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Slowly Pulsating B Star
A slowly pulsating B-type star (SPB), formerly known as a 53 Persei variable, is a type of pulsating variable star. They may also be termed a long-period pulsating B star (LPB). As the name implies, they are main sequence, main-sequence stars of B-type star, spectral type B2 to B9 (3 to 9 times as massive as the Sun) that pulsate with periods between approximately half a day and five days, however within this most member stars have been found to have multiple periods of oscillations. They display variability both in their light emission and in their spectral line profile. The variations in magnitude are generally smaller than 0.1 magnitudes, making it quite hard to observe variability with the naked eye in most cases. The variability increases with decreasing wavelength, thus they are more obviously variable in ultraviolet spectrum than visible light. Their pulsations are non-radial, that is, they vary in shape rather than volume; different parts of the star are expanding and contrac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulsating Variable
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically 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 periodically; for example, because the star 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 Eclipsing binaries, has an orbiting companion that sometimes eclipses it. Many, possibly most, stars exhibit at least some oscillation 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An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star, the eclipsin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apparent Magnitude
Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), extinction of the object's light caused by interstellar dust along the sightline, line of sight to the observer. Unless stated otherwise, the word ''magnitude'' in astronomy usually refers to a celestial object's apparent magnitude. The magnitude scale likely dates to before the ancient Ancient Greek astronomy#Astronomy in the Greco-Roman and Late Antique eras, Roman astronomer Ptolemy, Claudius Ptolemy, whose Star catalogue, star catalog popularized the system by listing stars from First-magnitude star, 1st magnitude (brightest) to 6th magnitude (dimmest). The modern scale was mathematically defined to closely match this historical system by Norman Robert Pogson, Norman Pogson in 1856. The scale is reverse logarithmic scale, logarithmic: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 131120
HD may refer to: Business * H-D or Harley-Davidson, a motorcycle manufacturer * The Home Depot, NYSE stock symbol: HD Chemistry * Hydrogen deuteride, a diatomic compound of hydrogen and deuterium * Mustard gas Codes * Air Do, formerly Hokkaido International Airlines, IATA designator * HD postcode area, covering Huddersfield, Brighouse and Holmfirth in England, UK * Heidelberg's vehicle registration plate code * Hunedoara County (Romania)'s ISO 3166 code Medicine * Hansen's disease or leprosy * Hirschsprung's disease, a disorder of the abdomen * Huntington's disease, a genetic disorder affecting the central nervous system ** HD (gene) or huntingtin, the IT15 gene, which codes for the huntingtin protein People * H.D. or Hilda Doolittle (1886–1961), American poet and novelist Other uses * ''Helsingborgs Dagblad'', a Swedish newspaper * Henry Draper Catalogue, an astronomical catalogue often used to designate stars * Department of Highways (other) * ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HY Velorum
HY Velorum is a binary star system in the southern constellation of Vela. It is a dim star but visible to the naked eye with an apparent visual magnitude of 4.83. The distance to this system, as estimated from its annual parallax shift of , is 460 light years. HY Vel most likely forms a gravitationally bound pair with the magnitude 5.45 binary system KT Vel (HD 74535); both are members of the IC 2391 open cluster. As of 1998, HY Vel and KT Vel had an angular separation of along a position angle of 311°. This is a single-lined spectroscopic binary system with an orbital period of 8.4 days and an eccentricity of 0.24. The visible component has an ''a'' sin ''i'' value of , where ''a'' is the semimajor axis and ''i'' is the (unknown) orbital inclination to the line of sight. In 1979, Shyam M. Jakate announced the discovery that the star's brightness varies. It was given its variable star designation, HY Velorum, in 1981. The primary, which is the variable s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nu Pavonis
Nu Pavonis is a possible triple star system in the southern constellation of Pavo. It is visible to the naked eye as a faint star that varies in apparent visual magnitude from 4.60 to 4.64 over a period of 0.85584 days. The system lies approximately 440 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +17 km/s. It is a possible member of the Wolf 630 group of co-moving stars. This is a single-lined spectroscopic binary system with an orbital period of just 1.71 days in a circular orbit. The unresolved components are close enough that their tidal interaction is significant. Nu Pavonis was discovered to be a variable star when the ''Hipparcos'' data was analyzed. The visible component is a slowly pulsating B-type star with a stellar classification of B7III. This implies it is an evolved giant star, but it is actually more likely to be on the main sequence. An X-ray emission has been detected from the pair. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau8 Eridani
Tau8 Eridani, Latinized from τ8 Eridani, is a binary star system in the constellation Eridanus. It is visible to the naked eye with a combined apparent visual magnitude of 4.65. The distance to this system can be estimated via the parallax method, yielding a value of around 380 light years. This is a single-lined spectroscopic binary star system with an orbital period of about 454 days and an eccentricity of 0.21. The primary component is a B-type main sequence star with a stellar classification of B6 V. Gautier Mathys ''et al.'' announced that the star is variable, in 1986. It is a slowly pulsating B-type star that undergoes radial-velocity variation with a frequency of 1.1569 times per day. The star has about five times the mass of the Sun and shines with 256 times the Sun's luminosity. The outer atmosphere has an effective temperature of 11,858 K and may possess a longitudinal magnetic field A magnetic field (sometimes called B-field) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 105382
