First Empire

Primary of Illapa.

The two components are yellow G-type main-sequence stars. The brighter component, Xi Ursae Majoris A, has a mean apparent magnitude of +4.41. It is classified as an RS Canum Venaticorum type variable star and its brightness varies by 0.01 magnitudes. The companion star, Xi Ursae Majoris B has an apparent magnitude of +4.87. The orbital period of the two stars is 59.84 years, and they are currently separated by 1.2 arcseconds, or at least 10 AUs.

Each component of this double star is itself a spectroscopic binary. B's binary companion, denoted Xi Ursae Majoris Bb, is unresolved, but the binary star is known to have an orbital period of 3.98 days. The masses of both A and B's companions (Ab and Bb) (deduced by the sum total mass of the system minus the likely masses of Aa and Ba determined by their class) indicate that they are probably MV stars (red dwarfs), Bb being on the cool end of the M spectrum, not much hotter than a brown dwarf.

It also has the proper name Alula Australis (and erroneously Alula Australe).

Primary of Tonapa.

Chi1 Orionis (χ1 Ori, χ1 Orionis) is a star about 28 light years away. It is in the constellation Orion.

χ1 Ori is a G0V main-sequence star. It has a faint companion with a mass estimated at about 15% of the mass of the Sun, an orbital period of 14.1 years, and an estimated stellar class of M6. The companion orbits an average distance of 6.1 AU from the primary, but has a fairly high orbital eccentricity, ranging from 3.3 AU out to 8.9 AU from the primary. Because of this red dwarf companion, the likelihood of habitable planets in this system is low.

χ1 Ori is a candidate stream star member of the Ursa Major Moving Group, although there is some evidence to the contrary.

Primary of Vaikuntha.

Zeta Tucanae (ζ Tuc, ζ Tucanae) is a star in the constellation Tucana. It is a spectral class F9.5 main sequence star with an apparent magnitude of +4.23. Despite having a slightly lower mass, this star is more luminous than the Sun. Based upon parallax measurements by the Hipparcos spacecraft, it is approximately 28.0 light years from Earth. This is one of the least variable stars observed during the Hipparcos mission.

The composition and mass of this star are very similar to the Sun, with a slightly lower mass and an estimated age of three billion years. The solar-like qualities make it a target of interest for investigating the possible existence of a life-bearing planet.

Based upon an excess emission of infrared radiation at 70 micrometres, this system is believed to have a debris disk. The disk is orbiting the star at a minimum radius of 2.3 astronomical units. It is radiating with a maximum temperature of 218 K. As of 2009, no planet has been discovered in orbit around this star.

The components of this star's space velocity are U = −60, V = −4 and W = −38 km/s. These correspond to the velocity toward the galactic center, the velocity along the direction of galactic rotation, and the velocity toward the north galactic pole, respectively. It is orbiting through the galaxy at a mean distance of 8.4 kpc from the galactic center and with an orbital eccentricity of 0.16.

Primary of Nahelennia.

61 Virginis (abbreviated 61 Vir) is a G5V class star slightly less massive than the Sun (G2V), located about 27.8 light-years away in the constellation of Virgo. The composition of this star is nearly identical to the Sun and there is only a low level of activity in the stellar chromosphere.

This star is rotating once every 29 days at the equator. The space velocity components of this star are U = –37.9, V = –35.3 and W = –24.7 km/s. 61 Vir is orbiting through the Milky Way galaxy at a distance of 6.9 kpc from the core, with an eccentricity of 0.15. It is believed to be a disk star with an estimated age of more than six billion years.

There was some evidence that it may have a jovian planet, but it seemed not to have a nearby massive companion. A subsequent study also failed to find the large substellar companion (with 20 to 80 times the mass of Jupiter) or a Jupiter-class planet, so it was a good candidate for possessing a family of terrestrial planets, with an orbit slightly smaller and a year slightly less than that of the Earth.

A survey of this star with the Spitzer Space Telescope revealed an excess of infrared radiation at a wavelength of 160 μm. This indicated the presence of a debris disk in orbit around the star. This disk was resolved at 70 μm, corresponding to an inner radius of 96 AU from the star. The outer radius is estimated as 195 AU and the total mass of the disk is 5 × 10−5 the mass of the Earth.

On 14 December 2009, scientists announced the discovery of three planets with masses between 5 and 25 times that of Earth orbiting around 61 Virginis. The three planets all orbit very near the star; when compared to the orbits of the planets in our solar system, all three would orbit inside the orbit of Venus. Additional data is needed to confirm the possibility of a fourth planet, although an Earth-mass planet in the star's habitable zone (which would still be too small to detect with current technology) remains possible.

Primary of Olympias.

The main star, Mu Herculis A is fairly similar to the Sun although more highly evolved with a stellar classification of G5 IV. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[4] Its mass is about 1.1 times that of the Sun, and it is beginning to expand to become a giant.

The secondary component consists of a pair of stars that orbit about each other with a period of 43.2 years. Mu Herculis A and the binary pair B-C are separated by 286 AUs. The stars B-C are separated from each other by 11.4 AUs. Their orbit is quite elliptic (e=0.18) and both stars swing each other between 9.4 and 13.5 AUs.

Star A is itself suspected to be a close binary with a low mass stellar or a large substellar companion, probably at 17.2 AUs in an elliptic orbit. Nevertheless the existence of such an object has still not been confirmed.

Primary of Nyambo.

The first companion is a yellow-white (class F) fourth-magnitude star with a mass approximately equal to that of the sun, but it is nearly twice as luminous. The second companion is an orange (class K) sixth-magnitude star, that is less massive and of lesser luminosity than the sun. In 1898 this system was reported to be a spectroscopic binary system, with an orbital period of 280.55 days. The two stars have an average separation of nearly an astronomical unit, which would disrupt the orbit of any Earth-like planet that was close enough to the primary to support liquid water. The two stars have less than half the abundance of heavy elements as the Sun and are approximately a billion years older.

