|
Gliese 818 ...
This is the list of notable stars in the constellation Equuleus, sorted by decreasing brightness. See also *List of stars by constellation References * * * * * * {{Stars of Equuleus *List Equuleus Equuleus ( ) is a constellation of stars that are visible in the night sky. Its name is Latin for "little horse", a foal. Located just north of the celestial equator, it was one of the 48 constellations listed by the 2nd century astronomer Ptolem ... [...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 Equulei
Alpha Equulei (α Equulei, abbreviated Alpha Equ, α Equ), officially named Kitalpha , is a star in the constellation of Equuleus. It is a high proper-motion star only 190 light-years away. Nomenclature ''α Equulei'' ( Latinised to ''Alpha Equulei'') is the star's Bayer designation. It bore the traditional name ''Kitalpha'' (rarely ''Kitel Phard'' or ''Kitalphar)'', a contraction of the Arabic name قطعة الفرس ''qiṭ‘a(t) al-faras''—"a piece of the horse". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name ''Kitalpha'' for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names. In Chinese, (), meaning Emptiness, is an asterism consisting of Alpha Equulei and Beta Aquarii. Consequently, the Chinese name for Alpha Equulei itself is (, en, the Second Star of Emptiness). Properties The overall appea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 199942
HD 199942 is a binary star system in the northern constellation of Equuleus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.98. The system is located at a distance of approximately 184 light years based on parallax, and it has an absolute magnitude of 1.59. It is drifting closer with a radial velocity of −26 km/s. This system is moving through the galaxy at a velocity of relative to the Sun. Its galactic orbit carry it somewhere between 25100-22000 light years from the galactic core, and it'll come at its closest to the Sun 2.1 million years from now, at a distance of . The binary nature of this system was discovered in 1934 by G. P. Kuiper, who found the pair had an angular separation of . The pair orbit each other with a period of 58.4 years and an eccentricity of 0.295. The primary component is of visual magnitude 6.23 and is a chemically-peculiar F-type main-sequence star An F-type main-sequence star (F V) is a main ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotating Variable
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either: * Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks. * Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes eclipses it. Many, possibly most, stars have at least some variation in luminosity: the energy output of the Sun, for example, varies by about 0.1% over an 11-year solar cycle. Discovery An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star, the eclipsing binary Algol. Of the modern astronomers, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 202951
HD 202951 is a probable binary star system located in the northern constellation of Equuleus. It is near the lower limit of visibility to the naked eye, having an apparent visual magnitude of 5.97. The distance to this system can be estimated from the annual parallax shift of , yielding a value of roughly 1,190 light years. It is moving closer with a heliocentric radial velocity of −37 km/s. Griffin (2012) found this to be a single-lined spectroscopic binary system with an orbital period of and an eccentricity of 0.23. The ''a'' sin ''i'' value for the primary component is , where ''a'' is the semimajor axis and ''i'' is the (unknown) orbital inclination. This value provides a lower bound for the actual semimajor axis. The visible component is an evolved K-type giant star with a stellar classification of K5 III. It is a candidate variable star of unknown type, showing an amplitude variation of 0.0115 magnitude with a frequency of 0.47645 times per day, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4 Equulei
4 Equulei is a binary star system in the constellation of Equuleus, located about 3° to the east of Alpha Equulei. With an apparent visual magnitude of 5.94, it is just barely visible to the naked eye under good seeing conditions. The system shows an annual parallax shift of 20.44 mas as measured from Earth's orbit, which yields a distance estimate of about 160 light years. It is moving closer to the Sun with a radial velocity of −13 km/s. This is a single-lined spectroscopic binary with an orbital period of and an eccentricity of 0.39. The value of Where ''a'' is the actual semimajor axis and ''i'' is the orbital inclination. for the primary is , providing a lower bound for the semimajor axis. Griffin (2011) noted that the mass of the secondary component is likely to be at least equal to that of the Sun, which, for an ordinary main sequence star, should make it visible in the spectrum. The lack of significant ultraviolet emission appears to rule out a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
9 Equulei
9 Equulei is an M-type star in the constellation Equuleus. It is an asymptotic giant branch (AGB) star, a star that has exhausted its core helium and is now fusing both hydrogen and helium in shells outside the core. It is also a suspected variable star with an amplitude of about 0.05 magnitudes. The spectral type is M2IIIa, meaning it is a relatively cool giant star. As an AGB star, it is burning hydrogen and helium in shells around an inert carbon-oxygen core. It has expanded to 58 times the radius of the Sun, and it radiates 720 times as much electromagnetic radiation from a photosphere with an effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ... of . References {{DEFAULTSORT:9 Equulei Equuleus M-type giants Equulei, 09 105413 203291 8 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeta Equulei