HD 105382 (also known as V863 Centauri) is a star in the constellation Centaurus. Its apparent magnitude is 4.47, making it visible to the naked eye under good observing conditions. From parallax measurements, it is located 130 parsecs (440 light years) from the Sun. In 1992, Luis A. Balona ''et al.'' announced their discovery that HD 105382 is a variable star. It was given its variable star designation, V863 Centauri, in 1993. HD 105382's apparent magnitude varies with an amplitude of 0.012 over a period of 1.295 days. It has been previously classified as a Be star, which would explain the variability as stellar pulsations, but this classification was probably due to accidental observation of the nearby Be star δ Centauri. A 2004 study showed that the 1.295 day period is actually the rotation period of the star, and that the variability is caused by non-homogeneous distribution of elements in the stellar surface. In particular, HD 105382 is a helium-weak chemically peculi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rho Lupi
Rho Lupi, Latinized from ρ Lupi, is a solitary star in the southern constellation of Lupus. It is visible to the naked eye with an apparent visual magnitude of 4.05. Based upon an annual parallax shift of 10.32 mas as seen from Earth, it is located about 316 light years from the Sun. It is a member of the Upper Centaurus–Lupus subgroup of the nearby Scorpius–Centaurus association. This is a B-type main sequence star with a stellar classification of B3/4 V. Rho Lupi was discovered to be a variable star when the ''Hipparcos'' data was analyzed. It is a microvariable with a period of 10.7 hours and an amplitude of 0.0046 in magnitude. With an age of just 44 million years, the star is spinning with a projected rotational velocity of 166 km/s. This is giving the star an oblate shape with an equatorial bulge that is an estimated 6% larger than the polar radius. It has an estimated 4.66 times the mass of the Sun and about 3.4 times the Sun's rad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algol Variable
Algol variables or Algol-type binaries are a class of eclipsing binary stars that are similar to the prototype member of this class, β Persei (Beta Persei, Algol). An Algol binary is a system where both stars are near-spherical such that the timing of the start and end of the eclipses is well-defined. The primary is generally a main sequence star well within its Roche lobe. The secondary may also be a main sequence star, referred to as a detached binary or it may be an evolved star filling its Roche lobe, referred to as a semidetached binary. When the cooler component passes in front of the hotter one, part of the latter's light is blocked, and the total brightness of the binary, as viewed from Earth, temporarily decreases. This is the primary minimum of the binary. Total brightness may also decrease, but less so, when the hotter component passes in front of the cooler one; this is the secondary minimum. The period, or time span between two primary minima, is very ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mu Eridani
Mu Eridani (μ Eridani) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.00. Based upon an annual parallax shift of 0.00625 arcseconds, it is located roughly 520 light years from the Sun. In 1910, this was determined to be a single-lined spectroscopic binary star system. The pair orbit each other with a period of 7.38 days and an eccentricity of 0.344, during which they undergo Algol-like eclipses. The primary is a slowly pulsating B-type star with a stellar classification of B5 IV. The variability of the star's brightness due to pulsations was first detected by Gerald Handler ''et al.'' in 2004. One year later, Mikołaj Jerzykiewicz ''et al.'' announced that eclipses had been detected. It has a relatively high rate of rotation with a projected rotational velocity of 130 km/s, which is at least 30% of the star's break-up velocity. The star has about six times the Sun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Herculis
Tau Herculis, a name Latinized from τ Herculis, is a variable star in the northern constellation of Hercules. It has a blue-white hue and is visible to the naked eye at night with an apparent visual magnitude that fluctuates around 3.91. The star is located at a distance of approximately 307 light years from the Sun based on parallax, but it is drifting closer with a radial velocity of −16 km/s. The stellar classification of Tau Hercules is B5 IV, and it serves as a standard spectrum in the modern Morgan–Keenan (MK) classification. It is estimated to be just 26 million years old with a relatively low projected rotational velocity of 32 km/s. Slowly rotating B-type stars are often chemically peculiar, so the mostly normal spectra of this star suggests we may be viewing it from near pole-on. The abundance of most heavier elements in this star are about 85% of those in the Sun. The star has four times the mass of the Sun and around 3.8 times ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Muscae
γ Muscae, Latinised as Gamma Muscae, is a blue-white hued star in the southern circumpolar constellation of Musca, the Fly. It can be seen with the naked eye, having an apparent visual magnitude of 3.87. Based upon an annual parallax shift of 10.04 mas as seen from Earth, it is located about 325 light years from the Sun. This is a B-type main-sequence star with a stellar classification of B5 V. It is a variable star that ranges between magnitudes 3.84 and 3.86 over a period of 2.7 days, and is classed as a slowly pulsating B star. It is around five times as massive as the Sun. The star is spinning rapidly with a projected rotational velocity of 205 km/s. This is giving it an oblate shape with an equatorial bulge that is 7% larger than the polar radius. Gamma Muscae is a proper motion Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