Primary of Nareau.

Spectral Class: A: K0 B: K5

More information.

Primary of Tros.

Fomalhaut (Alpha Piscis Austrini, Alpha PsA, α Piscis Austrini, α PsA) is the brightest star in the constellation Piscis Austrinus and one of the brightest stars in the sky. Fomalhaut can be seen low in the southern sky in the northern hemisphere in fall and early winter evenings. Near latitude 50˚N, it sets around the time Sirius rises, and does not reappear until Antares sets. Its name derives from Arabic fum al-ḥawt, meaning "mouth of the [Southern] Fish" (فُمْ اَلْحَوْتْ).

This is a class A star on the main sequence approximately 25 light-years (7.7 pc) from Earth as measured by the Hipparcos astrometry satellite. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It is classified as a Vega-like star that emits excess infrared radiation, indicating it is surrounded by a circumstellar disk. Fomalhaut and the K-type star TW Piscis Austrini constitute a binary system.

Fomalhaut holds a special significance in extrasolar planet research, as it is the center of the first stellar system with an extrasolar planet (Fomalhaut b) imaged at visible wavelengths. The image was published in Science in November 2008. It is the third brightest star known to have an orbiting planet, after Pollux and the Sun.

Fomalhaut was a later designation of 79 Aquarii.

Fomalhaut is a young star, for many years thought to be only 100 to 300 million years old, with a potential lifespan of a billion years. A 2012 reanalysis of the age for Fomalhaut by astronomer Eric Mamajek yielded an age of 440+-40 million years. The surface temperature of the star is around 8,590 K (8,320 °C). Fomalhaut's mass is about 1.92 times that of the Sun, its luminosity is about 16.6 times greater, and its diameter is roughly 1.84 times as large.

Fomalhaut is slightly metal-deficient as compared to the Sun, which means it is composed of a smaller percentage of elements other than hydrogen and helium. The metallicity is typically determined by measuring the abundance of iron in the photosphere relative to the abundance of hydrogen. A 1997 spectroscopic study measured a value equal to 93% of the Sun's abundance of iron. A second 1997 study deduced a value of 78% by assuming Fomalhaut has the same metallicity as the neighboring star TW Piscis Austrini, which has since been argued to be a physical companion. In 2004, a stellar evolutionary model of Fomalhaut yielded a metallicity of 79%.[3] Finally, in 2008, a spectroscopic measurement gave a significantly lower value of 46%.

Fomalhaut is a member of the 16 stars belonging to the Castor Moving Group. This is an association of stars that share a common motion through space and have been claimed to be physically associated. Other members of this group include Castor and Vega. This moving group has an estimated age of 200 ± 100 million years and originated from the same location.

Fomalhaut is a binary star with the nearby star TW Piscis Austrini. TW Piscis Austrini lies 0.28 parsecs away from Fomalhaut, and its space velocity agrees with that of Fomalhaut within 0.1+-0.5 km/s, consistent with being a bound companion. A recent age estimate for TW PsA (400+-70 million years), agrees very well with the isochronal age for Fomalhaut (450+-40 million years), further arguing for the two stars forming a physical binary.

Primary of Odudua.

Spectral Class: G5

Mu Cassiopeiae (μ Cas, μ Cassiopeiae) is a binary star system in the constellation Cassiopeia. This system shares the name Marfak with Theta Cassiopeiae, and the name was from Al Marfik or Al Mirfaq (المرفق), meaning "the elbow".

In 1961 the close binary nature of this system was discovered by Nicholas E. Wagman at the Allegheny Observatory. Since then the orbital elements of the two stars have been fairly well established. The two stars are separated by a semimajor axis of 7.61 AUs with distance range of 3.3-11.9 AUs. In 1966, the individual components were first resolved by the American astronomer Peter A. Wehinger using the 84-inch reflector at the Kitt Peak National Observatory, allowing an initial estimate of separate masses.

Compared to other nearby stars, this pair are moving at a relatively high velocity of 167 km/s through the Milky Way galaxy. They are low metal, Population II stars that are thought to have formed before the galactic disk first appeared.

This star will be in constellation Perseus around 5200 AD.

Primary of Hatshehogan.

Beta Hydri (β Hyi, β Hydri) is a star in the southern circumpolar constellation of Hydrus. (Note that Hydrus is not the same as Hydra.) With an apparent visual magnitude of 2.8, this is the brightest star the constellation. Based upon parallax measurements the distance to this star is about 24.33 light-years (7.46 parsecs).

This star has about 108% of the mass of the Sun and 181% of the Sun's radius, with more than three times the Sun's luminosity. The spectrum of this star matches a stellar classification of G2 IV, with the luminosity class of 'IV' indicating this is a subgiant star. As such, it is a slightly more evolved star than the Sun, with the supply at its core becoming exhausted. It is the nearest subgiant star to the Sun and one of the oldest stars in the solar neighborhood. This star bears some resemblance to what the Sun may look like in the far distant future, making it an object of interest to astronomers.

At around 150 BC, this star was two degrees away from the southern celestial pole. It is currently the nearest relatively bright star to the southern pole.

In 2002 Endl et al. inferred the possible presence of an unseen companion orbiting Beta Hydri as hinted by radial velocity linear trend with a periodicity exceeding 20 years. A substellar object with minimum mass of 4 Jupiter masses and orbital separation of roughly 8 AUs could explain the observed trend. If confirmed, it would be a true Jupiter-analogue, though 4 times more massive. So far no planetary/substellar object has been certainly detected.