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Beta Pictoris Moving Group
The Beta Pictoris Moving Group is a young moving group of stars located relatively near Earth. A moving group, in astronomy, is a group of stars that share a common motion through space as well as a common origin. This moving group is named for Beta Pictoris. The Beta Pictoris Moving Group is an important object for astronomical study as it is the closest youthful group of stars to the Earth. The star Beta Pictoris is known to have a large disk of gas and dust, possibly a protoplanetary disk. There is also evidence of a young gas giant planet around the star. A free-floating planet has also been found in the moving group, PSO J318.5-22. The age and distance of the group makes it a candidate for directly imaging extrasolar planets. Constituents The Beta Pictoris Moving Group consists of 17 stellar systems, comprising a total of 28 individual component stars, including identified brown dwarfs. The core of the group is located some 115 light-years from Earth, and has an average ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 (one million million, or billion in long scale). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the time-measurement word "year", the term ''light-year'' is sometimes misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years) which derives from astrometry; it is the distance at which one astronomical unit subtends an angle of one second of arc. Defini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown Dwarf
Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most massive gas giant planets and the least massive stars, approximately 13 to 80 times that of Jupiter (). However, they can fuse deuterium ( 2H), and the most massive ones (> ) can fuse lithium ( 7Li). Astronomers classify self-luminous objects by spectral class, a distinction intimately tied to the surface temperature, and brown dwarfs occupy types M, L, T, and Y. As brown dwarfs do not undergo stable hydrogen fusion, they cool down over time, progressively passing through later spectral types as they age. Despite their name, to the naked eye, brown dwarfs would appear in different colors depending on their temperature. The warmest ones are possibly orange or red, while cooler brown dwarfs would likely appear magenta or black to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravity
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 interactions, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a result, it has no significant influence at the level of subatomic particles. However, gravity is the most significant interaction between objects at the macroscopic scale, and it determines the motion of planets, stars, galaxies, and even light. On Earth, gravity gives weight to physical objects, and the Moon's gravity is responsible for sublunar tides in the oceans (the corresponding antipodal tide is caused by the inertia of the Earth and Moon orbiting one another). Gravity also has many important biological functions, helping to guide the growth of plants through the process of gravitropism and influencing the circ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Evolution
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star. Nuclear fusion powers a star for most of its existence. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing throug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Pog
Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondary color (made from magenta and yellow) in the CMYK color model, and is the complementary color of cyan. Reds range from the brilliant yellow-tinged scarlet and vermillion to bluish-red crimson, and vary in shade from the pale red pink to the dark red burgundy. Red pigment made from ochre was one of the first colors used in prehistoric art. The Ancient Egyptians and Mayans colored their faces red in ceremonies; Roman generals had their bodies colored red to celebrate victories. It was also an important color in China, where it was used to color early pottery and later the gates and walls of palaces. In the Renaissance, the brilliant red costumes for the nobility and wealthy were dyed with kermes and cochineal. The 19th century brought the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Trianguli Australis
Beta Trianguli Australis, Latinisation of names, Latinized from β Trianguli Australis, is a double star in the southern constellation of Triangulum Australe. It is approximately from Earth and has an apparent visual magnitude of +2.85. This star has a relatively high rate of proper motion across the celestial sphere. It is a F-type main-sequence star with a stellar classification of F1 V. Beta TrA has a 14th magnitude optical companion at an angular separation of 155 arcseconds. Observation with the Spitzer Space Telescope reveals what appears to be an infrared excess, excess infrared emission from this star. This suggests the presence of circumstellar material in this system, making it a debris disk candidate. This star may be a member of the Beta Pictoris moving group, an association of about 17 stars that share a common origin and a similar motion through space. If it is a member of this group, this would put the age of β TrA at about 12 million years; the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 172555
HD 172555 is a white-hot A7V star located relatively close by, 95 light years from Earth in the direction of the constellation Pavo. Spectrographic evidence indicates a relatively recent collision between two planet-sized bodies that destroyed the smaller of the two, which had been at least the size of Earth's moon, and severely damaged the larger one, which was at least the size of Mercury. Evidence of the collision was detected by NASA's Spitzer Space Telescope. Giant hypervelocity impact debris HD172555 was first recognized in the 1980s as being unusually bright in the mid-infrared by the IRAS sky survey. Follow-up, ground-based observations by Schütz et al. and the Spitzer Space Telescope, also in 2004, confirmed the unusually strong nature of the infrared spectral emission from this system, much brighter than what would be emitted normally from the star's surface. As part of the Beta Pictoris moving group, HD172555 is coeval with that more famous system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 165189
HD 165189 and HD 165190 are components of a visual binary star system located 145 light years away in the southern constellation of Corona Australis. It is visible to the naked eye with the primary having an apparent visual magnitude of . The system is a member of the Beta Pictoris Moving Group. The pair orbit each other with a period of 450 years and a large eccentricity of 0.650. They have a projected separation of . Both components are A-type main-sequence star An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen-burning) star of spectral type A and luminosity class V (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between ...s; the primary has a stellar classification of A6 V while the secondary is A7 V. They have similar masses of 1.59 and 1.58 times the mass of the Sun, respectively. References {{DEFAULTSORT:HD 165189 A-type main-sequence stars Beta Pi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 146624
HD 146624 (d Scorpii) is a single, white-hued star in the southern zodiac constellation of Scorpius. It is faintly visible to the naked eye, having an apparent visual magnitude of 4.80. The distance to HD 146624 can be estimated from its annual parallax shift of , yielding a separation of 142 light years. At that distance, the visual magnitude is reduced by an extinction of 0.17 due to interstellar dust. It is a member of the Beta Pictoris moving group, a set of ~12 million year old stars that share a common motion through space. This is an A-type main-sequence star with a stellar classification of A0 V, and is suspected to be chemically peculiar. It is a young star, just 10 million years old, with a projected rotational velocity of 39 km/s. The mass of the star is greater than the Sun's, with De Rosa et al. (2014) estimating 1.49 times the mass of the Sun, while Zorec and Royer (2012) gives a multiplier of . It has 1.60 times the Sun's radius and shines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
51 Eridani
51 Eridani is a star in the constellation Eridanus. It has an apparent magnitude of 5.22, meaning it is just visible to the unaided eye in suburban and rural skies. The primary star's absolute magnitude is 2.87. There is also a binary star named GJ 3305 which shares the same proper motion through space with it, making it overall a triple star system. General information Johann Bayer gave the star its Bayer designation of c Eridani, using lowercase letters once he had exhausted all the letters of the Greek alphabet, in his 1603 star chart ''Uranometria''. It was catalogued as 51 Eridani by John Flamsteed in 1725. Located around 97 light-years distant, it shines with a luminosity approximately 5.38 times that of the Sun and has a surface temperature of . A cold debris disk has been detected with a likely inner border of 82 astronomical units (AU). A yellow-white main-sequence star of spectral type F0V, 51 Eridani is a member of the Beta Pictoris moving group and hence th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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