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Pi2 Hydri
This is the list of notable stars in the constellation Hydrus, sorted by decreasing brightness. See also *List of stars by constellation All stars but one can be associated with an IAU constellation. IAU constellations are areas of the sky. Although there are only 88 IAU constellations, the sky is actually divided into 89 irregularly shaped boxes as the constellation Serpens is spli ... References * * * * * {{Stars of Hydrus *List Hydrus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sky, night, but their immense distances from Earth make them appear as fixed stars, fixed points of light. The most prominent stars have been categorised into constellations and asterism (astronomy), asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye, all within the Milky Way galaxy. A star's life star formation, begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Its stellar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Hydri
Alpha Hydri, Latinized from α Hydri, is the second brightest star in the southern circumpolar constellation of Hydrus. It is readily visible to the naked eye with an apparent visual magnitude of +2.9. It is sometimes informally known as the Head of Hydrus. This should not be confused with Alpha Hydrae (Alphard) in the constellation Hydra. Alpha Hydri is one of only three stars in the constellation Hydrus that are above the fourth visual magnitude. This star can be readily located as it lies to the south and east of the prominent star Achernar in the constellation Eridanus. Based upon parallax measurements from the Hipparcos mission, Alpha Hydri is located at a distance of about from Earth. This subgiant star is three times larger and twice as massive as the Sun, with a stellar classification of F0 IV. It is about 810 million years old and is radiating 21 times the Sun's luminosity from its outer atmosphere at an effective temperature of 7,087 K. Alpha H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iota Hydri
This is the list of notable stars in the constellation Hydrus, sorted by decreasing brightness. See also *List of stars by constellation All stars but one can be associated with an IAU constellation. IAU constellations are areas of the sky. Although there are only 88 IAU constellations, the sky is actually divided into 89 irregularly shaped boxes as the constellation Serpens is spli ... References * * * * * {{Stars of Hydrus *List Hydrus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta Hydri
Theta Hydri, Latinized from θ Hydri, is the Bayer designation for a blue-white hued star in the southern constellation of Hydrus. It is faintly visible to the naked eye with an apparent visual magnitude of +5.53. Based upon an annual parallax shift of as seen from Earth, is located approximately from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction of 0.10 due to interstellar dust. It is moving away from the Sun with a radial velocity of . A stellar classification of B8 III/IV suggests it is an evolving B-type star showing mixed traits of a subgiant or giant star. It is a PGa star – a sub-class of the higher temperature chemically peculiar stars known as mercury-manganese stars (HgMn stars). That is, it displays a rich spectra of singly-ionized phosphorus and gallium, in addition to ionized mercury and manganese. As such, Theta Hydri forms a typical example of this type. The absorption lines for these ionized eleme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mu Hydri
This is the list of notable stars in the constellation Hydrus, sorted by decreasing brightness. See also *List of stars by constellation All stars but one can be associated with an IAU constellation. IAU constellations are areas of the sky. Although there are only 88 IAU constellations, the sky is actually divided into 89 irregularly shaped boxes as the constellation Serpens is spli ... References * * * * * {{Stars of Hydrus *List Hydrus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambda Hydri
This is the list of notable stars in the constellation Hydrus, sorted by decreasing brightness. See also *List of stars by constellation All stars but one can be associated with an IAU constellation. IAU constellations are areas of the sky. Although there are only 88 IAU constellations, the sky is actually divided into 89 irregularly shaped boxes as the constellation Serpens is spli ... References * * * * * {{Stars of Hydrus *List Hydrus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeta Hydri
