and '''''Alpha Centauri B''''') orbited by a third red dwarf far companion, '''''Alpha Centauri C''''' or "'''''Proxima Centauri'''''" lying at about 15,000<small>AU</small> (~0.2<small>ly</small>) distant from the '''''Alpha Centauri AB''''' main pair.   
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'''Alpha Centauri''' (also called '''Rigil Kentaurus''' or '''Toliman''') is a multiple star system consisting of a main binary system ('''''Alpha Centauri A''''' and '''''Alpha Centauri B''''') as well as a third red dwarf companion, '''''Alpha Centauri C''''' or "'''''Proxima Centauri'''''" lying at about 5000<small>AU</small> (~0.1<small>ly</small>) distant from the main pair.   
 
  
 
== Description (Specifications) ==
 
== Description (Specifications) ==
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During the pair's 79.91-year orbit about a common center,[14] the distance between them varies from about that between Pluto and the Sun to that between Saturn and the Sun. Proxima is at the slightly smaller distance of 1.29 parsecs or 4.24 light years from the Sun, making it the closest star to the Sun, even though it is not visible to the naked eye. The separation of Proxima from Alpha Centauri AB is about 0.06 parsecs, 0.2 light years or 15,000 astronomical units (AU),[15] equivalent to 500 times the size of Neptune's orbit.   
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'''Alpha Centauri A''' and '''B''' orbit about a common center with an orbital period of about 79.91 years. The distance between them varies from as close as 11.2<small>AU</small> at periastron to as far as 35.6<small>AU</small> at apastron due to the binary's orbital eccentricity of e = 0.518. '''Alpha Centauri AB''' lies at a distance of about 1.34pc from the [[Sol (star)|Sol]] system.   
  
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'''Alpha Centauri A''' is the principal member, or primary, of the binary system, being slightly larger and more luminous than the Sun. It is a solar-like main-sequence star with a similar yellowish color,[17] whose stellar classification is spectral type G2 V. From the determined mutual orbital parameters, Alpha Centauri A is about 10% more massive than the Sun, with a radius about 23% larger. The projected rotational velocity ( v·sin i ) of this star is 2.7 ± 0.7 km·s−1, resulting in an estimated rotational period of 22 days,[18] which gives it a slightly faster rotational period than the Sun's 25 days. When considered among the individual brightest stars in the sky (excluding the Sun), Alpha Centauri A is the fourth brightest at an apparent visual magnitude of +0.01, being fractionally fainter than Arcturus at an apparent visual magnitude of −0.04.
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* '''Alpha Centauri A''' is a '''G2 V''' main-sequence [[Star|star]] that is slightly larger and more luminous than [[Sol (star)|Sol]] with a similar yellowish-white color. It has a mass of about 1.1 M<sub>Sol</sub> and a radius of about 1.23 R<sub>Sol</sub>, with a habitable zone lying at about 1.25<small>AU</small>.
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* '''Alpha Centauri B''' is slightly smaller and less luminous than [[Sol (star)|Sol]], and is a main-sequence [[Star|star]] of spectral type '''K1 V''', having a characteristic yellow-orange color. '''Alpha Centauri B''' has a mass of about 0.90 M<sub>Sol</sub> and a radius of about 0.86 R<sub>Sol</sub>, with a habitable zone ranging from 0.5 to 0.9 AU from the [[Star|star]]. Although it has a lower luminosity than the A-component, '''Alpha Centauri B''' emits more energy in the X-ray band.  
  
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'''Alpha Centauri B''' is the companion star, or secondary, of the binary system, and is slightly smaller and less luminous than the Sun. It is a main-sequence star of spectral type K1 V, making it more an orange color than the primary star.[17] Alpha Centauri B is about 90% the mass of the Sun and 14% smaller in radius. The projected rotational velocity ( v·sin i ) is 1.1 ± 0.8 km·s−1, resulting in an estimated rotational period of 41 days. (An earlier, 1995 estimate gave a similar rotation period of 36.8 days.)[19] Although it has a lower luminosity than component A, star B emits more energy in the X-ray band. The light curve of B varies on a short time scale and there has been at least one observed flare.[20] Alpha Centauri B at an apparent visual magnitude of 1.33 would be twenty-first in brightness if it could be seen independently of Alpha Centauri A.
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'''Proxima Centauri''' is of spectral class '''M5.5 Ve''', giving it a typically pinkish-orange coloration and making it subject to flare activity. It is likely bound gravitationally to '''Alpha Centauri AB''', and orbits with a period between 100,000 and 500,000 years. '''Proxima''' has a mass of about 0.123 M<sub>☉</sub> (or 129 M<sub>J</sub>) and a radius of 0.141 R<small>Sol</small> (= 1.5 R<sub>J</sub>). It is at a slightly smaller distance of 1.29 pc (4.24 ly) from [[Sol (star)|Sol]], making it the closest [[Star|star]] to the [[Sol (star)|Sol]] [[Star|star]] system. The separation of '''Proxima''' from '''Alpha Centauri AB''' is about 0.06 pc (0.2 ly), or 15,000<small>AU</small>. The habitable zone of '''Proxima Centauri''' lies at about 0.023–0.054<small>AU</small> from the [[Star|star]], and a world located here would have an orbital period of 3.6–14 days.
  