3 Equulei is a single star located in the small northern constellation of Equuleus. It is faintly visible to the naked eye at an apparent visual magnitude of 5.6. Based upon an annual parallax shift of 4.24 mas, 3 Equulei is roughly distant from Earth, give or take an 80 light-year margin of error. At that distance, the apparent brightness of the star is diminished by 0.15 in visual magnitude because of extinction from interstellar gas and dust. 3 Equulei has been referred to in some sources as ζ (Zeta) Equulei, although it was not given that designation by Bayer. Properties 3 Equulei is an evolved giant star with a stellar classification of K5 III. The measured angular diameter of this star, after correction for limb darkening, is . At the estimated distance of Delta Ophiuchi, this yields a physical size of about 63 times the radius of the Sun. It is radiating an estimated 949 times the luminosity of the Sun from this expanded outer envelope at an eff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epsilon Equulei
Epsilon Equulei, Latinized from ε Equulei, is a star system of apparent magnitude +5.23 in the constellation of Equuleus. It is located 180 light years away from the Solar System, based on its parallax. Star system Two stars make up the brighter part of the Epsilon Equulei star system. They are called Epsilon Equulei A and B and are main-sequence stars of spectral type of F5 and F6, respectively. The orbital period of this binary is about 101.5 years. Although the average separation between the two stars is about , the orbit is remarkably eccentric, at 0.705. The two stars passed their periastron in 1920. Finally, it is thought that Epsilon Equulei A may be, in turn, a spectroscopic binary. The orbital period of the latter would be 2.03133 days. Approximately 10 arcseconds away from A and B is Epsilon Equulei C (HIP 103571), with an apparent magnitude of 7.35. It is another F-type main-sequence stars, and based on its similar distance and proper motion Proper moti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Equulei
Beta Equulei, Latinized from β Equulei, is the Bayer designation for a solitary star in the northern constellation of Equuleus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.16. The annual parallax shift is 11.27 mas, indicating a separation of around 289 light years from the Sun. It is drifting closer with a radial velocity of −11 km/s. This is an ordinary A-type main sequence star with a stellar classification of A3 V. It has 2.7 times the mass of the Sun and about four times the Sun's radius. The star is around 600 million years old – 93% of the way through its main sequence lifetime – and is spinning with a projected rotational velocity of 58 km/s. It is radiating 78 times the luminosity of the Sun from its photosphere at an effective temperature of about 9,000 K. The star emits an infrared excess indicating the presence of a dusty debris disk. The mean temperature of the dust is 85 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rapidly Oscillating Ap Star
Rapidly oscillating Ap stars (roAp stars) are a subtype of the Ap star class that exhibit short-timescale rapid photometric or radial velocity variations. The known periods range between 5 and 23 minutes. They lie in the δ Scuti instability strip on the main sequence. Discovery The first roAp star to be discovered was HD 101065 ( Przybylski's Star). The oscillations were discovered by Donald Kurtz using the telescope at the South African Astronomical Observatory, who saw 10–20-millimagnitude variations in the light curve of the star with a period of 12.15 minutes. Classification The roAp stars are sometimes referred to as rapidly oscillating α2 Canum Venaticorum variables. Both the roAp stars and some α2 CVn variables lie on the δ Scuti instability strip and are magnetic chemically peculiar stars, but the roAp stars have very short periods less than an hour. Oscillations The roAp stars oscillate in high-overtone, low-degree, non-radial pressure modes. The usual model t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Star
In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes. This occurs because the pair either forms a binary star (i.e. a binary system of stars in mutual orbit, gravitationally bound to each other) or is an ''optical double'', a chance line-of-sight alignment of two stars at different distances from the observer. Binary stars are important to stellar astronomers as knowledge of their motions allows direct calculation of stellar mass and other stellar parameters. The only (possible) case of "binary star" whose two components are separately visible to the naked eye is the case of Mizar and Alcor (though actually a multiple-star system), but it is not known for sure whether Mizar and Alcor are gravitationally bound. Since the beginning of the 1780s, both professional and amateur double star observers have telescopically measured the distances and angles between d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