Zeta Hydri, Latinized from ζ Hydri, is a single, white-hued star in the southern constellation of Hydrus. It is faintly visible to the naked eye with an apparent magnitude of 4.83. This distance to this star can be estimated from its annual parallax shift of 11.47 mas, showing it to be about 284 light years away. It is moving further away from the Sun with a radial velocity of +3.6 km/s. The spectrum of this star matches a stellar classification of A2 IV, suggesting it is a subgiant star that is in the process of evolving away from the main sequence as the supply of hydrogen at its core becomes exhausted. It has a high rate of spin, showing a projected rotational velocity of 116 km/s. This is giving the star a slight oblate shape with an equatorial bulge that is 5% larger than the polar radius. It has 2.4 times the mass of the Sun and nearly four times the Sun's radius. Zeta Hydri is radiating 80 times the Sun's luminosity into space from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nu Hydri
ν Hydri, Latinized as Nu Hydri, is a single star in the southern circumpolar constellation of Hydrus. It is orange-hued and faintly visible to the naked eye with an apparent visual magnitude of 4.76. This object is located approximately 331 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +3 km/s. It is a member of the Ursa Major Moving Group of stars that share a common motion through space. This is an aging giant star with a stellar classification of K3III. With the supply of hydrogen at its core exhausted, the star has expanded and cooled. At present it has 21 times the girth of the Sun. It is 2.4 billion years old with estimates of its mass ranging from 1.8 to 3.5 times the mass of the Sun. The star is radiating 184 times the Sun's luminosity from its swollen photosphere at an effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eta² Hydri B
Eta2 Hydri b (η2 Hyi b, η2 Hydri b), commonly known as HD 11977 b, is an extrasolar planet that is approximately 217 light-years away in the constellation of Hydrus. The presence of the planet around an intermediately massive giant star provides indirect evidence for the existence of planetary system A planetary system is a set of gravitationally In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interacti ...s around A-type stars. References * External links * * Hydrus (constellation) Giant planets Exoplanets discovered in 2005 Exoplanets detected by radial velocity {{extrasolar-planet-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extrasolar Planet
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, initially detected in 1988, was confirmed in 2003. There are many methods of detecting exoplanets. Transit (astronomy), Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected are inside the tidal locking zone. In several cases, List of multiplanetary systems, multiple planets have been observed around a star. About 1 in 5 Solar analog, Sun-like starsFor the purpose of this 1 in 5 statistic, "Sun-like" means G-type star. Data for Sun-like stars was not available so this statistic is an extrapolation from data about K-type star, K-type stars. have an "Earth-sized"For the purpose of this 1 in 5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eta² Hydri
Eta2 Hydri, Latinized from η2 Hydri and often catalogued as HD 11977, is a star in the constellation of Hydrus. It is visible to the naked eye with an apparent visual magnitude of +4.68, and is one of the least variable stars known. The distance to Eta2 Hydri is approximately 222 light-years based on parallax measurements, but it is drifting closer to the Sun with a radial velocity of −18 km/s. The stellar classification of Eta2 Hydri is G8IIIb, which indicates this is a evolved giant star. It is located in the clump zone of the HR diagram, which indicates it has already ascended the red giant branch and is now generating energy by core helium fusion surrounded by a hydrogen fusing shell. Based on its mass, it was probably a class A star (similar to Vega or Fomalhaut) when it was on the main sequence. It is estimated to be around 1.3 billion years old and has expanded to 10 times the Sun's diameter, though is only around 1.9 times as massive as t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epsilon Hydri
Epsilon Hydri, Latinized from ε Hydri, is a single, blue-white hued star in the southern constellation of Hydrus. It is a faint star with an apparent visual magnitude of 4.12, but it can be seen with the naked eye. Measurements made by the Hipparcos spacecraft showed an annual parallax shift of 21.48 mas, which provides a distance estimate of 152 light years. The star is moving away from the Sun with a radial velocity of +13.6 km/s. It is a member of the Tucana-Horologium moving group, an association of stars that share a common motion through space. The stellar classification for this star is B9 Va, indicating that is it a B-type main-sequence star that is generating energy through hydrogen fusion at its core. It is a young star, just 133 million years in age, and has a high rate of spin with a projected rotational velocity of 96 km/s. This is giving the star a mild oblate shape with an equatorial bulge that is 5% greater than the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