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'''Alpha Centauri C''', also known as Proxima Centauri, is of spectral class M6 Ve, a small main-sequence star (Type V) with emission lines. Its B−V color index is +1.82 and its mass is about 0.123 solar masses (M☉), or 129 Jupiter masses.
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Because of its low mass, the interior of '''Proxima Centauri''' is completely convective, causing energy to be transferred to the exterior by the movement of plasma rather than through radiative transport. This convection means that the helium ash left over from the thermonuclear fusion of hydrogen does not accumulate at the core, but instead circulates throughout the [[Star|star]]. Unlike [[Sol (star)|Sol]], which will only burn through about 10% of its total hydrogen supply before leaving the main sequence, '''Proxima Centauri''' will consume nearly all of its fuel before the fusion of hydrogen comes to an end, becoming smaller and hotter as the fuel is used up and turning into a [[Star#Blue_Dwarf|"blue dwarf"]] as its end approaches. It will finally end its life as a [[Star#Degenerate_Dwarf|white dwarf]], without having passed through the [[Star#Giant_Star|red-giant]] phase.  
  
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With the orbital period of 79.91 years,[14] the A and B components of this binary star can approach each other to 11.2 astronomical units, equivalent to 1.67 billion km or about the mean distance between the Sun and Saturn, or may recede as far as 35.6 AU (5.3 billion km—approximately the distance from the Sun to Pluto).[14][51] This is a consequence of the binary's moderate orbital eccentricity e = 0.5179.[14] From the orbital elements, the total mass of both stars is about 2.0 M☉[52]—or twice that of the Sun.[51] The average individual stellar masses are 1.09 M☉ and 0.90 M☉, respectively,[53] though slightly higher masses have been quoted in recent years, such as 1.14 M☉ and 0.92 M☉,[54] or totalling 2.06 M☉. Alpha Centauri A and B have absolute magnitudes of +4.38 and +5.71, respectively. Stellar evolution theory implies both stars are slightly older than the Sun at 5 to 6 billion years, as derived by both mass and their spectral characteristics.[34][53]
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In about the year 6000<small>CE</small> (<small>IY</small>1500), due to the proper motion of [[Alpha Centauri (Star)|Alpha Centauri]], the [[Star|star]] will appear close enough to '''''Beta Centauri''''' (aka '''''Hadar''''' or '''''Agena''''')  from the vantage point of [[Terra]] to form an optical double [[Star|star]], though in fact the '''''Beta Centauri''''' system is far more distant from [[Sol (star)|Sol]] than the [[Alpha Centauri (Star)|Alpha Centauri]] system. 
  
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Viewed from Earth, the apparent orbit of this binary star means that its separation and position angle (P.A.) are in continuous change throughout its projected orbit. Observed stellar positions in 2010 are separated by 6.74 arcsec through the P.A. of 245.7°, reducing to 6.04 arcsec through 251.8° in 2011.[14] The closest approach in the future will be in February 2016, at 4.0 arcsec through 300°.[14][55] The observed maximum separation of these stars is about 22 arcsec, while the minimum distance is 1.7 arcsec.[56] The widest separation occurred during February 1976 and the next will be in January 2056.[14]
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The entire [[Alpha Centauri (Star)|Alpha Centauri]] system is rich in metal deposits. {{Page cite|name=Interstellar Wars|page=114|citeName=IW114}}
  
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In the true orbit, closest approach or periastron was in August 1955, and next in May 2035. Furthest orbital separation at apastron last occurred in May 1995 and the next will be in 2075. The apparent distance between the two stars is rapidly decreasing, at least until 2019.[14]
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The [[Alpha Centauri (Star)|Alpha Centauri]] '''star system''' is approximately 1.34pc from [[Terra]], and is located in a Coretrailing/Trailing direction from [[Terra]] at bearing 315.7<sup>o</sup> Galactic Longitude and -00.7<sup>o</sup> South Galactic Latitude.
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Proxima Centauri
 
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Main article: Proxima Centauri
 
  
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The much fainter red dwarf Proxima Centauri, or simply Proxima, is about 15,000 AU away from Alpha Centauri AB.[21][34][42] This is equivalent to 0.24 light years or 2.2 trillion kilometres—about 5% the distance between Alpha Centauri AB and the Sun. Proxima is likely gravitationally bound to Alpha Centauri AB, orbiting it with a period between 100,000 and 500,000 years.[34] However, it is also possible that Proxima is not gravitationally bound and thus moving along a hyperbolic trajectory[57] with respect to Alpha Centauri AB.[21]:72 The main evidence for a bound orbit is that Proxima's association with Alpha Centauri AB is unlikely to be coincidental, because they share approximately the same motion through space.[34] Theoretically, Proxima could leave the system after several million years.[58] It is not yet certain whether Proxima and Alpha Centauri are truly gravitationally bound.[59]
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== History & Background (Dossier) ==
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[[Alpha Centauri (Star)|Alpha Centauri]] '''A''' is the primary [[Star|star]] of the world {{World|Prometheus|Solomani Rim|Sol|2027}}, one of [[Terra (world)|Terra's]] earliest colonies.
  
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In about 4000 years, the proper motion of Alpha Centauri will mean that from the point of view of Earth it will appear close enough to Beta Centauri to form an optical double star. Beta Centauri is in reality far more distant than Alpha Centauri.
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=== Image Repository ===
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[[TravellerMap]] <small>([[T5SS]])</small>: <br> [https://travellermap.com/?options=58363&x=16.027&y=-106.998&scale=64]
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* The entire [[Alpha Centauri (Star)|Alpha Centauri]] system is rich in metal deposits.
 
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* The [[Alpha Centauri (Star)|Alpha Centauri]] star system is approximately 1.35pc from Terra, and is located in a Coretrailing/Trailing direction from [[Terra]] at bearing 315.7<sup>o</sup> Galactic Longitude and -00.7<sup>o</sup> South Galactic Latitude.  
 
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== History & Background (Dossier) ==
 
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[[Alpha Centauri (Star)|Alpha Centauri]] '''A''' is the primary star of the world {{World|Prometheus|Solomani Rim|Sol|2027}}, one of [[Terra (world)|Terra's]] earliest colonies.
 
  
 
== References & Contributors (Sources) ==
 
== References & Contributors (Sources) ==
 
{{metadata}}
 
{{metadata}}
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{{Advanced}}
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{{Wikipedia|Alpha_Centauri}}
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{{Wikipedia|Proxima_Centauri}}
 
{{Sources
 
{{Sources
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|S1= Travellermap [http://travellermap.com/?options=58363&x=16.027&y=-106.998&scale=64]
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|S1= {{Ludography cite|name=Solomani|version=Classic Traveller}}
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|S2= {{CT}}: [[Solomani (Alien Module)]]
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|S2= {{Ludography cite|name=Rim of Fire}}
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|S3= [[GURPS Traveller: Interstellar Wars]]
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|S3= {{Ludography cite|name=Interstellar Wars}}
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|S4= [[GURPS Traveller: Rim of Fire]]
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|S4= {{Ludography cite|name=Solomani Rim|version=Mongoose Traveller}}
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|S5=
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|S5= {{Ludography cite|name=Solomani|version=Mongoose Traveller}}
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|S6= EXTERNAL LINK: ''SIMBAD @ University of Strasbourg'': [http://simbad.u-strasbg.fr/simbad/sim-fid]
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|S7= [[Traveller Wiki Editorial Team]]
 +
|S8= Author & Contributor: [[User:WHULorigan|WHULorigan]]
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|S9= Author & Contributor: Lord (Marquis) and Master of Sophontology [[User:Maksim-Smelchak|Maksim-Smelchak]] of the [[Ministry of Science]]  
 
}}
 
}}
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{{Wikipedia|Alpha_Centauri}}
 
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:* '''External Link''':  ''SIMBAD @ University of Strasbourg'': [http://simbad.u-strasbg.fr/simbad/sim-fid]
 
  
  
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{{LE|Stars}}
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{{LE|Star}}

Revision as of 18:45, 16 January 2019

Alpha Centauri A
Imperial Sunburst-Sun-IISS-Traveller.gif
Spectral G2 V
Type Main Sequence
Multiple Trinary
Luminosity 1.519 LSol
Lum Rank 21st
Absolute magnitude +4.38
Mag Terra 0.01
Temperature 5,790° K
Mass 1.100 MSol
Radius 1.227 RSol
Companion Alpha Centauri B & Alpha Centauri C
Alpha Centauri B
Imperial Sunburst-Sun-IISS-Traveller.gif
Spectral K1 V
Type Main Sequence
Multiple Near Companion
Luminosity 0.50 LSol
Absolute magnitude +5.71
Mag Terra 1.33
Temperature 5,260° K
Mass 0.9 MSol
Radius 0.865 RSol
Alpha Centauri C (Proxima Centauri)
Imperial Sunburst-Sun-IISS-Traveller.gif
Spectral M5.5 Ve
Type Main Sequence
Multiple Far Companion
Luminosity 0.00005 LSol
Absolute magnitude +15.6
Mag Terra 11.05
Temperature 3,040° K
Mass 0.123 (= 129 MJ) MSol
Radius 0.141 RSol

Alpha Centauri (also called Rigil Kentaurus or Toliman) is a multiple star system consisting of a main binary pair (Alpha Centauri A and Alpha Centauri B) orbited by a third red dwarf far companion, Alpha Centauri C or "Proxima Centauri" lying at about 15,000AU (~0.2ly) distant from the Alpha Centauri AB main pair.

Description (Specifications)

Alpha Centauri A and B orbit about a common center with an orbital period of about 79.91 years. The distance between them varies from as close as 11.2AU at periastron to as far as 35.6AU at apastron due to the binary's orbital eccentricity of e = 0.518. Alpha Centauri AB lies at a distance of about 1.34pc from the Sol system.

  • Alpha Centauri A is a G2 V main-sequence star that is slightly larger and more luminous than Sol with a similar yellowish-white color. It has a mass of about 1.1 MSol and a radius of about 1.23 RSol, with a habitable zone lying at about 1.25AU.
  • Alpha Centauri B is slightly smaller and less luminous than Sol, and is a main-sequence star of spectral type K1 V, having a characteristic yellow-orange color. Alpha Centauri B has a mass of about 0.90 MSol and a radius of about 0.86 RSol, with a habitable zone ranging from 0.5 to 0.9 AU from the star. Although it has a lower luminosity than the A-component, Alpha Centauri B emits more energy in the X-ray band.

Proxima Centauri is of spectral class M5.5 Ve, giving it a typically pinkish-orange coloration and making it subject to flare activity. It is likely bound gravitationally to Alpha Centauri AB, and orbits with a period between 100,000 and 500,000 years. Proxima has a mass of about 0.123 M☉ (or 129 MJ) and a radius of 0.141 RSol (= 1.5 RJ). It is at a slightly smaller distance of 1.29 pc (4.24 ly) from Sol, making it the closest star to the Sol star system. The separation of Proxima from Alpha Centauri AB is about 0.06 pc (0.2 ly), or 15,000AU. The habitable zone of Proxima Centauri lies at about 0.023–0.054AU from the star, and a world located here would have an orbital period of 3.6–14 days.

Because of its low mass, the interior of Proxima Centauri is completely convective, causing energy to be transferred to the exterior by the movement of plasma rather than through radiative transport. This convection means that the helium ash left over from the thermonuclear fusion of hydrogen does not accumulate at the core, but instead circulates throughout the star. Unlike Sol, which will only burn through about 10% of its total hydrogen supply before leaving the main sequence, Proxima Centauri will consume nearly all of its fuel before the fusion of hydrogen comes to an end, becoming smaller and hotter as the fuel is used up and turning into a "blue dwarf" as its end approaches. It will finally end its life as a white dwarf, without having passed through the red-giant phase.

In about the year 6000CE (IY1500), due to the proper motion of Alpha Centauri, the star will appear close enough to Beta Centauri (aka Hadar or Agena) from the vantage point of Terra to form an optical double star, though in fact the Beta Centauri system is far more distant from Sol than the Alpha Centauri system.

The entire Alpha Centauri system is rich in metal deposits. [1]

The Alpha Centauri star system is approximately 1.34pc from Terra, and is located in a Coretrailing/Trailing direction from Terra at bearing 315.7o Galactic Longitude and -00.7o South Galactic Latitude.

History & Background (Dossier)

Alpha Centauri A is the primary star of the world Prometheus/Sol (Solomani Rim 2027), one of Terra's earliest colonies.

Image Repository

TravellerMap (T5SS):
[1]

References & Contributors (Sources)

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